[PATCH V4 0/4] vDPA/ifcvf: implement shared IRQ feature

[PATCH V4 0/4] vDPA/ifcvf: implement shared IRQ feature

[Zhu Lingshan]

It has been observed that on some platforms/devices, there may
not be enough MSI vectors for virtqueues and the config change.
Under such circumstances, the interrupt sources of a device
have to share vectors/IRQs.

This series implemented a shared IRQ feature for ifcvf.

Please help review.

For the test report, plase kindly refer to last version cover letter:
https://www.spinics.net/lists/netdev/msg795808.html

Changes from V3:
fix code indenting issues reported by LKP:

Changes from V2:
(1) Fix misuse of nvectors(in ifcvf_alloc_vectors return value)(Michael)
(2) Fix misuse of irq = get_vq_irq() in setup irqbypass(Michael)
(3) Coding style improvements(Michael)
(4) Better naming of device shared irq/shared vq irq

Changes from V1:
(1) Enable config interrupt when only one vector is allocated(Michael)
(2) Clean vectors/IRQs if failed to request config interrupt
since config interrupt is a must(Michael)
(3) Keep local vdpa_ops, disable irq_bypass by setting IRQ = -EINVAL
for shared IRQ case(Michael)
(4) Improvements on error messages(Michael)
(5) Squash functions implementation patches to the callers(Michael)

Zhu Lingshan (4):
  vDPA/ifcvf: implement IO read/write helpers in the header file
  vDPA/ifcvf: implement device MSIX vector allocator
  vhost_vdpa: don't setup irq offloading when irq_num < 0
  vDPA/ifcvf: implement shared IRQ feature

 drivers/vdpa/ifcvf/ifcvf_base.c |  67 +++-----
 drivers/vdpa/ifcvf/ifcvf_base.h |  60 +++++++-
 drivers/vdpa/ifcvf/ifcvf_main.c | 262 ++++++++++++++++++++++++++++----
 drivers/vhost/vdpa.c            |   4 +
 4 files changed, 314 insertions(+), 79 deletions(-)

-- 
2.27.0

[PATCH V4 1/4] vDPA/ifcvf: implement IO read/write helpers in the header file

[Zhu Lingshan]

re-implement IO read/write helpers in the header file, so that
they can be utilized among modules.

Signed-off-by: Zhu Lingshan <lingshan.zhu@intel.com>
---
 drivers/vdpa/ifcvf/ifcvf_base.c | 36 --------------------------------
 drivers/vdpa/ifcvf/ifcvf_base.h | 37 +++++++++++++++++++++++++++++++++
 2 files changed, 37 insertions(+), 36 deletions(-)

diff --git a/drivers/vdpa/ifcvf/ifcvf_base.c b/drivers/vdpa/ifcvf/ifcvf_base.c
index 7d41dfe48ade..397692ae671c 100644
--- a/drivers/vdpa/ifcvf/ifcvf_base.c
+++ b/drivers/vdpa/ifcvf/ifcvf_base.c
@@ -10,42 +10,6 @@
 
 #include "ifcvf_base.h"
 
-static inline u8 ifc_ioread8(u8 __iomem *addr)
-{
-	return ioread8(addr);
-}
-static inline u16 ifc_ioread16 (__le16 __iomem *addr)
-{
-	return ioread16(addr);
-}
-
-static inline u32 ifc_ioread32(__le32 __iomem *addr)
-{
-	return ioread32(addr);
-}
-
-static inline void ifc_iowrite8(u8 value, u8 __iomem *addr)
-{
-	iowrite8(value, addr);
-}
-
-static inline void ifc_iowrite16(u16 value, __le16 __iomem *addr)
-{
-	iowrite16(value, addr);
-}
-
-static inline void ifc_iowrite32(u32 value, __le32 __iomem *addr)
-{
-	iowrite32(value, addr);
-}
-
-static void ifc_iowrite64_twopart(u64 val,
-				  __le32 __iomem *lo, __le32 __iomem *hi)
-{
-	ifc_iowrite32((u32)val, lo);
-	ifc_iowrite32(val >> 32, hi);
-}
-
 struct ifcvf_adapter *vf_to_adapter(struct ifcvf_hw *hw)
 {
 	return container_of(hw, struct ifcvf_adapter, vf);
diff --git a/drivers/vdpa/ifcvf/ifcvf_base.h b/drivers/vdpa/ifcvf/ifcvf_base.h
index c486873f370a..949b4fb9d554 100644
--- a/drivers/vdpa/ifcvf/ifcvf_base.h
+++ b/drivers/vdpa/ifcvf/ifcvf_base.h
@@ -42,6 +42,43 @@
 #define ifcvf_private_to_vf(adapter) \
 	(&((struct ifcvf_adapter *)adapter)->vf)
 
+static inline u8 ifc_ioread8(u8 __iomem *addr)
+{
+	return ioread8(addr);
+}
+
+static inline u16 ifc_ioread16(__le16 __iomem *addr)
+{
+	return ioread16(addr);
+}
+
+static inline u32 ifc_ioread32(__le32 __iomem *addr)
+{
+	return ioread32(addr);
+}
+
+static inline void ifc_iowrite8(u8 value, u8 __iomem *addr)
+{
+	iowrite8(value, addr);
+}
+
+static inline void ifc_iowrite16(u16 value, __le16 __iomem *addr)
+{
+	iowrite16(value, addr);
+}
+
+static inline void ifc_iowrite32(u32 value, __le32 __iomem *addr)
+{
+	iowrite32(value, addr);
+}
+
+static inline void ifc_iowrite64_twopart(u64 val,
+				  __le32 __iomem *lo, __le32 __iomem *hi)
+{
+	ifc_iowrite32((u32)val, lo);
+	ifc_iowrite32(val >> 32, hi);
+}
+
 struct vring_info {
 	u64 desc;
 	u64 avail;
-- 
2.27.0

Re: [PATCH V4 1/4] vDPA/ifcvf: implement IO read/write helpers in the header file

[Jason Wang]

在 2022/2/3 下午3:27, Zhu Lingshan 写道:
> re-implement IO read/write helpers in the header file, so that
> they can be utilized among modules.
>
> Signed-off-by: Zhu Lingshan <lingshan.zhu@intel.com>


I wonder if we can simply use include/linux/virtio_pci_modern.h.

The accessors vp_ioreadX/writeX() there were decoupled from the 
virtio_pci_modern_device structure.

Thanks


> ---
>   drivers/vdpa/ifcvf/ifcvf_base.c | 36 --------------------------------
>   drivers/vdpa/ifcvf/ifcvf_base.h | 37 +++++++++++++++++++++++++++++++++
>   2 files changed, 37 insertions(+), 36 deletions(-)
>
> diff --git a/drivers/vdpa/ifcvf/ifcvf_base.c b/drivers/vdpa/ifcvf/ifcvf_base.c
> index 7d41dfe48ade..397692ae671c 100644
> --- a/drivers/vdpa/ifcvf/ifcvf_base.c
> +++ b/drivers/vdpa/ifcvf/ifcvf_base.c
> @@ -10,42 +10,6 @@
>   
>   #include "ifcvf_base.h"
>   
> -static inline u8 ifc_ioread8(u8 __iomem *addr)
> -{
> -	return ioread8(addr);
> -}
> -static inline u16 ifc_ioread16 (__le16 __iomem *addr)
> -{
> -	return ioread16(addr);
> -}
> -
> -static inline u32 ifc_ioread32(__le32 __iomem *addr)
> -{
> -	return ioread32(addr);
> -}
> -
> -static inline void ifc_iowrite8(u8 value, u8 __iomem *addr)
> -{
> -	iowrite8(value, addr);
> -}
> -
> -static inline void ifc_iowrite16(u16 value, __le16 __iomem *addr)
> -{
> -	iowrite16(value, addr);
> -}
> -
> -static inline void ifc_iowrite32(u32 value, __le32 __iomem *addr)
> -{
> -	iowrite32(value, addr);
> -}
> -
> -static void ifc_iowrite64_twopart(u64 val,
> -				  __le32 __iomem *lo, __le32 __iomem *hi)
> -{
> -	ifc_iowrite32((u32)val, lo);
> -	ifc_iowrite32(val >> 32, hi);
> -}
> -
>   struct ifcvf_adapter *vf_to_adapter(struct ifcvf_hw *hw)
>   {
>   	return container_of(hw, struct ifcvf_adapter, vf);
> diff --git a/drivers/vdpa/ifcvf/ifcvf_base.h b/drivers/vdpa/ifcvf/ifcvf_base.h
> index c486873f370a..949b4fb9d554 100644
> --- a/drivers/vdpa/ifcvf/ifcvf_base.h
> +++ b/drivers/vdpa/ifcvf/ifcvf_base.h
> @@ -42,6 +42,43 @@
>   #define ifcvf_private_to_vf(adapter) \
>   	(&((struct ifcvf_adapter *)adapter)->vf)
>   
> +static inline u8 ifc_ioread8(u8 __iomem *addr)
> +{
> +	return ioread8(addr);
> +}
> +
> +static inline u16 ifc_ioread16(__le16 __iomem *addr)
> +{
> +	return ioread16(addr);
> +}
> +
> +static inline u32 ifc_ioread32(__le32 __iomem *addr)
> +{
> +	return ioread32(addr);
> +}
> +
> +static inline void ifc_iowrite8(u8 value, u8 __iomem *addr)
> +{
> +	iowrite8(value, addr);
> +}
> +
> +static inline void ifc_iowrite16(u16 value, __le16 __iomem *addr)
> +{
> +	iowrite16(value, addr);
> +}
> +
> +static inline void ifc_iowrite32(u32 value, __le32 __iomem *addr)
> +{
> +	iowrite32(value, addr);
> +}
> +
> +static inline void ifc_iowrite64_twopart(u64 val,
> +				  __le32 __iomem *lo, __le32 __iomem *hi)
> +{
> +	ifc_iowrite32((u32)val, lo);
> +	ifc_iowrite32(val >> 32, hi);
> +}
> +
>   struct vring_info {
>   	u64 desc;
>   	u64 avail;

Re: [PATCH V4 1/4] vDPA/ifcvf: implement IO read/write helpers in the header file

[Zhu, Lingshan]

On 2/14/2022 2:15 PM, Jason Wang wrote:
>
> 在 2022/2/3 下午3:27, Zhu Lingshan 写道:
>> re-implement IO read/write helpers in the header file, so that
>> they can be utilized among modules.
>>
>> Signed-off-by: Zhu Lingshan <lingshan.zhu@intel.com>
>
>
> I wonder if we can simply use include/linux/virtio_pci_modern.h.
>
> The accessors vp_ioreadX/writeX() there were decoupled from the 
> virtio_pci_modern_device structure.
>
> Thanks
sure, can do.

Thanks
>
>
>> ---
>>   drivers/vdpa/ifcvf/ifcvf_base.c | 36 --------------------------------
>>   drivers/vdpa/ifcvf/ifcvf_base.h | 37 +++++++++++++++++++++++++++++++++
>>   2 files changed, 37 insertions(+), 36 deletions(-)
>>
>> diff --git a/drivers/vdpa/ifcvf/ifcvf_base.c 
>> b/drivers/vdpa/ifcvf/ifcvf_base.c
>> index 7d41dfe48ade..397692ae671c 100644
>> --- a/drivers/vdpa/ifcvf/ifcvf_base.c
>> +++ b/drivers/vdpa/ifcvf/ifcvf_base.c
>> @@ -10,42 +10,6 @@
>>     #include "ifcvf_base.h"
>>   -static inline u8 ifc_ioread8(u8 __iomem *addr)
>> -{
>> -    return ioread8(addr);
>> -}
>> -static inline u16 ifc_ioread16 (__le16 __iomem *addr)
>> -{
>> -    return ioread16(addr);
>> -}
>> -
>> -static inline u32 ifc_ioread32(__le32 __iomem *addr)
>> -{
>> -    return ioread32(addr);
>> -}
>> -
>> -static inline void ifc_iowrite8(u8 value, u8 __iomem *addr)
>> -{
>> -    iowrite8(value, addr);
>> -}
>> -
>> -static inline void ifc_iowrite16(u16 value, __le16 __iomem *addr)
>> -{
>> -    iowrite16(value, addr);
>> -}
>> -
>> -static inline void ifc_iowrite32(u32 value, __le32 __iomem *addr)
>> -{
>> -    iowrite32(value, addr);
>> -}
>> -
>> -static void ifc_iowrite64_twopart(u64 val,
>> -                  __le32 __iomem *lo, __le32 __iomem *hi)
>> -{
>> -    ifc_iowrite32((u32)val, lo);
>> -    ifc_iowrite32(val >> 32, hi);
>> -}
>> -
>>   struct ifcvf_adapter *vf_to_adapter(struct ifcvf_hw *hw)
>>   {
>>       return container_of(hw, struct ifcvf_adapter, vf);
>> diff --git a/drivers/vdpa/ifcvf/ifcvf_base.h 
>> b/drivers/vdpa/ifcvf/ifcvf_base.h
>> index c486873f370a..949b4fb9d554 100644
>> --- a/drivers/vdpa/ifcvf/ifcvf_base.h
>> +++ b/drivers/vdpa/ifcvf/ifcvf_base.h
>> @@ -42,6 +42,43 @@
>>   #define ifcvf_private_to_vf(adapter) \
>>       (&((struct ifcvf_adapter *)adapter)->vf)
>>   +static inline u8 ifc_ioread8(u8 __iomem *addr)
>> +{
>> +    return ioread8(addr);
>> +}
>> +
>> +static inline u16 ifc_ioread16(__le16 __iomem *addr)
>> +{
>> +    return ioread16(addr);
>> +}
>> +
>> +static inline u32 ifc_ioread32(__le32 __iomem *addr)
>> +{
>> +    return ioread32(addr);
>> +}
>> +
>> +static inline void ifc_iowrite8(u8 value, u8 __iomem *addr)
>> +{
>> +    iowrite8(value, addr);
>> +}
>> +
>> +static inline void ifc_iowrite16(u16 value, __le16 __iomem *addr)
>> +{
>> +    iowrite16(value, addr);
>> +}
>> +
>> +static inline void ifc_iowrite32(u32 value, __le32 __iomem *addr)
>> +{
>> +    iowrite32(value, addr);
>> +}
>> +
>> +static inline void ifc_iowrite64_twopart(u64 val,
>> +                  __le32 __iomem *lo, __le32 __iomem *hi)
>> +{
>> +    ifc_iowrite32((u32)val, lo);
>> +    ifc_iowrite32(val >> 32, hi);
>> +}
>> +
>>   struct vring_info {
>>       u64 desc;
>>       u64 avail;
>

[PATCH V4 2/4] vDPA/ifcvf: implement device MSIX vector allocator

[Zhu Lingshan]

This commit implements a MSIX vector allocation helper
for vqs and config interrupts.

Signed-off-by: Zhu Lingshan <lingshan.zhu@intel.com>
---
 drivers/vdpa/ifcvf/ifcvf_main.c | 35 +++++++++++++++++++++++++++++++--
 1 file changed, 33 insertions(+), 2 deletions(-)

diff --git a/drivers/vdpa/ifcvf/ifcvf_main.c b/drivers/vdpa/ifcvf/ifcvf_main.c
index d1a6b5ab543c..44c89ab0b6da 100644
--- a/drivers/vdpa/ifcvf/ifcvf_main.c
+++ b/drivers/vdpa/ifcvf/ifcvf_main.c
@@ -58,14 +58,45 @@ static void ifcvf_free_irq(struct ifcvf_adapter *adapter, int queues)
 	ifcvf_free_irq_vectors(pdev);
 }
 
+/* ifcvf MSIX vectors allocator, this helper tries to allocate
+ * vectors for all virtqueues and the config interrupt.
+ * It returns the number of allocated vectors, negative
+ * return value when fails.
+ */
+static int ifcvf_alloc_vectors(struct ifcvf_adapter *adapter)
+{
+	struct pci_dev *pdev = adapter->pdev;
+	struct ifcvf_hw *vf = &adapter->vf;
+	int max_intr, ret;
+
+	/* all queues and config interrupt  */
+	max_intr = vf->nr_vring + 1;
+	ret = pci_alloc_irq_vectors(pdev, 1, max_intr, PCI_IRQ_MSIX | PCI_IRQ_AFFINITY);
+
+	if (ret < 0) {
+		IFCVF_ERR(pdev, "Failed to alloc IRQ vectors\n");
+		return ret;
+	}
+
+	if (ret < max_intr)
+		IFCVF_INFO(pdev,
+			   "Requested %u vectors, however only %u allocated, lower performance\n",
+			   max_intr, ret);
+
+	return ret;
+}
+
 static int ifcvf_request_irq(struct ifcvf_adapter *adapter)
 {
 	struct pci_dev *pdev = adapter->pdev;
 	struct ifcvf_hw *vf = &adapter->vf;
-	int vector, i, ret, irq;
+	int vector, nvectors, i, ret, irq;
 	u16 max_intr;
 
-	/* all queues and config interrupt  */
+	nvectors = ifcvf_alloc_vectors(adapter);
+	if (!(nvectors > 0))
+		return nvectors;
+
 	max_intr = vf->nr_vring + 1;
 
 	ret = pci_alloc_irq_vectors(pdev, max_intr,
-- 
2.27.0

Re: [PATCH V4 2/4] vDPA/ifcvf: implement device MSIX vector allocator

[Jason Wang]

在 2022/2/3 下午3:27, Zhu Lingshan 写道:
> This commit implements a MSIX vector allocation helper
> for vqs and config interrupts.
>
> Signed-off-by: Zhu Lingshan <lingshan.zhu@intel.com>
> ---
>   drivers/vdpa/ifcvf/ifcvf_main.c | 35 +++++++++++++++++++++++++++++++--
>   1 file changed, 33 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/vdpa/ifcvf/ifcvf_main.c b/drivers/vdpa/ifcvf/ifcvf_main.c
> index d1a6b5ab543c..44c89ab0b6da 100644
> --- a/drivers/vdpa/ifcvf/ifcvf_main.c
> +++ b/drivers/vdpa/ifcvf/ifcvf_main.c
> @@ -58,14 +58,45 @@ static void ifcvf_free_irq(struct ifcvf_adapter *adapter, int queues)
>   	ifcvf_free_irq_vectors(pdev);
>   }
>   
> +/* ifcvf MSIX vectors allocator, this helper tries to allocate
> + * vectors for all virtqueues and the config interrupt.
> + * It returns the number of allocated vectors, negative
> + * return value when fails.
> + */
> +static int ifcvf_alloc_vectors(struct ifcvf_adapter *adapter)
> +{
> +	struct pci_dev *pdev = adapter->pdev;
> +	struct ifcvf_hw *vf = &adapter->vf;
> +	int max_intr, ret;
> +
> +	/* all queues and config interrupt  */
> +	max_intr = vf->nr_vring + 1;
> +	ret = pci_alloc_irq_vectors(pdev, 1, max_intr, PCI_IRQ_MSIX | PCI_IRQ_AFFINITY);
> +
> +	if (ret < 0) {
> +		IFCVF_ERR(pdev, "Failed to alloc IRQ vectors\n");
> +		return ret;
> +	}
> +
> +	if (ret < max_intr)
> +		IFCVF_INFO(pdev,
> +			   "Requested %u vectors, however only %u allocated, lower performance\n",
> +			   max_intr, ret);
> +
> +	return ret;
> +}
> +
>   static int ifcvf_request_irq(struct ifcvf_adapter *adapter)
>   {
>   	struct pci_dev *pdev = adapter->pdev;
>   	struct ifcvf_hw *vf = &adapter->vf;
> -	int vector, i, ret, irq;
> +	int vector, nvectors, i, ret, irq;
>   	u16 max_intr;
>   
> -	/* all queues and config interrupt  */
> +	nvectors = ifcvf_alloc_vectors(adapter);
> +	if (!(nvectors > 0))
> +		return nvectors;


Why not simply checking by using nvectors <= 0? If ifcvf_alloc_vectors 
can return 0 this breaks the ifcvf_request_irq() caller's assumption.


> +
>   	max_intr = vf->nr_vring + 1;
>   
>   	ret = pci_alloc_irq_vectors(pdev, max_intr,


So irq is allocated twice here?

Thanks

Re: [PATCH V4 2/4] vDPA/ifcvf: implement device MSIX vector allocator

[Zhu, Lingshan]

On 2/14/2022 2:26 PM, Jason Wang wrote:
>
> 在 2022/2/3 下午3:27, Zhu Lingshan 写道:
>> This commit implements a MSIX vector allocation helper
>> for vqs and config interrupts.
>>
>> Signed-off-by: Zhu Lingshan <lingshan.zhu@intel.com>
>> ---
>>   drivers/vdpa/ifcvf/ifcvf_main.c | 35 +++++++++++++++++++++++++++++++--
>>   1 file changed, 33 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/vdpa/ifcvf/ifcvf_main.c 
>> b/drivers/vdpa/ifcvf/ifcvf_main.c
>> index d1a6b5ab543c..44c89ab0b6da 100644
>> --- a/drivers/vdpa/ifcvf/ifcvf_main.c
>> +++ b/drivers/vdpa/ifcvf/ifcvf_main.c
>> @@ -58,14 +58,45 @@ static void ifcvf_free_irq(struct ifcvf_adapter 
>> *adapter, int queues)
>>       ifcvf_free_irq_vectors(pdev);
>>   }
>>   +/* ifcvf MSIX vectors allocator, this helper tries to allocate
>> + * vectors for all virtqueues and the config interrupt.
>> + * It returns the number of allocated vectors, negative
>> + * return value when fails.
>> + */
>> +static int ifcvf_alloc_vectors(struct ifcvf_adapter *adapter)
>> +{
>> +    struct pci_dev *pdev = adapter->pdev;
>> +    struct ifcvf_hw *vf = &adapter->vf;
>> +    int max_intr, ret;
>> +
>> +    /* all queues and config interrupt  */
>> +    max_intr = vf->nr_vring + 1;
>> +    ret = pci_alloc_irq_vectors(pdev, 1, max_intr, PCI_IRQ_MSIX | 
>> PCI_IRQ_AFFINITY);
>> +
>> +    if (ret < 0) {
>> +        IFCVF_ERR(pdev, "Failed to alloc IRQ vectors\n");
>> +        return ret;
>> +    }
>> +
>> +    if (ret < max_intr)
>> +        IFCVF_INFO(pdev,
>> +               "Requested %u vectors, however only %u allocated, 
>> lower performance\n",
>> +               max_intr, ret);
>> +
>> +    return ret;
>> +}
>> +
>>   static int ifcvf_request_irq(struct ifcvf_adapter *adapter)
>>   {
>>       struct pci_dev *pdev = adapter->pdev;
>>       struct ifcvf_hw *vf = &adapter->vf;
>> -    int vector, i, ret, irq;
>> +    int vector, nvectors, i, ret, irq;
>>       u16 max_intr;
>>   -    /* all queues and config interrupt  */
>> +    nvectors = ifcvf_alloc_vectors(adapter);
>> +    if (!(nvectors > 0))
>> +        return nvectors;
>
>
> Why not simply checking by using nvectors <= 0? If ifcvf_alloc_vectors 
> can return 0 this breaks the ifcvf_request_irq() caller's assumption.
It can return zero if no vectors allocated, then ifcvf_request_irq 
fails. For sure I can use <=0

Thanks!
>
>
>> +
>>       max_intr = vf->nr_vring + 1;
>>         ret = pci_alloc_irq_vectors(pdev, max_intr,
>
>
> So irq is allocated twice here?
Oh, it is a rebasing problem, I should move the deleting line here from 
the next patch.

Thanks
>
> Thanks
>
>

[PATCH V4 3/4] vhost_vdpa: don't setup irq offloading when irq_num < 0

[Zhu Lingshan]

When irq number is negative(e.g., -EINVAL), the virtqueue
may be disabled or the virtqueues are sharing a device irq.
In such case, we should not setup irq offloading for a virtqueue.

Signed-off-by: Zhu Lingshan <lingshan.zhu@intel.com>
---
 drivers/vhost/vdpa.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
index 851539807bc9..c4fcacb0de3a 100644
--- a/drivers/vhost/vdpa.c
+++ b/drivers/vhost/vdpa.c
@@ -96,6 +96,10 @@ static void vhost_vdpa_setup_vq_irq(struct vhost_vdpa *v, u16 qid)
 	if (!ops->get_vq_irq)
 		return;
 
+	irq = ops->get_vq_irq(vdpa, qid);
+	if (irq < 0)
+		return;
+
 	irq = ops->get_vq_irq(vdpa, qid);
 	irq_bypass_unregister_producer(&vq->call_ctx.producer);
 	if (!vq->call_ctx.ctx || irq < 0)
-- 
2.27.0

Re: [PATCH V4 3/4] vhost_vdpa: don't setup irq offloading when irq_num < 0

[Jason Wang]

在 2022/2/3 下午3:27, Zhu Lingshan 写道:
> When irq number is negative(e.g., -EINVAL), the virtqueue
> may be disabled or the virtqueues are sharing a device irq.
> In such case, we should not setup irq offloading for a virtqueue.
>
> Signed-off-by: Zhu Lingshan <lingshan.zhu@intel.com>
> ---
>   drivers/vhost/vdpa.c | 4 ++++
>   1 file changed, 4 insertions(+)
>
> diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
> index 851539807bc9..c4fcacb0de3a 100644
> --- a/drivers/vhost/vdpa.c
> +++ b/drivers/vhost/vdpa.c
> @@ -96,6 +96,10 @@ static void vhost_vdpa_setup_vq_irq(struct vhost_vdpa *v, u16 qid)
>   	if (!ops->get_vq_irq)
>   		return;
>   
> +	irq = ops->get_vq_irq(vdpa, qid);
> +	if (irq < 0)
> +		return;
> +
>   	irq = ops->get_vq_irq(vdpa, qid);


So the get_vq_irq() will be called twice?


>   	irq_bypass_unregister_producer(&vq->call_ctx.producer);
>   	if (!vq->call_ctx.ctx || irq < 0)


We're already checked irq against 0 here.

Thanks

Re: [PATCH V4 3/4] vhost_vdpa: don't setup irq offloading when irq_num < 0

[Zhu, Lingshan]

On 2/14/2022 2:28 PM, Jason Wang wrote:
>
> 在 2022/2/3 下午3:27, Zhu Lingshan 写道:
>> When irq number is negative(e.g., -EINVAL), the virtqueue
>> may be disabled or the virtqueues are sharing a device irq.
>> In such case, we should not setup irq offloading for a virtqueue.
>>
>> Signed-off-by: Zhu Lingshan <lingshan.zhu@intel.com>
>> ---
>>   drivers/vhost/vdpa.c | 4 ++++
>>   1 file changed, 4 insertions(+)
>>
>> diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
>> index 851539807bc9..c4fcacb0de3a 100644
>> --- a/drivers/vhost/vdpa.c
>> +++ b/drivers/vhost/vdpa.c
>> @@ -96,6 +96,10 @@ static void vhost_vdpa_setup_vq_irq(struct 
>> vhost_vdpa *v, u16 qid)
>>       if (!ops->get_vq_irq)
>>           return;
>>   +    irq = ops->get_vq_irq(vdpa, qid);
>> +    if (irq < 0)
>> +        return;
>> +
>>       irq = ops->get_vq_irq(vdpa, qid);
>
>
> So the get_vq_irq() will be called twice?
yes, the latter one should be removed
>
>
>> irq_bypass_unregister_producer(&vq->call_ctx.producer);
>>       if (!vq->call_ctx.ctx || irq < 0)
>
>
> We're already checked irq against 0 here.
sure, will remove this

Thanks!
>
>
> Thanks
>
>

[PATCH V4 4/4] vDPA/ifcvf: implement shared IRQ feature

[Zhu Lingshan]

On some platforms/devices, there may not be enough MSI vector
slots allocated for virtqueues and config changes. In such a case,
the interrupt sources(virtqueues, config changes) must share
an IRQ/vector, to avoid initialization failures, keep
the device functional.

This commit handles three cases:
(1) number of the allocated vectors == the number of virtqueues + 1
(config changes), every virtqueue and the config interrupt has
a separated vector/IRQ, the best and the most likely case.
(2) number of the allocated vectors is less than the best case, but
greater than 1. In this case, all virtqueues share a vector/IRQ,
the config interrupt has a separated vector/IRQ
(3) only one vector is allocated, in this case, the virtqueues and
the config interrupt share a vector/IRQ. The worst and most
unlikely case.

Otherwise, it needs to fail.

This commit introduces some helper functions:
ifcvf_set_vq_vector() and ifcvf_set_config_vector() sets virtqueue
vector and config vector in the device config space, so that
the device can send interrupt DMA.

This commit adds some fields in struct ifcvf_hw and re-placed
the existed fields to be aligned with the cacheline.

Signed-off-by: Zhu Lingshan <lingshan.zhu@intel.com>
---
 drivers/vdpa/ifcvf/ifcvf_base.c |  47 ++++--
 drivers/vdpa/ifcvf/ifcvf_base.h |  23 ++-
 drivers/vdpa/ifcvf/ifcvf_main.c | 243 +++++++++++++++++++++++++++-----
 3 files changed, 256 insertions(+), 57 deletions(-)

diff --git a/drivers/vdpa/ifcvf/ifcvf_base.c b/drivers/vdpa/ifcvf/ifcvf_base.c
index 397692ae671c..18dcb63ab1e3 100644
--- a/drivers/vdpa/ifcvf/ifcvf_base.c
+++ b/drivers/vdpa/ifcvf/ifcvf_base.c
@@ -15,6 +15,36 @@ struct ifcvf_adapter *vf_to_adapter(struct ifcvf_hw *hw)
 	return container_of(hw, struct ifcvf_adapter, vf);
 }
 
+int ifcvf_set_vq_vector(struct ifcvf_hw *hw, u16 qid, int vector)
+{
+	struct virtio_pci_common_cfg __iomem *cfg = hw->common_cfg;
+	struct ifcvf_adapter *ifcvf = vf_to_adapter(hw);
+
+	ifc_iowrite16(qid, &cfg->queue_select);
+	ifc_iowrite16(vector, &cfg->queue_msix_vector);
+	if (ifc_ioread16(&cfg->queue_msix_vector) == VIRTIO_MSI_NO_VECTOR) {
+		IFCVF_ERR(ifcvf->pdev, "No msix vector for queue %u\n", qid);
+			return -EINVAL;
+	}
+
+	return 0;
+}
+
+int ifcvf_set_config_vector(struct ifcvf_hw *hw, int vector)
+{
+	struct virtio_pci_common_cfg __iomem *cfg = hw->common_cfg;
+	struct ifcvf_adapter *ifcvf = vf_to_adapter(hw);
+
+	cfg = hw->common_cfg;
+	ifc_iowrite16(vector,  &cfg->msix_config);
+	if (ifc_ioread16(&cfg->msix_config) == VIRTIO_MSI_NO_VECTOR) {
+		IFCVF_ERR(ifcvf->pdev, "No msix vector for device config\n");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
 static void __iomem *get_cap_addr(struct ifcvf_hw *hw,
 				  struct virtio_pci_cap *cap)
 {
@@ -140,6 +170,8 @@ int ifcvf_init_hw(struct ifcvf_hw *hw, struct pci_dev *pdev)
 		  hw->common_cfg, hw->notify_base, hw->isr,
 		  hw->dev_cfg, hw->notify_off_multiplier);
 
+	hw->vqs_shared_irq = -EINVAL;
+
 	return 0;
 }
 
@@ -321,12 +353,6 @@ static int ifcvf_hw_enable(struct ifcvf_hw *hw)
 
 	ifcvf = vf_to_adapter(hw);
 	cfg = hw->common_cfg;
-	ifc_iowrite16(IFCVF_MSI_CONFIG_OFF, &cfg->msix_config);
-
-	if (ifc_ioread16(&cfg->msix_config) == VIRTIO_MSI_NO_VECTOR) {
-		IFCVF_ERR(ifcvf->pdev, "No msix vector for device config\n");
-		return -EINVAL;
-	}
 
 	for (i = 0; i < hw->nr_vring; i++) {
 		if (!hw->vring[i].ready)
@@ -340,15 +366,6 @@ static int ifcvf_hw_enable(struct ifcvf_hw *hw)
 		ifc_iowrite64_twopart(hw->vring[i].used, &cfg->queue_used_lo,
 				     &cfg->queue_used_hi);
 		ifc_iowrite16(hw->vring[i].size, &cfg->queue_size);
-		ifc_iowrite16(i + IFCVF_MSI_QUEUE_OFF, &cfg->queue_msix_vector);
-
-		if (ifc_ioread16(&cfg->queue_msix_vector) ==
-		    VIRTIO_MSI_NO_VECTOR) {
-			IFCVF_ERR(ifcvf->pdev,
-				  "No msix vector for queue %u\n", i);
-			return -EINVAL;
-		}
-
 		ifcvf_set_vq_state(hw, i, hw->vring[i].last_avail_idx);
 		ifc_iowrite16(1, &cfg->queue_enable);
 	}
diff --git a/drivers/vdpa/ifcvf/ifcvf_base.h b/drivers/vdpa/ifcvf/ifcvf_base.h
index 949b4fb9d554..9cfe088c82e9 100644
--- a/drivers/vdpa/ifcvf/ifcvf_base.h
+++ b/drivers/vdpa/ifcvf/ifcvf_base.h
@@ -27,8 +27,6 @@
 
 #define IFCVF_QUEUE_ALIGNMENT	PAGE_SIZE
 #define IFCVF_QUEUE_MAX		32768
-#define IFCVF_MSI_CONFIG_OFF	0
-#define IFCVF_MSI_QUEUE_OFF	1
 #define IFCVF_PCI_MAX_RESOURCE	6
 
 #define IFCVF_LM_CFG_SIZE		0x40
@@ -42,6 +40,13 @@
 #define ifcvf_private_to_vf(adapter) \
 	(&((struct ifcvf_adapter *)adapter)->vf)
 
+/* all vqs and config interrupt has its own vector */
+#define MSIX_VECTOR_PER_VQ_AND_CONFIG		1
+/* all vqs share a vector, and config interrupt has a separate vector */
+#define MSIX_VECTOR_SHARED_VQ_AND_CONFIG	2
+/* all vqs and config interrupt share a vector */
+#define MSIX_VECTOR_DEV_SHARED			3
+
 static inline u8 ifc_ioread8(u8 __iomem *addr)
 {
 	return ioread8(addr);
@@ -97,25 +102,27 @@ struct ifcvf_hw {
 	u8 __iomem *isr;
 	/* Live migration */
 	u8 __iomem *lm_cfg;
-	u16 nr_vring;
 	/* Notification bar number */
 	u8 notify_bar;
+	u8 msix_vector_status;
+	/* virtio-net or virtio-blk device config size */
+	u32 config_size;
 	/* Notificaiton bar address */
 	void __iomem *notify_base;
 	phys_addr_t notify_base_pa;
 	u32 notify_off_multiplier;
+	u32 dev_type;
 	u64 req_features;
 	u64 hw_features;
-	u32 dev_type;
 	struct virtio_pci_common_cfg __iomem *common_cfg;
 	void __iomem *dev_cfg;
 	struct vring_info vring[IFCVF_MAX_QUEUES];
 	void __iomem * const *base;
 	char config_msix_name[256];
 	struct vdpa_callback config_cb;
-	unsigned int config_irq;
-	/* virtio-net or virtio-blk device config size */
-	u32 config_size;
+	int config_irq;
+	int vqs_shared_irq;
+	u16 nr_vring;
 };
 
 struct ifcvf_adapter {
@@ -160,4 +167,6 @@ int ifcvf_set_vq_state(struct ifcvf_hw *hw, u16 qid, u16 num);
 struct ifcvf_adapter *vf_to_adapter(struct ifcvf_hw *hw);
 int ifcvf_probed_virtio_net(struct ifcvf_hw *hw);
 u32 ifcvf_get_config_size(struct ifcvf_hw *hw);
+int ifcvf_set_vq_vector(struct ifcvf_hw *hw, u16 qid, int vector);
+int ifcvf_set_config_vector(struct ifcvf_hw *hw, int vector);
 #endif /* _IFCVF_H_ */
diff --git a/drivers/vdpa/ifcvf/ifcvf_main.c b/drivers/vdpa/ifcvf/ifcvf_main.c
index 44c89ab0b6da..ca414399f040 100644
--- a/drivers/vdpa/ifcvf/ifcvf_main.c
+++ b/drivers/vdpa/ifcvf/ifcvf_main.c
@@ -17,6 +17,7 @@
 #define DRIVER_AUTHOR   "Intel Corporation"
 #define IFCVF_DRIVER_NAME       "ifcvf"
 
+/* handles config interrupt */
 static irqreturn_t ifcvf_config_changed(int irq, void *arg)
 {
 	struct ifcvf_hw *vf = arg;
@@ -27,6 +28,7 @@ static irqreturn_t ifcvf_config_changed(int irq, void *arg)
 	return IRQ_HANDLED;
 }
 
+/* handles vqs interrupt */
 static irqreturn_t ifcvf_intr_handler(int irq, void *arg)
 {
 	struct vring_info *vring = arg;
@@ -37,24 +39,78 @@ static irqreturn_t ifcvf_intr_handler(int irq, void *arg)
 	return IRQ_HANDLED;
 }
 
+/* handls vqs shared interrupt */
+static irqreturn_t ifcvf_vq_shared_intr_handler(int irq, void *arg)
+{
+	struct ifcvf_hw *vf = arg;
+	struct vring_info *vring;
+	int i;
+
+	for (i = 0; i < vf->nr_vring; i++) {
+		vring = &vf->vring[i];
+		if (vring->cb.callback)
+			vf->vring->cb.callback(vring->cb.private);
+	}
+
+	return IRQ_HANDLED;
+}
+
+/* handles a shared interrupt for vqs and config */
+static irqreturn_t ifcvf_dev_shared_intr_handler(int irq, void *arg)
+{
+	struct ifcvf_hw *vf = arg;
+	u8 isr;
+
+	isr = ifc_ioread8(vf->isr);
+	if (isr & VIRTIO_PCI_ISR_CONFIG)
+		ifcvf_config_changed(irq, arg);
+
+	return ifcvf_vq_shared_intr_handler(irq, arg);
+}
+
 static void ifcvf_free_irq_vectors(void *data)
 {
 	pci_free_irq_vectors(data);
 }
 
-static void ifcvf_free_irq(struct ifcvf_adapter *adapter, int queues)
+static void ifcvf_free_vq_irq(struct ifcvf_adapter *adapter, int queues)
 {
 	struct pci_dev *pdev = adapter->pdev;
 	struct ifcvf_hw *vf = &adapter->vf;
 	int i;
 
+	if (vf->msix_vector_status == MSIX_VECTOR_PER_VQ_AND_CONFIG) {
+		for (i = 0; i < queues; i++) {
+			devm_free_irq(&pdev->dev, vf->vring[i].irq, &vf->vring[i]);
+			vf->vring[i].irq = -EINVAL;
+		}
+	} else {
+		devm_free_irq(&pdev->dev, vf->vqs_shared_irq, vf);
+		vf->vqs_shared_irq = -EINVAL;
+	}
+}
 
-	for (i = 0; i < queues; i++) {
-		devm_free_irq(&pdev->dev, vf->vring[i].irq, &vf->vring[i]);
-		vf->vring[i].irq = -EINVAL;
+static void ifcvf_free_config_irq(struct ifcvf_adapter *adapter)
+{
+	struct pci_dev *pdev = adapter->pdev;
+	struct ifcvf_hw *vf = &adapter->vf;
+
+	/* If the irq is shared by all vqs and the config interrupt,
+	 * it is already freed in ifcvf_free_vq_irq, so here only
+	 * need to free config irq when msix_vector_status != MSIX_VECTOR_DEV_SHARED
+	 */
+	if (vf->msix_vector_status != MSIX_VECTOR_DEV_SHARED) {
+		devm_free_irq(&pdev->dev, vf->config_irq, vf);
+		vf->config_irq = -EINVAL;
 	}
+}
+
+static void ifcvf_free_irq(struct ifcvf_adapter *adapter, int queues)
+{
+	struct pci_dev *pdev = adapter->pdev;
 
-	devm_free_irq(&pdev->dev, vf->config_irq, vf);
+	ifcvf_free_vq_irq(adapter, queues);
+	ifcvf_free_config_irq(adapter);
 	ifcvf_free_irq_vectors(pdev);
 }
 
@@ -86,58 +142,172 @@ static int ifcvf_alloc_vectors(struct ifcvf_adapter *adapter)
 	return ret;
 }
 
-static int ifcvf_request_irq(struct ifcvf_adapter *adapter)
+static int ifcvf_request_per_vq_irq(struct ifcvf_adapter *adapter)
 {
 	struct pci_dev *pdev = adapter->pdev;
 	struct ifcvf_hw *vf = &adapter->vf;
-	int vector, nvectors, i, ret, irq;
-	u16 max_intr;
+	int i, vector, ret, irq;
 
-	nvectors = ifcvf_alloc_vectors(adapter);
-	if (!(nvectors > 0))
-		return nvectors;
+	for (i = 0; i < vf->nr_vring; i++) {
+		snprintf(vf->vring[i].msix_name, 256, "ifcvf[%s]-%d\n", pci_name(pdev), i);
+		vector = i;
+		irq = pci_irq_vector(pdev, vector);
+		ret = devm_request_irq(&pdev->dev, irq,
+				       ifcvf_intr_handler, 0,
+				       vf->vring[i].msix_name,
+				       &vf->vring[i]);
+		if (ret) {
+			IFCVF_ERR(pdev, "Failed to request irq for vq %d\n", i);
+			ifcvf_free_vq_irq(adapter, i);
+		} else {
+			vf->vring[i].irq = irq;
+			ifcvf_set_vq_vector(vf, i, vector);
+		}
+	}
 
-	max_intr = vf->nr_vring + 1;
+	vf->vqs_shared_irq = -EINVAL;
+
+	return 0;
+}
+
+static int ifcvf_request_shared_vq_irq(struct ifcvf_adapter *adapter)
+{
+	struct pci_dev *pdev = adapter->pdev;
+	struct ifcvf_hw *vf = &adapter->vf;
+	int i, vector, ret, irq;
+
+	vector = 0;
+	/* reuse msix_name[256] space of vring0 to store shared vqs interrupt name */
+	snprintf(vf->vring[0].msix_name, 256, "ifcvf[%s]-vqs-shared-irq\n", pci_name(pdev));
+	irq = pci_irq_vector(pdev, vector);
+	ret = devm_request_irq(&pdev->dev, irq,
+			       ifcvf_vq_shared_intr_handler, 0,
+			       vf->vring[0].msix_name, vf);
+	if (ret) {
+		IFCVF_ERR(pdev, "Failed to request shared irq for vf\n");
+
+		return ret;
+	}
+
+	vf->vqs_shared_irq = irq;
+	for (i = 0; i < vf->nr_vring; i++) {
+		vf->vring[i].irq = -EINVAL;
+		ifcvf_set_vq_vector(vf, i, vector);
+	}
+
+	return 0;
+
+}
+
+static int ifcvf_request_dev_shared_irq(struct ifcvf_adapter *adapter)
+{
+	struct pci_dev *pdev = adapter->pdev;
+	struct ifcvf_hw *vf = &adapter->vf;
+	int i, vector, ret, irq;
+
+	vector = 0;
+	/* reuse msix_name[256] space of vring0 to store shared device interrupt name */
+	snprintf(vf->vring[0].msix_name, 256, "ifcvf[%s]-dev-shared-irq\n", pci_name(pdev));
+	irq = pci_irq_vector(pdev, vector);
+	ret = devm_request_irq(&pdev->dev, irq,
+			       ifcvf_dev_shared_intr_handler, 0,
+			       vf->vring[0].msix_name, vf);
+	if (ret) {
+		IFCVF_ERR(pdev, "Failed to request shared irq for vf\n");
 
-	ret = pci_alloc_irq_vectors(pdev, max_intr,
-				    max_intr, PCI_IRQ_MSIX);
-	if (ret < 0) {
-		IFCVF_ERR(pdev, "Failed to alloc IRQ vectors\n");
 		return ret;
 	}
 
+	vf->vqs_shared_irq = irq;
+	for (i = 0; i < vf->nr_vring; i++) {
+		vf->vring[i].irq = -EINVAL;
+		ifcvf_set_vq_vector(vf, i, vector);
+	}
+
+	vf->config_irq = irq;
+	ifcvf_set_config_vector(vf, vector);
+
+	return 0;
+
+}
+
+static int ifcvf_request_vq_irq(struct ifcvf_adapter *adapter)
+{
+	struct ifcvf_hw *vf = &adapter->vf;
+	int ret;
+
+	if (vf->msix_vector_status == MSIX_VECTOR_PER_VQ_AND_CONFIG)
+		ret = ifcvf_request_per_vq_irq(adapter);
+	else
+		ret = ifcvf_request_shared_vq_irq(adapter);
+
+	return ret;
+}
+
+static int ifcvf_request_config_irq(struct ifcvf_adapter *adapter)
+{
+	struct pci_dev *pdev = adapter->pdev;
+	struct ifcvf_hw *vf = &adapter->vf;
+	int config_vector, ret;
+
+	if (vf->msix_vector_status == MSIX_VECTOR_DEV_SHARED)
+		return 0;
+
+	if (vf->msix_vector_status == MSIX_VECTOR_PER_VQ_AND_CONFIG)
+		/* vector 0 ~ vf->nr_vring for vqs, num vf->nr_vring vector for config interrupt */
+		config_vector = vf->nr_vring;
+
+	if (vf->msix_vector_status ==  MSIX_VECTOR_SHARED_VQ_AND_CONFIG)
+		/* vector 0 for vqs and 1 for config interrupt */
+		config_vector = 1;
+
 	snprintf(vf->config_msix_name, 256, "ifcvf[%s]-config\n",
 		 pci_name(pdev));
-	vector = 0;
-	vf->config_irq = pci_irq_vector(pdev, vector);
+	vf->config_irq = pci_irq_vector(pdev, config_vector);
 	ret = devm_request_irq(&pdev->dev, vf->config_irq,
 			       ifcvf_config_changed, 0,
 			       vf->config_msix_name, vf);
 	if (ret) {
 		IFCVF_ERR(pdev, "Failed to request config irq\n");
+		ifcvf_free_vq_irq(adapter, vf->nr_vring);
 		return ret;
 	}
 
-	for (i = 0; i < vf->nr_vring; i++) {
-		snprintf(vf->vring[i].msix_name, 256, "ifcvf[%s]-%d\n",
-			 pci_name(pdev), i);
-		vector = i + IFCVF_MSI_QUEUE_OFF;
-		irq = pci_irq_vector(pdev, vector);
-		ret = devm_request_irq(&pdev->dev, irq,
-				       ifcvf_intr_handler, 0,
-				       vf->vring[i].msix_name,
-				       &vf->vring[i]);
-		if (ret) {
-			IFCVF_ERR(pdev,
-				  "Failed to request irq for vq %d\n", i);
-			ifcvf_free_irq(adapter, i);
+	ifcvf_set_config_vector(vf, config_vector);
 
-			return ret;
-		}
+	return 0;
+}
+
+static int ifcvf_request_irq(struct ifcvf_adapter *adapter)
+{
+	struct ifcvf_hw *vf = &adapter->vf;
+	int nvectors, ret, max_intr;
 
-		vf->vring[i].irq = irq;
+	nvectors = ifcvf_alloc_vectors(adapter);
+	if (!(nvectors > 0))
+		return nvectors;
+
+	vf->msix_vector_status = MSIX_VECTOR_PER_VQ_AND_CONFIG;
+	max_intr = vf->nr_vring + 1;
+	if (nvectors < max_intr)
+		vf->msix_vector_status = MSIX_VECTOR_SHARED_VQ_AND_CONFIG;
+
+	if (nvectors == 1) {
+		vf->msix_vector_status = MSIX_VECTOR_DEV_SHARED;
+		ret = ifcvf_request_dev_shared_irq(adapter);
+
+		return ret;
 	}
 
+	ret = ifcvf_request_vq_irq(adapter);
+	if (ret)
+		return ret;
+
+	ret = ifcvf_request_config_irq(adapter);
+
+	if (ret)
+		return ret;
+
 	return 0;
 }
 
@@ -441,7 +611,10 @@ static int ifcvf_vdpa_get_vq_irq(struct vdpa_device *vdpa_dev,
 {
 	struct ifcvf_hw *vf = vdpa_to_vf(vdpa_dev);
 
-	return vf->vring[qid].irq;
+	if (vf->vqs_shared_irq < 0)
+		return vf->vring[qid].irq;
+	else
+		return -EINVAL;
 }
 
 static struct vdpa_notification_area ifcvf_get_vq_notification(struct vdpa_device *vdpa_dev,
-- 
2.27.0

Re: [PATCH V4 4/4] vDPA/ifcvf: implement shared IRQ feature

[Jason Wang]

在 2022/2/3 下午3:27, Zhu Lingshan 写道:
> On some platforms/devices, there may not be enough MSI vector
> slots allocated for virtqueues and config changes. In such a case,
> the interrupt sources(virtqueues, config changes) must share
> an IRQ/vector, to avoid initialization failures, keep
> the device functional.
>
> This commit handles three cases:
> (1) number of the allocated vectors == the number of virtqueues + 1
> (config changes), every virtqueue and the config interrupt has
> a separated vector/IRQ, the best and the most likely case.
> (2) number of the allocated vectors is less than the best case, but
> greater than 1. In this case, all virtqueues share a vector/IRQ,
> the config interrupt has a separated vector/IRQ
> (3) only one vector is allocated, in this case, the virtqueues and
> the config interrupt share a vector/IRQ. The worst and most
> unlikely case.
>
> Otherwise, it needs to fail.
>
> This commit introduces some helper functions:
> ifcvf_set_vq_vector() and ifcvf_set_config_vector() sets virtqueue
> vector and config vector in the device config space, so that
> the device can send interrupt DMA.
>
> This commit adds some fields in struct ifcvf_hw and re-placed
> the existed fields to be aligned with the cacheline.
>
> Signed-off-by: Zhu Lingshan <lingshan.zhu@intel.com>
> ---
>   drivers/vdpa/ifcvf/ifcvf_base.c |  47 ++++--
>   drivers/vdpa/ifcvf/ifcvf_base.h |  23 ++-
>   drivers/vdpa/ifcvf/ifcvf_main.c | 243 +++++++++++++++++++++++++++-----
>   3 files changed, 256 insertions(+), 57 deletions(-)
>
> diff --git a/drivers/vdpa/ifcvf/ifcvf_base.c b/drivers/vdpa/ifcvf/ifcvf_base.c
> index 397692ae671c..18dcb63ab1e3 100644
> --- a/drivers/vdpa/ifcvf/ifcvf_base.c
> +++ b/drivers/vdpa/ifcvf/ifcvf_base.c
> @@ -15,6 +15,36 @@ struct ifcvf_adapter *vf_to_adapter(struct ifcvf_hw *hw)
>   	return container_of(hw, struct ifcvf_adapter, vf);
>   }
>   
> +int ifcvf_set_vq_vector(struct ifcvf_hw *hw, u16 qid, int vector)
> +{
> +	struct virtio_pci_common_cfg __iomem *cfg = hw->common_cfg;
> +	struct ifcvf_adapter *ifcvf = vf_to_adapter(hw);
> +
> +	ifc_iowrite16(qid, &cfg->queue_select);
> +	ifc_iowrite16(vector, &cfg->queue_msix_vector);
> +	if (ifc_ioread16(&cfg->queue_msix_vector) == VIRTIO_MSI_NO_VECTOR) {
> +		IFCVF_ERR(ifcvf->pdev, "No msix vector for queue %u\n", qid);
> +			return -EINVAL;
> +	}


Let's leave this check for the caller, E.g can caller try to assign 
NO_VECTOR during uni-nit?


> +
> +	return 0;
> +}
> +
> +int ifcvf_set_config_vector(struct ifcvf_hw *hw, int vector)
> +{
> +	struct virtio_pci_common_cfg __iomem *cfg = hw->common_cfg;
> +	struct ifcvf_adapter *ifcvf = vf_to_adapter(hw);
> +
> +	cfg = hw->common_cfg;
> +	ifc_iowrite16(vector,  &cfg->msix_config);
> +	if (ifc_ioread16(&cfg->msix_config) == VIRTIO_MSI_NO_VECTOR) {
> +		IFCVF_ERR(ifcvf->pdev, "No msix vector for device config\n");
> +		return -EINVAL;
> +	}


Similar question as above.


> +
> +	return 0;
> +}
> +
>   static void __iomem *get_cap_addr(struct ifcvf_hw *hw,
>   				  struct virtio_pci_cap *cap)
>   {
> @@ -140,6 +170,8 @@ int ifcvf_init_hw(struct ifcvf_hw *hw, struct pci_dev *pdev)
>   		  hw->common_cfg, hw->notify_base, hw->isr,
>   		  hw->dev_cfg, hw->notify_off_multiplier);
>   
> +	hw->vqs_shared_irq = -EINVAL;
> +
>   	return 0;
>   }
>   
> @@ -321,12 +353,6 @@ static int ifcvf_hw_enable(struct ifcvf_hw *hw)
>   
>   	ifcvf = vf_to_adapter(hw);
>   	cfg = hw->common_cfg;
> -	ifc_iowrite16(IFCVF_MSI_CONFIG_OFF, &cfg->msix_config);
> -
> -	if (ifc_ioread16(&cfg->msix_config) == VIRTIO_MSI_NO_VECTOR) {
> -		IFCVF_ERR(ifcvf->pdev, "No msix vector for device config\n");
> -		return -EINVAL;
> -	}
>   
>   	for (i = 0; i < hw->nr_vring; i++) {
>   		if (!hw->vring[i].ready)
> @@ -340,15 +366,6 @@ static int ifcvf_hw_enable(struct ifcvf_hw *hw)
>   		ifc_iowrite64_twopart(hw->vring[i].used, &cfg->queue_used_lo,
>   				     &cfg->queue_used_hi);
>   		ifc_iowrite16(hw->vring[i].size, &cfg->queue_size);
> -		ifc_iowrite16(i + IFCVF_MSI_QUEUE_OFF, &cfg->queue_msix_vector);
> -
> -		if (ifc_ioread16(&cfg->queue_msix_vector) ==
> -		    VIRTIO_MSI_NO_VECTOR) {
> -			IFCVF_ERR(ifcvf->pdev,
> -				  "No msix vector for queue %u\n", i);
> -			return -EINVAL;
> -		}
> -
>   		ifcvf_set_vq_state(hw, i, hw->vring[i].last_avail_idx);
>   		ifc_iowrite16(1, &cfg->queue_enable);
>   	}
> diff --git a/drivers/vdpa/ifcvf/ifcvf_base.h b/drivers/vdpa/ifcvf/ifcvf_base.h
> index 949b4fb9d554..9cfe088c82e9 100644
> --- a/drivers/vdpa/ifcvf/ifcvf_base.h
> +++ b/drivers/vdpa/ifcvf/ifcvf_base.h
> @@ -27,8 +27,6 @@
>   
>   #define IFCVF_QUEUE_ALIGNMENT	PAGE_SIZE
>   #define IFCVF_QUEUE_MAX		32768
> -#define IFCVF_MSI_CONFIG_OFF	0
> -#define IFCVF_MSI_QUEUE_OFF	1
>   #define IFCVF_PCI_MAX_RESOURCE	6
>   
>   #define IFCVF_LM_CFG_SIZE		0x40
> @@ -42,6 +40,13 @@
>   #define ifcvf_private_to_vf(adapter) \
>   	(&((struct ifcvf_adapter *)adapter)->vf)
>   
> +/* all vqs and config interrupt has its own vector */
> +#define MSIX_VECTOR_PER_VQ_AND_CONFIG		1
> +/* all vqs share a vector, and config interrupt has a separate vector */
> +#define MSIX_VECTOR_SHARED_VQ_AND_CONFIG	2
> +/* all vqs and config interrupt share a vector */
> +#define MSIX_VECTOR_DEV_SHARED			3


I think there's no much value to differ 2 from 3 consider config 
interrupt should be rare.


> +
>   static inline u8 ifc_ioread8(u8 __iomem *addr)
>   {
>   	return ioread8(addr);
> @@ -97,25 +102,27 @@ struct ifcvf_hw {
>   	u8 __iomem *isr;
>   	/* Live migration */
>   	u8 __iomem *lm_cfg;
> -	u16 nr_vring;


Any reason for moving nv_vring, config_size, and other stuffs?


>   	/* Notification bar number */
>   	u8 notify_bar;
> +	u8 msix_vector_status;
> +	/* virtio-net or virtio-blk device config size */
> +	u32 config_size;
>   	/* Notificaiton bar address */
>   	void __iomem *notify_base;
>   	phys_addr_t notify_base_pa;
>   	u32 notify_off_multiplier;
> +	u32 dev_type;
>   	u64 req_features;
>   	u64 hw_features;
> -	u32 dev_type;
>   	struct virtio_pci_common_cfg __iomem *common_cfg;
>   	void __iomem *dev_cfg;
>   	struct vring_info vring[IFCVF_MAX_QUEUES];
>   	void __iomem * const *base;
>   	char config_msix_name[256];
>   	struct vdpa_callback config_cb;
> -	unsigned int config_irq;
> -	/* virtio-net or virtio-blk device config size */
> -	u32 config_size;
> +	int config_irq;
> +	int vqs_shared_irq;
> +	u16 nr_vring;
>   };
>   
>   struct ifcvf_adapter {
> @@ -160,4 +167,6 @@ int ifcvf_set_vq_state(struct ifcvf_hw *hw, u16 qid, u16 num);
>   struct ifcvf_adapter *vf_to_adapter(struct ifcvf_hw *hw);
>   int ifcvf_probed_virtio_net(struct ifcvf_hw *hw);
>   u32 ifcvf_get_config_size(struct ifcvf_hw *hw);
> +int ifcvf_set_vq_vector(struct ifcvf_hw *hw, u16 qid, int vector);
> +int ifcvf_set_config_vector(struct ifcvf_hw *hw, int vector);
>   #endif /* _IFCVF_H_ */
> diff --git a/drivers/vdpa/ifcvf/ifcvf_main.c b/drivers/vdpa/ifcvf/ifcvf_main.c
> index 44c89ab0b6da..ca414399f040 100644
> --- a/drivers/vdpa/ifcvf/ifcvf_main.c
> +++ b/drivers/vdpa/ifcvf/ifcvf_main.c
> @@ -17,6 +17,7 @@
>   #define DRIVER_AUTHOR   "Intel Corporation"
>   #define IFCVF_DRIVER_NAME       "ifcvf"
>   
> +/* handles config interrupt */


This seems unrelated to the shared IRQ logic and it looks useless since 
it's easily to deduce it from the function name below.


>   static irqreturn_t ifcvf_config_changed(int irq, void *arg)
>   {
>   	struct ifcvf_hw *vf = arg;
> @@ -27,6 +28,7 @@ static irqreturn_t ifcvf_config_changed(int irq, void *arg)
>   	return IRQ_HANDLED;
>   }
>   
> +/* handles vqs interrupt */


So did this.


>   static irqreturn_t ifcvf_intr_handler(int irq, void *arg)
>   {
>   	struct vring_info *vring = arg;
> @@ -37,24 +39,78 @@ static irqreturn_t ifcvf_intr_handler(int irq, void *arg)
>   	return IRQ_HANDLED;
>   }
>   
> +/* handls vqs shared interrupt */
> +static irqreturn_t ifcvf_vq_shared_intr_handler(int irq, void *arg)
> +{
> +	struct ifcvf_hw *vf = arg;
> +	struct vring_info *vring;
> +	int i;
> +
> +	for (i = 0; i < vf->nr_vring; i++) {
> +		vring = &vf->vring[i];
> +		if (vring->cb.callback)
> +			vf->vring->cb.callback(vring->cb.private);
> +	}
> +
> +	return IRQ_HANDLED;
> +}
> +
> +/* handles a shared interrupt for vqs and config */
> +static irqreturn_t ifcvf_dev_shared_intr_handler(int irq, void *arg)
> +{
> +	struct ifcvf_hw *vf = arg;
> +	u8 isr;
> +
> +	isr = ifc_ioread8(vf->isr);


We need to exactly what vp_interrupt do here. Checking against vf->isr 
first and return IRQ_NONE if it is not set.

Always return IRQ_HANDLED will break the device who shares an irq with 
IFCVF.


> +	if (isr & VIRTIO_PCI_ISR_CONFIG)
> +		ifcvf_config_changed(irq, arg);
> +
> +	return ifcvf_vq_shared_intr_handler(irq, arg);
> +}
> +
>   static void ifcvf_free_irq_vectors(void *data)
>   {
>   	pci_free_irq_vectors(data);
>   }
>   
> -static void ifcvf_free_irq(struct ifcvf_adapter *adapter, int queues)
> +static void ifcvf_free_vq_irq(struct ifcvf_adapter *adapter, int queues)
>   {
>   	struct pci_dev *pdev = adapter->pdev;
>   	struct ifcvf_hw *vf = &adapter->vf;
>   	int i;
>   
> +	if (vf->msix_vector_status == MSIX_VECTOR_PER_VQ_AND_CONFIG) {
> +		for (i = 0; i < queues; i++) {
> +			devm_free_irq(&pdev->dev, vf->vring[i].irq, &vf->vring[i]);
> +			vf->vring[i].irq = -EINVAL;
> +		}
> +	} else {
> +		devm_free_irq(&pdev->dev, vf->vqs_shared_irq, vf);
> +		vf->vqs_shared_irq = -EINVAL;
> +	}
> +}
>   
> -	for (i = 0; i < queues; i++) {
> -		devm_free_irq(&pdev->dev, vf->vring[i].irq, &vf->vring[i]);
> -		vf->vring[i].irq = -EINVAL;
> +static void ifcvf_free_config_irq(struct ifcvf_adapter *adapter)
> +{
> +	struct pci_dev *pdev = adapter->pdev;
> +	struct ifcvf_hw *vf = &adapter->vf;
> +
> +	/* If the irq is shared by all vqs and the config interrupt,
> +	 * it is already freed in ifcvf_free_vq_irq, so here only
> +	 * need to free config irq when msix_vector_status != MSIX_VECTOR_DEV_SHARED
> +	 */
> +	if (vf->msix_vector_status != MSIX_VECTOR_DEV_SHARED) {
> +		devm_free_irq(&pdev->dev, vf->config_irq, vf);
> +		vf->config_irq = -EINVAL;
>   	}
> +}
> +
> +static void ifcvf_free_irq(struct ifcvf_adapter *adapter, int queues)
> +{
> +	struct pci_dev *pdev = adapter->pdev;
>   
> -	devm_free_irq(&pdev->dev, vf->config_irq, vf);
> +	ifcvf_free_vq_irq(adapter, queues);
> +	ifcvf_free_config_irq(adapter);
>   	ifcvf_free_irq_vectors(pdev);
>   }
>   
> @@ -86,58 +142,172 @@ static int ifcvf_alloc_vectors(struct ifcvf_adapter *adapter)
>   	return ret;
>   }
>   
> -static int ifcvf_request_irq(struct ifcvf_adapter *adapter)
> +static int ifcvf_request_per_vq_irq(struct ifcvf_adapter *adapter)
>   {
>   	struct pci_dev *pdev = adapter->pdev;
>   	struct ifcvf_hw *vf = &adapter->vf;
> -	int vector, nvectors, i, ret, irq;
> -	u16 max_intr;
> +	int i, vector, ret, irq;
>   
> -	nvectors = ifcvf_alloc_vectors(adapter);
> -	if (!(nvectors > 0))
> -		return nvectors;
> +	for (i = 0; i < vf->nr_vring; i++) {
> +		snprintf(vf->vring[i].msix_name, 256, "ifcvf[%s]-%d\n", pci_name(pdev), i);
> +		vector = i;
> +		irq = pci_irq_vector(pdev, vector);
> +		ret = devm_request_irq(&pdev->dev, irq,
> +				       ifcvf_intr_handler, 0,
> +				       vf->vring[i].msix_name,
> +				       &vf->vring[i]);
> +		if (ret) {
> +			IFCVF_ERR(pdev, "Failed to request irq for vq %d\n", i);
> +			ifcvf_free_vq_irq(adapter, i);
> +		} else {
> +			vf->vring[i].irq = irq;
> +			ifcvf_set_vq_vector(vf, i, vector);
> +		}
> +	}
>   
> -	max_intr = vf->nr_vring + 1;
> +	vf->vqs_shared_irq = -EINVAL;
> +
> +	return 0;
> +}
> +
> +static int ifcvf_request_shared_vq_irq(struct ifcvf_adapter *adapter)
> +{
> +	struct pci_dev *pdev = adapter->pdev;
> +	struct ifcvf_hw *vf = &adapter->vf;
> +	int i, vector, ret, irq;
> +
> +	vector = 0;
> +	/* reuse msix_name[256] space of vring0 to store shared vqs interrupt name */


I think we can remove this comment since the code is straightforward.


> +	snprintf(vf->vring[0].msix_name, 256, "ifcvf[%s]-vqs-shared-irq\n", pci_name(pdev));
> +	irq = pci_irq_vector(pdev, vector);
> +	ret = devm_request_irq(&pdev->dev, irq,
> +			       ifcvf_vq_shared_intr_handler, 0,
> +			       vf->vring[0].msix_name, vf);
> +	if (ret) {
> +		IFCVF_ERR(pdev, "Failed to request shared irq for vf\n");
> +
> +		return ret;
> +	}
> +
> +	vf->vqs_shared_irq = irq;
> +	for (i = 0; i < vf->nr_vring; i++) {
> +		vf->vring[i].irq = -EINVAL;
> +		ifcvf_set_vq_vector(vf, i, vector);
> +	}
> +
> +	return 0;
> +
> +}
> +
> +static int ifcvf_request_dev_shared_irq(struct ifcvf_adapter *adapter)
> +{
> +	struct pci_dev *pdev = adapter->pdev;
> +	struct ifcvf_hw *vf = &adapter->vf;
> +	int i, vector, ret, irq;
> +
> +	vector = 0;
> +	/* reuse msix_name[256] space of vring0 to store shared device interrupt name */
> +	snprintf(vf->vring[0].msix_name, 256, "ifcvf[%s]-dev-shared-irq\n", pci_name(pdev));
> +	irq = pci_irq_vector(pdev, vector);
> +	ret = devm_request_irq(&pdev->dev, irq,
> +			       ifcvf_dev_shared_intr_handler, 0,
> +			       vf->vring[0].msix_name, vf);
> +	if (ret) {
> +		IFCVF_ERR(pdev, "Failed to request shared irq for vf\n");
>   
> -	ret = pci_alloc_irq_vectors(pdev, max_intr,
> -				    max_intr, PCI_IRQ_MSIX);
> -	if (ret < 0) {
> -		IFCVF_ERR(pdev, "Failed to alloc IRQ vectors\n");
>   		return ret;
>   	}
>   
> +	vf->vqs_shared_irq = irq;
> +	for (i = 0; i < vf->nr_vring; i++) {
> +		vf->vring[i].irq = -EINVAL;
> +		ifcvf_set_vq_vector(vf, i, vector);
> +	}
> +
> +	vf->config_irq = irq;
> +	ifcvf_set_config_vector(vf, vector);
> +
> +	return 0;
> +
> +}
> +
> +static int ifcvf_request_vq_irq(struct ifcvf_adapter *adapter)
> +{
> +	struct ifcvf_hw *vf = &adapter->vf;
> +	int ret;
> +
> +	if (vf->msix_vector_status == MSIX_VECTOR_PER_VQ_AND_CONFIG)
> +		ret = ifcvf_request_per_vq_irq(adapter);
> +	else
> +		ret = ifcvf_request_shared_vq_irq(adapter);
> +
> +	return ret;
> +}
> +
> +static int ifcvf_request_config_irq(struct ifcvf_adapter *adapter)
> +{
> +	struct pci_dev *pdev = adapter->pdev;
> +	struct ifcvf_hw *vf = &adapter->vf;
> +	int config_vector, ret;
> +
> +	if (vf->msix_vector_status == MSIX_VECTOR_DEV_SHARED)
> +		return 0;
> +
> +	if (vf->msix_vector_status == MSIX_VECTOR_PER_VQ_AND_CONFIG)
> +		/* vector 0 ~ vf->nr_vring for vqs, num vf->nr_vring vector for config interrupt */
> +		config_vector = vf->nr_vring;
> +
> +	if (vf->msix_vector_status ==  MSIX_VECTOR_SHARED_VQ_AND_CONFIG)
> +		/* vector 0 for vqs and 1 for config interrupt */
> +		config_vector = 1;
> +
>   	snprintf(vf->config_msix_name, 256, "ifcvf[%s]-config\n",
>   		 pci_name(pdev));
> -	vector = 0;
> -	vf->config_irq = pci_irq_vector(pdev, vector);
> +	vf->config_irq = pci_irq_vector(pdev, config_vector);
>   	ret = devm_request_irq(&pdev->dev, vf->config_irq,
>   			       ifcvf_config_changed, 0,
>   			       vf->config_msix_name, vf);
>   	if (ret) {
>   		IFCVF_ERR(pdev, "Failed to request config irq\n");
> +		ifcvf_free_vq_irq(adapter, vf->nr_vring);
>   		return ret;
>   	}
>   
> -	for (i = 0; i < vf->nr_vring; i++) {
> -		snprintf(vf->vring[i].msix_name, 256, "ifcvf[%s]-%d\n",
> -			 pci_name(pdev), i);
> -		vector = i + IFCVF_MSI_QUEUE_OFF;
> -		irq = pci_irq_vector(pdev, vector);
> -		ret = devm_request_irq(&pdev->dev, irq,
> -				       ifcvf_intr_handler, 0,
> -				       vf->vring[i].msix_name,
> -				       &vf->vring[i]);
> -		if (ret) {
> -			IFCVF_ERR(pdev,
> -				  "Failed to request irq for vq %d\n", i);
> -			ifcvf_free_irq(adapter, i);
> +	ifcvf_set_config_vector(vf, config_vector);
>   
> -			return ret;
> -		}
> +	return 0;
> +}
> +
> +static int ifcvf_request_irq(struct ifcvf_adapter *adapter)
> +{


As replied above, I think having two modes should be sufficient and the 
code could be greatly simplified.

Thanks


> +	struct ifcvf_hw *vf = &adapter->vf;
> +	int nvectors, ret, max_intr;
>   
> -		vf->vring[i].irq = irq;
> +	nvectors = ifcvf_alloc_vectors(adapter);
> +	if (!(nvectors > 0))
> +		return nvectors;
> +
> +	vf->msix_vector_status = MSIX_VECTOR_PER_VQ_AND_CONFIG;
> +	max_intr = vf->nr_vring + 1;
> +	if (nvectors < max_intr)
> +		vf->msix_vector_status = MSIX_VECTOR_SHARED_VQ_AND_CONFIG;
> +
> +	if (nvectors == 1) {
> +		vf->msix_vector_status = MSIX_VECTOR_DEV_SHARED;
> +		ret = ifcvf_request_dev_shared_irq(adapter);
> +
> +		return ret;
>   	}
>   
> +	ret = ifcvf_request_vq_irq(adapter);
> +	if (ret)
> +		return ret;
> +
> +	ret = ifcvf_request_config_irq(adapter);
> +
> +	if (ret)
> +		return ret;
> +
>   	return 0;
>   }
>   
> @@ -441,7 +611,10 @@ static int ifcvf_vdpa_get_vq_irq(struct vdpa_device *vdpa_dev,
>   {
>   	struct ifcvf_hw *vf = vdpa_to_vf(vdpa_dev);
>   
> -	return vf->vring[qid].irq;
> +	if (vf->vqs_shared_irq < 0)
> +		return vf->vring[qid].irq;
> +	else
> +		return -EINVAL;
>   }
>   
>   static struct vdpa_notification_area ifcvf_get_vq_notification(struct vdpa_device *vdpa_dev,

Re: [PATCH V4 4/4] vDPA/ifcvf: implement shared IRQ feature

[Zhu Lingshan]

On 2/14/2022 3:19 PM, Jason Wang wrote:
>
> 在 2022/2/3 下午3:27, Zhu Lingshan 写道:
>> On some platforms/devices, there may not be enough MSI vector
>> slots allocated for virtqueues and config changes. In such a case,
>> the interrupt sources(virtqueues, config changes) must share
>> an IRQ/vector, to avoid initialization failures, keep
>> the device functional.
>>
>> This commit handles three cases:
>> (1) number of the allocated vectors == the number of virtqueues + 1
>> (config changes), every virtqueue and the config interrupt has
>> a separated vector/IRQ, the best and the most likely case.
>> (2) number of the allocated vectors is less than the best case, but
>> greater than 1. In this case, all virtqueues share a vector/IRQ,
>> the config interrupt has a separated vector/IRQ
>> (3) only one vector is allocated, in this case, the virtqueues and
>> the config interrupt share a vector/IRQ. The worst and most
>> unlikely case.
>>
>> Otherwise, it needs to fail.
>>
>> This commit introduces some helper functions:
>> ifcvf_set_vq_vector() and ifcvf_set_config_vector() sets virtqueue
>> vector and config vector in the device config space, so that
>> the device can send interrupt DMA.
>>
>> This commit adds some fields in struct ifcvf_hw and re-placed
>> the existed fields to be aligned with the cacheline.
>>
>> Signed-off-by: Zhu Lingshan <lingshan.zhu@intel.com>
>> ---
>>   drivers/vdpa/ifcvf/ifcvf_base.c |  47 ++++--
>>   drivers/vdpa/ifcvf/ifcvf_base.h |  23 ++-
>>   drivers/vdpa/ifcvf/ifcvf_main.c | 243 +++++++++++++++++++++++++++-----
>>   3 files changed, 256 insertions(+), 57 deletions(-)
>>
>> diff --git a/drivers/vdpa/ifcvf/ifcvf_base.c 
>> b/drivers/vdpa/ifcvf/ifcvf_base.c
>> index 397692ae671c..18dcb63ab1e3 100644
>> --- a/drivers/vdpa/ifcvf/ifcvf_base.c
>> +++ b/drivers/vdpa/ifcvf/ifcvf_base.c
>> @@ -15,6 +15,36 @@ struct ifcvf_adapter *vf_to_adapter(struct 
>> ifcvf_hw *hw)
>>       return container_of(hw, struct ifcvf_adapter, vf);
>>   }
>>   +int ifcvf_set_vq_vector(struct ifcvf_hw *hw, u16 qid, int vector)
>> +{
>> +    struct virtio_pci_common_cfg __iomem *cfg = hw->common_cfg;
>> +    struct ifcvf_adapter *ifcvf = vf_to_adapter(hw);
>> +
>> +    ifc_iowrite16(qid, &cfg->queue_select);
>> +    ifc_iowrite16(vector, &cfg->queue_msix_vector);
>> +    if (ifc_ioread16(&cfg->queue_msix_vector) == 
>> VIRTIO_MSI_NO_VECTOR) {
>> +        IFCVF_ERR(ifcvf->pdev, "No msix vector for queue %u\n", qid);
>> +            return -EINVAL;
>> +    }
>
>
> Let's leave this check for the caller, E.g can caller try to assign 
> NO_VECTOR during uni-nit?
ifcvf driver sets NO_VECTOR when call hw_disable(). I am not sure 
whether I get it,
Yes we can let the caller check a vq vector, however this may cause more 
than three levels brackets, may looks ugly.
>
>
>> +
>> +    return 0;
>> +}
>> +
>> +int ifcvf_set_config_vector(struct ifcvf_hw *hw, int vector)
>> +{
>> +    struct virtio_pci_common_cfg __iomem *cfg = hw->common_cfg;
>> +    struct ifcvf_adapter *ifcvf = vf_to_adapter(hw);
>> +
>> +    cfg = hw->common_cfg;
>> +    ifc_iowrite16(vector,  &cfg->msix_config);
>> +    if (ifc_ioread16(&cfg->msix_config) == VIRTIO_MSI_NO_VECTOR) {
>> +        IFCVF_ERR(ifcvf->pdev, "No msix vector for device config\n");
>> +        return -EINVAL;
>> +    }
>
>
> Similar question as above.
>
>
>> +
>> +    return 0;
>> +}
>> +
>>   static void __iomem *get_cap_addr(struct ifcvf_hw *hw,
>>                     struct virtio_pci_cap *cap)
>>   {
>> @@ -140,6 +170,8 @@ int ifcvf_init_hw(struct ifcvf_hw *hw, struct 
>> pci_dev *pdev)
>>             hw->common_cfg, hw->notify_base, hw->isr,
>>             hw->dev_cfg, hw->notify_off_multiplier);
>>   +    hw->vqs_shared_irq = -EINVAL;
>> +
>>       return 0;
>>   }
>>   @@ -321,12 +353,6 @@ static int ifcvf_hw_enable(struct ifcvf_hw *hw)
>>         ifcvf = vf_to_adapter(hw);
>>       cfg = hw->common_cfg;
>> -    ifc_iowrite16(IFCVF_MSI_CONFIG_OFF, &cfg->msix_config);
>> -
>> -    if (ifc_ioread16(&cfg->msix_config) == VIRTIO_MSI_NO_VECTOR) {
>> -        IFCVF_ERR(ifcvf->pdev, "No msix vector for device config\n");
>> -        return -EINVAL;
>> -    }
>>         for (i = 0; i < hw->nr_vring; i++) {
>>           if (!hw->vring[i].ready)
>> @@ -340,15 +366,6 @@ static int ifcvf_hw_enable(struct ifcvf_hw *hw)
>>           ifc_iowrite64_twopart(hw->vring[i].used, &cfg->queue_used_lo,
>>                        &cfg->queue_used_hi);
>>           ifc_iowrite16(hw->vring[i].size, &cfg->queue_size);
>> -        ifc_iowrite16(i + IFCVF_MSI_QUEUE_OFF, 
>> &cfg->queue_msix_vector);
>> -
>> -        if (ifc_ioread16(&cfg->queue_msix_vector) ==
>> -            VIRTIO_MSI_NO_VECTOR) {
>> -            IFCVF_ERR(ifcvf->pdev,
>> -                  "No msix vector for queue %u\n", i);
>> -            return -EINVAL;
>> -        }
>> -
>>           ifcvf_set_vq_state(hw, i, hw->vring[i].last_avail_idx);
>>           ifc_iowrite16(1, &cfg->queue_enable);
>>       }
>> diff --git a/drivers/vdpa/ifcvf/ifcvf_base.h 
>> b/drivers/vdpa/ifcvf/ifcvf_base.h
>> index 949b4fb9d554..9cfe088c82e9 100644
>> --- a/drivers/vdpa/ifcvf/ifcvf_base.h
>> +++ b/drivers/vdpa/ifcvf/ifcvf_base.h
>> @@ -27,8 +27,6 @@
>>     #define IFCVF_QUEUE_ALIGNMENT    PAGE_SIZE
>>   #define IFCVF_QUEUE_MAX        32768
>> -#define IFCVF_MSI_CONFIG_OFF    0
>> -#define IFCVF_MSI_QUEUE_OFF    1
>>   #define IFCVF_PCI_MAX_RESOURCE    6
>>     #define IFCVF_LM_CFG_SIZE        0x40
>> @@ -42,6 +40,13 @@
>>   #define ifcvf_private_to_vf(adapter) \
>>       (&((struct ifcvf_adapter *)adapter)->vf)
>>   +/* all vqs and config interrupt has its own vector */
>> +#define MSIX_VECTOR_PER_VQ_AND_CONFIG        1
>> +/* all vqs share a vector, and config interrupt has a separate 
>> vector */
>> +#define MSIX_VECTOR_SHARED_VQ_AND_CONFIG    2
>> +/* all vqs and config interrupt share a vector */
>> +#define MSIX_VECTOR_DEV_SHARED            3
>
>
> I think there's no much value to differ 2 from 3 consider config 
> interrupt should be rare.
IMHO we still need 2 and 3, because MSIX_VECTOR_SHARED_VQ_AND_CONFIG 
means there are at least 2 vectors,
the vqs share one vector, config change has its own vector.
MSIX_VECTOR_DEV_SHARED means three are only one vector, all vqs and 
config changes need to share this vector.
>
>
>
>> +
>>   static inline u8 ifc_ioread8(u8 __iomem *addr)
>>   {
>>       return ioread8(addr);
>> @@ -97,25 +102,27 @@ struct ifcvf_hw {
>>       u8 __iomem *isr;
>>       /* Live migration */
>>       u8 __iomem *lm_cfg;
>> -    u16 nr_vring;
>
>
> Any reason for moving nv_vring, config_size, and other stuffs?
for cacheline alignment.
>
>
>
>>       /* Notification bar number */
>>       u8 notify_bar;
>> +    u8 msix_vector_status;
>> +    /* virtio-net or virtio-blk device config size */
>> +    u32 config_size;
>>       /* Notificaiton bar address */
>>       void __iomem *notify_base;
>>       phys_addr_t notify_base_pa;
>>       u32 notify_off_multiplier;
>> +    u32 dev_type;
>>       u64 req_features;
>>       u64 hw_features;
>> -    u32 dev_type;
>>       struct virtio_pci_common_cfg __iomem *common_cfg;
>>       void __iomem *dev_cfg;
>>       struct vring_info vring[IFCVF_MAX_QUEUES];
>>       void __iomem * const *base;
>>       char config_msix_name[256];
>>       struct vdpa_callback config_cb;
>> -    unsigned int config_irq;
>> -    /* virtio-net or virtio-blk device config size */
>> -    u32 config_size;
>> +    int config_irq;
>> +    int vqs_shared_irq;
>> +    u16 nr_vring;
>>   };
>>     struct ifcvf_adapter {
>> @@ -160,4 +167,6 @@ int ifcvf_set_vq_state(struct ifcvf_hw *hw, u16 
>> qid, u16 num);
>>   struct ifcvf_adapter *vf_to_adapter(struct ifcvf_hw *hw);
>>   int ifcvf_probed_virtio_net(struct ifcvf_hw *hw);
>>   u32 ifcvf_get_config_size(struct ifcvf_hw *hw);
>> +int ifcvf_set_vq_vector(struct ifcvf_hw *hw, u16 qid, int vector);
>> +int ifcvf_set_config_vector(struct ifcvf_hw *hw, int vector);
>>   #endif /* _IFCVF_H_ */
>> diff --git a/drivers/vdpa/ifcvf/ifcvf_main.c 
>> b/drivers/vdpa/ifcvf/ifcvf_main.c
>> index 44c89ab0b6da..ca414399f040 100644
>> --- a/drivers/vdpa/ifcvf/ifcvf_main.c
>> +++ b/drivers/vdpa/ifcvf/ifcvf_main.c
>> @@ -17,6 +17,7 @@
>>   #define DRIVER_AUTHOR   "Intel Corporation"
>>   #define IFCVF_DRIVER_NAME       "ifcvf"
>>   +/* handles config interrupt */
>
>
> This seems unrelated to the shared IRQ logic and it looks useless 
> since it's easily to deduce it from the function name below.
OK, do you mean the comments? I can remove these comments.
>
>
>>   static irqreturn_t ifcvf_config_changed(int irq, void *arg)
>>   {
>>       struct ifcvf_hw *vf = arg;
>> @@ -27,6 +28,7 @@ static irqreturn_t ifcvf_config_changed(int irq, 
>> void *arg)
>>       return IRQ_HANDLED;
>>   }
>>   +/* handles vqs interrupt */
>
>
> So did this.
>
>
>>   static irqreturn_t ifcvf_intr_handler(int irq, void *arg)
>>   {
>>       struct vring_info *vring = arg;
>> @@ -37,24 +39,78 @@ static irqreturn_t ifcvf_intr_handler(int irq, 
>> void *arg)
>>       return IRQ_HANDLED;
>>   }
>>   +/* handls vqs shared interrupt */
>> +static irqreturn_t ifcvf_vq_shared_intr_handler(int irq, void *arg)
>> +{
>> +    struct ifcvf_hw *vf = arg;
>> +    struct vring_info *vring;
>> +    int i;
>> +
>> +    for (i = 0; i < vf->nr_vring; i++) {
>> +        vring = &vf->vring[i];
>> +        if (vring->cb.callback)
>> + vf->vring->cb.callback(vring->cb.private);
>> +    }
>> +
>> +    return IRQ_HANDLED;
>> +}
>> +
>> +/* handles a shared interrupt for vqs and config */
>> +static irqreturn_t ifcvf_dev_shared_intr_handler(int irq, void *arg)
>> +{
>> +    struct ifcvf_hw *vf = arg;
>> +    u8 isr;
>> +
>> +    isr = ifc_ioread8(vf->isr);
>
>
> We need to exactly what vp_interrupt do here. Checking against vf->isr 
> first and return IRQ_NONE if it is not set.
>
> Always return IRQ_HANDLED will break the device who shares an irq with 
> IFCVF.
as we discussed in another thread(spec inconsistency about ISR), ISR may 
only works for INTx for now,
but VFs don't have INTx, and a VF may not share its vectors with other 
devices, so I guess it can work
and may be our best try for now.
>
>
>> +    if (isr & VIRTIO_PCI_ISR_CONFIG)
>> +        ifcvf_config_changed(irq, arg);
>> +
>> +    return ifcvf_vq_shared_intr_handler(irq, arg);
>> +}
>> +
>>   static void ifcvf_free_irq_vectors(void *data)
>>   {
>>       pci_free_irq_vectors(data);
>>   }
>>   -static void ifcvf_free_irq(struct ifcvf_adapter *adapter, int queues)
>> +static void ifcvf_free_vq_irq(struct ifcvf_adapter *adapter, int 
>> queues)
>>   {
>>       struct pci_dev *pdev = adapter->pdev;
>>       struct ifcvf_hw *vf = &adapter->vf;
>>       int i;
>>   +    if (vf->msix_vector_status == MSIX_VECTOR_PER_VQ_AND_CONFIG) {
>> +        for (i = 0; i < queues; i++) {
>> +            devm_free_irq(&pdev->dev, vf->vring[i].irq, &vf->vring[i]);
>> +            vf->vring[i].irq = -EINVAL;
>> +        }
>> +    } else {
>> +        devm_free_irq(&pdev->dev, vf->vqs_shared_irq, vf);
>> +        vf->vqs_shared_irq = -EINVAL;
>> +    }
>> +}
>>   -    for (i = 0; i < queues; i++) {
>> -        devm_free_irq(&pdev->dev, vf->vring[i].irq, &vf->vring[i]);
>> -        vf->vring[i].irq = -EINVAL;
>> +static void ifcvf_free_config_irq(struct ifcvf_adapter *adapter)
>> +{
>> +    struct pci_dev *pdev = adapter->pdev;
>> +    struct ifcvf_hw *vf = &adapter->vf;
>> +
>> +    /* If the irq is shared by all vqs and the config interrupt,
>> +     * it is already freed in ifcvf_free_vq_irq, so here only
>> +     * need to free config irq when msix_vector_status != 
>> MSIX_VECTOR_DEV_SHARED
>> +     */
>> +    if (vf->msix_vector_status != MSIX_VECTOR_DEV_SHARED) {
>> +        devm_free_irq(&pdev->dev, vf->config_irq, vf);
>> +        vf->config_irq = -EINVAL;
>>       }
>> +}
>> +
>> +static void ifcvf_free_irq(struct ifcvf_adapter *adapter, int queues)
>> +{
>> +    struct pci_dev *pdev = adapter->pdev;
>>   -    devm_free_irq(&pdev->dev, vf->config_irq, vf);
>> +    ifcvf_free_vq_irq(adapter, queues);
>> +    ifcvf_free_config_irq(adapter);
>>       ifcvf_free_irq_vectors(pdev);
>>   }
>>   @@ -86,58 +142,172 @@ static int ifcvf_alloc_vectors(struct 
>> ifcvf_adapter *adapter)
>>       return ret;
>>   }
>>   -static int ifcvf_request_irq(struct ifcvf_adapter *adapter)
>> +static int ifcvf_request_per_vq_irq(struct ifcvf_adapter *adapter)
>>   {
>>       struct pci_dev *pdev = adapter->pdev;
>>       struct ifcvf_hw *vf = &adapter->vf;
>> -    int vector, nvectors, i, ret, irq;
>> -    u16 max_intr;
>> +    int i, vector, ret, irq;
>>   -    nvectors = ifcvf_alloc_vectors(adapter);
>> -    if (!(nvectors > 0))
>> -        return nvectors;
>> +    for (i = 0; i < vf->nr_vring; i++) {
>> +        snprintf(vf->vring[i].msix_name, 256, "ifcvf[%s]-%d\n", 
>> pci_name(pdev), i);
>> +        vector = i;
>> +        irq = pci_irq_vector(pdev, vector);
>> +        ret = devm_request_irq(&pdev->dev, irq,
>> +                       ifcvf_intr_handler, 0,
>> +                       vf->vring[i].msix_name,
>> +                       &vf->vring[i]);
>> +        if (ret) {
>> +            IFCVF_ERR(pdev, "Failed to request irq for vq %d\n", i);
>> +            ifcvf_free_vq_irq(adapter, i);
>> +        } else {
>> +            vf->vring[i].irq = irq;
>> +            ifcvf_set_vq_vector(vf, i, vector);
>> +        }
>> +    }
>>   -    max_intr = vf->nr_vring + 1;
>> +    vf->vqs_shared_irq = -EINVAL;
>> +
>> +    return 0;
>> +}
>> +
>> +static int ifcvf_request_shared_vq_irq(struct ifcvf_adapter *adapter)
>> +{
>> +    struct pci_dev *pdev = adapter->pdev;
>> +    struct ifcvf_hw *vf = &adapter->vf;
>> +    int i, vector, ret, irq;
>> +
>> +    vector = 0;
>> +    /* reuse msix_name[256] space of vring0 to store shared vqs 
>> interrupt name */
>
>
> I think we can remove this comment since the code is straightforward.
sure
>
>
>> + snprintf(vf->vring[0].msix_name, 256, "ifcvf[%s]-vqs-shared-irq\n", 
>> pci_name(pdev));
>> +    irq = pci_irq_vector(pdev, vector);
>> +    ret = devm_request_irq(&pdev->dev, irq,
>> +                   ifcvf_vq_shared_intr_handler, 0,
>> +                   vf->vring[0].msix_name, vf);
>> +    if (ret) {
>> +        IFCVF_ERR(pdev, "Failed to request shared irq for vf\n");
>> +
>> +        return ret;
>> +    }
>> +
>> +    vf->vqs_shared_irq = irq;
>> +    for (i = 0; i < vf->nr_vring; i++) {
>> +        vf->vring[i].irq = -EINVAL;
>> +        ifcvf_set_vq_vector(vf, i, vector);
>> +    }
>> +
>> +    return 0;
>> +
>> +}
>> +
>> +static int ifcvf_request_dev_shared_irq(struct ifcvf_adapter *adapter)
>> +{
>> +    struct pci_dev *pdev = adapter->pdev;
>> +    struct ifcvf_hw *vf = &adapter->vf;
>> +    int i, vector, ret, irq;
>> +
>> +    vector = 0;
>> +    /* reuse msix_name[256] space of vring0 to store shared device 
>> interrupt name */
>> +    snprintf(vf->vring[0].msix_name, 256, 
>> "ifcvf[%s]-dev-shared-irq\n", pci_name(pdev));
>> +    irq = pci_irq_vector(pdev, vector);
>> +    ret = devm_request_irq(&pdev->dev, irq,
>> +                   ifcvf_dev_shared_intr_handler, 0,
>> +                   vf->vring[0].msix_name, vf);
>> +    if (ret) {
>> +        IFCVF_ERR(pdev, "Failed to request shared irq for vf\n");
>>   -    ret = pci_alloc_irq_vectors(pdev, max_intr,
>> -                    max_intr, PCI_IRQ_MSIX);
>> -    if (ret < 0) {
>> -        IFCVF_ERR(pdev, "Failed to alloc IRQ vectors\n");
>>           return ret;
>>       }
>>   +    vf->vqs_shared_irq = irq;
>> +    for (i = 0; i < vf->nr_vring; i++) {
>> +        vf->vring[i].irq = -EINVAL;
>> +        ifcvf_set_vq_vector(vf, i, vector);
>> +    }
>> +
>> +    vf->config_irq = irq;
>> +    ifcvf_set_config_vector(vf, vector);
>> +
>> +    return 0;
>> +
>> +}
>> +
>> +static int ifcvf_request_vq_irq(struct ifcvf_adapter *adapter)
>> +{
>> +    struct ifcvf_hw *vf = &adapter->vf;
>> +    int ret;
>> +
>> +    if (vf->msix_vector_status == MSIX_VECTOR_PER_VQ_AND_CONFIG)
>> +        ret = ifcvf_request_per_vq_irq(adapter);
>> +    else
>> +        ret = ifcvf_request_shared_vq_irq(adapter);
>> +
>> +    return ret;
>> +}
>> +
>> +static int ifcvf_request_config_irq(struct ifcvf_adapter *adapter)
>> +{
>> +    struct pci_dev *pdev = adapter->pdev;
>> +    struct ifcvf_hw *vf = &adapter->vf;
>> +    int config_vector, ret;
>> +
>> +    if (vf->msix_vector_status == MSIX_VECTOR_DEV_SHARED)
>> +        return 0;
>> +
>> +    if (vf->msix_vector_status == MSIX_VECTOR_PER_VQ_AND_CONFIG)
>> +        /* vector 0 ~ vf->nr_vring for vqs, num vf->nr_vring vector 
>> for config interrupt */
>> +        config_vector = vf->nr_vring;
>> +
>> +    if (vf->msix_vector_status == MSIX_VECTOR_SHARED_VQ_AND_CONFIG)
>> +        /* vector 0 for vqs and 1 for config interrupt */
>> +        config_vector = 1;
>> +
>>       snprintf(vf->config_msix_name, 256, "ifcvf[%s]-config\n",
>>            pci_name(pdev));
>> -    vector = 0;
>> -    vf->config_irq = pci_irq_vector(pdev, vector);
>> +    vf->config_irq = pci_irq_vector(pdev, config_vector);
>>       ret = devm_request_irq(&pdev->dev, vf->config_irq,
>>                      ifcvf_config_changed, 0,
>>                      vf->config_msix_name, vf);
>>       if (ret) {
>>           IFCVF_ERR(pdev, "Failed to request config irq\n");
>> +        ifcvf_free_vq_irq(adapter, vf->nr_vring);
>>           return ret;
>>       }
>>   -    for (i = 0; i < vf->nr_vring; i++) {
>> -        snprintf(vf->vring[i].msix_name, 256, "ifcvf[%s]-%d\n",
>> -             pci_name(pdev), i);
>> -        vector = i + IFCVF_MSI_QUEUE_OFF;
>> -        irq = pci_irq_vector(pdev, vector);
>> -        ret = devm_request_irq(&pdev->dev, irq,
>> -                       ifcvf_intr_handler, 0,
>> -                       vf->vring[i].msix_name,
>> -                       &vf->vring[i]);
>> -        if (ret) {
>> -            IFCVF_ERR(pdev,
>> -                  "Failed to request irq for vq %d\n", i);
>> -            ifcvf_free_irq(adapter, i);
>> +    ifcvf_set_config_vector(vf, config_vector);
>>   -            return ret;
>> -        }
>> +    return 0;
>> +}
>> +
>> +static int ifcvf_request_irq(struct ifcvf_adapter *adapter)
>> +{
>
>
> As replied above, I think having two modes should be sufficient and 
> the code could be greatly simplified.
Do you mean if we don't get enough vectors, just use only one vector for 
the vqs and config changes? I guess this
only works if ISR work for MSIX as we expects, or we may waste some time 
in the device config space.

Thanks,
Zhu Lingshan
>
> Thanks
>
>
>> +    struct ifcvf_hw *vf = &adapter->vf;
>> +    int nvectors, ret, max_intr;
>>   -        vf->vring[i].irq = irq;
>> +    nvectors = ifcvf_alloc_vectors(adapter);
>> +    if (!(nvectors > 0))
>> +        return nvectors;
>> +
>> +    vf->msix_vector_status = MSIX_VECTOR_PER_VQ_AND_CONFIG;
>> +    max_intr = vf->nr_vring + 1;
>> +    if (nvectors < max_intr)
>> +        vf->msix_vector_status = MSIX_VECTOR_SHARED_VQ_AND_CONFIG;
>> +
>> +    if (nvectors == 1) {
>> +        vf->msix_vector_status = MSIX_VECTOR_DEV_SHARED;
>> +        ret = ifcvf_request_dev_shared_irq(adapter);
>> +
>> +        return ret;
>>       }
>>   +    ret = ifcvf_request_vq_irq(adapter);
>> +    if (ret)
>> +        return ret;
>> +
>> +    ret = ifcvf_request_config_irq(adapter);
>> +
>> +    if (ret)
>> +        return ret;
>> +
>>       return 0;
>>   }
>>   @@ -441,7 +611,10 @@ static int ifcvf_vdpa_get_vq_irq(struct 
>> vdpa_device *vdpa_dev,
>>   {
>>       struct ifcvf_hw *vf = vdpa_to_vf(vdpa_dev);
>>   -    return vf->vring[qid].irq;
>> +    if (vf->vqs_shared_irq < 0)
>> +        return vf->vring[qid].irq;
>> +    else
>> +        return -EINVAL;
>>   }
>>     static struct vdpa_notification_area 
>> ifcvf_get_vq_notification(struct vdpa_device *vdpa_dev,
>
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> Virtualization mailing list
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Re: [PATCH V4 4/4] vDPA/ifcvf: implement shared IRQ feature

[Michael S. Tsirkin]

On Mon, Feb 14, 2022 at 06:01:56PM +0800, Zhu Lingshan wrote:
> 
> 
> On 2/14/2022 3:19 PM, Jason Wang wrote:
> > 
> > 在 2022/2/3 下午3:27, Zhu Lingshan 写道:
> > > On some platforms/devices, there may not be enough MSI vector
> > > slots allocated for virtqueues and config changes. In such a case,
> > > the interrupt sources(virtqueues, config changes) must share
> > > an IRQ/vector, to avoid initialization failures, keep
> > > the device functional.
> > > 
> > > This commit handles three cases:
> > > (1) number of the allocated vectors == the number of virtqueues + 1
> > > (config changes), every virtqueue and the config interrupt has
> > > a separated vector/IRQ, the best and the most likely case.
> > > (2) number of the allocated vectors is less than the best case, but
> > > greater than 1. In this case, all virtqueues share a vector/IRQ,
> > > the config interrupt has a separated vector/IRQ
> > > (3) only one vector is allocated, in this case, the virtqueues and
> > > the config interrupt share a vector/IRQ. The worst and most
> > > unlikely case.
> > > 
> > > Otherwise, it needs to fail.
> > > 
> > > This commit introduces some helper functions:
> > > ifcvf_set_vq_vector() and ifcvf_set_config_vector() sets virtqueue
> > > vector and config vector in the device config space, so that
> > > the device can send interrupt DMA.
> > > 
> > > This commit adds some fields in struct ifcvf_hw and re-placed
> > > the existed fields to be aligned with the cacheline.
> > > 
> > > Signed-off-by: Zhu Lingshan <lingshan.zhu@intel.com>
> > > ---
> > >   drivers/vdpa/ifcvf/ifcvf_base.c |  47 ++++--
> > >   drivers/vdpa/ifcvf/ifcvf_base.h |  23 ++-
> > >   drivers/vdpa/ifcvf/ifcvf_main.c | 243 +++++++++++++++++++++++++++-----
> > >   3 files changed, 256 insertions(+), 57 deletions(-)
> > > 
> > > diff --git a/drivers/vdpa/ifcvf/ifcvf_base.c
> > > b/drivers/vdpa/ifcvf/ifcvf_base.c
> > > index 397692ae671c..18dcb63ab1e3 100644
> > > --- a/drivers/vdpa/ifcvf/ifcvf_base.c
> > > +++ b/drivers/vdpa/ifcvf/ifcvf_base.c
> > > @@ -15,6 +15,36 @@ struct ifcvf_adapter *vf_to_adapter(struct
> > > ifcvf_hw *hw)
> > >       return container_of(hw, struct ifcvf_adapter, vf);
> > >   }
> > >   +int ifcvf_set_vq_vector(struct ifcvf_hw *hw, u16 qid, int vector)
> > > +{
> > > +    struct virtio_pci_common_cfg __iomem *cfg = hw->common_cfg;
> > > +    struct ifcvf_adapter *ifcvf = vf_to_adapter(hw);
> > > +
> > > +    ifc_iowrite16(qid, &cfg->queue_select);
> > > +    ifc_iowrite16(vector, &cfg->queue_msix_vector);
> > > +    if (ifc_ioread16(&cfg->queue_msix_vector) ==
> > > VIRTIO_MSI_NO_VECTOR) {
> > > +        IFCVF_ERR(ifcvf->pdev, "No msix vector for queue %u\n", qid);
> > > +            return -EINVAL;
> > > +    }
> > 
> > 
> > Let's leave this check for the caller, E.g can caller try to assign
> > NO_VECTOR during uni-nit?
> ifcvf driver sets NO_VECTOR when call hw_disable(). I am not sure whether I
> get it,
> Yes we can let the caller check a vq vector, however this may cause more
> than three levels brackets, may looks ugly.
> > 
> > 
> > > +
> > > +    return 0;
> > > +}
> > > +
> > > +int ifcvf_set_config_vector(struct ifcvf_hw *hw, int vector)
> > > +{
> > > +    struct virtio_pci_common_cfg __iomem *cfg = hw->common_cfg;
> > > +    struct ifcvf_adapter *ifcvf = vf_to_adapter(hw);
> > > +
> > > +    cfg = hw->common_cfg;
> > > +    ifc_iowrite16(vector,  &cfg->msix_config);
> > > +    if (ifc_ioread16(&cfg->msix_config) == VIRTIO_MSI_NO_VECTOR) {
> > > +        IFCVF_ERR(ifcvf->pdev, "No msix vector for device config\n");
> > > +        return -EINVAL;
> > > +    }
> > 
> > 
> > Similar question as above.
> > 
> > 
> > > +
> > > +    return 0;
> > > +}
> > > +
> > >   static void __iomem *get_cap_addr(struct ifcvf_hw *hw,
> > >                     struct virtio_pci_cap *cap)
> > >   {
> > > @@ -140,6 +170,8 @@ int ifcvf_init_hw(struct ifcvf_hw *hw, struct
> > > pci_dev *pdev)
> > >             hw->common_cfg, hw->notify_base, hw->isr,
> > >             hw->dev_cfg, hw->notify_off_multiplier);
> > >   +    hw->vqs_shared_irq = -EINVAL;
> > > +
> > >       return 0;
> > >   }
> > >   @@ -321,12 +353,6 @@ static int ifcvf_hw_enable(struct ifcvf_hw *hw)
> > >         ifcvf = vf_to_adapter(hw);
> > >       cfg = hw->common_cfg;
> > > -    ifc_iowrite16(IFCVF_MSI_CONFIG_OFF, &cfg->msix_config);
> > > -
> > > -    if (ifc_ioread16(&cfg->msix_config) == VIRTIO_MSI_NO_VECTOR) {
> > > -        IFCVF_ERR(ifcvf->pdev, "No msix vector for device config\n");
> > > -        return -EINVAL;
> > > -    }
> > >         for (i = 0; i < hw->nr_vring; i++) {
> > >           if (!hw->vring[i].ready)
> > > @@ -340,15 +366,6 @@ static int ifcvf_hw_enable(struct ifcvf_hw *hw)
> > >           ifc_iowrite64_twopart(hw->vring[i].used, &cfg->queue_used_lo,
> > >                        &cfg->queue_used_hi);
> > >           ifc_iowrite16(hw->vring[i].size, &cfg->queue_size);
> > > -        ifc_iowrite16(i + IFCVF_MSI_QUEUE_OFF,
> > > &cfg->queue_msix_vector);
> > > -
> > > -        if (ifc_ioread16(&cfg->queue_msix_vector) ==
> > > -            VIRTIO_MSI_NO_VECTOR) {
> > > -            IFCVF_ERR(ifcvf->pdev,
> > > -                  "No msix vector for queue %u\n", i);
> > > -            return -EINVAL;
> > > -        }
> > > -
> > >           ifcvf_set_vq_state(hw, i, hw->vring[i].last_avail_idx);
> > >           ifc_iowrite16(1, &cfg->queue_enable);
> > >       }
> > > diff --git a/drivers/vdpa/ifcvf/ifcvf_base.h
> > > b/drivers/vdpa/ifcvf/ifcvf_base.h
> > > index 949b4fb9d554..9cfe088c82e9 100644
> > > --- a/drivers/vdpa/ifcvf/ifcvf_base.h
> > > +++ b/drivers/vdpa/ifcvf/ifcvf_base.h
> > > @@ -27,8 +27,6 @@
> > >     #define IFCVF_QUEUE_ALIGNMENT    PAGE_SIZE
> > >   #define IFCVF_QUEUE_MAX        32768
> > > -#define IFCVF_MSI_CONFIG_OFF    0
> > > -#define IFCVF_MSI_QUEUE_OFF    1
> > >   #define IFCVF_PCI_MAX_RESOURCE    6
> > >     #define IFCVF_LM_CFG_SIZE        0x40
> > > @@ -42,6 +40,13 @@
> > >   #define ifcvf_private_to_vf(adapter) \
> > >       (&((struct ifcvf_adapter *)adapter)->vf)
> > >   +/* all vqs and config interrupt has its own vector */
> > > +#define MSIX_VECTOR_PER_VQ_AND_CONFIG        1
> > > +/* all vqs share a vector, and config interrupt has a separate
> > > vector */
> > > +#define MSIX_VECTOR_SHARED_VQ_AND_CONFIG    2
> > > +/* all vqs and config interrupt share a vector */
> > > +#define MSIX_VECTOR_DEV_SHARED            3
> > 
> > 
> > I think there's no much value to differ 2 from 3 consider config
> > interrupt should be rare.
> IMHO we still need 2 and 3, because MSIX_VECTOR_SHARED_VQ_AND_CONFIG means
> there are at least 2 vectors,
> the vqs share one vector, config change has its own vector.
> MSIX_VECTOR_DEV_SHARED means three are only one vector, all vqs and config
> changes need to share this vector.
> > 
> > 
> > 
> > > +
> > >   static inline u8 ifc_ioread8(u8 __iomem *addr)
> > >   {
> > >       return ioread8(addr);
> > > @@ -97,25 +102,27 @@ struct ifcvf_hw {
> > >       u8 __iomem *isr;
> > >       /* Live migration */
> > >       u8 __iomem *lm_cfg;
> > > -    u16 nr_vring;
> > 
> > 
> > Any reason for moving nv_vring, config_size, and other stuffs?
> for cacheline alignment.

maybe a separate patch then.

> > 
> > 
> > 
> > >       /* Notification bar number */
> > >       u8 notify_bar;
> > > +    u8 msix_vector_status;
> > > +    /* virtio-net or virtio-blk device config size */
> > > +    u32 config_size;
> > >       /* Notificaiton bar address */
> > >       void __iomem *notify_base;
> > >       phys_addr_t notify_base_pa;
> > >       u32 notify_off_multiplier;
> > > +    u32 dev_type;
> > >       u64 req_features;
> > >       u64 hw_features;
> > > -    u32 dev_type;
> > >       struct virtio_pci_common_cfg __iomem *common_cfg;
> > >       void __iomem *dev_cfg;
> > >       struct vring_info vring[IFCVF_MAX_QUEUES];
> > >       void __iomem * const *base;
> > >       char config_msix_name[256];
> > >       struct vdpa_callback config_cb;
> > > -    unsigned int config_irq;
> > > -    /* virtio-net or virtio-blk device config size */
> > > -    u32 config_size;
> > > +    int config_irq;
> > > +    int vqs_shared_irq;
> > > +    u16 nr_vring;
> > >   };
> > >     struct ifcvf_adapter {
> > > @@ -160,4 +167,6 @@ int ifcvf_set_vq_state(struct ifcvf_hw *hw, u16
> > > qid, u16 num);
> > >   struct ifcvf_adapter *vf_to_adapter(struct ifcvf_hw *hw);
> > >   int ifcvf_probed_virtio_net(struct ifcvf_hw *hw);
> > >   u32 ifcvf_get_config_size(struct ifcvf_hw *hw);
> > > +int ifcvf_set_vq_vector(struct ifcvf_hw *hw, u16 qid, int vector);
> > > +int ifcvf_set_config_vector(struct ifcvf_hw *hw, int vector);
> > >   #endif /* _IFCVF_H_ */
> > > diff --git a/drivers/vdpa/ifcvf/ifcvf_main.c
> > > b/drivers/vdpa/ifcvf/ifcvf_main.c
> > > index 44c89ab0b6da..ca414399f040 100644
> > > --- a/drivers/vdpa/ifcvf/ifcvf_main.c
> > > +++ b/drivers/vdpa/ifcvf/ifcvf_main.c
> > > @@ -17,6 +17,7 @@
> > >   #define DRIVER_AUTHOR   "Intel Corporation"
> > >   #define IFCVF_DRIVER_NAME       "ifcvf"
> > >   +/* handles config interrupt */
> > 
> > 
> > This seems unrelated to the shared IRQ logic and it looks useless since
> > it's easily to deduce it from the function name below.
> OK, do you mean the comments? I can remove these comments.
> > 
> > 
> > >   static irqreturn_t ifcvf_config_changed(int irq, void *arg)
> > >   {
> > >       struct ifcvf_hw *vf = arg;
> > > @@ -27,6 +28,7 @@ static irqreturn_t ifcvf_config_changed(int irq,
> > > void *arg)
> > >       return IRQ_HANDLED;
> > >   }
> > >   +/* handles vqs interrupt */
> > 
> > 
> > So did this.
> > 
> > 
> > >   static irqreturn_t ifcvf_intr_handler(int irq, void *arg)
> > >   {
> > >       struct vring_info *vring = arg;
> > > @@ -37,24 +39,78 @@ static irqreturn_t ifcvf_intr_handler(int irq,
> > > void *arg)
> > >       return IRQ_HANDLED;
> > >   }
> > >   +/* handls vqs shared interrupt */
> > > +static irqreturn_t ifcvf_vq_shared_intr_handler(int irq, void *arg)
> > > +{
> > > +    struct ifcvf_hw *vf = arg;
> > > +    struct vring_info *vring;
> > > +    int i;
> > > +
> > > +    for (i = 0; i < vf->nr_vring; i++) {
> > > +        vring = &vf->vring[i];
> > > +        if (vring->cb.callback)
> > > + vf->vring->cb.callback(vring->cb.private);
> > > +    }
> > > +
> > > +    return IRQ_HANDLED;
> > > +}
> > > +
> > > +/* handles a shared interrupt for vqs and config */
> > > +static irqreturn_t ifcvf_dev_shared_intr_handler(int irq, void *arg)
> > > +{
> > > +    struct ifcvf_hw *vf = arg;
> > > +    u8 isr;
> > > +
> > > +    isr = ifc_ioread8(vf->isr);
> > 
> > 
> > We need to exactly what vp_interrupt do here. Checking against vf->isr
> > first and return IRQ_NONE if it is not set.
> > 
> > Always return IRQ_HANDLED will break the device who shares an irq with
> > IFCVF.
> as we discussed in another thread(spec inconsistency about ISR), ISR may
> only works for INTx for now,
> but VFs don't have INTx, and a VF may not share its vectors with other
> devices, so I guess it can work
> and may be our best try for now.
> > 
> > 
> > > +    if (isr & VIRTIO_PCI_ISR_CONFIG)
> > > +        ifcvf_config_changed(irq, arg);
> > > +
> > > +    return ifcvf_vq_shared_intr_handler(irq, arg);
> > > +}
> > > +
> > >   static void ifcvf_free_irq_vectors(void *data)
> > >   {
> > >       pci_free_irq_vectors(data);
> > >   }
> > >   -static void ifcvf_free_irq(struct ifcvf_adapter *adapter, int queues)
> > > +static void ifcvf_free_vq_irq(struct ifcvf_adapter *adapter, int
> > > queues)
> > >   {
> > >       struct pci_dev *pdev = adapter->pdev;
> > >       struct ifcvf_hw *vf = &adapter->vf;
> > >       int i;
> > >   +    if (vf->msix_vector_status == MSIX_VECTOR_PER_VQ_AND_CONFIG) {
> > > +        for (i = 0; i < queues; i++) {
> > > +            devm_free_irq(&pdev->dev, vf->vring[i].irq, &vf->vring[i]);
> > > +            vf->vring[i].irq = -EINVAL;
> > > +        }
> > > +    } else {
> > > +        devm_free_irq(&pdev->dev, vf->vqs_shared_irq, vf);
> > > +        vf->vqs_shared_irq = -EINVAL;
> > > +    }
> > > +}
> > >   -    for (i = 0; i < queues; i++) {
> > > -        devm_free_irq(&pdev->dev, vf->vring[i].irq, &vf->vring[i]);
> > > -        vf->vring[i].irq = -EINVAL;
> > > +static void ifcvf_free_config_irq(struct ifcvf_adapter *adapter)
> > > +{
> > > +    struct pci_dev *pdev = adapter->pdev;
> > > +    struct ifcvf_hw *vf = &adapter->vf;
> > > +
> > > +    /* If the irq is shared by all vqs and the config interrupt,
> > > +     * it is already freed in ifcvf_free_vq_irq, so here only
> > > +     * need to free config irq when msix_vector_status !=
> > > MSIX_VECTOR_DEV_SHARED
> > > +     */
> > > +    if (vf->msix_vector_status != MSIX_VECTOR_DEV_SHARED) {
> > > +        devm_free_irq(&pdev->dev, vf->config_irq, vf);
> > > +        vf->config_irq = -EINVAL;
> > >       }
> > > +}
> > > +
> > > +static void ifcvf_free_irq(struct ifcvf_adapter *adapter, int queues)
> > > +{
> > > +    struct pci_dev *pdev = adapter->pdev;
> > >   -    devm_free_irq(&pdev->dev, vf->config_irq, vf);
> > > +    ifcvf_free_vq_irq(adapter, queues);
> > > +    ifcvf_free_config_irq(adapter);
> > >       ifcvf_free_irq_vectors(pdev);
> > >   }
> > >   @@ -86,58 +142,172 @@ static int ifcvf_alloc_vectors(struct
> > > ifcvf_adapter *adapter)
> > >       return ret;
> > >   }
> > >   -static int ifcvf_request_irq(struct ifcvf_adapter *adapter)
> > > +static int ifcvf_request_per_vq_irq(struct ifcvf_adapter *adapter)
> > >   {
> > >       struct pci_dev *pdev = adapter->pdev;
> > >       struct ifcvf_hw *vf = &adapter->vf;
> > > -    int vector, nvectors, i, ret, irq;
> > > -    u16 max_intr;
> > > +    int i, vector, ret, irq;
> > >   -    nvectors = ifcvf_alloc_vectors(adapter);
> > > -    if (!(nvectors > 0))
> > > -        return nvectors;
> > > +    for (i = 0; i < vf->nr_vring; i++) {
> > > +        snprintf(vf->vring[i].msix_name, 256, "ifcvf[%s]-%d\n",
> > > pci_name(pdev), i);
> > > +        vector = i;
> > > +        irq = pci_irq_vector(pdev, vector);
> > > +        ret = devm_request_irq(&pdev->dev, irq,
> > > +                       ifcvf_intr_handler, 0,
> > > +                       vf->vring[i].msix_name,
> > > +                       &vf->vring[i]);
> > > +        if (ret) {
> > > +            IFCVF_ERR(pdev, "Failed to request irq for vq %d\n", i);
> > > +            ifcvf_free_vq_irq(adapter, i);
> > > +        } else {
> > > +            vf->vring[i].irq = irq;
> > > +            ifcvf_set_vq_vector(vf, i, vector);
> > > +        }
> > > +    }
> > >   -    max_intr = vf->nr_vring + 1;
> > > +    vf->vqs_shared_irq = -EINVAL;
> > > +
> > > +    return 0;
> > > +}
> > > +
> > > +static int ifcvf_request_shared_vq_irq(struct ifcvf_adapter *adapter)
> > > +{
> > > +    struct pci_dev *pdev = adapter->pdev;
> > > +    struct ifcvf_hw *vf = &adapter->vf;
> > > +    int i, vector, ret, irq;
> > > +
> > > +    vector = 0;
> > > +    /* reuse msix_name[256] space of vring0 to store shared vqs
> > > interrupt name */
> > 
> > 
> > I think we can remove this comment since the code is straightforward.
> sure
> > 
> > 
> > > + snprintf(vf->vring[0].msix_name, 256,
> > > "ifcvf[%s]-vqs-shared-irq\n", pci_name(pdev));
> > > +    irq = pci_irq_vector(pdev, vector);
> > > +    ret = devm_request_irq(&pdev->dev, irq,
> > > +                   ifcvf_vq_shared_intr_handler, 0,
> > > +                   vf->vring[0].msix_name, vf);
> > > +    if (ret) {
> > > +        IFCVF_ERR(pdev, "Failed to request shared irq for vf\n");
> > > +
> > > +        return ret;
> > > +    }
> > > +
> > > +    vf->vqs_shared_irq = irq;
> > > +    for (i = 0; i < vf->nr_vring; i++) {
> > > +        vf->vring[i].irq = -EINVAL;
> > > +        ifcvf_set_vq_vector(vf, i, vector);
> > > +    }
> > > +
> > > +    return 0;
> > > +
> > > +}
> > > +
> > > +static int ifcvf_request_dev_shared_irq(struct ifcvf_adapter *adapter)
> > > +{
> > > +    struct pci_dev *pdev = adapter->pdev;
> > > +    struct ifcvf_hw *vf = &adapter->vf;
> > > +    int i, vector, ret, irq;
> > > +
> > > +    vector = 0;
> > > +    /* reuse msix_name[256] space of vring0 to store shared device
> > > interrupt name */
> > > +    snprintf(vf->vring[0].msix_name, 256,
> > > "ifcvf[%s]-dev-shared-irq\n", pci_name(pdev));
> > > +    irq = pci_irq_vector(pdev, vector);
> > > +    ret = devm_request_irq(&pdev->dev, irq,
> > > +                   ifcvf_dev_shared_intr_handler, 0,
> > > +                   vf->vring[0].msix_name, vf);
> > > +    if (ret) {
> > > +        IFCVF_ERR(pdev, "Failed to request shared irq for vf\n");
> > >   -    ret = pci_alloc_irq_vectors(pdev, max_intr,
> > > -                    max_intr, PCI_IRQ_MSIX);
> > > -    if (ret < 0) {
> > > -        IFCVF_ERR(pdev, "Failed to alloc IRQ vectors\n");
> > >           return ret;
> > >       }
> > >   +    vf->vqs_shared_irq = irq;
> > > +    for (i = 0; i < vf->nr_vring; i++) {
> > > +        vf->vring[i].irq = -EINVAL;
> > > +        ifcvf_set_vq_vector(vf, i, vector);
> > > +    }
> > > +
> > > +    vf->config_irq = irq;
> > > +    ifcvf_set_config_vector(vf, vector);
> > > +
> > > +    return 0;
> > > +
> > > +}
> > > +
> > > +static int ifcvf_request_vq_irq(struct ifcvf_adapter *adapter)
> > > +{
> > > +    struct ifcvf_hw *vf = &adapter->vf;
> > > +    int ret;
> > > +
> > > +    if (vf->msix_vector_status == MSIX_VECTOR_PER_VQ_AND_CONFIG)
> > > +        ret = ifcvf_request_per_vq_irq(adapter);
> > > +    else
> > > +        ret = ifcvf_request_shared_vq_irq(adapter);
> > > +
> > > +    return ret;
> > > +}
> > > +
> > > +static int ifcvf_request_config_irq(struct ifcvf_adapter *adapter)
> > > +{
> > > +    struct pci_dev *pdev = adapter->pdev;
> > > +    struct ifcvf_hw *vf = &adapter->vf;
> > > +    int config_vector, ret;
> > > +
> > > +    if (vf->msix_vector_status == MSIX_VECTOR_DEV_SHARED)
> > > +        return 0;
> > > +
> > > +    if (vf->msix_vector_status == MSIX_VECTOR_PER_VQ_AND_CONFIG)
> > > +        /* vector 0 ~ vf->nr_vring for vqs, num vf->nr_vring vector
> > > for config interrupt */
> > > +        config_vector = vf->nr_vring;
> > > +
> > > +    if (vf->msix_vector_status == MSIX_VECTOR_SHARED_VQ_AND_CONFIG)
> > > +        /* vector 0 for vqs and 1 for config interrupt */
> > > +        config_vector = 1;
> > > +
> > >       snprintf(vf->config_msix_name, 256, "ifcvf[%s]-config\n",
> > >            pci_name(pdev));
> > > -    vector = 0;
> > > -    vf->config_irq = pci_irq_vector(pdev, vector);
> > > +    vf->config_irq = pci_irq_vector(pdev, config_vector);
> > >       ret = devm_request_irq(&pdev->dev, vf->config_irq,
> > >                      ifcvf_config_changed, 0,
> > >                      vf->config_msix_name, vf);
> > >       if (ret) {
> > >           IFCVF_ERR(pdev, "Failed to request config irq\n");
> > > +        ifcvf_free_vq_irq(adapter, vf->nr_vring);
> > >           return ret;
> > >       }
> > >   -    for (i = 0; i < vf->nr_vring; i++) {
> > > -        snprintf(vf->vring[i].msix_name, 256, "ifcvf[%s]-%d\n",
> > > -             pci_name(pdev), i);
> > > -        vector = i + IFCVF_MSI_QUEUE_OFF;
> > > -        irq = pci_irq_vector(pdev, vector);
> > > -        ret = devm_request_irq(&pdev->dev, irq,
> > > -                       ifcvf_intr_handler, 0,
> > > -                       vf->vring[i].msix_name,
> > > -                       &vf->vring[i]);
> > > -        if (ret) {
> > > -            IFCVF_ERR(pdev,
> > > -                  "Failed to request irq for vq %d\n", i);
> > > -            ifcvf_free_irq(adapter, i);
> > > +    ifcvf_set_config_vector(vf, config_vector);
> > >   -            return ret;
> > > -        }
> > > +    return 0;
> > > +}
> > > +
> > > +static int ifcvf_request_irq(struct ifcvf_adapter *adapter)
> > > +{
> > 
> > 
> > As replied above, I think having two modes should be sufficient and the
> > code could be greatly simplified.
> Do you mean if we don't get enough vectors, just use only one vector for the
> vqs and config changes? I guess this
> only works if ISR work for MSIX as we expects, or we may waste some time in
> the device config space.
> 
> Thanks,
> Zhu Lingshan
> > 
> > Thanks
> > 
> > 
> > > +    struct ifcvf_hw *vf = &adapter->vf;
> > > +    int nvectors, ret, max_intr;
> > >   -        vf->vring[i].irq = irq;
> > > +    nvectors = ifcvf_alloc_vectors(adapter);
> > > +    if (!(nvectors > 0))
> > > +        return nvectors;
> > > +
> > > +    vf->msix_vector_status = MSIX_VECTOR_PER_VQ_AND_CONFIG;
> > > +    max_intr = vf->nr_vring + 1;
> > > +    if (nvectors < max_intr)
> > > +        vf->msix_vector_status = MSIX_VECTOR_SHARED_VQ_AND_CONFIG;
> > > +
> > > +    if (nvectors == 1) {
> > > +        vf->msix_vector_status = MSIX_VECTOR_DEV_SHARED;
> > > +        ret = ifcvf_request_dev_shared_irq(adapter);
> > > +
> > > +        return ret;
> > >       }
> > >   +    ret = ifcvf_request_vq_irq(adapter);
> > > +    if (ret)
> > > +        return ret;
> > > +
> > > +    ret = ifcvf_request_config_irq(adapter);
> > > +
> > > +    if (ret)
> > > +        return ret;
> > > +
> > >       return 0;
> > >   }
> > >   @@ -441,7 +611,10 @@ static int ifcvf_vdpa_get_vq_irq(struct
> > > vdpa_device *vdpa_dev,
> > >   {
> > >       struct ifcvf_hw *vf = vdpa_to_vf(vdpa_dev);
> > >   -    return vf->vring[qid].irq;
> > > +    if (vf->vqs_shared_irq < 0)
> > > +        return vf->vring[qid].irq;
> > > +    else
> > > +        return -EINVAL;
> > >   }
> > >     static struct vdpa_notification_area
> > > ifcvf_get_vq_notification(struct vdpa_device *vdpa_dev,
> > 
> > _______________________________________________
> > Virtualization mailing list
> > Virtualization@lists.linux-foundation.org
> > https://lists.linuxfoundation.org/mailman/listinfo/virtualization

Re: [PATCH V4 4/4] vDPA/ifcvf: implement shared IRQ feature

[Zhu, Lingshan]

On 2/14/2022 10:27 PM, Michael S. Tsirkin wrote:
> On Mon, Feb 14, 2022 at 06:01:56PM +0800, Zhu Lingshan wrote:
>>
>> On 2/14/2022 3:19 PM, Jason Wang wrote:
>>> 在 2022/2/3 下午3:27, Zhu Lingshan 写道:
>>>> On some platforms/devices, there may not be enough MSI vector
>>>> slots allocated for virtqueues and config changes. In such a case,
>>>> the interrupt sources(virtqueues, config changes) must share
>>>> an IRQ/vector, to avoid initialization failures, keep
>>>> the device functional.
>>>>
>>>> This commit handles three cases:
>>>> (1) number of the allocated vectors == the number of virtqueues + 1
>>>> (config changes), every virtqueue and the config interrupt has
>>>> a separated vector/IRQ, the best and the most likely case.
>>>> (2) number of the allocated vectors is less than the best case, but
>>>> greater than 1. In this case, all virtqueues share a vector/IRQ,
>>>> the config interrupt has a separated vector/IRQ
>>>> (3) only one vector is allocated, in this case, the virtqueues and
>>>> the config interrupt share a vector/IRQ. The worst and most
>>>> unlikely case.
>>>>
>>>> Otherwise, it needs to fail.
>>>>
>>>> This commit introduces some helper functions:
>>>> ifcvf_set_vq_vector() and ifcvf_set_config_vector() sets virtqueue
>>>> vector and config vector in the device config space, so that
>>>> the device can send interrupt DMA.
>>>>
>>>> This commit adds some fields in struct ifcvf_hw and re-placed
>>>> the existed fields to be aligned with the cacheline.
>>>>
>>>> Signed-off-by: Zhu Lingshan <lingshan.zhu@intel.com>
>>>> ---
>>>>    drivers/vdpa/ifcvf/ifcvf_base.c |  47 ++++--
>>>>    drivers/vdpa/ifcvf/ifcvf_base.h |  23 ++-
>>>>    drivers/vdpa/ifcvf/ifcvf_main.c | 243 +++++++++++++++++++++++++++-----
>>>>    3 files changed, 256 insertions(+), 57 deletions(-)
>>>>
>>>> diff --git a/drivers/vdpa/ifcvf/ifcvf_base.c
>>>> b/drivers/vdpa/ifcvf/ifcvf_base.c
>>>> index 397692ae671c..18dcb63ab1e3 100644
>>>> --- a/drivers/vdpa/ifcvf/ifcvf_base.c
>>>> +++ b/drivers/vdpa/ifcvf/ifcvf_base.c
>>>> @@ -15,6 +15,36 @@ struct ifcvf_adapter *vf_to_adapter(struct
>>>> ifcvf_hw *hw)
>>>>        return container_of(hw, struct ifcvf_adapter, vf);
>>>>    }
>>>>    +int ifcvf_set_vq_vector(struct ifcvf_hw *hw, u16 qid, int vector)
>>>> +{
>>>> +    struct virtio_pci_common_cfg __iomem *cfg = hw->common_cfg;
>>>> +    struct ifcvf_adapter *ifcvf = vf_to_adapter(hw);
>>>> +
>>>> +    ifc_iowrite16(qid, &cfg->queue_select);
>>>> +    ifc_iowrite16(vector, &cfg->queue_msix_vector);
>>>> +    if (ifc_ioread16(&cfg->queue_msix_vector) ==
>>>> VIRTIO_MSI_NO_VECTOR) {
>>>> +        IFCVF_ERR(ifcvf->pdev, "No msix vector for queue %u\n", qid);
>>>> +            return -EINVAL;
>>>> +    }
>>>
>>> Let's leave this check for the caller, E.g can caller try to assign
>>> NO_VECTOR during uni-nit?
>> ifcvf driver sets NO_VECTOR when call hw_disable(). I am not sure whether I
>> get it,
>> Yes we can let the caller check a vq vector, however this may cause more
>> than three levels brackets, may looks ugly.
>>>
>>>> +
>>>> +    return 0;
>>>> +}
>>>> +
>>>> +int ifcvf_set_config_vector(struct ifcvf_hw *hw, int vector)
>>>> +{
>>>> +    struct virtio_pci_common_cfg __iomem *cfg = hw->common_cfg;
>>>> +    struct ifcvf_adapter *ifcvf = vf_to_adapter(hw);
>>>> +
>>>> +    cfg = hw->common_cfg;
>>>> +    ifc_iowrite16(vector,  &cfg->msix_config);
>>>> +    if (ifc_ioread16(&cfg->msix_config) == VIRTIO_MSI_NO_VECTOR) {
>>>> +        IFCVF_ERR(ifcvf->pdev, "No msix vector for device config\n");
>>>> +        return -EINVAL;
>>>> +    }
>>>
>>> Similar question as above.
>>>
>>>
>>>> +
>>>> +    return 0;
>>>> +}
>>>> +
>>>>    static void __iomem *get_cap_addr(struct ifcvf_hw *hw,
>>>>                      struct virtio_pci_cap *cap)
>>>>    {
>>>> @@ -140,6 +170,8 @@ int ifcvf_init_hw(struct ifcvf_hw *hw, struct
>>>> pci_dev *pdev)
>>>>              hw->common_cfg, hw->notify_base, hw->isr,
>>>>              hw->dev_cfg, hw->notify_off_multiplier);
>>>>    +    hw->vqs_shared_irq = -EINVAL;
>>>> +
>>>>        return 0;
>>>>    }
>>>>    @@ -321,12 +353,6 @@ static int ifcvf_hw_enable(struct ifcvf_hw *hw)
>>>>          ifcvf = vf_to_adapter(hw);
>>>>        cfg = hw->common_cfg;
>>>> -    ifc_iowrite16(IFCVF_MSI_CONFIG_OFF, &cfg->msix_config);
>>>> -
>>>> -    if (ifc_ioread16(&cfg->msix_config) == VIRTIO_MSI_NO_VECTOR) {
>>>> -        IFCVF_ERR(ifcvf->pdev, "No msix vector for device config\n");
>>>> -        return -EINVAL;
>>>> -    }
>>>>          for (i = 0; i < hw->nr_vring; i++) {
>>>>            if (!hw->vring[i].ready)
>>>> @@ -340,15 +366,6 @@ static int ifcvf_hw_enable(struct ifcvf_hw *hw)
>>>>            ifc_iowrite64_twopart(hw->vring[i].used, &cfg->queue_used_lo,
>>>>                         &cfg->queue_used_hi);
>>>>            ifc_iowrite16(hw->vring[i].size, &cfg->queue_size);
>>>> -        ifc_iowrite16(i + IFCVF_MSI_QUEUE_OFF,
>>>> &cfg->queue_msix_vector);
>>>> -
>>>> -        if (ifc_ioread16(&cfg->queue_msix_vector) ==
>>>> -            VIRTIO_MSI_NO_VECTOR) {
>>>> -            IFCVF_ERR(ifcvf->pdev,
>>>> -                  "No msix vector for queue %u\n", i);
>>>> -            return -EINVAL;
>>>> -        }
>>>> -
>>>>            ifcvf_set_vq_state(hw, i, hw->vring[i].last_avail_idx);
>>>>            ifc_iowrite16(1, &cfg->queue_enable);
>>>>        }
>>>> diff --git a/drivers/vdpa/ifcvf/ifcvf_base.h
>>>> b/drivers/vdpa/ifcvf/ifcvf_base.h
>>>> index 949b4fb9d554..9cfe088c82e9 100644
>>>> --- a/drivers/vdpa/ifcvf/ifcvf_base.h
>>>> +++ b/drivers/vdpa/ifcvf/ifcvf_base.h
>>>> @@ -27,8 +27,6 @@
>>>>      #define IFCVF_QUEUE_ALIGNMENT    PAGE_SIZE
>>>>    #define IFCVF_QUEUE_MAX        32768
>>>> -#define IFCVF_MSI_CONFIG_OFF    0
>>>> -#define IFCVF_MSI_QUEUE_OFF    1
>>>>    #define IFCVF_PCI_MAX_RESOURCE    6
>>>>      #define IFCVF_LM_CFG_SIZE        0x40
>>>> @@ -42,6 +40,13 @@
>>>>    #define ifcvf_private_to_vf(adapter) \
>>>>        (&((struct ifcvf_adapter *)adapter)->vf)
>>>>    +/* all vqs and config interrupt has its own vector */
>>>> +#define MSIX_VECTOR_PER_VQ_AND_CONFIG        1
>>>> +/* all vqs share a vector, and config interrupt has a separate
>>>> vector */
>>>> +#define MSIX_VECTOR_SHARED_VQ_AND_CONFIG    2
>>>> +/* all vqs and config interrupt share a vector */
>>>> +#define MSIX_VECTOR_DEV_SHARED            3
>>>
>>> I think there's no much value to differ 2 from 3 consider config
>>> interrupt should be rare.
>> IMHO we still need 2 and 3, because MSIX_VECTOR_SHARED_VQ_AND_CONFIG means
>> there are at least 2 vectors,
>> the vqs share one vector, config change has its own vector.
>> MSIX_VECTOR_DEV_SHARED means three are only one vector, all vqs and config
>> changes need to share this vector.
>>>
>>>
>>>> +
>>>>    static inline u8 ifc_ioread8(u8 __iomem *addr)
>>>>    {
>>>>        return ioread8(addr);
>>>> @@ -97,25 +102,27 @@ struct ifcvf_hw {
>>>>        u8 __iomem *isr;
>>>>        /* Live migration */
>>>>        u8 __iomem *lm_cfg;
>>>> -    u16 nr_vring;
>>>
>>> Any reason for moving nv_vring, config_size, and other stuffs?
>> for cacheline alignment.
> maybe a separate patch then.
Sure

Thanks!
>
>>>
>>>
>>>>        /* Notification bar number */
>>>>        u8 notify_bar;
>>>> +    u8 msix_vector_status;
>>>> +    /* virtio-net or virtio-blk device config size */
>>>> +    u32 config_size;
>>>>        /* Notificaiton bar address */
>>>>        void __iomem *notify_base;
>>>>        phys_addr_t notify_base_pa;
>>>>        u32 notify_off_multiplier;
>>>> +    u32 dev_type;
>>>>        u64 req_features;
>>>>        u64 hw_features;
>>>> -    u32 dev_type;
>>>>        struct virtio_pci_common_cfg __iomem *common_cfg;
>>>>        void __iomem *dev_cfg;
>>>>        struct vring_info vring[IFCVF_MAX_QUEUES];
>>>>        void __iomem * const *base;
>>>>        char config_msix_name[256];
>>>>        struct vdpa_callback config_cb;
>>>> -    unsigned int config_irq;
>>>> -    /* virtio-net or virtio-blk device config size */
>>>> -    u32 config_size;
>>>> +    int config_irq;
>>>> +    int vqs_shared_irq;
>>>> +    u16 nr_vring;
>>>>    };
>>>>      struct ifcvf_adapter {
>>>> @@ -160,4 +167,6 @@ int ifcvf_set_vq_state(struct ifcvf_hw *hw, u16
>>>> qid, u16 num);
>>>>    struct ifcvf_adapter *vf_to_adapter(struct ifcvf_hw *hw);
>>>>    int ifcvf_probed_virtio_net(struct ifcvf_hw *hw);
>>>>    u32 ifcvf_get_config_size(struct ifcvf_hw *hw);
>>>> +int ifcvf_set_vq_vector(struct ifcvf_hw *hw, u16 qid, int vector);
>>>> +int ifcvf_set_config_vector(struct ifcvf_hw *hw, int vector);
>>>>    #endif /* _IFCVF_H_ */
>>>> diff --git a/drivers/vdpa/ifcvf/ifcvf_main.c
>>>> b/drivers/vdpa/ifcvf/ifcvf_main.c
>>>> index 44c89ab0b6da..ca414399f040 100644
>>>> --- a/drivers/vdpa/ifcvf/ifcvf_main.c
>>>> +++ b/drivers/vdpa/ifcvf/ifcvf_main.c
>>>> @@ -17,6 +17,7 @@
>>>>    #define DRIVER_AUTHOR   "Intel Corporation"
>>>>    #define IFCVF_DRIVER_NAME       "ifcvf"
>>>>    +/* handles config interrupt */
>>>
>>> This seems unrelated to the shared IRQ logic and it looks useless since
>>> it's easily to deduce it from the function name below.
>> OK, do you mean the comments? I can remove these comments.
>>>
>>>>    static irqreturn_t ifcvf_config_changed(int irq, void *arg)
>>>>    {
>>>>        struct ifcvf_hw *vf = arg;
>>>> @@ -27,6 +28,7 @@ static irqreturn_t ifcvf_config_changed(int irq,
>>>> void *arg)
>>>>        return IRQ_HANDLED;
>>>>    }
>>>>    +/* handles vqs interrupt */
>>>
>>> So did this.
>>>
>>>
>>>>    static irqreturn_t ifcvf_intr_handler(int irq, void *arg)
>>>>    {
>>>>        struct vring_info *vring = arg;
>>>> @@ -37,24 +39,78 @@ static irqreturn_t ifcvf_intr_handler(int irq,
>>>> void *arg)
>>>>        return IRQ_HANDLED;
>>>>    }
>>>>    +/* handls vqs shared interrupt */
>>>> +static irqreturn_t ifcvf_vq_shared_intr_handler(int irq, void *arg)
>>>> +{
>>>> +    struct ifcvf_hw *vf = arg;
>>>> +    struct vring_info *vring;
>>>> +    int i;
>>>> +
>>>> +    for (i = 0; i < vf->nr_vring; i++) {
>>>> +        vring = &vf->vring[i];
>>>> +        if (vring->cb.callback)
>>>> + vf->vring->cb.callback(vring->cb.private);
>>>> +    }
>>>> +
>>>> +    return IRQ_HANDLED;
>>>> +}
>>>> +
>>>> +/* handles a shared interrupt for vqs and config */
>>>> +static irqreturn_t ifcvf_dev_shared_intr_handler(int irq, void *arg)
>>>> +{
>>>> +    struct ifcvf_hw *vf = arg;
>>>> +    u8 isr;
>>>> +
>>>> +    isr = ifc_ioread8(vf->isr);
>>>
>>> We need to exactly what vp_interrupt do here. Checking against vf->isr
>>> first and return IRQ_NONE if it is not set.
>>>
>>> Always return IRQ_HANDLED will break the device who shares an irq with
>>> IFCVF.
>> as we discussed in another thread(spec inconsistency about ISR), ISR may
>> only works for INTx for now,
>> but VFs don't have INTx, and a VF may not share its vectors with other
>> devices, so I guess it can work
>> and may be our best try for now.
>>>
>>>> +    if (isr & VIRTIO_PCI_ISR_CONFIG)
>>>> +        ifcvf_config_changed(irq, arg);
>>>> +
>>>> +    return ifcvf_vq_shared_intr_handler(irq, arg);
>>>> +}
>>>> +
>>>>    static void ifcvf_free_irq_vectors(void *data)
>>>>    {
>>>>        pci_free_irq_vectors(data);
>>>>    }
>>>>    -static void ifcvf_free_irq(struct ifcvf_adapter *adapter, int queues)
>>>> +static void ifcvf_free_vq_irq(struct ifcvf_adapter *adapter, int
>>>> queues)
>>>>    {
>>>>        struct pci_dev *pdev = adapter->pdev;
>>>>        struct ifcvf_hw *vf = &adapter->vf;
>>>>        int i;
>>>>    +    if (vf->msix_vector_status == MSIX_VECTOR_PER_VQ_AND_CONFIG) {
>>>> +        for (i = 0; i < queues; i++) {
>>>> +            devm_free_irq(&pdev->dev, vf->vring[i].irq, &vf->vring[i]);
>>>> +            vf->vring[i].irq = -EINVAL;
>>>> +        }
>>>> +    } else {
>>>> +        devm_free_irq(&pdev->dev, vf->vqs_shared_irq, vf);
>>>> +        vf->vqs_shared_irq = -EINVAL;
>>>> +    }
>>>> +}
>>>>    -    for (i = 0; i < queues; i++) {
>>>> -        devm_free_irq(&pdev->dev, vf->vring[i].irq, &vf->vring[i]);
>>>> -        vf->vring[i].irq = -EINVAL;
>>>> +static void ifcvf_free_config_irq(struct ifcvf_adapter *adapter)
>>>> +{
>>>> +    struct pci_dev *pdev = adapter->pdev;
>>>> +    struct ifcvf_hw *vf = &adapter->vf;
>>>> +
>>>> +    /* If the irq is shared by all vqs and the config interrupt,
>>>> +     * it is already freed in ifcvf_free_vq_irq, so here only
>>>> +     * need to free config irq when msix_vector_status !=
>>>> MSIX_VECTOR_DEV_SHARED
>>>> +     */
>>>> +    if (vf->msix_vector_status != MSIX_VECTOR_DEV_SHARED) {
>>>> +        devm_free_irq(&pdev->dev, vf->config_irq, vf);
>>>> +        vf->config_irq = -EINVAL;
>>>>        }
>>>> +}
>>>> +
>>>> +static void ifcvf_free_irq(struct ifcvf_adapter *adapter, int queues)
>>>> +{
>>>> +    struct pci_dev *pdev = adapter->pdev;
>>>>    -    devm_free_irq(&pdev->dev, vf->config_irq, vf);
>>>> +    ifcvf_free_vq_irq(adapter, queues);
>>>> +    ifcvf_free_config_irq(adapter);
>>>>        ifcvf_free_irq_vectors(pdev);
>>>>    }
>>>>    @@ -86,58 +142,172 @@ static int ifcvf_alloc_vectors(struct
>>>> ifcvf_adapter *adapter)
>>>>        return ret;
>>>>    }
>>>>    -static int ifcvf_request_irq(struct ifcvf_adapter *adapter)
>>>> +static int ifcvf_request_per_vq_irq(struct ifcvf_adapter *adapter)
>>>>    {
>>>>        struct pci_dev *pdev = adapter->pdev;
>>>>        struct ifcvf_hw *vf = &adapter->vf;
>>>> -    int vector, nvectors, i, ret, irq;
>>>> -    u16 max_intr;
>>>> +    int i, vector, ret, irq;
>>>>    -    nvectors = ifcvf_alloc_vectors(adapter);
>>>> -    if (!(nvectors > 0))
>>>> -        return nvectors;
>>>> +    for (i = 0; i < vf->nr_vring; i++) {
>>>> +        snprintf(vf->vring[i].msix_name, 256, "ifcvf[%s]-%d\n",
>>>> pci_name(pdev), i);
>>>> +        vector = i;
>>>> +        irq = pci_irq_vector(pdev, vector);
>>>> +        ret = devm_request_irq(&pdev->dev, irq,
>>>> +                       ifcvf_intr_handler, 0,
>>>> +                       vf->vring[i].msix_name,
>>>> +                       &vf->vring[i]);
>>>> +        if (ret) {
>>>> +            IFCVF_ERR(pdev, "Failed to request irq for vq %d\n", i);
>>>> +            ifcvf_free_vq_irq(adapter, i);
>>>> +        } else {
>>>> +            vf->vring[i].irq = irq;
>>>> +            ifcvf_set_vq_vector(vf, i, vector);
>>>> +        }
>>>> +    }
>>>>    -    max_intr = vf->nr_vring + 1;
>>>> +    vf->vqs_shared_irq = -EINVAL;
>>>> +
>>>> +    return 0;
>>>> +}
>>>> +
>>>> +static int ifcvf_request_shared_vq_irq(struct ifcvf_adapter *adapter)
>>>> +{
>>>> +    struct pci_dev *pdev = adapter->pdev;
>>>> +    struct ifcvf_hw *vf = &adapter->vf;
>>>> +    int i, vector, ret, irq;
>>>> +
>>>> +    vector = 0;
>>>> +    /* reuse msix_name[256] space of vring0 to store shared vqs
>>>> interrupt name */
>>>
>>> I think we can remove this comment since the code is straightforward.
>> sure
>>>
>>>> + snprintf(vf->vring[0].msix_name, 256,
>>>> "ifcvf[%s]-vqs-shared-irq\n", pci_name(pdev));
>>>> +    irq = pci_irq_vector(pdev, vector);
>>>> +    ret = devm_request_irq(&pdev->dev, irq,
>>>> +                   ifcvf_vq_shared_intr_handler, 0,
>>>> +                   vf->vring[0].msix_name, vf);
>>>> +    if (ret) {
>>>> +        IFCVF_ERR(pdev, "Failed to request shared irq for vf\n");
>>>> +
>>>> +        return ret;
>>>> +    }
>>>> +
>>>> +    vf->vqs_shared_irq = irq;
>>>> +    for (i = 0; i < vf->nr_vring; i++) {
>>>> +        vf->vring[i].irq = -EINVAL;
>>>> +        ifcvf_set_vq_vector(vf, i, vector);
>>>> +    }
>>>> +
>>>> +    return 0;
>>>> +
>>>> +}
>>>> +
>>>> +static int ifcvf_request_dev_shared_irq(struct ifcvf_adapter *adapter)
>>>> +{
>>>> +    struct pci_dev *pdev = adapter->pdev;
>>>> +    struct ifcvf_hw *vf = &adapter->vf;
>>>> +    int i, vector, ret, irq;
>>>> +
>>>> +    vector = 0;
>>>> +    /* reuse msix_name[256] space of vring0 to store shared device
>>>> interrupt name */
>>>> +    snprintf(vf->vring[0].msix_name, 256,
>>>> "ifcvf[%s]-dev-shared-irq\n", pci_name(pdev));
>>>> +    irq = pci_irq_vector(pdev, vector);
>>>> +    ret = devm_request_irq(&pdev->dev, irq,
>>>> +                   ifcvf_dev_shared_intr_handler, 0,
>>>> +                   vf->vring[0].msix_name, vf);
>>>> +    if (ret) {
>>>> +        IFCVF_ERR(pdev, "Failed to request shared irq for vf\n");
>>>>    -    ret = pci_alloc_irq_vectors(pdev, max_intr,
>>>> -                    max_intr, PCI_IRQ_MSIX);
>>>> -    if (ret < 0) {
>>>> -        IFCVF_ERR(pdev, "Failed to alloc IRQ vectors\n");
>>>>            return ret;
>>>>        }
>>>>    +    vf->vqs_shared_irq = irq;
>>>> +    for (i = 0; i < vf->nr_vring; i++) {
>>>> +        vf->vring[i].irq = -EINVAL;
>>>> +        ifcvf_set_vq_vector(vf, i, vector);
>>>> +    }
>>>> +
>>>> +    vf->config_irq = irq;
>>>> +    ifcvf_set_config_vector(vf, vector);
>>>> +
>>>> +    return 0;
>>>> +
>>>> +}
>>>> +
>>>> +static int ifcvf_request_vq_irq(struct ifcvf_adapter *adapter)
>>>> +{
>>>> +    struct ifcvf_hw *vf = &adapter->vf;
>>>> +    int ret;
>>>> +
>>>> +    if (vf->msix_vector_status == MSIX_VECTOR_PER_VQ_AND_CONFIG)
>>>> +        ret = ifcvf_request_per_vq_irq(adapter);
>>>> +    else
>>>> +        ret = ifcvf_request_shared_vq_irq(adapter);
>>>> +
>>>> +    return ret;
>>>> +}
>>>> +
>>>> +static int ifcvf_request_config_irq(struct ifcvf_adapter *adapter)
>>>> +{
>>>> +    struct pci_dev *pdev = adapter->pdev;
>>>> +    struct ifcvf_hw *vf = &adapter->vf;
>>>> +    int config_vector, ret;
>>>> +
>>>> +    if (vf->msix_vector_status == MSIX_VECTOR_DEV_SHARED)
>>>> +        return 0;
>>>> +
>>>> +    if (vf->msix_vector_status == MSIX_VECTOR_PER_VQ_AND_CONFIG)
>>>> +        /* vector 0 ~ vf->nr_vring for vqs, num vf->nr_vring vector
>>>> for config interrupt */
>>>> +        config_vector = vf->nr_vring;
>>>> +
>>>> +    if (vf->msix_vector_status == MSIX_VECTOR_SHARED_VQ_AND_CONFIG)
>>>> +        /* vector 0 for vqs and 1 for config interrupt */
>>>> +        config_vector = 1;
>>>> +
>>>>        snprintf(vf->config_msix_name, 256, "ifcvf[%s]-config\n",
>>>>             pci_name(pdev));
>>>> -    vector = 0;
>>>> -    vf->config_irq = pci_irq_vector(pdev, vector);
>>>> +    vf->config_irq = pci_irq_vector(pdev, config_vector);
>>>>        ret = devm_request_irq(&pdev->dev, vf->config_irq,
>>>>                       ifcvf_config_changed, 0,
>>>>                       vf->config_msix_name, vf);
>>>>        if (ret) {
>>>>            IFCVF_ERR(pdev, "Failed to request config irq\n");
>>>> +        ifcvf_free_vq_irq(adapter, vf->nr_vring);
>>>>            return ret;
>>>>        }
>>>>    -    for (i = 0; i < vf->nr_vring; i++) {
>>>> -        snprintf(vf->vring[i].msix_name, 256, "ifcvf[%s]-%d\n",
>>>> -             pci_name(pdev), i);
>>>> -        vector = i + IFCVF_MSI_QUEUE_OFF;
>>>> -        irq = pci_irq_vector(pdev, vector);
>>>> -        ret = devm_request_irq(&pdev->dev, irq,
>>>> -                       ifcvf_intr_handler, 0,
>>>> -                       vf->vring[i].msix_name,
>>>> -                       &vf->vring[i]);
>>>> -        if (ret) {
>>>> -            IFCVF_ERR(pdev,
>>>> -                  "Failed to request irq for vq %d\n", i);
>>>> -            ifcvf_free_irq(adapter, i);
>>>> +    ifcvf_set_config_vector(vf, config_vector);
>>>>    -            return ret;
>>>> -        }
>>>> +    return 0;
>>>> +}
>>>> +
>>>> +static int ifcvf_request_irq(struct ifcvf_adapter *adapter)
>>>> +{
>>>
>>> As replied above, I think having two modes should be sufficient and the
>>> code could be greatly simplified.
>> Do you mean if we don't get enough vectors, just use only one vector for the
>> vqs and config changes? I guess this
>> only works if ISR work for MSIX as we expects, or we may waste some time in
>> the device config space.
>>
>> Thanks,
>> Zhu Lingshan
>>> Thanks
>>>
>>>
>>>> +    struct ifcvf_hw *vf = &adapter->vf;
>>>> +    int nvectors, ret, max_intr;
>>>>    -        vf->vring[i].irq = irq;
>>>> +    nvectors = ifcvf_alloc_vectors(adapter);
>>>> +    if (!(nvectors > 0))
>>>> +        return nvectors;
>>>> +
>>>> +    vf->msix_vector_status = MSIX_VECTOR_PER_VQ_AND_CONFIG;
>>>> +    max_intr = vf->nr_vring + 1;
>>>> +    if (nvectors < max_intr)
>>>> +        vf->msix_vector_status = MSIX_VECTOR_SHARED_VQ_AND_CONFIG;
>>>> +
>>>> +    if (nvectors == 1) {
>>>> +        vf->msix_vector_status = MSIX_VECTOR_DEV_SHARED;
>>>> +        ret = ifcvf_request_dev_shared_irq(adapter);
>>>> +
>>>> +        return ret;
>>>>        }
>>>>    +    ret = ifcvf_request_vq_irq(adapter);
>>>> +    if (ret)
>>>> +        return ret;
>>>> +
>>>> +    ret = ifcvf_request_config_irq(adapter);
>>>> +
>>>> +    if (ret)
>>>> +        return ret;
>>>> +
>>>>        return 0;
>>>>    }
>>>>    @@ -441,7 +611,10 @@ static int ifcvf_vdpa_get_vq_irq(struct
>>>> vdpa_device *vdpa_dev,
>>>>    {
>>>>        struct ifcvf_hw *vf = vdpa_to_vf(vdpa_dev);
>>>>    -    return vf->vring[qid].irq;
>>>> +    if (vf->vqs_shared_irq < 0)
>>>> +        return vf->vring[qid].irq;
>>>> +    else
>>>> +        return -EINVAL;
>>>>    }
>>>>      static struct vdpa_notification_area
>>>> ifcvf_get_vq_notification(struct vdpa_device *vdpa_dev,
>>> _______________________________________________
>>> Virtualization mailing list
>>> Virtualization@lists.linux-foundation.org
>>> https://lists.linuxfoundation.org/mailman/listinfo/virtualization

Re: [PATCH V4 4/4] vDPA/ifcvf: implement shared IRQ feature

[Jason Wang]

On Tue, Feb 15, 2022 at 10:18 AM Zhu, Lingshan <lingshan.zhu@intel.com> wrote:
>
>
>
> On 2/14/2022 10:27 PM, Michael S. Tsirkin wrote:
> > On Mon, Feb 14, 2022 at 06:01:56PM +0800, Zhu Lingshan wrote:
> >>
> >> On 2/14/2022 3:19 PM, Jason Wang wrote:
> >>> 在 2022/2/3 下午3:27, Zhu Lingshan 写道:
> >>>> On some platforms/devices, there may not be enough MSI vector
> >>>> slots allocated for virtqueues and config changes. In such a case,
> >>>> the interrupt sources(virtqueues, config changes) must share
> >>>> an IRQ/vector, to avoid initialization failures, keep
> >>>> the device functional.
> >>>>
> >>>> This commit handles three cases:
> >>>> (1) number of the allocated vectors == the number of virtqueues + 1
> >>>> (config changes), every virtqueue and the config interrupt has
> >>>> a separated vector/IRQ, the best and the most likely case.
> >>>> (2) number of the allocated vectors is less than the best case, but
> >>>> greater than 1. In this case, all virtqueues share a vector/IRQ,
> >>>> the config interrupt has a separated vector/IRQ
> >>>> (3) only one vector is allocated, in this case, the virtqueues and
> >>>> the config interrupt share a vector/IRQ. The worst and most
> >>>> unlikely case.
> >>>>
> >>>> Otherwise, it needs to fail.
> >>>>
> >>>> This commit introduces some helper functions:
> >>>> ifcvf_set_vq_vector() and ifcvf_set_config_vector() sets virtqueue
> >>>> vector and config vector in the device config space, so that
> >>>> the device can send interrupt DMA.
> >>>>
> >>>> This commit adds some fields in struct ifcvf_hw and re-placed
> >>>> the existed fields to be aligned with the cacheline.
> >>>>
> >>>> Signed-off-by: Zhu Lingshan <lingshan.zhu@intel.com>
> >>>> ---
> >>>>    drivers/vdpa/ifcvf/ifcvf_base.c |  47 ++++--
> >>>>    drivers/vdpa/ifcvf/ifcvf_base.h |  23 ++-
> >>>>    drivers/vdpa/ifcvf/ifcvf_main.c | 243 +++++++++++++++++++++++++++-----
> >>>>    3 files changed, 256 insertions(+), 57 deletions(-)
> >>>>
> >>>> diff --git a/drivers/vdpa/ifcvf/ifcvf_base.c
> >>>> b/drivers/vdpa/ifcvf/ifcvf_base.c
> >>>> index 397692ae671c..18dcb63ab1e3 100644
> >>>> --- a/drivers/vdpa/ifcvf/ifcvf_base.c
> >>>> +++ b/drivers/vdpa/ifcvf/ifcvf_base.c
> >>>> @@ -15,6 +15,36 @@ struct ifcvf_adapter *vf_to_adapter(struct
> >>>> ifcvf_hw *hw)
> >>>>        return container_of(hw, struct ifcvf_adapter, vf);
> >>>>    }
> >>>>    +int ifcvf_set_vq_vector(struct ifcvf_hw *hw, u16 qid, int vector)
> >>>> +{
> >>>> +    struct virtio_pci_common_cfg __iomem *cfg = hw->common_cfg;
> >>>> +    struct ifcvf_adapter *ifcvf = vf_to_adapter(hw);
> >>>> +
> >>>> +    ifc_iowrite16(qid, &cfg->queue_select);
> >>>> +    ifc_iowrite16(vector, &cfg->queue_msix_vector);
> >>>> +    if (ifc_ioread16(&cfg->queue_msix_vector) ==
> >>>> VIRTIO_MSI_NO_VECTOR) {
> >>>> +        IFCVF_ERR(ifcvf->pdev, "No msix vector for queue %u\n", qid);
> >>>> +            return -EINVAL;
> >>>> +    }
> >>>
> >>> Let's leave this check for the caller, E.g can caller try to assign
> >>> NO_VECTOR during uni-nit?
> >> ifcvf driver sets NO_VECTOR when call hw_disable(). I am not sure whether I
> >> get it,

I meant you invent the ifcvf_set_vq_vector() you'd better use that in
hw_disable() as well.

> >> Yes we can let the caller check a vq vector, however this may cause more
> >> than three levels brackets, may looks ugly.

I don't understand here, this is how virito_pci did:

/*
 * vp_modern_queue_vector - set the MSIX vector for a specific virtqueue
 * @mdev: the modern virtio-pci device
 * @index: queue index
 * @vector: the config vector
 *
 * Returns the config vector read from the device
 */
u16 vp_modern_queue_vector(struct virtio_pci_modern_device *mdev,
                           u16 index, u16 vector)
{
        struct virtio_pci_common_cfg __iomem *cfg = mdev->common;

        vp_iowrite16(index, &cfg->queue_select);
        vp_iowrite16(vector, &cfg->queue_msix_vector);
        /* Flush the write out to device */
        return vp_ioread16(&cfg->queue_msix_vector);
}
EXPORT_SYMBOL_GPL(vp_modern_queue_vector);

> >>>
> >>>> +
> >>>> +    return 0;
> >>>> +}
> >>>> +
> >>>> +int ifcvf_set_config_vector(struct ifcvf_hw *hw, int vector)
> >>>> +{
> >>>> +    struct virtio_pci_common_cfg __iomem *cfg = hw->common_cfg;
> >>>> +    struct ifcvf_adapter *ifcvf = vf_to_adapter(hw);
> >>>> +
> >>>> +    cfg = hw->common_cfg;
> >>>> +    ifc_iowrite16(vector,  &cfg->msix_config);
> >>>> +    if (ifc_ioread16(&cfg->msix_config) == VIRTIO_MSI_NO_VECTOR) {
> >>>> +        IFCVF_ERR(ifcvf->pdev, "No msix vector for device config\n");
> >>>> +        return -EINVAL;
> >>>> +    }
> >>>
> >>> Similar question as above.
> >>>
> >>>
> >>>> +
> >>>> +    return 0;
> >>>> +}
> >>>> +
> >>>>    static void __iomem *get_cap_addr(struct ifcvf_hw *hw,
> >>>>                      struct virtio_pci_cap *cap)
> >>>>    {
> >>>> @@ -140,6 +170,8 @@ int ifcvf_init_hw(struct ifcvf_hw *hw, struct
> >>>> pci_dev *pdev)
> >>>>              hw->common_cfg, hw->notify_base, hw->isr,
> >>>>              hw->dev_cfg, hw->notify_off_multiplier);
> >>>>    +    hw->vqs_shared_irq = -EINVAL;
> >>>> +
> >>>>        return 0;
> >>>>    }
> >>>>    @@ -321,12 +353,6 @@ static int ifcvf_hw_enable(struct ifcvf_hw *hw)
> >>>>          ifcvf = vf_to_adapter(hw);
> >>>>        cfg = hw->common_cfg;
> >>>> -    ifc_iowrite16(IFCVF_MSI_CONFIG_OFF, &cfg->msix_config);
> >>>> -
> >>>> -    if (ifc_ioread16(&cfg->msix_config) == VIRTIO_MSI_NO_VECTOR) {
> >>>> -        IFCVF_ERR(ifcvf->pdev, "No msix vector for device config\n");
> >>>> -        return -EINVAL;
> >>>> -    }
> >>>>          for (i = 0; i < hw->nr_vring; i++) {
> >>>>            if (!hw->vring[i].ready)
> >>>> @@ -340,15 +366,6 @@ static int ifcvf_hw_enable(struct ifcvf_hw *hw)
> >>>>            ifc_iowrite64_twopart(hw->vring[i].used, &cfg->queue_used_lo,
> >>>>                         &cfg->queue_used_hi);
> >>>>            ifc_iowrite16(hw->vring[i].size, &cfg->queue_size);
> >>>> -        ifc_iowrite16(i + IFCVF_MSI_QUEUE_OFF,
> >>>> &cfg->queue_msix_vector);
> >>>> -
> >>>> -        if (ifc_ioread16(&cfg->queue_msix_vector) ==
> >>>> -            VIRTIO_MSI_NO_VECTOR) {
> >>>> -            IFCVF_ERR(ifcvf->pdev,
> >>>> -                  "No msix vector for queue %u\n", i);
> >>>> -            return -EINVAL;
> >>>> -        }
> >>>> -
> >>>>            ifcvf_set_vq_state(hw, i, hw->vring[i].last_avail_idx);
> >>>>            ifc_iowrite16(1, &cfg->queue_enable);
> >>>>        }
> >>>> diff --git a/drivers/vdpa/ifcvf/ifcvf_base.h
> >>>> b/drivers/vdpa/ifcvf/ifcvf_base.h
> >>>> index 949b4fb9d554..9cfe088c82e9 100644
> >>>> --- a/drivers/vdpa/ifcvf/ifcvf_base.h
> >>>> +++ b/drivers/vdpa/ifcvf/ifcvf_base.h
> >>>> @@ -27,8 +27,6 @@
> >>>>      #define IFCVF_QUEUE_ALIGNMENT    PAGE_SIZE
> >>>>    #define IFCVF_QUEUE_MAX        32768
> >>>> -#define IFCVF_MSI_CONFIG_OFF    0
> >>>> -#define IFCVF_MSI_QUEUE_OFF    1
> >>>>    #define IFCVF_PCI_MAX_RESOURCE    6
> >>>>      #define IFCVF_LM_CFG_SIZE        0x40
> >>>> @@ -42,6 +40,13 @@
> >>>>    #define ifcvf_private_to_vf(adapter) \
> >>>>        (&((struct ifcvf_adapter *)adapter)->vf)
> >>>>    +/* all vqs and config interrupt has its own vector */
> >>>> +#define MSIX_VECTOR_PER_VQ_AND_CONFIG        1
> >>>> +/* all vqs share a vector, and config interrupt has a separate
> >>>> vector */
> >>>> +#define MSIX_VECTOR_SHARED_VQ_AND_CONFIG    2
> >>>> +/* all vqs and config interrupt share a vector */
> >>>> +#define MSIX_VECTOR_DEV_SHARED            3
> >>>
> >>> I think there's no much value to differ 2 from 3 consider config
> >>> interrupt should be rare.
> >> IMHO we still need 2 and 3, because MSIX_VECTOR_SHARED_VQ_AND_CONFIG means
> >> there are at least 2 vectors,
> >> the vqs share one vector, config change has its own vector.

I want to know the value of having a dedicated vector for config?

> >> MSIX_VECTOR_DEV_SHARED means three are only one vector, all vqs and config
> >> changes need to share this vector.
> >>>
> >>>
> >>>> +
> >>>>    static inline u8 ifc_ioread8(u8 __iomem *addr)
> >>>>    {
> >>>>        return ioread8(addr);
> >>>> @@ -97,25 +102,27 @@ struct ifcvf_hw {
> >>>>        u8 __iomem *isr;
> >>>>        /* Live migration */
> >>>>        u8 __iomem *lm_cfg;
> >>>> -    u16 nr_vring;
> >>>
> >>> Any reason for moving nv_vring, config_size, and other stuffs?
> >> for cacheline alignment.
> > maybe a separate patch then.
> Sure
>
> Thanks!
> >
> >>>
> >>>
> >>>>        /* Notification bar number */
> >>>>        u8 notify_bar;
> >>>> +    u8 msix_vector_status;
> >>>> +    /* virtio-net or virtio-blk device config size */
> >>>> +    u32 config_size;
> >>>>        /* Notificaiton bar address */
> >>>>        void __iomem *notify_base;
> >>>>        phys_addr_t notify_base_pa;
> >>>>        u32 notify_off_multiplier;
> >>>> +    u32 dev_type;
> >>>>        u64 req_features;
> >>>>        u64 hw_features;
> >>>> -    u32 dev_type;
> >>>>        struct virtio_pci_common_cfg __iomem *common_cfg;
> >>>>        void __iomem *dev_cfg;
> >>>>        struct vring_info vring[IFCVF_MAX_QUEUES];
> >>>>        void __iomem * const *base;
> >>>>        char config_msix_name[256];
> >>>>        struct vdpa_callback config_cb;
> >>>> -    unsigned int config_irq;
> >>>> -    /* virtio-net or virtio-blk device config size */
> >>>> -    u32 config_size;
> >>>> +    int config_irq;
> >>>> +    int vqs_shared_irq;
> >>>> +    u16 nr_vring;
> >>>>    };
> >>>>      struct ifcvf_adapter {
> >>>> @@ -160,4 +167,6 @@ int ifcvf_set_vq_state(struct ifcvf_hw *hw, u16
> >>>> qid, u16 num);
> >>>>    struct ifcvf_adapter *vf_to_adapter(struct ifcvf_hw *hw);
> >>>>    int ifcvf_probed_virtio_net(struct ifcvf_hw *hw);
> >>>>    u32 ifcvf_get_config_size(struct ifcvf_hw *hw);
> >>>> +int ifcvf_set_vq_vector(struct ifcvf_hw *hw, u16 qid, int vector);
> >>>> +int ifcvf_set_config_vector(struct ifcvf_hw *hw, int vector);
> >>>>    #endif /* _IFCVF_H_ */
> >>>> diff --git a/drivers/vdpa/ifcvf/ifcvf_main.c
> >>>> b/drivers/vdpa/ifcvf/ifcvf_main.c
> >>>> index 44c89ab0b6da..ca414399f040 100644
> >>>> --- a/drivers/vdpa/ifcvf/ifcvf_main.c
> >>>> +++ b/drivers/vdpa/ifcvf/ifcvf_main.c
> >>>> @@ -17,6 +17,7 @@
> >>>>    #define DRIVER_AUTHOR   "Intel Corporation"
> >>>>    #define IFCVF_DRIVER_NAME       "ifcvf"
> >>>>    +/* handles config interrupt */
> >>>
> >>> This seems unrelated to the shared IRQ logic and it looks useless since
> >>> it's easily to deduce it from the function name below.
> >> OK, do you mean the comments? I can remove these comments.

Yes.

> >>>
> >>>>    static irqreturn_t ifcvf_config_changed(int irq, void *arg)
> >>>>    {
> >>>>        struct ifcvf_hw *vf = arg;
> >>>> @@ -27,6 +28,7 @@ static irqreturn_t ifcvf_config_changed(int irq,
> >>>> void *arg)
> >>>>        return IRQ_HANDLED;
> >>>>    }
> >>>>    +/* handles vqs interrupt */
> >>>
> >>> So did this.
> >>>
> >>>
> >>>>    static irqreturn_t ifcvf_intr_handler(int irq, void *arg)
> >>>>    {
> >>>>        struct vring_info *vring = arg;
> >>>> @@ -37,24 +39,78 @@ static irqreturn_t ifcvf_intr_handler(int irq,
> >>>> void *arg)
> >>>>        return IRQ_HANDLED;
> >>>>    }
> >>>>    +/* handls vqs shared interrupt */
> >>>> +static irqreturn_t ifcvf_vq_shared_intr_handler(int irq, void *arg)
> >>>> +{
> >>>> +    struct ifcvf_hw *vf = arg;
> >>>> +    struct vring_info *vring;
> >>>> +    int i;
> >>>> +
> >>>> +    for (i = 0; i < vf->nr_vring; i++) {
> >>>> +        vring = &vf->vring[i];
> >>>> +        if (vring->cb.callback)
> >>>> + vf->vring->cb.callback(vring->cb.private);
> >>>> +    }
> >>>> +
> >>>> +    return IRQ_HANDLED;
> >>>> +}
> >>>> +
> >>>> +/* handles a shared interrupt for vqs and config */
> >>>> +static irqreturn_t ifcvf_dev_shared_intr_handler(int irq, void *arg)
> >>>> +{
> >>>> +    struct ifcvf_hw *vf = arg;
> >>>> +    u8 isr;
> >>>> +
> >>>> +    isr = ifc_ioread8(vf->isr);
> >>>
> >>> We need to exactly what vp_interrupt do here. Checking against vf->isr
> >>> first and return IRQ_NONE if it is not set.
> >>>
> >>> Always return IRQ_HANDLED will break the device who shares an irq with
> >>> IFCVF.
> >> as we discussed in another thread(spec inconsistency about ISR), ISR may
> >> only works for INTx for now,
> >> but VFs don't have INTx, and a VF may not share its vectors with other
> >> devices, so I guess it can work
> >> and may be our best try for now.

Right, I thought you're using shared irq but actually not.

> >>>
> >>>> +    if (isr & VIRTIO_PCI_ISR_CONFIG)
> >>>> +        ifcvf_config_changed(irq, arg);

I wonder how ISR works in IFCVF, if ISR doesn't work for MSI, we need
to remove the check of isr otherwise we will break config interrupt?

> >>>> +
> >>>> +    return ifcvf_vq_shared_intr_handler(irq, arg);
> >>>> +}
> >>>> +
> >>>>    static void ifcvf_free_irq_vectors(void *data)
> >>>>    {
> >>>>        pci_free_irq_vectors(data);
> >>>>    }
> >>>>    -static void ifcvf_free_irq(struct ifcvf_adapter *adapter, int queues)
> >>>> +static void ifcvf_free_vq_irq(struct ifcvf_adapter *adapter, int
> >>>> queues)
> >>>>    {
> >>>>        struct pci_dev *pdev = adapter->pdev;
> >>>>        struct ifcvf_hw *vf = &adapter->vf;
> >>>>        int i;
> >>>>    +    if (vf->msix_vector_status == MSIX_VECTOR_PER_VQ_AND_CONFIG) {
> >>>> +        for (i = 0; i < queues; i++) {
> >>>> +            devm_free_irq(&pdev->dev, vf->vring[i].irq, &vf->vring[i]);
> >>>> +            vf->vring[i].irq = -EINVAL;
> >>>> +        }
> >>>> +    } else {
> >>>> +        devm_free_irq(&pdev->dev, vf->vqs_shared_irq, vf);
> >>>> +        vf->vqs_shared_irq = -EINVAL;
> >>>> +    }
> >>>> +}
> >>>>    -    for (i = 0; i < queues; i++) {
> >>>> -        devm_free_irq(&pdev->dev, vf->vring[i].irq, &vf->vring[i]);
> >>>> -        vf->vring[i].irq = -EINVAL;
> >>>> +static void ifcvf_free_config_irq(struct ifcvf_adapter *adapter)
> >>>> +{
> >>>> +    struct pci_dev *pdev = adapter->pdev;
> >>>> +    struct ifcvf_hw *vf = &adapter->vf;
> >>>> +
> >>>> +    /* If the irq is shared by all vqs and the config interrupt,
> >>>> +     * it is already freed in ifcvf_free_vq_irq, so here only
> >>>> +     * need to free config irq when msix_vector_status !=
> >>>> MSIX_VECTOR_DEV_SHARED
> >>>> +     */
> >>>> +    if (vf->msix_vector_status != MSIX_VECTOR_DEV_SHARED) {
> >>>> +        devm_free_irq(&pdev->dev, vf->config_irq, vf);
> >>>> +        vf->config_irq = -EINVAL;
> >>>>        }
> >>>> +}
> >>>> +
> >>>> +static void ifcvf_free_irq(struct ifcvf_adapter *adapter, int queues)
> >>>> +{
> >>>> +    struct pci_dev *pdev = adapter->pdev;
> >>>>    -    devm_free_irq(&pdev->dev, vf->config_irq, vf);
> >>>> +    ifcvf_free_vq_irq(adapter, queues);
> >>>> +    ifcvf_free_config_irq(adapter);
> >>>>        ifcvf_free_irq_vectors(pdev);
> >>>>    }
> >>>>    @@ -86,58 +142,172 @@ static int ifcvf_alloc_vectors(struct
> >>>> ifcvf_adapter *adapter)
> >>>>        return ret;
> >>>>    }
> >>>>    -static int ifcvf_request_irq(struct ifcvf_adapter *adapter)
> >>>> +static int ifcvf_request_per_vq_irq(struct ifcvf_adapter *adapter)
> >>>>    {
> >>>>        struct pci_dev *pdev = adapter->pdev;
> >>>>        struct ifcvf_hw *vf = &adapter->vf;
> >>>> -    int vector, nvectors, i, ret, irq;
> >>>> -    u16 max_intr;
> >>>> +    int i, vector, ret, irq;
> >>>>    -    nvectors = ifcvf_alloc_vectors(adapter);
> >>>> -    if (!(nvectors > 0))
> >>>> -        return nvectors;
> >>>> +    for (i = 0; i < vf->nr_vring; i++) {
> >>>> +        snprintf(vf->vring[i].msix_name, 256, "ifcvf[%s]-%d\n",
> >>>> pci_name(pdev), i);
> >>>> +        vector = i;
> >>>> +        irq = pci_irq_vector(pdev, vector);
> >>>> +        ret = devm_request_irq(&pdev->dev, irq,
> >>>> +                       ifcvf_intr_handler, 0,
> >>>> +                       vf->vring[i].msix_name,
> >>>> +                       &vf->vring[i]);
> >>>> +        if (ret) {
> >>>> +            IFCVF_ERR(pdev, "Failed to request irq for vq %d\n", i);
> >>>> +            ifcvf_free_vq_irq(adapter, i);
> >>>> +        } else {
> >>>> +            vf->vring[i].irq = irq;
> >>>> +            ifcvf_set_vq_vector(vf, i, vector);
> >>>> +        }
> >>>> +    }
> >>>>    -    max_intr = vf->nr_vring + 1;
> >>>> +    vf->vqs_shared_irq = -EINVAL;
> >>>> +
> >>>> +    return 0;
> >>>> +}
> >>>> +
> >>>> +static int ifcvf_request_shared_vq_irq(struct ifcvf_adapter *adapter)
> >>>> +{
> >>>> +    struct pci_dev *pdev = adapter->pdev;
> >>>> +    struct ifcvf_hw *vf = &adapter->vf;
> >>>> +    int i, vector, ret, irq;
> >>>> +
> >>>> +    vector = 0;
> >>>> +    /* reuse msix_name[256] space of vring0 to store shared vqs
> >>>> interrupt name */
> >>>
> >>> I think we can remove this comment since the code is straightforward.
> >> sure
> >>>
> >>>> + snprintf(vf->vring[0].msix_name, 256,
> >>>> "ifcvf[%s]-vqs-shared-irq\n", pci_name(pdev));
> >>>> +    irq = pci_irq_vector(pdev, vector);
> >>>> +    ret = devm_request_irq(&pdev->dev, irq,
> >>>> +                   ifcvf_vq_shared_intr_handler, 0,
> >>>> +                   vf->vring[0].msix_name, vf);
> >>>> +    if (ret) {
> >>>> +        IFCVF_ERR(pdev, "Failed to request shared irq for vf\n");
> >>>> +
> >>>> +        return ret;
> >>>> +    }
> >>>> +
> >>>> +    vf->vqs_shared_irq = irq;
> >>>> +    for (i = 0; i < vf->nr_vring; i++) {
> >>>> +        vf->vring[i].irq = -EINVAL;
> >>>> +        ifcvf_set_vq_vector(vf, i, vector);
> >>>> +    }
> >>>> +
> >>>> +    return 0;
> >>>> +
> >>>> +}
> >>>> +
> >>>> +static int ifcvf_request_dev_shared_irq(struct ifcvf_adapter *adapter)
> >>>> +{
> >>>> +    struct pci_dev *pdev = adapter->pdev;
> >>>> +    struct ifcvf_hw *vf = &adapter->vf;
> >>>> +    int i, vector, ret, irq;
> >>>> +
> >>>> +    vector = 0;
> >>>> +    /* reuse msix_name[256] space of vring0 to store shared device
> >>>> interrupt name */
> >>>> +    snprintf(vf->vring[0].msix_name, 256,
> >>>> "ifcvf[%s]-dev-shared-irq\n", pci_name(pdev));
> >>>> +    irq = pci_irq_vector(pdev, vector);
> >>>> +    ret = devm_request_irq(&pdev->dev, irq,
> >>>> +                   ifcvf_dev_shared_intr_handler, 0,
> >>>> +                   vf->vring[0].msix_name, vf);
> >>>> +    if (ret) {
> >>>> +        IFCVF_ERR(pdev, "Failed to request shared irq for vf\n");
> >>>>    -    ret = pci_alloc_irq_vectors(pdev, max_intr,
> >>>> -                    max_intr, PCI_IRQ_MSIX);
> >>>> -    if (ret < 0) {
> >>>> -        IFCVF_ERR(pdev, "Failed to alloc IRQ vectors\n");
> >>>>            return ret;
> >>>>        }
> >>>>    +    vf->vqs_shared_irq = irq;
> >>>> +    for (i = 0; i < vf->nr_vring; i++) {
> >>>> +        vf->vring[i].irq = -EINVAL;
> >>>> +        ifcvf_set_vq_vector(vf, i, vector);
> >>>> +    }
> >>>> +
> >>>> +    vf->config_irq = irq;
> >>>> +    ifcvf_set_config_vector(vf, vector);
> >>>> +
> >>>> +    return 0;
> >>>> +
> >>>> +}
> >>>> +
> >>>> +static int ifcvf_request_vq_irq(struct ifcvf_adapter *adapter)
> >>>> +{
> >>>> +    struct ifcvf_hw *vf = &adapter->vf;
> >>>> +    int ret;
> >>>> +
> >>>> +    if (vf->msix_vector_status == MSIX_VECTOR_PER_VQ_AND_CONFIG)
> >>>> +        ret = ifcvf_request_per_vq_irq(adapter);
> >>>> +    else
> >>>> +        ret = ifcvf_request_shared_vq_irq(adapter);
> >>>> +
> >>>> +    return ret;
> >>>> +}
> >>>> +
> >>>> +static int ifcvf_request_config_irq(struct ifcvf_adapter *adapter)
> >>>> +{
> >>>> +    struct pci_dev *pdev = adapter->pdev;
> >>>> +    struct ifcvf_hw *vf = &adapter->vf;
> >>>> +    int config_vector, ret;
> >>>> +
> >>>> +    if (vf->msix_vector_status == MSIX_VECTOR_DEV_SHARED)
> >>>> +        return 0;
> >>>> +
> >>>> +    if (vf->msix_vector_status == MSIX_VECTOR_PER_VQ_AND_CONFIG)
> >>>> +        /* vector 0 ~ vf->nr_vring for vqs, num vf->nr_vring vector
> >>>> for config interrupt */
> >>>> +        config_vector = vf->nr_vring;
> >>>> +
> >>>> +    if (vf->msix_vector_status == MSIX_VECTOR_SHARED_VQ_AND_CONFIG)
> >>>> +        /* vector 0 for vqs and 1 for config interrupt */
> >>>> +        config_vector = 1;
> >>>> +
> >>>>        snprintf(vf->config_msix_name, 256, "ifcvf[%s]-config\n",
> >>>>             pci_name(pdev));
> >>>> -    vector = 0;
> >>>> -    vf->config_irq = pci_irq_vector(pdev, vector);
> >>>> +    vf->config_irq = pci_irq_vector(pdev, config_vector);
> >>>>        ret = devm_request_irq(&pdev->dev, vf->config_irq,
> >>>>                       ifcvf_config_changed, 0,
> >>>>                       vf->config_msix_name, vf);
> >>>>        if (ret) {
> >>>>            IFCVF_ERR(pdev, "Failed to request config irq\n");
> >>>> +        ifcvf_free_vq_irq(adapter, vf->nr_vring);
> >>>>            return ret;
> >>>>        }
> >>>>    -    for (i = 0; i < vf->nr_vring; i++) {
> >>>> -        snprintf(vf->vring[i].msix_name, 256, "ifcvf[%s]-%d\n",
> >>>> -             pci_name(pdev), i);
> >>>> -        vector = i + IFCVF_MSI_QUEUE_OFF;
> >>>> -        irq = pci_irq_vector(pdev, vector);
> >>>> -        ret = devm_request_irq(&pdev->dev, irq,
> >>>> -                       ifcvf_intr_handler, 0,
> >>>> -                       vf->vring[i].msix_name,
> >>>> -                       &vf->vring[i]);
> >>>> -        if (ret) {
> >>>> -            IFCVF_ERR(pdev,
> >>>> -                  "Failed to request irq for vq %d\n", i);
> >>>> -            ifcvf_free_irq(adapter, i);
> >>>> +    ifcvf_set_config_vector(vf, config_vector);
> >>>>    -            return ret;
> >>>> -        }
> >>>> +    return 0;
> >>>> +}
> >>>> +
> >>>> +static int ifcvf_request_irq(struct ifcvf_adapter *adapter)
> >>>> +{
> >>>
> >>> As replied above, I think having two modes should be sufficient and the
> >>> code could be greatly simplified.
> >> Do you mean if we don't get enough vectors, just use only one vector for the
> >> vqs and config changes? I guess this
> >> only works if ISR work for MSIX as we expects, or we may waste some time in
> >> the device config space.

Ok, I think I got you here. It's better to document this in the change log.

Thanks

> >>
> >> Thanks,
> >> Zhu Lingshan
> >>> Thanks
> >>>
> >>>
> >>>> +    struct ifcvf_hw *vf = &adapter->vf;
> >>>> +    int nvectors, ret, max_intr;
> >>>>    -        vf->vring[i].irq = irq;
> >>>> +    nvectors = ifcvf_alloc_vectors(adapter);
> >>>> +    if (!(nvectors > 0))
> >>>> +        return nvectors;
> >>>> +
> >>>> +    vf->msix_vector_status = MSIX_VECTOR_PER_VQ_AND_CONFIG;
> >>>> +    max_intr = vf->nr_vring + 1;
> >>>> +    if (nvectors < max_intr)
> >>>> +        vf->msix_vector_status = MSIX_VECTOR_SHARED_VQ_AND_CONFIG;
> >>>> +
> >>>> +    if (nvectors == 1) {
> >>>> +        vf->msix_vector_status = MSIX_VECTOR_DEV_SHARED;
> >>>> +        ret = ifcvf_request_dev_shared_irq(adapter);
> >>>> +
> >>>> +        return ret;
> >>>>        }
> >>>>    +    ret = ifcvf_request_vq_irq(adapter);
> >>>> +    if (ret)
> >>>> +        return ret;
> >>>> +
> >>>> +    ret = ifcvf_request_config_irq(adapter);
> >>>> +
> >>>> +    if (ret)
> >>>> +        return ret;
> >>>> +
> >>>>        return 0;
> >>>>    }
> >>>>    @@ -441,7 +611,10 @@ static int ifcvf_vdpa_get_vq_irq(struct
> >>>> vdpa_device *vdpa_dev,
> >>>>    {
> >>>>        struct ifcvf_hw *vf = vdpa_to_vf(vdpa_dev);
> >>>>    -    return vf->vring[qid].irq;
> >>>> +    if (vf->vqs_shared_irq < 0)
> >>>> +        return vf->vring[qid].irq;
> >>>> +    else
> >>>> +        return -EINVAL;
> >>>>    }
> >>>>      static struct vdpa_notification_area
> >>>> ifcvf_get_vq_notification(struct vdpa_device *vdpa_dev,
> >>> _______________________________________________
> >>> Virtualization mailing list
> >>> Virtualization@lists.linux-foundation.org
> >>> https://lists.linuxfoundation.org/mailman/listinfo/virtualization
>

Re: [PATCH V4 4/4] vDPA/ifcvf: implement shared IRQ feature

[Zhu, Lingshan]

On 2/15/2022 11:03 AM, Jason Wang wrote:
> On Tue, Feb 15, 2022 at 10:18 AM Zhu, Lingshan <lingshan.zhu@intel.com> wrote:
>>
>>
>> On 2/14/2022 10:27 PM, Michael S. Tsirkin wrote:
>>> On Mon, Feb 14, 2022 at 06:01:56PM +0800, Zhu Lingshan wrote:
>>>> On 2/14/2022 3:19 PM, Jason Wang wrote:
>>>>> 在 2022/2/3 下午3:27, Zhu Lingshan 写道:
>>>>>> On some platforms/devices, there may not be enough MSI vector
>>>>>> slots allocated for virtqueues and config changes. In such a case,
>>>>>> the interrupt sources(virtqueues, config changes) must share
>>>>>> an IRQ/vector, to avoid initialization failures, keep
>>>>>> the device functional.
>>>>>>
>>>>>> This commit handles three cases:
>>>>>> (1) number of the allocated vectors == the number of virtqueues + 1
>>>>>> (config changes), every virtqueue and the config interrupt has
>>>>>> a separated vector/IRQ, the best and the most likely case.
>>>>>> (2) number of the allocated vectors is less than the best case, but
>>>>>> greater than 1. In this case, all virtqueues share a vector/IRQ,
>>>>>> the config interrupt has a separated vector/IRQ
>>>>>> (3) only one vector is allocated, in this case, the virtqueues and
>>>>>> the config interrupt share a vector/IRQ. The worst and most
>>>>>> unlikely case.
>>>>>>
>>>>>> Otherwise, it needs to fail.
>>>>>>
>>>>>> This commit introduces some helper functions:
>>>>>> ifcvf_set_vq_vector() and ifcvf_set_config_vector() sets virtqueue
>>>>>> vector and config vector in the device config space, so that
>>>>>> the device can send interrupt DMA.
>>>>>>
>>>>>> This commit adds some fields in struct ifcvf_hw and re-placed
>>>>>> the existed fields to be aligned with the cacheline.
>>>>>>
>>>>>> Signed-off-by: Zhu Lingshan <lingshan.zhu@intel.com>
>>>>>> ---
>>>>>>     drivers/vdpa/ifcvf/ifcvf_base.c |  47 ++++--
>>>>>>     drivers/vdpa/ifcvf/ifcvf_base.h |  23 ++-
>>>>>>     drivers/vdpa/ifcvf/ifcvf_main.c | 243 +++++++++++++++++++++++++++-----
>>>>>>     3 files changed, 256 insertions(+), 57 deletions(-)
>>>>>>
>>>>>> diff --git a/drivers/vdpa/ifcvf/ifcvf_base.c
>>>>>> b/drivers/vdpa/ifcvf/ifcvf_base.c
>>>>>> index 397692ae671c..18dcb63ab1e3 100644
>>>>>> --- a/drivers/vdpa/ifcvf/ifcvf_base.c
>>>>>> +++ b/drivers/vdpa/ifcvf/ifcvf_base.c
>>>>>> @@ -15,6 +15,36 @@ struct ifcvf_adapter *vf_to_adapter(struct
>>>>>> ifcvf_hw *hw)
>>>>>>         return container_of(hw, struct ifcvf_adapter, vf);
>>>>>>     }
>>>>>>     +int ifcvf_set_vq_vector(struct ifcvf_hw *hw, u16 qid, int vector)
>>>>>> +{
>>>>>> +    struct virtio_pci_common_cfg __iomem *cfg = hw->common_cfg;
>>>>>> +    struct ifcvf_adapter *ifcvf = vf_to_adapter(hw);
>>>>>> +
>>>>>> +    ifc_iowrite16(qid, &cfg->queue_select);
>>>>>> +    ifc_iowrite16(vector, &cfg->queue_msix_vector);
>>>>>> +    if (ifc_ioread16(&cfg->queue_msix_vector) ==
>>>>>> VIRTIO_MSI_NO_VECTOR) {
>>>>>> +        IFCVF_ERR(ifcvf->pdev, "No msix vector for queue %u\n", qid);
>>>>>> +            return -EINVAL;
>>>>>> +    }
>>>>> Let's leave this check for the caller, E.g can caller try to assign
>>>>> NO_VECTOR during uni-nit?
>>>> ifcvf driver sets NO_VECTOR when call hw_disable(). I am not sure whether I
>>>> get it,
> I meant you invent the ifcvf_set_vq_vector() you'd better use that in
> hw_disable() as well.
OK
>
>>>> Yes we can let the caller check a vq vector, however this may cause more
>>>> than three levels brackets, may looks ugly.
> I don't understand here, this is how virito_pci did:
>
> /*
>   * vp_modern_queue_vector - set the MSIX vector for a specific virtqueue
>   * @mdev: the modern virtio-pci device
>   * @index: queue index
>   * @vector: the config vector
>   *
>   * Returns the config vector read from the device
>   */
> u16 vp_modern_queue_vector(struct virtio_pci_modern_device *mdev,
>                             u16 index, u16 vector)
> {
>          struct virtio_pci_common_cfg __iomem *cfg = mdev->common;
>
>          vp_iowrite16(index, &cfg->queue_select);
>          vp_iowrite16(vector, &cfg->queue_msix_vector);
>          /* Flush the write out to device */
>          return vp_ioread16(&cfg->queue_msix_vector);
> }
> EXPORT_SYMBOL_GPL(vp_modern_queue_vector);
I mean if we leave the checks for the caller, it may look like:
+       for (i = 0; i < vf->nr_vring; i++) {
+               snprintf(vf->vring[i].msix_name, 256, "ifcvf[%s]-%d\n", 
pci_name(pdev), i);
+               vector = i;
+               irq = pci_irq_vector(pdev, vector);
+               ret = devm_request_irq(&pdev->dev, irq,
+                                      ifcvf_intr_handler, 0,
+                                      vf->vring[i].msix_name,
+                                      &vf->vring[i]);
+               if (ret) {
+                       IFCVF_ERR(pdev, "Failed to request irq for vq 
%d\n", i);
+                       ifcvf_free_vq_irq(adapter, i);
+               } else {
+                       vf->vring[i].irq = irq;
+                       ifcvf_set_vq_vector(vf, i, vector);
                             if (xxxxx) {
                                 xxxxxxxxxxx;
                             }
+               }
+       }

Too many brackets.
>
>>>>>> +
>>>>>> +    return 0;
>>>>>> +}
>>>>>> +
>>>>>> +int ifcvf_set_config_vector(struct ifcvf_hw *hw, int vector)
>>>>>> +{
>>>>>> +    struct virtio_pci_common_cfg __iomem *cfg = hw->common_cfg;
>>>>>> +    struct ifcvf_adapter *ifcvf = vf_to_adapter(hw);
>>>>>> +
>>>>>> +    cfg = hw->common_cfg;
>>>>>> +    ifc_iowrite16(vector,  &cfg->msix_config);
>>>>>> +    if (ifc_ioread16(&cfg->msix_config) == VIRTIO_MSI_NO_VECTOR) {
>>>>>> +        IFCVF_ERR(ifcvf->pdev, "No msix vector for device config\n");
>>>>>> +        return -EINVAL;
>>>>>> +    }
>>>>> Similar question as above.
>>>>>
>>>>>
>>>>>> +
>>>>>> +    return 0;
>>>>>> +}
>>>>>> +
>>>>>>     static void __iomem *get_cap_addr(struct ifcvf_hw *hw,
>>>>>>                       struct virtio_pci_cap *cap)
>>>>>>     {
>>>>>> @@ -140,6 +170,8 @@ int ifcvf_init_hw(struct ifcvf_hw *hw, struct
>>>>>> pci_dev *pdev)
>>>>>>               hw->common_cfg, hw->notify_base, hw->isr,
>>>>>>               hw->dev_cfg, hw->notify_off_multiplier);
>>>>>>     +    hw->vqs_shared_irq = -EINVAL;
>>>>>> +
>>>>>>         return 0;
>>>>>>     }
>>>>>>     @@ -321,12 +353,6 @@ static int ifcvf_hw_enable(struct ifcvf_hw *hw)
>>>>>>           ifcvf = vf_to_adapter(hw);
>>>>>>         cfg = hw->common_cfg;
>>>>>> -    ifc_iowrite16(IFCVF_MSI_CONFIG_OFF, &cfg->msix_config);
>>>>>> -
>>>>>> -    if (ifc_ioread16(&cfg->msix_config) == VIRTIO_MSI_NO_VECTOR) {
>>>>>> -        IFCVF_ERR(ifcvf->pdev, "No msix vector for device config\n");
>>>>>> -        return -EINVAL;
>>>>>> -    }
>>>>>>           for (i = 0; i < hw->nr_vring; i++) {
>>>>>>             if (!hw->vring[i].ready)
>>>>>> @@ -340,15 +366,6 @@ static int ifcvf_hw_enable(struct ifcvf_hw *hw)
>>>>>>             ifc_iowrite64_twopart(hw->vring[i].used, &cfg->queue_used_lo,
>>>>>>                          &cfg->queue_used_hi);
>>>>>>             ifc_iowrite16(hw->vring[i].size, &cfg->queue_size);
>>>>>> -        ifc_iowrite16(i + IFCVF_MSI_QUEUE_OFF,
>>>>>> &cfg->queue_msix_vector);
>>>>>> -
>>>>>> -        if (ifc_ioread16(&cfg->queue_msix_vector) ==
>>>>>> -            VIRTIO_MSI_NO_VECTOR) {
>>>>>> -            IFCVF_ERR(ifcvf->pdev,
>>>>>> -                  "No msix vector for queue %u\n", i);
>>>>>> -            return -EINVAL;
>>>>>> -        }
>>>>>> -
>>>>>>             ifcvf_set_vq_state(hw, i, hw->vring[i].last_avail_idx);
>>>>>>             ifc_iowrite16(1, &cfg->queue_enable);
>>>>>>         }
>>>>>> diff --git a/drivers/vdpa/ifcvf/ifcvf_base.h
>>>>>> b/drivers/vdpa/ifcvf/ifcvf_base.h
>>>>>> index 949b4fb9d554..9cfe088c82e9 100644
>>>>>> --- a/drivers/vdpa/ifcvf/ifcvf_base.h
>>>>>> +++ b/drivers/vdpa/ifcvf/ifcvf_base.h
>>>>>> @@ -27,8 +27,6 @@
>>>>>>       #define IFCVF_QUEUE_ALIGNMENT    PAGE_SIZE
>>>>>>     #define IFCVF_QUEUE_MAX        32768
>>>>>> -#define IFCVF_MSI_CONFIG_OFF    0
>>>>>> -#define IFCVF_MSI_QUEUE_OFF    1
>>>>>>     #define IFCVF_PCI_MAX_RESOURCE    6
>>>>>>       #define IFCVF_LM_CFG_SIZE        0x40
>>>>>> @@ -42,6 +40,13 @@
>>>>>>     #define ifcvf_private_to_vf(adapter) \
>>>>>>         (&((struct ifcvf_adapter *)adapter)->vf)
>>>>>>     +/* all vqs and config interrupt has its own vector */
>>>>>> +#define MSIX_VECTOR_PER_VQ_AND_CONFIG        1
>>>>>> +/* all vqs share a vector, and config interrupt has a separate
>>>>>> vector */
>>>>>> +#define MSIX_VECTOR_SHARED_VQ_AND_CONFIG    2
>>>>>> +/* all vqs and config interrupt share a vector */
>>>>>> +#define MSIX_VECTOR_DEV_SHARED            3
>>>>> I think there's no much value to differ 2 from 3 consider config
>>>>> interrupt should be rare.
>>>> IMHO we still need 2 and 3, because MSIX_VECTOR_SHARED_VQ_AND_CONFIG means
>>>> there are at least 2 vectors,
>>>> the vqs share one vector, config change has its own vector.
> I want to know the value of having a dedicated vector for config?
I think a dedicated vector for config changes can help us avoid 
operations on config space when vq interrupt triggered.
>
>>>> MSIX_VECTOR_DEV_SHARED means three are only one vector, all vqs and config
>>>> changes need to share this vector.
>>>>>
>>>>>> +
>>>>>>     static inline u8 ifc_ioread8(u8 __iomem *addr)
>>>>>>     {
>>>>>>         return ioread8(addr);
>>>>>> @@ -97,25 +102,27 @@ struct ifcvf_hw {
>>>>>>         u8 __iomem *isr;
>>>>>>         /* Live migration */
>>>>>>         u8 __iomem *lm_cfg;
>>>>>> -    u16 nr_vring;
>>>>> Any reason for moving nv_vring, config_size, and other stuffs?
>>>> for cacheline alignment.
>>> maybe a separate patch then.
>> Sure
>>
>> Thanks!
>>>>>
>>>>>>         /* Notification bar number */
>>>>>>         u8 notify_bar;
>>>>>> +    u8 msix_vector_status;
>>>>>> +    /* virtio-net or virtio-blk device config size */
>>>>>> +    u32 config_size;
>>>>>>         /* Notificaiton bar address */
>>>>>>         void __iomem *notify_base;
>>>>>>         phys_addr_t notify_base_pa;
>>>>>>         u32 notify_off_multiplier;
>>>>>> +    u32 dev_type;
>>>>>>         u64 req_features;
>>>>>>         u64 hw_features;
>>>>>> -    u32 dev_type;
>>>>>>         struct virtio_pci_common_cfg __iomem *common_cfg;
>>>>>>         void __iomem *dev_cfg;
>>>>>>         struct vring_info vring[IFCVF_MAX_QUEUES];
>>>>>>         void __iomem * const *base;
>>>>>>         char config_msix_name[256];
>>>>>>         struct vdpa_callback config_cb;
>>>>>> -    unsigned int config_irq;
>>>>>> -    /* virtio-net or virtio-blk device config size */
>>>>>> -    u32 config_size;
>>>>>> +    int config_irq;
>>>>>> +    int vqs_shared_irq;
>>>>>> +    u16 nr_vring;
>>>>>>     };
>>>>>>       struct ifcvf_adapter {
>>>>>> @@ -160,4 +167,6 @@ int ifcvf_set_vq_state(struct ifcvf_hw *hw, u16
>>>>>> qid, u16 num);
>>>>>>     struct ifcvf_adapter *vf_to_adapter(struct ifcvf_hw *hw);
>>>>>>     int ifcvf_probed_virtio_net(struct ifcvf_hw *hw);
>>>>>>     u32 ifcvf_get_config_size(struct ifcvf_hw *hw);
>>>>>> +int ifcvf_set_vq_vector(struct ifcvf_hw *hw, u16 qid, int vector);
>>>>>> +int ifcvf_set_config_vector(struct ifcvf_hw *hw, int vector);
>>>>>>     #endif /* _IFCVF_H_ */
>>>>>> diff --git a/drivers/vdpa/ifcvf/ifcvf_main.c
>>>>>> b/drivers/vdpa/ifcvf/ifcvf_main.c
>>>>>> index 44c89ab0b6da..ca414399f040 100644
>>>>>> --- a/drivers/vdpa/ifcvf/ifcvf_main.c
>>>>>> +++ b/drivers/vdpa/ifcvf/ifcvf_main.c
>>>>>> @@ -17,6 +17,7 @@
>>>>>>     #define DRIVER_AUTHOR   "Intel Corporation"
>>>>>>     #define IFCVF_DRIVER_NAME       "ifcvf"
>>>>>>     +/* handles config interrupt */
>>>>> This seems unrelated to the shared IRQ logic and it looks useless since
>>>>> it's easily to deduce it from the function name below.
>>>> OK, do you mean the comments? I can remove these comments.
> Yes.
>
>>>>>>     static irqreturn_t ifcvf_config_changed(int irq, void *arg)
>>>>>>     {
>>>>>>         struct ifcvf_hw *vf = arg;
>>>>>> @@ -27,6 +28,7 @@ static irqreturn_t ifcvf_config_changed(int irq,
>>>>>> void *arg)
>>>>>>         return IRQ_HANDLED;
>>>>>>     }
>>>>>>     +/* handles vqs interrupt */
>>>>> So did this.
>>>>>
>>>>>
>>>>>>     static irqreturn_t ifcvf_intr_handler(int irq, void *arg)
>>>>>>     {
>>>>>>         struct vring_info *vring = arg;
>>>>>> @@ -37,24 +39,78 @@ static irqreturn_t ifcvf_intr_handler(int irq,
>>>>>> void *arg)
>>>>>>         return IRQ_HANDLED;
>>>>>>     }
>>>>>>     +/* handls vqs shared interrupt */
>>>>>> +static irqreturn_t ifcvf_vq_shared_intr_handler(int irq, void *arg)
>>>>>> +{
>>>>>> +    struct ifcvf_hw *vf = arg;
>>>>>> +    struct vring_info *vring;
>>>>>> +    int i;
>>>>>> +
>>>>>> +    for (i = 0; i < vf->nr_vring; i++) {
>>>>>> +        vring = &vf->vring[i];
>>>>>> +        if (vring->cb.callback)
>>>>>> + vf->vring->cb.callback(vring->cb.private);
>>>>>> +    }
>>>>>> +
>>>>>> +    return IRQ_HANDLED;
>>>>>> +}
>>>>>> +
>>>>>> +/* handles a shared interrupt for vqs and config */
>>>>>> +static irqreturn_t ifcvf_dev_shared_intr_handler(int irq, void *arg)
>>>>>> +{
>>>>>> +    struct ifcvf_hw *vf = arg;
>>>>>> +    u8 isr;
>>>>>> +
>>>>>> +    isr = ifc_ioread8(vf->isr);
>>>>> We need to exactly what vp_interrupt do here. Checking against vf->isr
>>>>> first and return IRQ_NONE if it is not set.
>>>>>
>>>>> Always return IRQ_HANDLED will break the device who shares an irq with
>>>>> IFCVF.
>>>> as we discussed in another thread(spec inconsistency about ISR), ISR may
>>>> only works for INTx for now,
>>>> but VFs don't have INTx, and a VF may not share its vectors with other
>>>> devices, so I guess it can work
>>>> and may be our best try for now.
> Right, I thought you're using shared irq but actually not.
>
>>>>>> +    if (isr & VIRTIO_PCI_ISR_CONFIG)
>>>>>> +        ifcvf_config_changed(irq, arg);
> I wonder how ISR works in IFCVF, if ISR doesn't work for MSI, we need
> to remove the check of isr otherwise we will break config interrupt?
>
>>>>>> +
>>>>>> +    return ifcvf_vq_shared_intr_handler(irq, arg);
>>>>>> +}
>>>>>> +
>>>>>>     static void ifcvf_free_irq_vectors(void *data)
>>>>>>     {
>>>>>>         pci_free_irq_vectors(data);
>>>>>>     }
>>>>>>     -static void ifcvf_free_irq(struct ifcvf_adapter *adapter, int queues)
>>>>>> +static void ifcvf_free_vq_irq(struct ifcvf_adapter *adapter, int
>>>>>> queues)
>>>>>>     {
>>>>>>         struct pci_dev *pdev = adapter->pdev;
>>>>>>         struct ifcvf_hw *vf = &adapter->vf;
>>>>>>         int i;
>>>>>>     +    if (vf->msix_vector_status == MSIX_VECTOR_PER_VQ_AND_CONFIG) {
>>>>>> +        for (i = 0; i < queues; i++) {
>>>>>> +            devm_free_irq(&pdev->dev, vf->vring[i].irq, &vf->vring[i]);
>>>>>> +            vf->vring[i].irq = -EINVAL;
>>>>>> +        }
>>>>>> +    } else {
>>>>>> +        devm_free_irq(&pdev->dev, vf->vqs_shared_irq, vf);
>>>>>> +        vf->vqs_shared_irq = -EINVAL;
>>>>>> +    }
>>>>>> +}
>>>>>>     -    for (i = 0; i < queues; i++) {
>>>>>> -        devm_free_irq(&pdev->dev, vf->vring[i].irq, &vf->vring[i]);
>>>>>> -        vf->vring[i].irq = -EINVAL;
>>>>>> +static void ifcvf_free_config_irq(struct ifcvf_adapter *adapter)
>>>>>> +{
>>>>>> +    struct pci_dev *pdev = adapter->pdev;
>>>>>> +    struct ifcvf_hw *vf = &adapter->vf;
>>>>>> +
>>>>>> +    /* If the irq is shared by all vqs and the config interrupt,
>>>>>> +     * it is already freed in ifcvf_free_vq_irq, so here only
>>>>>> +     * need to free config irq when msix_vector_status !=
>>>>>> MSIX_VECTOR_DEV_SHARED
>>>>>> +     */
>>>>>> +    if (vf->msix_vector_status != MSIX_VECTOR_DEV_SHARED) {
>>>>>> +        devm_free_irq(&pdev->dev, vf->config_irq, vf);
>>>>>> +        vf->config_irq = -EINVAL;
>>>>>>         }
>>>>>> +}
>>>>>> +
>>>>>> +static void ifcvf_free_irq(struct ifcvf_adapter *adapter, int queues)
>>>>>> +{
>>>>>> +    struct pci_dev *pdev = adapter->pdev;
>>>>>>     -    devm_free_irq(&pdev->dev, vf->config_irq, vf);
>>>>>> +    ifcvf_free_vq_irq(adapter, queues);
>>>>>> +    ifcvf_free_config_irq(adapter);
>>>>>>         ifcvf_free_irq_vectors(pdev);
>>>>>>     }
>>>>>>     @@ -86,58 +142,172 @@ static int ifcvf_alloc_vectors(struct
>>>>>> ifcvf_adapter *adapter)
>>>>>>         return ret;
>>>>>>     }
>>>>>>     -static int ifcvf_request_irq(struct ifcvf_adapter *adapter)
>>>>>> +static int ifcvf_request_per_vq_irq(struct ifcvf_adapter *adapter)
>>>>>>     {
>>>>>>         struct pci_dev *pdev = adapter->pdev;
>>>>>>         struct ifcvf_hw *vf = &adapter->vf;
>>>>>> -    int vector, nvectors, i, ret, irq;
>>>>>> -    u16 max_intr;
>>>>>> +    int i, vector, ret, irq;
>>>>>>     -    nvectors = ifcvf_alloc_vectors(adapter);
>>>>>> -    if (!(nvectors > 0))
>>>>>> -        return nvectors;
>>>>>> +    for (i = 0; i < vf->nr_vring; i++) {
>>>>>> +        snprintf(vf->vring[i].msix_name, 256, "ifcvf[%s]-%d\n",
>>>>>> pci_name(pdev), i);
>>>>>> +        vector = i;
>>>>>> +        irq = pci_irq_vector(pdev, vector);
>>>>>> +        ret = devm_request_irq(&pdev->dev, irq,
>>>>>> +                       ifcvf_intr_handler, 0,
>>>>>> +                       vf->vring[i].msix_name,
>>>>>> +                       &vf->vring[i]);
>>>>>> +        if (ret) {
>>>>>> +            IFCVF_ERR(pdev, "Failed to request irq for vq %d\n", i);
>>>>>> +            ifcvf_free_vq_irq(adapter, i);
>>>>>> +        } else {
>>>>>> +            vf->vring[i].irq = irq;
>>>>>> +            ifcvf_set_vq_vector(vf, i, vector);
>>>>>> +        }
>>>>>> +    }
>>>>>>     -    max_intr = vf->nr_vring + 1;
>>>>>> +    vf->vqs_shared_irq = -EINVAL;
>>>>>> +
>>>>>> +    return 0;
>>>>>> +}
>>>>>> +
>>>>>> +static int ifcvf_request_shared_vq_irq(struct ifcvf_adapter *adapter)
>>>>>> +{
>>>>>> +    struct pci_dev *pdev = adapter->pdev;
>>>>>> +    struct ifcvf_hw *vf = &adapter->vf;
>>>>>> +    int i, vector, ret, irq;
>>>>>> +
>>>>>> +    vector = 0;
>>>>>> +    /* reuse msix_name[256] space of vring0 to store shared vqs
>>>>>> interrupt name */
>>>>> I think we can remove this comment since the code is straightforward.
>>>> sure
>>>>>> + snprintf(vf->vring[0].msix_name, 256,
>>>>>> "ifcvf[%s]-vqs-shared-irq\n", pci_name(pdev));
>>>>>> +    irq = pci_irq_vector(pdev, vector);
>>>>>> +    ret = devm_request_irq(&pdev->dev, irq,
>>>>>> +                   ifcvf_vq_shared_intr_handler, 0,
>>>>>> +                   vf->vring[0].msix_name, vf);
>>>>>> +    if (ret) {
>>>>>> +        IFCVF_ERR(pdev, "Failed to request shared irq for vf\n");
>>>>>> +
>>>>>> +        return ret;
>>>>>> +    }
>>>>>> +
>>>>>> +    vf->vqs_shared_irq = irq;
>>>>>> +    for (i = 0; i < vf->nr_vring; i++) {
>>>>>> +        vf->vring[i].irq = -EINVAL;
>>>>>> +        ifcvf_set_vq_vector(vf, i, vector);
>>>>>> +    }
>>>>>> +
>>>>>> +    return 0;
>>>>>> +
>>>>>> +}
>>>>>> +
>>>>>> +static int ifcvf_request_dev_shared_irq(struct ifcvf_adapter *adapter)
>>>>>> +{
>>>>>> +    struct pci_dev *pdev = adapter->pdev;
>>>>>> +    struct ifcvf_hw *vf = &adapter->vf;
>>>>>> +    int i, vector, ret, irq;
>>>>>> +
>>>>>> +    vector = 0;
>>>>>> +    /* reuse msix_name[256] space of vring0 to store shared device
>>>>>> interrupt name */
>>>>>> +    snprintf(vf->vring[0].msix_name, 256,
>>>>>> "ifcvf[%s]-dev-shared-irq\n", pci_name(pdev));
>>>>>> +    irq = pci_irq_vector(pdev, vector);
>>>>>> +    ret = devm_request_irq(&pdev->dev, irq,
>>>>>> +                   ifcvf_dev_shared_intr_handler, 0,
>>>>>> +                   vf->vring[0].msix_name, vf);
>>>>>> +    if (ret) {
>>>>>> +        IFCVF_ERR(pdev, "Failed to request shared irq for vf\n");
>>>>>>     -    ret = pci_alloc_irq_vectors(pdev, max_intr,
>>>>>> -                    max_intr, PCI_IRQ_MSIX);
>>>>>> -    if (ret < 0) {
>>>>>> -        IFCVF_ERR(pdev, "Failed to alloc IRQ vectors\n");
>>>>>>             return ret;
>>>>>>         }
>>>>>>     +    vf->vqs_shared_irq = irq;
>>>>>> +    for (i = 0; i < vf->nr_vring; i++) {
>>>>>> +        vf->vring[i].irq = -EINVAL;
>>>>>> +        ifcvf_set_vq_vector(vf, i, vector);
>>>>>> +    }
>>>>>> +
>>>>>> +    vf->config_irq = irq;
>>>>>> +    ifcvf_set_config_vector(vf, vector);
>>>>>> +
>>>>>> +    return 0;
>>>>>> +
>>>>>> +}
>>>>>> +
>>>>>> +static int ifcvf_request_vq_irq(struct ifcvf_adapter *adapter)
>>>>>> +{
>>>>>> +    struct ifcvf_hw *vf = &adapter->vf;
>>>>>> +    int ret;
>>>>>> +
>>>>>> +    if (vf->msix_vector_status == MSIX_VECTOR_PER_VQ_AND_CONFIG)
>>>>>> +        ret = ifcvf_request_per_vq_irq(adapter);
>>>>>> +    else
>>>>>> +        ret = ifcvf_request_shared_vq_irq(adapter);
>>>>>> +
>>>>>> +    return ret;
>>>>>> +}
>>>>>> +
>>>>>> +static int ifcvf_request_config_irq(struct ifcvf_adapter *adapter)
>>>>>> +{
>>>>>> +    struct pci_dev *pdev = adapter->pdev;
>>>>>> +    struct ifcvf_hw *vf = &adapter->vf;
>>>>>> +    int config_vector, ret;
>>>>>> +
>>>>>> +    if (vf->msix_vector_status == MSIX_VECTOR_DEV_SHARED)
>>>>>> +        return 0;
>>>>>> +
>>>>>> +    if (vf->msix_vector_status == MSIX_VECTOR_PER_VQ_AND_CONFIG)
>>>>>> +        /* vector 0 ~ vf->nr_vring for vqs, num vf->nr_vring vector
>>>>>> for config interrupt */
>>>>>> +        config_vector = vf->nr_vring;
>>>>>> +
>>>>>> +    if (vf->msix_vector_status == MSIX_VECTOR_SHARED_VQ_AND_CONFIG)
>>>>>> +        /* vector 0 for vqs and 1 for config interrupt */
>>>>>> +        config_vector = 1;
>>>>>> +
>>>>>>         snprintf(vf->config_msix_name, 256, "ifcvf[%s]-config\n",
>>>>>>              pci_name(pdev));
>>>>>> -    vector = 0;
>>>>>> -    vf->config_irq = pci_irq_vector(pdev, vector);
>>>>>> +    vf->config_irq = pci_irq_vector(pdev, config_vector);
>>>>>>         ret = devm_request_irq(&pdev->dev, vf->config_irq,
>>>>>>                        ifcvf_config_changed, 0,
>>>>>>                        vf->config_msix_name, vf);
>>>>>>         if (ret) {
>>>>>>             IFCVF_ERR(pdev, "Failed to request config irq\n");
>>>>>> +        ifcvf_free_vq_irq(adapter, vf->nr_vring);
>>>>>>             return ret;
>>>>>>         }
>>>>>>     -    for (i = 0; i < vf->nr_vring; i++) {
>>>>>> -        snprintf(vf->vring[i].msix_name, 256, "ifcvf[%s]-%d\n",
>>>>>> -             pci_name(pdev), i);
>>>>>> -        vector = i + IFCVF_MSI_QUEUE_OFF;
>>>>>> -        irq = pci_irq_vector(pdev, vector);
>>>>>> -        ret = devm_request_irq(&pdev->dev, irq,
>>>>>> -                       ifcvf_intr_handler, 0,
>>>>>> -                       vf->vring[i].msix_name,
>>>>>> -                       &vf->vring[i]);
>>>>>> -        if (ret) {
>>>>>> -            IFCVF_ERR(pdev,
>>>>>> -                  "Failed to request irq for vq %d\n", i);
>>>>>> -            ifcvf_free_irq(adapter, i);
>>>>>> +    ifcvf_set_config_vector(vf, config_vector);
>>>>>>     -            return ret;
>>>>>> -        }
>>>>>> +    return 0;
>>>>>> +}
>>>>>> +
>>>>>> +static int ifcvf_request_irq(struct ifcvf_adapter *adapter)
>>>>>> +{
>>>>> As replied above, I think having two modes should be sufficient and the
>>>>> code could be greatly simplified.
>>>> Do you mean if we don't get enough vectors, just use only one vector for the
>>>> vqs and config changes? I guess this
>>>> only works if ISR work for MSIX as we expects, or we may waste some time in
>>>> the device config space.
> Ok, I think I got you here. It's better to document this in the change log.
>
> Thanks
>
>>>> Thanks,
>>>> Zhu Lingshan
>>>>> Thanks
>>>>>
>>>>>
>>>>>> +    struct ifcvf_hw *vf = &adapter->vf;
>>>>>> +    int nvectors, ret, max_intr;
>>>>>>     -        vf->vring[i].irq = irq;
>>>>>> +    nvectors = ifcvf_alloc_vectors(adapter);
>>>>>> +    if (!(nvectors > 0))
>>>>>> +        return nvectors;
>>>>>> +
>>>>>> +    vf->msix_vector_status = MSIX_VECTOR_PER_VQ_AND_CONFIG;
>>>>>> +    max_intr = vf->nr_vring + 1;
>>>>>> +    if (nvectors < max_intr)
>>>>>> +        vf->msix_vector_status = MSIX_VECTOR_SHARED_VQ_AND_CONFIG;
>>>>>> +
>>>>>> +    if (nvectors == 1) {
>>>>>> +        vf->msix_vector_status = MSIX_VECTOR_DEV_SHARED;
>>>>>> +        ret = ifcvf_request_dev_shared_irq(adapter);
>>>>>> +
>>>>>> +        return ret;
>>>>>>         }
>>>>>>     +    ret = ifcvf_request_vq_irq(adapter);
>>>>>> +    if (ret)
>>>>>> +        return ret;
>>>>>> +
>>>>>> +    ret = ifcvf_request_config_irq(adapter);
>>>>>> +
>>>>>> +    if (ret)
>>>>>> +        return ret;
>>>>>> +
>>>>>>         return 0;
>>>>>>     }
>>>>>>     @@ -441,7 +611,10 @@ static int ifcvf_vdpa_get_vq_irq(struct
>>>>>> vdpa_device *vdpa_dev,
>>>>>>     {
>>>>>>         struct ifcvf_hw *vf = vdpa_to_vf(vdpa_dev);
>>>>>>     -    return vf->vring[qid].irq;
>>>>>> +    if (vf->vqs_shared_irq < 0)
>>>>>> +        return vf->vring[qid].irq;
>>>>>> +    else
>>>>>> +        return -EINVAL;
>>>>>>     }
>>>>>>       static struct vdpa_notification_area
>>>>>> ifcvf_get_vq_notification(struct vdpa_device *vdpa_dev,
>>>>> _______________________________________________
>>>>> Virtualization mailing list
>>>>> Virtualization@lists.linux-foundation.org
>>>>> https://lists.linuxfoundation.org/mailman/listinfo/virtualization

Re: [PATCH V4 4/4] vDPA/ifcvf: implement shared IRQ feature

[Jason Wang]

On Tue, Feb 15, 2022 at 11:29 AM Zhu, Lingshan <lingshan.zhu@intel.com> wrote:
>
>
>
> On 2/15/2022 11:03 AM, Jason Wang wrote:
> > On Tue, Feb 15, 2022 at 10:18 AM Zhu, Lingshan <lingshan.zhu@intel.com> wrote:
> >>
> >>
> >> On 2/14/2022 10:27 PM, Michael S. Tsirkin wrote:
> >>> On Mon, Feb 14, 2022 at 06:01:56PM +0800, Zhu Lingshan wrote:
> >>>> On 2/14/2022 3:19 PM, Jason Wang wrote:
> >>>>> 在 2022/2/3 下午3:27, Zhu Lingshan 写道:
> >>>>>> On some platforms/devices, there may not be enough MSI vector
> >>>>>> slots allocated for virtqueues and config changes. In such a case,
> >>>>>> the interrupt sources(virtqueues, config changes) must share
> >>>>>> an IRQ/vector, to avoid initialization failures, keep
> >>>>>> the device functional.
> >>>>>>
> >>>>>> This commit handles three cases:
> >>>>>> (1) number of the allocated vectors == the number of virtqueues + 1
> >>>>>> (config changes), every virtqueue and the config interrupt has
> >>>>>> a separated vector/IRQ, the best and the most likely case.
> >>>>>> (2) number of the allocated vectors is less than the best case, but
> >>>>>> greater than 1. In this case, all virtqueues share a vector/IRQ,
> >>>>>> the config interrupt has a separated vector/IRQ
> >>>>>> (3) only one vector is allocated, in this case, the virtqueues and
> >>>>>> the config interrupt share a vector/IRQ. The worst and most
> >>>>>> unlikely case.
> >>>>>>
> >>>>>> Otherwise, it needs to fail.
> >>>>>>
> >>>>>> This commit introduces some helper functions:
> >>>>>> ifcvf_set_vq_vector() and ifcvf_set_config_vector() sets virtqueue
> >>>>>> vector and config vector in the device config space, so that
> >>>>>> the device can send interrupt DMA.
> >>>>>>
> >>>>>> This commit adds some fields in struct ifcvf_hw and re-placed
> >>>>>> the existed fields to be aligned with the cacheline.
> >>>>>>
> >>>>>> Signed-off-by: Zhu Lingshan <lingshan.zhu@intel.com>
> >>>>>> ---
> >>>>>>     drivers/vdpa/ifcvf/ifcvf_base.c |  47 ++++--
> >>>>>>     drivers/vdpa/ifcvf/ifcvf_base.h |  23 ++-
> >>>>>>     drivers/vdpa/ifcvf/ifcvf_main.c | 243 +++++++++++++++++++++++++++-----
> >>>>>>     3 files changed, 256 insertions(+), 57 deletions(-)
> >>>>>>
> >>>>>> diff --git a/drivers/vdpa/ifcvf/ifcvf_base.c
> >>>>>> b/drivers/vdpa/ifcvf/ifcvf_base.c
> >>>>>> index 397692ae671c..18dcb63ab1e3 100644
> >>>>>> --- a/drivers/vdpa/ifcvf/ifcvf_base.c
> >>>>>> +++ b/drivers/vdpa/ifcvf/ifcvf_base.c
> >>>>>> @@ -15,6 +15,36 @@ struct ifcvf_adapter *vf_to_adapter(struct
> >>>>>> ifcvf_hw *hw)
> >>>>>>         return container_of(hw, struct ifcvf_adapter, vf);
> >>>>>>     }
> >>>>>>     +int ifcvf_set_vq_vector(struct ifcvf_hw *hw, u16 qid, int vector)
> >>>>>> +{
> >>>>>> +    struct virtio_pci_common_cfg __iomem *cfg = hw->common_cfg;
> >>>>>> +    struct ifcvf_adapter *ifcvf = vf_to_adapter(hw);
> >>>>>> +
> >>>>>> +    ifc_iowrite16(qid, &cfg->queue_select);
> >>>>>> +    ifc_iowrite16(vector, &cfg->queue_msix_vector);
> >>>>>> +    if (ifc_ioread16(&cfg->queue_msix_vector) ==
> >>>>>> VIRTIO_MSI_NO_VECTOR) {
> >>>>>> +        IFCVF_ERR(ifcvf->pdev, "No msix vector for queue %u\n", qid);
> >>>>>> +            return -EINVAL;
> >>>>>> +    }
> >>>>> Let's leave this check for the caller, E.g can caller try to assign
> >>>>> NO_VECTOR during uni-nit?
> >>>> ifcvf driver sets NO_VECTOR when call hw_disable(). I am not sure whether I
> >>>> get it,
> > I meant you invent the ifcvf_set_vq_vector() you'd better use that in
> > hw_disable() as well.
> OK
> >
> >>>> Yes we can let the caller check a vq vector, however this may cause more
> >>>> than three levels brackets, may looks ugly.
> > I don't understand here, this is how virito_pci did:
> >
> > /*
> >   * vp_modern_queue_vector - set the MSIX vector for a specific virtqueue
> >   * @mdev: the modern virtio-pci device
> >   * @index: queue index
> >   * @vector: the config vector
> >   *
> >   * Returns the config vector read from the device
> >   */
> > u16 vp_modern_queue_vector(struct virtio_pci_modern_device *mdev,
> >                             u16 index, u16 vector)
> > {
> >          struct virtio_pci_common_cfg __iomem *cfg = mdev->common;
> >
> >          vp_iowrite16(index, &cfg->queue_select);
> >          vp_iowrite16(vector, &cfg->queue_msix_vector);
> >          /* Flush the write out to device */
> >          return vp_ioread16(&cfg->queue_msix_vector);
> > }
> > EXPORT_SYMBOL_GPL(vp_modern_queue_vector);
> I mean if we leave the checks for the caller, it may look like:
> +       for (i = 0; i < vf->nr_vring; i++) {
> +               snprintf(vf->vring[i].msix_name, 256, "ifcvf[%s]-%d\n",
> pci_name(pdev), i);
> +               vector = i;
> +               irq = pci_irq_vector(pdev, vector);
> +               ret = devm_request_irq(&pdev->dev, irq,
> +                                      ifcvf_intr_handler, 0,
> +                                      vf->vring[i].msix_name,
> +                                      &vf->vring[i]);
> +               if (ret) {
> +                       IFCVF_ERR(pdev, "Failed to request irq for vq
> %d\n", i);
> +                       ifcvf_free_vq_irq(adapter, i);
> +               } else {
> +                       vf->vring[i].irq = irq;
> +                       ifcvf_set_vq_vector(vf, i, vector);
>                              if (xxxxx) {
>                                  xxxxxxxxxxx;
>                              }
> +               }
> +       }

If the brackets are the only concern, you can factor out the per vq
logic into a dedicated function.

Thanks

>
> Too many brackets.
> >
> >>>>>> +
> >>>>>> +    return 0;
> >>>>>> +}
> >>>>>> +
> >>>>>> +int ifcvf_set_config_vector(struct ifcvf_hw *hw, int vector)
> >>>>>> +{
> >>>>>> +    struct virtio_pci_common_cfg __iomem *cfg = hw->common_cfg;
> >>>>>> +    struct ifcvf_adapter *ifcvf = vf_to_adapter(hw);
> >>>>>> +
> >>>>>> +    cfg = hw->common_cfg;
> >>>>>> +    ifc_iowrite16(vector,  &cfg->msix_config);
> >>>>>> +    if (ifc_ioread16(&cfg->msix_config) == VIRTIO_MSI_NO_VECTOR) {
> >>>>>> +        IFCVF_ERR(ifcvf->pdev, "No msix vector for device config\n");
> >>>>>> +        return -EINVAL;
> >>>>>> +    }
> >>>>> Similar question as above.
> >>>>>
> >>>>>
> >>>>>> +
> >>>>>> +    return 0;
> >>>>>> +}
> >>>>>> +
> >>>>>>     static void __iomem *get_cap_addr(struct ifcvf_hw *hw,
> >>>>>>                       struct virtio_pci_cap *cap)
> >>>>>>     {
> >>>>>> @@ -140,6 +170,8 @@ int ifcvf_init_hw(struct ifcvf_hw *hw, struct
> >>>>>> pci_dev *pdev)
> >>>>>>               hw->common_cfg, hw->notify_base, hw->isr,
> >>>>>>               hw->dev_cfg, hw->notify_off_multiplier);
> >>>>>>     +    hw->vqs_shared_irq = -EINVAL;
> >>>>>> +
> >>>>>>         return 0;
> >>>>>>     }
> >>>>>>     @@ -321,12 +353,6 @@ static int ifcvf_hw_enable(struct ifcvf_hw *hw)
> >>>>>>           ifcvf = vf_to_adapter(hw);
> >>>>>>         cfg = hw->common_cfg;
> >>>>>> -    ifc_iowrite16(IFCVF_MSI_CONFIG_OFF, &cfg->msix_config);
> >>>>>> -
> >>>>>> -    if (ifc_ioread16(&cfg->msix_config) == VIRTIO_MSI_NO_VECTOR) {
> >>>>>> -        IFCVF_ERR(ifcvf->pdev, "No msix vector for device config\n");
> >>>>>> -        return -EINVAL;
> >>>>>> -    }
> >>>>>>           for (i = 0; i < hw->nr_vring; i++) {
> >>>>>>             if (!hw->vring[i].ready)
> >>>>>> @@ -340,15 +366,6 @@ static int ifcvf_hw_enable(struct ifcvf_hw *hw)
> >>>>>>             ifc_iowrite64_twopart(hw->vring[i].used, &cfg->queue_used_lo,
> >>>>>>                          &cfg->queue_used_hi);
> >>>>>>             ifc_iowrite16(hw->vring[i].size, &cfg->queue_size);
> >>>>>> -        ifc_iowrite16(i + IFCVF_MSI_QUEUE_OFF,
> >>>>>> &cfg->queue_msix_vector);
> >>>>>> -
> >>>>>> -        if (ifc_ioread16(&cfg->queue_msix_vector) ==
> >>>>>> -            VIRTIO_MSI_NO_VECTOR) {
> >>>>>> -            IFCVF_ERR(ifcvf->pdev,
> >>>>>> -                  "No msix vector for queue %u\n", i);
> >>>>>> -            return -EINVAL;
> >>>>>> -        }
> >>>>>> -
> >>>>>>             ifcvf_set_vq_state(hw, i, hw->vring[i].last_avail_idx);
> >>>>>>             ifc_iowrite16(1, &cfg->queue_enable);
> >>>>>>         }
> >>>>>> diff --git a/drivers/vdpa/ifcvf/ifcvf_base.h
> >>>>>> b/drivers/vdpa/ifcvf/ifcvf_base.h
> >>>>>> index 949b4fb9d554..9cfe088c82e9 100644
> >>>>>> --- a/drivers/vdpa/ifcvf/ifcvf_base.h
> >>>>>> +++ b/drivers/vdpa/ifcvf/ifcvf_base.h
> >>>>>> @@ -27,8 +27,6 @@
> >>>>>>       #define IFCVF_QUEUE_ALIGNMENT    PAGE_SIZE
> >>>>>>     #define IFCVF_QUEUE_MAX        32768
> >>>>>> -#define IFCVF_MSI_CONFIG_OFF    0
> >>>>>> -#define IFCVF_MSI_QUEUE_OFF    1
> >>>>>>     #define IFCVF_PCI_MAX_RESOURCE    6
> >>>>>>       #define IFCVF_LM_CFG_SIZE        0x40
> >>>>>> @@ -42,6 +40,13 @@
> >>>>>>     #define ifcvf_private_to_vf(adapter) \
> >>>>>>         (&((struct ifcvf_adapter *)adapter)->vf)
> >>>>>>     +/* all vqs and config interrupt has its own vector */
> >>>>>> +#define MSIX_VECTOR_PER_VQ_AND_CONFIG        1
> >>>>>> +/* all vqs share a vector, and config interrupt has a separate
> >>>>>> vector */
> >>>>>> +#define MSIX_VECTOR_SHARED_VQ_AND_CONFIG    2
> >>>>>> +/* all vqs and config interrupt share a vector */
> >>>>>> +#define MSIX_VECTOR_DEV_SHARED            3
> >>>>> I think there's no much value to differ 2 from 3 consider config
> >>>>> interrupt should be rare.
> >>>> IMHO we still need 2 and 3, because MSIX_VECTOR_SHARED_VQ_AND_CONFIG means
> >>>> there are at least 2 vectors,
> >>>> the vqs share one vector, config change has its own vector.
> > I want to know the value of having a dedicated vector for config?
> I think a dedicated vector for config changes can help us avoid
> operations on config space when vq interrupt triggered.
> >
> >>>> MSIX_VECTOR_DEV_SHARED means three are only one vector, all vqs and config
> >>>> changes need to share this vector.
> >>>>>
> >>>>>> +
> >>>>>>     static inline u8 ifc_ioread8(u8 __iomem *addr)
> >>>>>>     {
> >>>>>>         return ioread8(addr);
> >>>>>> @@ -97,25 +102,27 @@ struct ifcvf_hw {
> >>>>>>         u8 __iomem *isr;
> >>>>>>         /* Live migration */
> >>>>>>         u8 __iomem *lm_cfg;
> >>>>>> -    u16 nr_vring;
> >>>>> Any reason for moving nv_vring, config_size, and other stuffs?
> >>>> for cacheline alignment.
> >>> maybe a separate patch then.
> >> Sure
> >>
> >> Thanks!
> >>>>>
> >>>>>>         /* Notification bar number */
> >>>>>>         u8 notify_bar;
> >>>>>> +    u8 msix_vector_status;
> >>>>>> +    /* virtio-net or virtio-blk device config size */
> >>>>>> +    u32 config_size;
> >>>>>>         /* Notificaiton bar address */
> >>>>>>         void __iomem *notify_base;
> >>>>>>         phys_addr_t notify_base_pa;
> >>>>>>         u32 notify_off_multiplier;
> >>>>>> +    u32 dev_type;
> >>>>>>         u64 req_features;
> >>>>>>         u64 hw_features;
> >>>>>> -    u32 dev_type;
> >>>>>>         struct virtio_pci_common_cfg __iomem *common_cfg;
> >>>>>>         void __iomem *dev_cfg;
> >>>>>>         struct vring_info vring[IFCVF_MAX_QUEUES];
> >>>>>>         void __iomem * const *base;
> >>>>>>         char config_msix_name[256];
> >>>>>>         struct vdpa_callback config_cb;
> >>>>>> -    unsigned int config_irq;
> >>>>>> -    /* virtio-net or virtio-blk device config size */
> >>>>>> -    u32 config_size;
> >>>>>> +    int config_irq;
> >>>>>> +    int vqs_shared_irq;
> >>>>>> +    u16 nr_vring;
> >>>>>>     };
> >>>>>>       struct ifcvf_adapter {
> >>>>>> @@ -160,4 +167,6 @@ int ifcvf_set_vq_state(struct ifcvf_hw *hw, u16
> >>>>>> qid, u16 num);
> >>>>>>     struct ifcvf_adapter *vf_to_adapter(struct ifcvf_hw *hw);
> >>>>>>     int ifcvf_probed_virtio_net(struct ifcvf_hw *hw);
> >>>>>>     u32 ifcvf_get_config_size(struct ifcvf_hw *hw);
> >>>>>> +int ifcvf_set_vq_vector(struct ifcvf_hw *hw, u16 qid, int vector);
> >>>>>> +int ifcvf_set_config_vector(struct ifcvf_hw *hw, int vector);
> >>>>>>     #endif /* _IFCVF_H_ */
> >>>>>> diff --git a/drivers/vdpa/ifcvf/ifcvf_main.c
> >>>>>> b/drivers/vdpa/ifcvf/ifcvf_main.c
> >>>>>> index 44c89ab0b6da..ca414399f040 100644
> >>>>>> --- a/drivers/vdpa/ifcvf/ifcvf_main.c
> >>>>>> +++ b/drivers/vdpa/ifcvf/ifcvf_main.c
> >>>>>> @@ -17,6 +17,7 @@
> >>>>>>     #define DRIVER_AUTHOR   "Intel Corporation"
> >>>>>>     #define IFCVF_DRIVER_NAME       "ifcvf"
> >>>>>>     +/* handles config interrupt */
> >>>>> This seems unrelated to the shared IRQ logic and it looks useless since
> >>>>> it's easily to deduce it from the function name below.
> >>>> OK, do you mean the comments? I can remove these comments.
> > Yes.
> >
> >>>>>>     static irqreturn_t ifcvf_config_changed(int irq, void *arg)
> >>>>>>     {
> >>>>>>         struct ifcvf_hw *vf = arg;
> >>>>>> @@ -27,6 +28,7 @@ static irqreturn_t ifcvf_config_changed(int irq,
> >>>>>> void *arg)
> >>>>>>         return IRQ_HANDLED;
> >>>>>>     }
> >>>>>>     +/* handles vqs interrupt */
> >>>>> So did this.
> >>>>>
> >>>>>
> >>>>>>     static irqreturn_t ifcvf_intr_handler(int irq, void *arg)
> >>>>>>     {
> >>>>>>         struct vring_info *vring = arg;
> >>>>>> @@ -37,24 +39,78 @@ static irqreturn_t ifcvf_intr_handler(int irq,
> >>>>>> void *arg)
> >>>>>>         return IRQ_HANDLED;
> >>>>>>     }
> >>>>>>     +/* handls vqs shared interrupt */
> >>>>>> +static irqreturn_t ifcvf_vq_shared_intr_handler(int irq, void *arg)
> >>>>>> +{
> >>>>>> +    struct ifcvf_hw *vf = arg;
> >>>>>> +    struct vring_info *vring;
> >>>>>> +    int i;
> >>>>>> +
> >>>>>> +    for (i = 0; i < vf->nr_vring; i++) {
> >>>>>> +        vring = &vf->vring[i];
> >>>>>> +        if (vring->cb.callback)
> >>>>>> + vf->vring->cb.callback(vring->cb.private);
> >>>>>> +    }
> >>>>>> +
> >>>>>> +    return IRQ_HANDLED;
> >>>>>> +}
> >>>>>> +
> >>>>>> +/* handles a shared interrupt for vqs and config */
> >>>>>> +static irqreturn_t ifcvf_dev_shared_intr_handler(int irq, void *arg)
> >>>>>> +{
> >>>>>> +    struct ifcvf_hw *vf = arg;
> >>>>>> +    u8 isr;
> >>>>>> +
> >>>>>> +    isr = ifc_ioread8(vf->isr);
> >>>>> We need to exactly what vp_interrupt do here. Checking against vf->isr
> >>>>> first and return IRQ_NONE if it is not set.
> >>>>>
> >>>>> Always return IRQ_HANDLED will break the device who shares an irq with
> >>>>> IFCVF.
> >>>> as we discussed in another thread(spec inconsistency about ISR), ISR may
> >>>> only works for INTx for now,
> >>>> but VFs don't have INTx, and a VF may not share its vectors with other
> >>>> devices, so I guess it can work
> >>>> and may be our best try for now.
> > Right, I thought you're using shared irq but actually not.
> >
> >>>>>> +    if (isr & VIRTIO_PCI_ISR_CONFIG)
> >>>>>> +        ifcvf_config_changed(irq, arg);
> > I wonder how ISR works in IFCVF, if ISR doesn't work for MSI, we need
> > to remove the check of isr otherwise we will break config interrupt?
> >
> >>>>>> +
> >>>>>> +    return ifcvf_vq_shared_intr_handler(irq, arg);
> >>>>>> +}
> >>>>>> +
> >>>>>>     static void ifcvf_free_irq_vectors(void *data)
> >>>>>>     {
> >>>>>>         pci_free_irq_vectors(data);
> >>>>>>     }
> >>>>>>     -static void ifcvf_free_irq(struct ifcvf_adapter *adapter, int queues)
> >>>>>> +static void ifcvf_free_vq_irq(struct ifcvf_adapter *adapter, int
> >>>>>> queues)
> >>>>>>     {
> >>>>>>         struct pci_dev *pdev = adapter->pdev;
> >>>>>>         struct ifcvf_hw *vf = &adapter->vf;
> >>>>>>         int i;
> >>>>>>     +    if (vf->msix_vector_status == MSIX_VECTOR_PER_VQ_AND_CONFIG) {
> >>>>>> +        for (i = 0; i < queues; i++) {
> >>>>>> +            devm_free_irq(&pdev->dev, vf->vring[i].irq, &vf->vring[i]);
> >>>>>> +            vf->vring[i].irq = -EINVAL;
> >>>>>> +        }
> >>>>>> +    } else {
> >>>>>> +        devm_free_irq(&pdev->dev, vf->vqs_shared_irq, vf);
> >>>>>> +        vf->vqs_shared_irq = -EINVAL;
> >>>>>> +    }
> >>>>>> +}
> >>>>>>     -    for (i = 0; i < queues; i++) {
> >>>>>> -        devm_free_irq(&pdev->dev, vf->vring[i].irq, &vf->vring[i]);
> >>>>>> -        vf->vring[i].irq = -EINVAL;
> >>>>>> +static void ifcvf_free_config_irq(struct ifcvf_adapter *adapter)
> >>>>>> +{
> >>>>>> +    struct pci_dev *pdev = adapter->pdev;
> >>>>>> +    struct ifcvf_hw *vf = &adapter->vf;
> >>>>>> +
> >>>>>> +    /* If the irq is shared by all vqs and the config interrupt,
> >>>>>> +     * it is already freed in ifcvf_free_vq_irq, so here only
> >>>>>> +     * need to free config irq when msix_vector_status !=
> >>>>>> MSIX_VECTOR_DEV_SHARED
> >>>>>> +     */
> >>>>>> +    if (vf->msix_vector_status != MSIX_VECTOR_DEV_SHARED) {
> >>>>>> +        devm_free_irq(&pdev->dev, vf->config_irq, vf);
> >>>>>> +        vf->config_irq = -EINVAL;
> >>>>>>         }
> >>>>>> +}
> >>>>>> +
> >>>>>> +static void ifcvf_free_irq(struct ifcvf_adapter *adapter, int queues)
> >>>>>> +{
> >>>>>> +    struct pci_dev *pdev = adapter->pdev;
> >>>>>>     -    devm_free_irq(&pdev->dev, vf->config_irq, vf);
> >>>>>> +    ifcvf_free_vq_irq(adapter, queues);
> >>>>>> +    ifcvf_free_config_irq(adapter);
> >>>>>>         ifcvf_free_irq_vectors(pdev);
> >>>>>>     }
> >>>>>>     @@ -86,58 +142,172 @@ static int ifcvf_alloc_vectors(struct
> >>>>>> ifcvf_adapter *adapter)
> >>>>>>         return ret;
> >>>>>>     }
> >>>>>>     -static int ifcvf_request_irq(struct ifcvf_adapter *adapter)
> >>>>>> +static int ifcvf_request_per_vq_irq(struct ifcvf_adapter *adapter)
> >>>>>>     {
> >>>>>>         struct pci_dev *pdev = adapter->pdev;
> >>>>>>         struct ifcvf_hw *vf = &adapter->vf;
> >>>>>> -    int vector, nvectors, i, ret, irq;
> >>>>>> -    u16 max_intr;
> >>>>>> +    int i, vector, ret, irq;
> >>>>>>     -    nvectors = ifcvf_alloc_vectors(adapter);
> >>>>>> -    if (!(nvectors > 0))
> >>>>>> -        return nvectors;
> >>>>>> +    for (i = 0; i < vf->nr_vring; i++) {
> >>>>>> +        snprintf(vf->vring[i].msix_name, 256, "ifcvf[%s]-%d\n",
> >>>>>> pci_name(pdev), i);
> >>>>>> +        vector = i;
> >>>>>> +        irq = pci_irq_vector(pdev, vector);
> >>>>>> +        ret = devm_request_irq(&pdev->dev, irq,
> >>>>>> +                       ifcvf_intr_handler, 0,
> >>>>>> +                       vf->vring[i].msix_name,
> >>>>>> +                       &vf->vring[i]);
> >>>>>> +        if (ret) {
> >>>>>> +            IFCVF_ERR(pdev, "Failed to request irq for vq %d\n", i);
> >>>>>> +            ifcvf_free_vq_irq(adapter, i);
> >>>>>> +        } else {
> >>>>>> +            vf->vring[i].irq = irq;
> >>>>>> +            ifcvf_set_vq_vector(vf, i, vector);
> >>>>>> +        }
> >>>>>> +    }
> >>>>>>     -    max_intr = vf->nr_vring + 1;
> >>>>>> +    vf->vqs_shared_irq = -EINVAL;
> >>>>>> +
> >>>>>> +    return 0;
> >>>>>> +}
> >>>>>> +
> >>>>>> +static int ifcvf_request_shared_vq_irq(struct ifcvf_adapter *adapter)
> >>>>>> +{
> >>>>>> +    struct pci_dev *pdev = adapter->pdev;
> >>>>>> +    struct ifcvf_hw *vf = &adapter->vf;
> >>>>>> +    int i, vector, ret, irq;
> >>>>>> +
> >>>>>> +    vector = 0;
> >>>>>> +    /* reuse msix_name[256] space of vring0 to store shared vqs
> >>>>>> interrupt name */
> >>>>> I think we can remove this comment since the code is straightforward.
> >>>> sure
> >>>>>> + snprintf(vf->vring[0].msix_name, 256,
> >>>>>> "ifcvf[%s]-vqs-shared-irq\n", pci_name(pdev));
> >>>>>> +    irq = pci_irq_vector(pdev, vector);
> >>>>>> +    ret = devm_request_irq(&pdev->dev, irq,
> >>>>>> +                   ifcvf_vq_shared_intr_handler, 0,
> >>>>>> +                   vf->vring[0].msix_name, vf);
> >>>>>> +    if (ret) {
> >>>>>> +        IFCVF_ERR(pdev, "Failed to request shared irq for vf\n");
> >>>>>> +
> >>>>>> +        return ret;
> >>>>>> +    }
> >>>>>> +
> >>>>>> +    vf->vqs_shared_irq = irq;
> >>>>>> +    for (i = 0; i < vf->nr_vring; i++) {
> >>>>>> +        vf->vring[i].irq = -EINVAL;
> >>>>>> +        ifcvf_set_vq_vector(vf, i, vector);
> >>>>>> +    }
> >>>>>> +
> >>>>>> +    return 0;
> >>>>>> +
> >>>>>> +}
> >>>>>> +
> >>>>>> +static int ifcvf_request_dev_shared_irq(struct ifcvf_adapter *adapter)
> >>>>>> +{
> >>>>>> +    struct pci_dev *pdev = adapter->pdev;
> >>>>>> +    struct ifcvf_hw *vf = &adapter->vf;
> >>>>>> +    int i, vector, ret, irq;
> >>>>>> +
> >>>>>> +    vector = 0;
> >>>>>> +    /* reuse msix_name[256] space of vring0 to store shared device
> >>>>>> interrupt name */
> >>>>>> +    snprintf(vf->vring[0].msix_name, 256,
> >>>>>> "ifcvf[%s]-dev-shared-irq\n", pci_name(pdev));
> >>>>>> +    irq = pci_irq_vector(pdev, vector);
> >>>>>> +    ret = devm_request_irq(&pdev->dev, irq,
> >>>>>> +                   ifcvf_dev_shared_intr_handler, 0,
> >>>>>> +                   vf->vring[0].msix_name, vf);
> >>>>>> +    if (ret) {
> >>>>>> +        IFCVF_ERR(pdev, "Failed to request shared irq for vf\n");
> >>>>>>     -    ret = pci_alloc_irq_vectors(pdev, max_intr,
> >>>>>> -                    max_intr, PCI_IRQ_MSIX);
> >>>>>> -    if (ret < 0) {
> >>>>>> -        IFCVF_ERR(pdev, "Failed to alloc IRQ vectors\n");
> >>>>>>             return ret;
> >>>>>>         }
> >>>>>>     +    vf->vqs_shared_irq = irq;
> >>>>>> +    for (i = 0; i < vf->nr_vring; i++) {
> >>>>>> +        vf->vring[i].irq = -EINVAL;
> >>>>>> +        ifcvf_set_vq_vector(vf, i, vector);
> >>>>>> +    }
> >>>>>> +
> >>>>>> +    vf->config_irq = irq;
> >>>>>> +    ifcvf_set_config_vector(vf, vector);
> >>>>>> +
> >>>>>> +    return 0;
> >>>>>> +
> >>>>>> +}
> >>>>>> +
> >>>>>> +static int ifcvf_request_vq_irq(struct ifcvf_adapter *adapter)
> >>>>>> +{
> >>>>>> +    struct ifcvf_hw *vf = &adapter->vf;
> >>>>>> +    int ret;
> >>>>>> +
> >>>>>> +    if (vf->msix_vector_status == MSIX_VECTOR_PER_VQ_AND_CONFIG)
> >>>>>> +        ret = ifcvf_request_per_vq_irq(adapter);
> >>>>>> +    else
> >>>>>> +        ret = ifcvf_request_shared_vq_irq(adapter);
> >>>>>> +
> >>>>>> +    return ret;
> >>>>>> +}
> >>>>>> +
> >>>>>> +static int ifcvf_request_config_irq(struct ifcvf_adapter *adapter)
> >>>>>> +{
> >>>>>> +    struct pci_dev *pdev = adapter->pdev;
> >>>>>> +    struct ifcvf_hw *vf = &adapter->vf;
> >>>>>> +    int config_vector, ret;
> >>>>>> +
> >>>>>> +    if (vf->msix_vector_status == MSIX_VECTOR_DEV_SHARED)
> >>>>>> +        return 0;
> >>>>>> +
> >>>>>> +    if (vf->msix_vector_status == MSIX_VECTOR_PER_VQ_AND_CONFIG)
> >>>>>> +        /* vector 0 ~ vf->nr_vring for vqs, num vf->nr_vring vector
> >>>>>> for config interrupt */
> >>>>>> +        config_vector = vf->nr_vring;
> >>>>>> +
> >>>>>> +    if (vf->msix_vector_status == MSIX_VECTOR_SHARED_VQ_AND_CONFIG)
> >>>>>> +        /* vector 0 for vqs and 1 for config interrupt */
> >>>>>> +        config_vector = 1;
> >>>>>> +
> >>>>>>         snprintf(vf->config_msix_name, 256, "ifcvf[%s]-config\n",
> >>>>>>              pci_name(pdev));
> >>>>>> -    vector = 0;
> >>>>>> -    vf->config_irq = pci_irq_vector(pdev, vector);
> >>>>>> +    vf->config_irq = pci_irq_vector(pdev, config_vector);
> >>>>>>         ret = devm_request_irq(&pdev->dev, vf->config_irq,
> >>>>>>                        ifcvf_config_changed, 0,
> >>>>>>                        vf->config_msix_name, vf);
> >>>>>>         if (ret) {
> >>>>>>             IFCVF_ERR(pdev, "Failed to request config irq\n");
> >>>>>> +        ifcvf_free_vq_irq(adapter, vf->nr_vring);
> >>>>>>             return ret;
> >>>>>>         }
> >>>>>>     -    for (i = 0; i < vf->nr_vring; i++) {
> >>>>>> -        snprintf(vf->vring[i].msix_name, 256, "ifcvf[%s]-%d\n",
> >>>>>> -             pci_name(pdev), i);
> >>>>>> -        vector = i + IFCVF_MSI_QUEUE_OFF;
> >>>>>> -        irq = pci_irq_vector(pdev, vector);
> >>>>>> -        ret = devm_request_irq(&pdev->dev, irq,
> >>>>>> -                       ifcvf_intr_handler, 0,
> >>>>>> -                       vf->vring[i].msix_name,
> >>>>>> -                       &vf->vring[i]);
> >>>>>> -        if (ret) {
> >>>>>> -            IFCVF_ERR(pdev,
> >>>>>> -                  "Failed to request irq for vq %d\n", i);
> >>>>>> -            ifcvf_free_irq(adapter, i);
> >>>>>> +    ifcvf_set_config_vector(vf, config_vector);
> >>>>>>     -            return ret;
> >>>>>> -        }
> >>>>>> +    return 0;
> >>>>>> +}
> >>>>>> +
> >>>>>> +static int ifcvf_request_irq(struct ifcvf_adapter *adapter)
> >>>>>> +{
> >>>>> As replied above, I think having two modes should be sufficient and the
> >>>>> code could be greatly simplified.
> >>>> Do you mean if we don't get enough vectors, just use only one vector for the
> >>>> vqs and config changes? I guess this
> >>>> only works if ISR work for MSIX as we expects, or we may waste some time in
> >>>> the device config space.
> > Ok, I think I got you here. It's better to document this in the change log.
> >
> > Thanks
> >
> >>>> Thanks,
> >>>> Zhu Lingshan
> >>>>> Thanks
> >>>>>
> >>>>>
> >>>>>> +    struct ifcvf_hw *vf = &adapter->vf;
> >>>>>> +    int nvectors, ret, max_intr;
> >>>>>>     -        vf->vring[i].irq = irq;
> >>>>>> +    nvectors = ifcvf_alloc_vectors(adapter);
> >>>>>> +    if (!(nvectors > 0))
> >>>>>> +        return nvectors;
> >>>>>> +
> >>>>>> +    vf->msix_vector_status = MSIX_VECTOR_PER_VQ_AND_CONFIG;
> >>>>>> +    max_intr = vf->nr_vring + 1;
> >>>>>> +    if (nvectors < max_intr)
> >>>>>> +        vf->msix_vector_status = MSIX_VECTOR_SHARED_VQ_AND_CONFIG;
> >>>>>> +
> >>>>>> +    if (nvectors == 1) {
> >>>>>> +        vf->msix_vector_status = MSIX_VECTOR_DEV_SHARED;
> >>>>>> +        ret = ifcvf_request_dev_shared_irq(adapter);
> >>>>>> +
> >>>>>> +        return ret;
> >>>>>>         }
> >>>>>>     +    ret = ifcvf_request_vq_irq(adapter);
> >>>>>> +    if (ret)
> >>>>>> +        return ret;
> >>>>>> +
> >>>>>> +    ret = ifcvf_request_config_irq(adapter);
> >>>>>> +
> >>>>>> +    if (ret)
> >>>>>> +        return ret;
> >>>>>> +
> >>>>>>         return 0;
> >>>>>>     }
> >>>>>>     @@ -441,7 +611,10 @@ static int ifcvf_vdpa_get_vq_irq(struct
> >>>>>> vdpa_device *vdpa_dev,
> >>>>>>     {
> >>>>>>         struct ifcvf_hw *vf = vdpa_to_vf(vdpa_dev);
> >>>>>>     -    return vf->vring[qid].irq;
> >>>>>> +    if (vf->vqs_shared_irq < 0)
> >>>>>> +        return vf->vring[qid].irq;
> >>>>>> +    else
> >>>>>> +        return -EINVAL;
> >>>>>>     }
> >>>>>>       static struct vdpa_notification_area
> >>>>>> ifcvf_get_vq_notification(struct vdpa_device *vdpa_dev,
> >>>>> _______________________________________________
> >>>>> Virtualization mailing list
> >>>>> Virtualization@lists.linux-foundation.org
> >>>>> https://lists.linuxfoundation.org/mailman/listinfo/virtualization
>

Re: [PATCH V4 4/4] vDPA/ifcvf: implement shared IRQ feature

[Michael S. Tsirkin]

On Mon, Feb 14, 2022 at 03:19:25PM +0800, Jason Wang wrote:
> 
> 在 2022/2/3 下午3:27, Zhu Lingshan 写道:
> > On some platforms/devices, there may not be enough MSI vector
> > slots allocated for virtqueues and config changes. In such a case,
> > the interrupt sources(virtqueues, config changes) must share
> > an IRQ/vector, to avoid initialization failures, keep
> > the device functional.
> > 
> > This commit handles three cases:
> > (1) number of the allocated vectors == the number of virtqueues + 1
> > (config changes), every virtqueue and the config interrupt has
> > a separated vector/IRQ, the best and the most likely case.
> > (2) number of the allocated vectors is less than the best case, but
> > greater than 1. In this case, all virtqueues share a vector/IRQ,
> > the config interrupt has a separated vector/IRQ
> > (3) only one vector is allocated, in this case, the virtqueues and
> > the config interrupt share a vector/IRQ. The worst and most
> > unlikely case.
> > 
> > Otherwise, it needs to fail.
> > 
> > This commit introduces some helper functions:
> > ifcvf_set_vq_vector() and ifcvf_set_config_vector() sets virtqueue
> > vector and config vector in the device config space, so that
> > the device can send interrupt DMA.
> > 
> > This commit adds some fields in struct ifcvf_hw and re-placed
> > the existed fields to be aligned with the cacheline.
> > 
> > Signed-off-by: Zhu Lingshan <lingshan.zhu@intel.com>
> > ---
> >   drivers/vdpa/ifcvf/ifcvf_base.c |  47 ++++--
> >   drivers/vdpa/ifcvf/ifcvf_base.h |  23 ++-
> >   drivers/vdpa/ifcvf/ifcvf_main.c | 243 +++++++++++++++++++++++++++-----
> >   3 files changed, 256 insertions(+), 57 deletions(-)
> > 
> > diff --git a/drivers/vdpa/ifcvf/ifcvf_base.c b/drivers/vdpa/ifcvf/ifcvf_base.c
> > index 397692ae671c..18dcb63ab1e3 100644
> > --- a/drivers/vdpa/ifcvf/ifcvf_base.c
> > +++ b/drivers/vdpa/ifcvf/ifcvf_base.c
> > @@ -15,6 +15,36 @@ struct ifcvf_adapter *vf_to_adapter(struct ifcvf_hw *hw)
> >   	return container_of(hw, struct ifcvf_adapter, vf);
> >   }
> > +int ifcvf_set_vq_vector(struct ifcvf_hw *hw, u16 qid, int vector)
> > +{
> > +	struct virtio_pci_common_cfg __iomem *cfg = hw->common_cfg;
> > +	struct ifcvf_adapter *ifcvf = vf_to_adapter(hw);
> > +
> > +	ifc_iowrite16(qid, &cfg->queue_select);
> > +	ifc_iowrite16(vector, &cfg->queue_msix_vector);
> > +	if (ifc_ioread16(&cfg->queue_msix_vector) == VIRTIO_MSI_NO_VECTOR) {
> > +		IFCVF_ERR(ifcvf->pdev, "No msix vector for queue %u\n", qid);
> > +			return -EINVAL;
> > +	}
> 
> 
> Let's leave this check for the caller, E.g can caller try to assign
> NO_VECTOR during uni-nit?


Hmm I'm not sure I agree. Caller will have to write queue select
again, and that's an extra IO, which is a waste.
And having function checking itself just seems better contained.

> 
> > +
> > +	return 0;
> > +}
> > +
> > +int ifcvf_set_config_vector(struct ifcvf_hw *hw, int vector)
> > +{
> > +	struct virtio_pci_common_cfg __iomem *cfg = hw->common_cfg;
> > +	struct ifcvf_adapter *ifcvf = vf_to_adapter(hw);
> > +
> > +	cfg = hw->common_cfg;
> > +	ifc_iowrite16(vector,  &cfg->msix_config);
> > +	if (ifc_ioread16(&cfg->msix_config) == VIRTIO_MSI_NO_VECTOR) {
> > +		IFCVF_ERR(ifcvf->pdev, "No msix vector for device config\n");
> > +		return -EINVAL;
> > +	}
> 
> 
> Similar question as above.
> 
> 
> > +
> > +	return 0;
> > +}
> > +
> >   static void __iomem *get_cap_addr(struct ifcvf_hw *hw,
> >   				  struct virtio_pci_cap *cap)
> >   {
> > @@ -140,6 +170,8 @@ int ifcvf_init_hw(struct ifcvf_hw *hw, struct pci_dev *pdev)
> >   		  hw->common_cfg, hw->notify_base, hw->isr,
> >   		  hw->dev_cfg, hw->notify_off_multiplier);
> > +	hw->vqs_shared_irq = -EINVAL;
> > +
> >   	return 0;
> >   }
> > @@ -321,12 +353,6 @@ static int ifcvf_hw_enable(struct ifcvf_hw *hw)
> >   	ifcvf = vf_to_adapter(hw);
> >   	cfg = hw->common_cfg;
> > -	ifc_iowrite16(IFCVF_MSI_CONFIG_OFF, &cfg->msix_config);
> > -
> > -	if (ifc_ioread16(&cfg->msix_config) == VIRTIO_MSI_NO_VECTOR) {
> > -		IFCVF_ERR(ifcvf->pdev, "No msix vector for device config\n");
> > -		return -EINVAL;
> > -	}
> >   	for (i = 0; i < hw->nr_vring; i++) {
> >   		if (!hw->vring[i].ready)
> > @@ -340,15 +366,6 @@ static int ifcvf_hw_enable(struct ifcvf_hw *hw)
> >   		ifc_iowrite64_twopart(hw->vring[i].used, &cfg->queue_used_lo,
> >   				     &cfg->queue_used_hi);
> >   		ifc_iowrite16(hw->vring[i].size, &cfg->queue_size);
> > -		ifc_iowrite16(i + IFCVF_MSI_QUEUE_OFF, &cfg->queue_msix_vector);
> > -
> > -		if (ifc_ioread16(&cfg->queue_msix_vector) ==
> > -		    VIRTIO_MSI_NO_VECTOR) {
> > -			IFCVF_ERR(ifcvf->pdev,
> > -				  "No msix vector for queue %u\n", i);
> > -			return -EINVAL;
> > -		}
> > -
> >   		ifcvf_set_vq_state(hw, i, hw->vring[i].last_avail_idx);
> >   		ifc_iowrite16(1, &cfg->queue_enable);
> >   	}
> > diff --git a/drivers/vdpa/ifcvf/ifcvf_base.h b/drivers/vdpa/ifcvf/ifcvf_base.h
> > index 949b4fb9d554..9cfe088c82e9 100644
> > --- a/drivers/vdpa/ifcvf/ifcvf_base.h
> > +++ b/drivers/vdpa/ifcvf/ifcvf_base.h
> > @@ -27,8 +27,6 @@
> >   #define IFCVF_QUEUE_ALIGNMENT	PAGE_SIZE
> >   #define IFCVF_QUEUE_MAX		32768
> > -#define IFCVF_MSI_CONFIG_OFF	0
> > -#define IFCVF_MSI_QUEUE_OFF	1
> >   #define IFCVF_PCI_MAX_RESOURCE	6
> >   #define IFCVF_LM_CFG_SIZE		0x40
> > @@ -42,6 +40,13 @@
> >   #define ifcvf_private_to_vf(adapter) \
> >   	(&((struct ifcvf_adapter *)adapter)->vf)
> > +/* all vqs and config interrupt has its own vector */
> > +#define MSIX_VECTOR_PER_VQ_AND_CONFIG		1
> > +/* all vqs share a vector, and config interrupt has a separate vector */
> > +#define MSIX_VECTOR_SHARED_VQ_AND_CONFIG	2
> > +/* all vqs and config interrupt share a vector */
> > +#define MSIX_VECTOR_DEV_SHARED			3
> 
> 
> I think there's no much value to differ 2 from 3 consider config interrupt
> should be rare.


Yes but if we do not have a dedicated vector then we need an
extra device IO (in fact, a read) on each interrupt.

> 
> > +
> >   static inline u8 ifc_ioread8(u8 __iomem *addr)
> >   {
> >   	return ioread8(addr);
> > @@ -97,25 +102,27 @@ struct ifcvf_hw {
> >   	u8 __iomem *isr;
> >   	/* Live migration */
> >   	u8 __iomem *lm_cfg;
> > -	u16 nr_vring;
> 
> 
> Any reason for moving nv_vring, config_size, and other stuffs?
> 
> 
> >   	/* Notification bar number */
> >   	u8 notify_bar;
> > +	u8 msix_vector_status;
> > +	/* virtio-net or virtio-blk device config size */
> > +	u32 config_size;
> >   	/* Notificaiton bar address */
> >   	void __iomem *notify_base;
> >   	phys_addr_t notify_base_pa;
> >   	u32 notify_off_multiplier;
> > +	u32 dev_type;
> >   	u64 req_features;
> >   	u64 hw_features;
> > -	u32 dev_type;
> >   	struct virtio_pci_common_cfg __iomem *common_cfg;
> >   	void __iomem *dev_cfg;
> >   	struct vring_info vring[IFCVF_MAX_QUEUES];
> >   	void __iomem * const *base;
> >   	char config_msix_name[256];
> >   	struct vdpa_callback config_cb;
> > -	unsigned int config_irq;
> > -	/* virtio-net or virtio-blk device config size */
> > -	u32 config_size;
> > +	int config_irq;
> > +	int vqs_shared_irq;
> > +	u16 nr_vring;
> >   };
> >   struct ifcvf_adapter {
> > @@ -160,4 +167,6 @@ int ifcvf_set_vq_state(struct ifcvf_hw *hw, u16 qid, u16 num);
> >   struct ifcvf_adapter *vf_to_adapter(struct ifcvf_hw *hw);
> >   int ifcvf_probed_virtio_net(struct ifcvf_hw *hw);
> >   u32 ifcvf_get_config_size(struct ifcvf_hw *hw);
> > +int ifcvf_set_vq_vector(struct ifcvf_hw *hw, u16 qid, int vector);
> > +int ifcvf_set_config_vector(struct ifcvf_hw *hw, int vector);
> >   #endif /* _IFCVF_H_ */
> > diff --git a/drivers/vdpa/ifcvf/ifcvf_main.c b/drivers/vdpa/ifcvf/ifcvf_main.c
> > index 44c89ab0b6da..ca414399f040 100644
> > --- a/drivers/vdpa/ifcvf/ifcvf_main.c
> > +++ b/drivers/vdpa/ifcvf/ifcvf_main.c
> > @@ -17,6 +17,7 @@
> >   #define DRIVER_AUTHOR   "Intel Corporation"
> >   #define IFCVF_DRIVER_NAME       "ifcvf"
> > +/* handles config interrupt */
> 
> 
> This seems unrelated to the shared IRQ logic and it looks useless since it's
> easily to deduce it from the function name below.
> 
> 
> >   static irqreturn_t ifcvf_config_changed(int irq, void *arg)
> >   {
> >   	struct ifcvf_hw *vf = arg;
> > @@ -27,6 +28,7 @@ static irqreturn_t ifcvf_config_changed(int irq, void *arg)
> >   	return IRQ_HANDLED;
> >   }
> > +/* handles vqs interrupt */
> 
> 
> So did this.
> 
> 
> >   static irqreturn_t ifcvf_intr_handler(int irq, void *arg)
> >   {
> >   	struct vring_info *vring = arg;
> > @@ -37,24 +39,78 @@ static irqreturn_t ifcvf_intr_handler(int irq, void *arg)
> >   	return IRQ_HANDLED;
> >   }
> > +/* handls vqs shared interrupt */
> > +static irqreturn_t ifcvf_vq_shared_intr_handler(int irq, void *arg)
> > +{
> > +	struct ifcvf_hw *vf = arg;
> > +	struct vring_info *vring;
> > +	int i;
> > +
> > +	for (i = 0; i < vf->nr_vring; i++) {
> > +		vring = &vf->vring[i];
> > +		if (vring->cb.callback)
> > +			vf->vring->cb.callback(vring->cb.private);
> > +	}
> > +
> > +	return IRQ_HANDLED;
> > +}
> > +
> > +/* handles a shared interrupt for vqs and config */
> > +static irqreturn_t ifcvf_dev_shared_intr_handler(int irq, void *arg)

shared is not a good name given IRQ_SHARED is not set.
maybe "common"? "reused"?

> > +{
> > +	struct ifcvf_hw *vf = arg;
> > +	u8 isr;
> > +
> > +	isr = ifc_ioread8(vf->isr);
> 
> 
> We need to exactly what vp_interrupt do here. Checking against vf->isr first
> and return IRQ_NONE if it is not set.

no, vf->isr is not set for VQ interrupts. If need to actually poke
at the VQ to know.

> Always return IRQ_HANDLED will break the device who shares an irq with
> IFCVF.


It's a MSI, not INT#. So interrupt is not shared as such - it's only
sharing vector between config and vq.


> 
> > +	if (isr & VIRTIO_PCI_ISR_CONFIG)
> > +		ifcvf_config_changed(irq, arg);
> > +
> > +	return ifcvf_vq_shared_intr_handler(irq, arg);
> > +}
> > +
> >   static void ifcvf_free_irq_vectors(void *data)
> >   {
> >   	pci_free_irq_vectors(data);
> >   }
> > -static void ifcvf_free_irq(struct ifcvf_adapter *adapter, int queues)
> > +static void ifcvf_free_vq_irq(struct ifcvf_adapter *adapter, int queues)
> >   {
> >   	struct pci_dev *pdev = adapter->pdev;
> >   	struct ifcvf_hw *vf = &adapter->vf;
> >   	int i;
> > +	if (vf->msix_vector_status == MSIX_VECTOR_PER_VQ_AND_CONFIG) {
> > +		for (i = 0; i < queues; i++) {
> > +			devm_free_irq(&pdev->dev, vf->vring[i].irq, &vf->vring[i]);
> > +			vf->vring[i].irq = -EINVAL;
> > +		}
> > +	} else {
> > +		devm_free_irq(&pdev->dev, vf->vqs_shared_irq, vf);
> > +		vf->vqs_shared_irq = -EINVAL;
> > +	}
> > +}
> > -	for (i = 0; i < queues; i++) {
> > -		devm_free_irq(&pdev->dev, vf->vring[i].irq, &vf->vring[i]);
> > -		vf->vring[i].irq = -EINVAL;
> > +static void ifcvf_free_config_irq(struct ifcvf_adapter *adapter)
> > +{
> > +	struct pci_dev *pdev = adapter->pdev;
> > +	struct ifcvf_hw *vf = &adapter->vf;
> > +
> > +	/* If the irq is shared by all vqs and the config interrupt,
> > +	 * it is already freed in ifcvf_free_vq_irq, so here only
> > +	 * need to free config irq when msix_vector_status != MSIX_VECTOR_DEV_SHARED
> > +	 */
> > +	if (vf->msix_vector_status != MSIX_VECTOR_DEV_SHARED) {
> > +		devm_free_irq(&pdev->dev, vf->config_irq, vf);
> > +		vf->config_irq = -EINVAL;
> >   	}
> > +}
> > +
> > +static void ifcvf_free_irq(struct ifcvf_adapter *adapter, int queues)
> > +{
> > +	struct pci_dev *pdev = adapter->pdev;
> > -	devm_free_irq(&pdev->dev, vf->config_irq, vf);
> > +	ifcvf_free_vq_irq(adapter, queues);
> > +	ifcvf_free_config_irq(adapter);
> >   	ifcvf_free_irq_vectors(pdev);
> >   }
> > @@ -86,58 +142,172 @@ static int ifcvf_alloc_vectors(struct ifcvf_adapter *adapter)
> >   	return ret;
> >   }
> > -static int ifcvf_request_irq(struct ifcvf_adapter *adapter)
> > +static int ifcvf_request_per_vq_irq(struct ifcvf_adapter *adapter)
> >   {
> >   	struct pci_dev *pdev = adapter->pdev;
> >   	struct ifcvf_hw *vf = &adapter->vf;
> > -	int vector, nvectors, i, ret, irq;
> > -	u16 max_intr;
> > +	int i, vector, ret, irq;
> > -	nvectors = ifcvf_alloc_vectors(adapter);
> > -	if (!(nvectors > 0))
> > -		return nvectors;
> > +	for (i = 0; i < vf->nr_vring; i++) {
> > +		snprintf(vf->vring[i].msix_name, 256, "ifcvf[%s]-%d\n", pci_name(pdev), i);
> > +		vector = i;
> > +		irq = pci_irq_vector(pdev, vector);
> > +		ret = devm_request_irq(&pdev->dev, irq,
> > +				       ifcvf_intr_handler, 0,
> > +				       vf->vring[i].msix_name,
> > +				       &vf->vring[i]);
> > +		if (ret) {
> > +			IFCVF_ERR(pdev, "Failed to request irq for vq %d\n", i);
> > +			ifcvf_free_vq_irq(adapter, i);
> > +		} else {
> > +			vf->vring[i].irq = irq;
> > +			ifcvf_set_vq_vector(vf, i, vector);
> > +		}
> > +	}
> > -	max_intr = vf->nr_vring + 1;
> > +	vf->vqs_shared_irq = -EINVAL;
> > +
> > +	return 0;
> > +}
> > +
> > +static int ifcvf_request_shared_vq_irq(struct ifcvf_adapter *adapter)
> > +{
> > +	struct pci_dev *pdev = adapter->pdev;
> > +	struct ifcvf_hw *vf = &adapter->vf;
> > +	int i, vector, ret, irq;
> > +
> > +	vector = 0;
> > +	/* reuse msix_name[256] space of vring0 to store shared vqs interrupt name */
> 
> 
> I think we can remove this comment since the code is straightforward.
> 
> 
> > +	snprintf(vf->vring[0].msix_name, 256, "ifcvf[%s]-vqs-shared-irq\n", pci_name(pdev));
> > +	irq = pci_irq_vector(pdev, vector);
> > +	ret = devm_request_irq(&pdev->dev, irq,
> > +			       ifcvf_vq_shared_intr_handler, 0,
> > +			       vf->vring[0].msix_name, vf);
> > +	if (ret) {
> > +		IFCVF_ERR(pdev, "Failed to request shared irq for vf\n");
> > +
> > +		return ret;
> > +	}
> > +
> > +	vf->vqs_shared_irq = irq;
> > +	for (i = 0; i < vf->nr_vring; i++) {
> > +		vf->vring[i].irq = -EINVAL;
> > +		ifcvf_set_vq_vector(vf, i, vector);
> > +	}
> > +
> > +	return 0;
> > +
> > +}
> > +
> > +static int ifcvf_request_dev_shared_irq(struct ifcvf_adapter *adapter)
> > +{
> > +	struct pci_dev *pdev = adapter->pdev;
> > +	struct ifcvf_hw *vf = &adapter->vf;
> > +	int i, vector, ret, irq;
> > +
> > +	vector = 0;
> > +	/* reuse msix_name[256] space of vring0 to store shared device interrupt name */
> > +	snprintf(vf->vring[0].msix_name, 256, "ifcvf[%s]-dev-shared-irq\n", pci_name(pdev));
> > +	irq = pci_irq_vector(pdev, vector);
> > +	ret = devm_request_irq(&pdev->dev, irq,
> > +			       ifcvf_dev_shared_intr_handler, 0,
> > +			       vf->vring[0].msix_name, vf);
> > +	if (ret) {
> > +		IFCVF_ERR(pdev, "Failed to request shared irq for vf\n");
> > -	ret = pci_alloc_irq_vectors(pdev, max_intr,
> > -				    max_intr, PCI_IRQ_MSIX);
> > -	if (ret < 0) {
> > -		IFCVF_ERR(pdev, "Failed to alloc IRQ vectors\n");
> >   		return ret;
> >   	}
> > +	vf->vqs_shared_irq = irq;
> > +	for (i = 0; i < vf->nr_vring; i++) {
> > +		vf->vring[i].irq = -EINVAL;
> > +		ifcvf_set_vq_vector(vf, i, vector);
> > +	}
> > +
> > +	vf->config_irq = irq;
> > +	ifcvf_set_config_vector(vf, vector);
> > +
> > +	return 0;
> > +
> > +}
> > +
> > +static int ifcvf_request_vq_irq(struct ifcvf_adapter *adapter)
> > +{
> > +	struct ifcvf_hw *vf = &adapter->vf;
> > +	int ret;
> > +
> > +	if (vf->msix_vector_status == MSIX_VECTOR_PER_VQ_AND_CONFIG)
> > +		ret = ifcvf_request_per_vq_irq(adapter);
> > +	else
> > +		ret = ifcvf_request_shared_vq_irq(adapter);
> > +
> > +	return ret;
> > +}
> > +
> > +static int ifcvf_request_config_irq(struct ifcvf_adapter *adapter)
> > +{
> > +	struct pci_dev *pdev = adapter->pdev;
> > +	struct ifcvf_hw *vf = &adapter->vf;
> > +	int config_vector, ret;
> > +
> > +	if (vf->msix_vector_status == MSIX_VECTOR_DEV_SHARED)
> > +		return 0;
> > +
> > +	if (vf->msix_vector_status == MSIX_VECTOR_PER_VQ_AND_CONFIG)
> > +		/* vector 0 ~ vf->nr_vring for vqs, num vf->nr_vring vector for config interrupt */
> > +		config_vector = vf->nr_vring;
> > +
> > +	if (vf->msix_vector_status ==  MSIX_VECTOR_SHARED_VQ_AND_CONFIG)
> > +		/* vector 0 for vqs and 1 for config interrupt */
> > +		config_vector = 1;
> > +
> >   	snprintf(vf->config_msix_name, 256, "ifcvf[%s]-config\n",
> >   		 pci_name(pdev));
> > -	vector = 0;
> > -	vf->config_irq = pci_irq_vector(pdev, vector);
> > +	vf->config_irq = pci_irq_vector(pdev, config_vector);
> >   	ret = devm_request_irq(&pdev->dev, vf->config_irq,
> >   			       ifcvf_config_changed, 0,
> >   			       vf->config_msix_name, vf);
> >   	if (ret) {
> >   		IFCVF_ERR(pdev, "Failed to request config irq\n");
> > +		ifcvf_free_vq_irq(adapter, vf->nr_vring);
> >   		return ret;
> >   	}
> > -	for (i = 0; i < vf->nr_vring; i++) {
> > -		snprintf(vf->vring[i].msix_name, 256, "ifcvf[%s]-%d\n",
> > -			 pci_name(pdev), i);
> > -		vector = i + IFCVF_MSI_QUEUE_OFF;
> > -		irq = pci_irq_vector(pdev, vector);
> > -		ret = devm_request_irq(&pdev->dev, irq,
> > -				       ifcvf_intr_handler, 0,
> > -				       vf->vring[i].msix_name,
> > -				       &vf->vring[i]);
> > -		if (ret) {
> > -			IFCVF_ERR(pdev,
> > -				  "Failed to request irq for vq %d\n", i);
> > -			ifcvf_free_irq(adapter, i);
> > +	ifcvf_set_config_vector(vf, config_vector);
> > -			return ret;
> > -		}
> > +	return 0;
> > +}
> > +
> > +static int ifcvf_request_irq(struct ifcvf_adapter *adapter)
> > +{
> 
> 
> As replied above, I think having two modes should be sufficient and the code
> could be greatly simplified.
> 
> Thanks
> 

Well it is claimed there are platforms where we are short
on vectors. 3 versus 2 seems a 50% saving. You disagree?

> > +	struct ifcvf_hw *vf = &adapter->vf;
> > +	int nvectors, ret, max_intr;
> > -		vf->vring[i].irq = irq;
> > +	nvectors = ifcvf_alloc_vectors(adapter);
> > +	if (!(nvectors > 0))
> > +		return nvectors;
> > +
> > +	vf->msix_vector_status = MSIX_VECTOR_PER_VQ_AND_CONFIG;
> > +	max_intr = vf->nr_vring + 1;
> > +	if (nvectors < max_intr)
> > +		vf->msix_vector_status = MSIX_VECTOR_SHARED_VQ_AND_CONFIG;
> > +
> > +	if (nvectors == 1) {
> > +		vf->msix_vector_status = MSIX_VECTOR_DEV_SHARED;
> > +		ret = ifcvf_request_dev_shared_irq(adapter);
> > +
> > +		return ret;
> >   	}
> > +	ret = ifcvf_request_vq_irq(adapter);
> > +	if (ret)
> > +		return ret;
> > +
> > +	ret = ifcvf_request_config_irq(adapter);
> > +
> > +	if (ret)
> > +		return ret;
> > +
> >   	return 0;
> >   }
> > @@ -441,7 +611,10 @@ static int ifcvf_vdpa_get_vq_irq(struct vdpa_device *vdpa_dev,
> >   {
> >   	struct ifcvf_hw *vf = vdpa_to_vf(vdpa_dev);
> > -	return vf->vring[qid].irq;
> > +	if (vf->vqs_shared_irq < 0)
> > +		return vf->vring[qid].irq;
> > +	else
> > +		return -EINVAL;
> >   }
> >   static struct vdpa_notification_area ifcvf_get_vq_notification(struct vdpa_device *vdpa_dev,

Re: [PATCH V4 4/4] vDPA/ifcvf: implement shared IRQ feature

[Zhu, Lingshan]

On 2/14/2022 10:25 PM, Michael S. Tsirkin wrote:
> On Mon, Feb 14, 2022 at 03:19:25PM +0800, Jason Wang wrote:
>> 在 2022/2/3 下午3:27, Zhu Lingshan 写道:
>>> On some platforms/devices, there may not be enough MSI vector
>>> slots allocated for virtqueues and config changes. In such a case,
>>> the interrupt sources(virtqueues, config changes) must share
>>> an IRQ/vector, to avoid initialization failures, keep
>>> the device functional.
>>>
>>> This commit handles three cases:
>>> (1) number of the allocated vectors == the number of virtqueues + 1
>>> (config changes), every virtqueue and the config interrupt has
>>> a separated vector/IRQ, the best and the most likely case.
>>> (2) number of the allocated vectors is less than the best case, but
>>> greater than 1. In this case, all virtqueues share a vector/IRQ,
>>> the config interrupt has a separated vector/IRQ
>>> (3) only one vector is allocated, in this case, the virtqueues and
>>> the config interrupt share a vector/IRQ. The worst and most
>>> unlikely case.
>>>
>>> Otherwise, it needs to fail.
>>>
>>> This commit introduces some helper functions:
>>> ifcvf_set_vq_vector() and ifcvf_set_config_vector() sets virtqueue
>>> vector and config vector in the device config space, so that
>>> the device can send interrupt DMA.
>>>
>>> This commit adds some fields in struct ifcvf_hw and re-placed
>>> the existed fields to be aligned with the cacheline.
>>>
>>> Signed-off-by: Zhu Lingshan <lingshan.zhu@intel.com>
>>> ---
>>>    drivers/vdpa/ifcvf/ifcvf_base.c |  47 ++++--
>>>    drivers/vdpa/ifcvf/ifcvf_base.h |  23 ++-
>>>    drivers/vdpa/ifcvf/ifcvf_main.c | 243 +++++++++++++++++++++++++++-----
>>>    3 files changed, 256 insertions(+), 57 deletions(-)
>>>
>>> diff --git a/drivers/vdpa/ifcvf/ifcvf_base.c b/drivers/vdpa/ifcvf/ifcvf_base.c
>>> index 397692ae671c..18dcb63ab1e3 100644
>>> --- a/drivers/vdpa/ifcvf/ifcvf_base.c
>>> +++ b/drivers/vdpa/ifcvf/ifcvf_base.c
>>> @@ -15,6 +15,36 @@ struct ifcvf_adapter *vf_to_adapter(struct ifcvf_hw *hw)
>>>    	return container_of(hw, struct ifcvf_adapter, vf);
>>>    }
>>> +int ifcvf_set_vq_vector(struct ifcvf_hw *hw, u16 qid, int vector)
>>> +{
>>> +	struct virtio_pci_common_cfg __iomem *cfg = hw->common_cfg;
>>> +	struct ifcvf_adapter *ifcvf = vf_to_adapter(hw);
>>> +
>>> +	ifc_iowrite16(qid, &cfg->queue_select);
>>> +	ifc_iowrite16(vector, &cfg->queue_msix_vector);
>>> +	if (ifc_ioread16(&cfg->queue_msix_vector) == VIRTIO_MSI_NO_VECTOR) {
>>> +		IFCVF_ERR(ifcvf->pdev, "No msix vector for queue %u\n", qid);
>>> +			return -EINVAL;
>>> +	}
>>
>> Let's leave this check for the caller, E.g can caller try to assign
>> NO_VECTOR during uni-nit?
>
> Hmm I'm not sure I agree. Caller will have to write queue select
> again, and that's an extra IO, which is a waste.
> And having function checking itself just seems better contained.
>
>>> +
>>> +	return 0;
>>> +}
>>> +
>>> +int ifcvf_set_config_vector(struct ifcvf_hw *hw, int vector)
>>> +{
>>> +	struct virtio_pci_common_cfg __iomem *cfg = hw->common_cfg;
>>> +	struct ifcvf_adapter *ifcvf = vf_to_adapter(hw);
>>> +
>>> +	cfg = hw->common_cfg;
>>> +	ifc_iowrite16(vector,  &cfg->msix_config);
>>> +	if (ifc_ioread16(&cfg->msix_config) == VIRTIO_MSI_NO_VECTOR) {
>>> +		IFCVF_ERR(ifcvf->pdev, "No msix vector for device config\n");
>>> +		return -EINVAL;
>>> +	}
>>
>> Similar question as above.
>>
>>
>>> +
>>> +	return 0;
>>> +}
>>> +
>>>    static void __iomem *get_cap_addr(struct ifcvf_hw *hw,
>>>    				  struct virtio_pci_cap *cap)
>>>    {
>>> @@ -140,6 +170,8 @@ int ifcvf_init_hw(struct ifcvf_hw *hw, struct pci_dev *pdev)
>>>    		  hw->common_cfg, hw->notify_base, hw->isr,
>>>    		  hw->dev_cfg, hw->notify_off_multiplier);
>>> +	hw->vqs_shared_irq = -EINVAL;
>>> +
>>>    	return 0;
>>>    }
>>> @@ -321,12 +353,6 @@ static int ifcvf_hw_enable(struct ifcvf_hw *hw)
>>>    	ifcvf = vf_to_adapter(hw);
>>>    	cfg = hw->common_cfg;
>>> -	ifc_iowrite16(IFCVF_MSI_CONFIG_OFF, &cfg->msix_config);
>>> -
>>> -	if (ifc_ioread16(&cfg->msix_config) == VIRTIO_MSI_NO_VECTOR) {
>>> -		IFCVF_ERR(ifcvf->pdev, "No msix vector for device config\n");
>>> -		return -EINVAL;
>>> -	}
>>>    	for (i = 0; i < hw->nr_vring; i++) {
>>>    		if (!hw->vring[i].ready)
>>> @@ -340,15 +366,6 @@ static int ifcvf_hw_enable(struct ifcvf_hw *hw)
>>>    		ifc_iowrite64_twopart(hw->vring[i].used, &cfg->queue_used_lo,
>>>    				     &cfg->queue_used_hi);
>>>    		ifc_iowrite16(hw->vring[i].size, &cfg->queue_size);
>>> -		ifc_iowrite16(i + IFCVF_MSI_QUEUE_OFF, &cfg->queue_msix_vector);
>>> -
>>> -		if (ifc_ioread16(&cfg->queue_msix_vector) ==
>>> -		    VIRTIO_MSI_NO_VECTOR) {
>>> -			IFCVF_ERR(ifcvf->pdev,
>>> -				  "No msix vector for queue %u\n", i);
>>> -			return -EINVAL;
>>> -		}
>>> -
>>>    		ifcvf_set_vq_state(hw, i, hw->vring[i].last_avail_idx);
>>>    		ifc_iowrite16(1, &cfg->queue_enable);
>>>    	}
>>> diff --git a/drivers/vdpa/ifcvf/ifcvf_base.h b/drivers/vdpa/ifcvf/ifcvf_base.h
>>> index 949b4fb9d554..9cfe088c82e9 100644
>>> --- a/drivers/vdpa/ifcvf/ifcvf_base.h
>>> +++ b/drivers/vdpa/ifcvf/ifcvf_base.h
>>> @@ -27,8 +27,6 @@
>>>    #define IFCVF_QUEUE_ALIGNMENT	PAGE_SIZE
>>>    #define IFCVF_QUEUE_MAX		32768
>>> -#define IFCVF_MSI_CONFIG_OFF	0
>>> -#define IFCVF_MSI_QUEUE_OFF	1
>>>    #define IFCVF_PCI_MAX_RESOURCE	6
>>>    #define IFCVF_LM_CFG_SIZE		0x40
>>> @@ -42,6 +40,13 @@
>>>    #define ifcvf_private_to_vf(adapter) \
>>>    	(&((struct ifcvf_adapter *)adapter)->vf)
>>> +/* all vqs and config interrupt has its own vector */
>>> +#define MSIX_VECTOR_PER_VQ_AND_CONFIG		1
>>> +/* all vqs share a vector, and config interrupt has a separate vector */
>>> +#define MSIX_VECTOR_SHARED_VQ_AND_CONFIG	2
>>> +/* all vqs and config interrupt share a vector */
>>> +#define MSIX_VECTOR_DEV_SHARED			3
>>
>> I think there's no much value to differ 2 from 3 consider config interrupt
>> should be rare.
>
> Yes but if we do not have a dedicated vector then we need an
> extra device IO (in fact, a read) on each interrupt.
>
>>> +
>>>    static inline u8 ifc_ioread8(u8 __iomem *addr)
>>>    {
>>>    	return ioread8(addr);
>>> @@ -97,25 +102,27 @@ struct ifcvf_hw {
>>>    	u8 __iomem *isr;
>>>    	/* Live migration */
>>>    	u8 __iomem *lm_cfg;
>>> -	u16 nr_vring;
>>
>> Any reason for moving nv_vring, config_size, and other stuffs?
>>
>>
>>>    	/* Notification bar number */
>>>    	u8 notify_bar;
>>> +	u8 msix_vector_status;
>>> +	/* virtio-net or virtio-blk device config size */
>>> +	u32 config_size;
>>>    	/* Notificaiton bar address */
>>>    	void __iomem *notify_base;
>>>    	phys_addr_t notify_base_pa;
>>>    	u32 notify_off_multiplier;
>>> +	u32 dev_type;
>>>    	u64 req_features;
>>>    	u64 hw_features;
>>> -	u32 dev_type;
>>>    	struct virtio_pci_common_cfg __iomem *common_cfg;
>>>    	void __iomem *dev_cfg;
>>>    	struct vring_info vring[IFCVF_MAX_QUEUES];
>>>    	void __iomem * const *base;
>>>    	char config_msix_name[256];
>>>    	struct vdpa_callback config_cb;
>>> -	unsigned int config_irq;
>>> -	/* virtio-net or virtio-blk device config size */
>>> -	u32 config_size;
>>> +	int config_irq;
>>> +	int vqs_shared_irq;
>>> +	u16 nr_vring;
>>>    };
>>>    struct ifcvf_adapter {
>>> @@ -160,4 +167,6 @@ int ifcvf_set_vq_state(struct ifcvf_hw *hw, u16 qid, u16 num);
>>>    struct ifcvf_adapter *vf_to_adapter(struct ifcvf_hw *hw);
>>>    int ifcvf_probed_virtio_net(struct ifcvf_hw *hw);
>>>    u32 ifcvf_get_config_size(struct ifcvf_hw *hw);
>>> +int ifcvf_set_vq_vector(struct ifcvf_hw *hw, u16 qid, int vector);
>>> +int ifcvf_set_config_vector(struct ifcvf_hw *hw, int vector);
>>>    #endif /* _IFCVF_H_ */
>>> diff --git a/drivers/vdpa/ifcvf/ifcvf_main.c b/drivers/vdpa/ifcvf/ifcvf_main.c
>>> index 44c89ab0b6da..ca414399f040 100644
>>> --- a/drivers/vdpa/ifcvf/ifcvf_main.c
>>> +++ b/drivers/vdpa/ifcvf/ifcvf_main.c
>>> @@ -17,6 +17,7 @@
>>>    #define DRIVER_AUTHOR   "Intel Corporation"
>>>    #define IFCVF_DRIVER_NAME       "ifcvf"
>>> +/* handles config interrupt */
>>
>> This seems unrelated to the shared IRQ logic and it looks useless since it's
>> easily to deduce it from the function name below.
>>
>>
>>>    static irqreturn_t ifcvf_config_changed(int irq, void *arg)
>>>    {
>>>    	struct ifcvf_hw *vf = arg;
>>> @@ -27,6 +28,7 @@ static irqreturn_t ifcvf_config_changed(int irq, void *arg)
>>>    	return IRQ_HANDLED;
>>>    }
>>> +/* handles vqs interrupt */
>>
>> So did this.
>>
>>
>>>    static irqreturn_t ifcvf_intr_handler(int irq, void *arg)
>>>    {
>>>    	struct vring_info *vring = arg;
>>> @@ -37,24 +39,78 @@ static irqreturn_t ifcvf_intr_handler(int irq, void *arg)
>>>    	return IRQ_HANDLED;
>>>    }
>>> +/* handls vqs shared interrupt */
>>> +static irqreturn_t ifcvf_vq_shared_intr_handler(int irq, void *arg)
>>> +{
>>> +	struct ifcvf_hw *vf = arg;
>>> +	struct vring_info *vring;
>>> +	int i;
>>> +
>>> +	for (i = 0; i < vf->nr_vring; i++) {
>>> +		vring = &vf->vring[i];
>>> +		if (vring->cb.callback)
>>> +			vf->vring->cb.callback(vring->cb.private);
>>> +	}
>>> +
>>> +	return IRQ_HANDLED;
>>> +}
>>> +
>>> +/* handles a shared interrupt for vqs and config */
>>> +static irqreturn_t ifcvf_dev_shared_intr_handler(int irq, void *arg)
> shared is not a good name given IRQ_SHARED is not set.
> maybe "common"? "reused"?
Sure, I can do better naming

Thanks
>
>>> +{
>>> +	struct ifcvf_hw *vf = arg;
>>> +	u8 isr;
>>> +
>>> +	isr = ifc_ioread8(vf->isr);
>>
>> We need to exactly what vp_interrupt do here. Checking against vf->isr first
>> and return IRQ_NONE if it is not set.
> no, vf->isr is not set for VQ interrupts. If need to actually poke
> at the VQ to know.
>
>> Always return IRQ_HANDLED will break the device who shares an irq with
>> IFCVF.
>
> It's a MSI, not INT#. So interrupt is not shared as such - it's only
> sharing vector between config and vq.
>
>
>>> +	if (isr & VIRTIO_PCI_ISR_CONFIG)
>>> +		ifcvf_config_changed(irq, arg);
>>> +
>>> +	return ifcvf_vq_shared_intr_handler(irq, arg);
>>> +}
>>> +
>>>    static void ifcvf_free_irq_vectors(void *data)
>>>    {
>>>    	pci_free_irq_vectors(data);
>>>    }
>>> -static void ifcvf_free_irq(struct ifcvf_adapter *adapter, int queues)
>>> +static void ifcvf_free_vq_irq(struct ifcvf_adapter *adapter, int queues)
>>>    {
>>>    	struct pci_dev *pdev = adapter->pdev;
>>>    	struct ifcvf_hw *vf = &adapter->vf;
>>>    	int i;
>>> +	if (vf->msix_vector_status == MSIX_VECTOR_PER_VQ_AND_CONFIG) {
>>> +		for (i = 0; i < queues; i++) {
>>> +			devm_free_irq(&pdev->dev, vf->vring[i].irq, &vf->vring[i]);
>>> +			vf->vring[i].irq = -EINVAL;
>>> +		}
>>> +	} else {
>>> +		devm_free_irq(&pdev->dev, vf->vqs_shared_irq, vf);
>>> +		vf->vqs_shared_irq = -EINVAL;
>>> +	}
>>> +}
>>> -	for (i = 0; i < queues; i++) {
>>> -		devm_free_irq(&pdev->dev, vf->vring[i].irq, &vf->vring[i]);
>>> -		vf->vring[i].irq = -EINVAL;
>>> +static void ifcvf_free_config_irq(struct ifcvf_adapter *adapter)
>>> +{
>>> +	struct pci_dev *pdev = adapter->pdev;
>>> +	struct ifcvf_hw *vf = &adapter->vf;
>>> +
>>> +	/* If the irq is shared by all vqs and the config interrupt,
>>> +	 * it is already freed in ifcvf_free_vq_irq, so here only
>>> +	 * need to free config irq when msix_vector_status != MSIX_VECTOR_DEV_SHARED
>>> +	 */
>>> +	if (vf->msix_vector_status != MSIX_VECTOR_DEV_SHARED) {
>>> +		devm_free_irq(&pdev->dev, vf->config_irq, vf);
>>> +		vf->config_irq = -EINVAL;
>>>    	}
>>> +}
>>> +
>>> +static void ifcvf_free_irq(struct ifcvf_adapter *adapter, int queues)
>>> +{
>>> +	struct pci_dev *pdev = adapter->pdev;
>>> -	devm_free_irq(&pdev->dev, vf->config_irq, vf);
>>> +	ifcvf_free_vq_irq(adapter, queues);
>>> +	ifcvf_free_config_irq(adapter);
>>>    	ifcvf_free_irq_vectors(pdev);
>>>    }
>>> @@ -86,58 +142,172 @@ static int ifcvf_alloc_vectors(struct ifcvf_adapter *adapter)
>>>    	return ret;
>>>    }
>>> -static int ifcvf_request_irq(struct ifcvf_adapter *adapter)
>>> +static int ifcvf_request_per_vq_irq(struct ifcvf_adapter *adapter)
>>>    {
>>>    	struct pci_dev *pdev = adapter->pdev;
>>>    	struct ifcvf_hw *vf = &adapter->vf;
>>> -	int vector, nvectors, i, ret, irq;
>>> -	u16 max_intr;
>>> +	int i, vector, ret, irq;
>>> -	nvectors = ifcvf_alloc_vectors(adapter);
>>> -	if (!(nvectors > 0))
>>> -		return nvectors;
>>> +	for (i = 0; i < vf->nr_vring; i++) {
>>> +		snprintf(vf->vring[i].msix_name, 256, "ifcvf[%s]-%d\n", pci_name(pdev), i);
>>> +		vector = i;
>>> +		irq = pci_irq_vector(pdev, vector);
>>> +		ret = devm_request_irq(&pdev->dev, irq,
>>> +				       ifcvf_intr_handler, 0,
>>> +				       vf->vring[i].msix_name,
>>> +				       &vf->vring[i]);
>>> +		if (ret) {
>>> +			IFCVF_ERR(pdev, "Failed to request irq for vq %d\n", i);
>>> +			ifcvf_free_vq_irq(adapter, i);
>>> +		} else {
>>> +			vf->vring[i].irq = irq;
>>> +			ifcvf_set_vq_vector(vf, i, vector);
>>> +		}
>>> +	}
>>> -	max_intr = vf->nr_vring + 1;
>>> +	vf->vqs_shared_irq = -EINVAL;
>>> +
>>> +	return 0;
>>> +}
>>> +
>>> +static int ifcvf_request_shared_vq_irq(struct ifcvf_adapter *adapter)
>>> +{
>>> +	struct pci_dev *pdev = adapter->pdev;
>>> +	struct ifcvf_hw *vf = &adapter->vf;
>>> +	int i, vector, ret, irq;
>>> +
>>> +	vector = 0;
>>> +	/* reuse msix_name[256] space of vring0 to store shared vqs interrupt name */
>>
>> I think we can remove this comment since the code is straightforward.
>>
>>
>>> +	snprintf(vf->vring[0].msix_name, 256, "ifcvf[%s]-vqs-shared-irq\n", pci_name(pdev));
>>> +	irq = pci_irq_vector(pdev, vector);
>>> +	ret = devm_request_irq(&pdev->dev, irq,
>>> +			       ifcvf_vq_shared_intr_handler, 0,
>>> +			       vf->vring[0].msix_name, vf);
>>> +	if (ret) {
>>> +		IFCVF_ERR(pdev, "Failed to request shared irq for vf\n");
>>> +
>>> +		return ret;
>>> +	}
>>> +
>>> +	vf->vqs_shared_irq = irq;
>>> +	for (i = 0; i < vf->nr_vring; i++) {
>>> +		vf->vring[i].irq = -EINVAL;
>>> +		ifcvf_set_vq_vector(vf, i, vector);
>>> +	}
>>> +
>>> +	return 0;
>>> +
>>> +}
>>> +
>>> +static int ifcvf_request_dev_shared_irq(struct ifcvf_adapter *adapter)
>>> +{
>>> +	struct pci_dev *pdev = adapter->pdev;
>>> +	struct ifcvf_hw *vf = &adapter->vf;
>>> +	int i, vector, ret, irq;
>>> +
>>> +	vector = 0;
>>> +	/* reuse msix_name[256] space of vring0 to store shared device interrupt name */
>>> +	snprintf(vf->vring[0].msix_name, 256, "ifcvf[%s]-dev-shared-irq\n", pci_name(pdev));
>>> +	irq = pci_irq_vector(pdev, vector);
>>> +	ret = devm_request_irq(&pdev->dev, irq,
>>> +			       ifcvf_dev_shared_intr_handler, 0,
>>> +			       vf->vring[0].msix_name, vf);
>>> +	if (ret) {
>>> +		IFCVF_ERR(pdev, "Failed to request shared irq for vf\n");
>>> -	ret = pci_alloc_irq_vectors(pdev, max_intr,
>>> -				    max_intr, PCI_IRQ_MSIX);
>>> -	if (ret < 0) {
>>> -		IFCVF_ERR(pdev, "Failed to alloc IRQ vectors\n");
>>>    		return ret;
>>>    	}
>>> +	vf->vqs_shared_irq = irq;
>>> +	for (i = 0; i < vf->nr_vring; i++) {
>>> +		vf->vring[i].irq = -EINVAL;
>>> +		ifcvf_set_vq_vector(vf, i, vector);
>>> +	}
>>> +
>>> +	vf->config_irq = irq;
>>> +	ifcvf_set_config_vector(vf, vector);
>>> +
>>> +	return 0;
>>> +
>>> +}
>>> +
>>> +static int ifcvf_request_vq_irq(struct ifcvf_adapter *adapter)
>>> +{
>>> +	struct ifcvf_hw *vf = &adapter->vf;
>>> +	int ret;
>>> +
>>> +	if (vf->msix_vector_status == MSIX_VECTOR_PER_VQ_AND_CONFIG)
>>> +		ret = ifcvf_request_per_vq_irq(adapter);
>>> +	else
>>> +		ret = ifcvf_request_shared_vq_irq(adapter);
>>> +
>>> +	return ret;
>>> +}
>>> +
>>> +static int ifcvf_request_config_irq(struct ifcvf_adapter *adapter)
>>> +{
>>> +	struct pci_dev *pdev = adapter->pdev;
>>> +	struct ifcvf_hw *vf = &adapter->vf;
>>> +	int config_vector, ret;
>>> +
>>> +	if (vf->msix_vector_status == MSIX_VECTOR_DEV_SHARED)
>>> +		return 0;
>>> +
>>> +	if (vf->msix_vector_status == MSIX_VECTOR_PER_VQ_AND_CONFIG)
>>> +		/* vector 0 ~ vf->nr_vring for vqs, num vf->nr_vring vector for config interrupt */
>>> +		config_vector = vf->nr_vring;
>>> +
>>> +	if (vf->msix_vector_status ==  MSIX_VECTOR_SHARED_VQ_AND_CONFIG)
>>> +		/* vector 0 for vqs and 1 for config interrupt */
>>> +		config_vector = 1;
>>> +
>>>    	snprintf(vf->config_msix_name, 256, "ifcvf[%s]-config\n",
>>>    		 pci_name(pdev));
>>> -	vector = 0;
>>> -	vf->config_irq = pci_irq_vector(pdev, vector);
>>> +	vf->config_irq = pci_irq_vector(pdev, config_vector);
>>>    	ret = devm_request_irq(&pdev->dev, vf->config_irq,
>>>    			       ifcvf_config_changed, 0,
>>>    			       vf->config_msix_name, vf);
>>>    	if (ret) {
>>>    		IFCVF_ERR(pdev, "Failed to request config irq\n");
>>> +		ifcvf_free_vq_irq(adapter, vf->nr_vring);
>>>    		return ret;
>>>    	}
>>> -	for (i = 0; i < vf->nr_vring; i++) {
>>> -		snprintf(vf->vring[i].msix_name, 256, "ifcvf[%s]-%d\n",
>>> -			 pci_name(pdev), i);
>>> -		vector = i + IFCVF_MSI_QUEUE_OFF;
>>> -		irq = pci_irq_vector(pdev, vector);
>>> -		ret = devm_request_irq(&pdev->dev, irq,
>>> -				       ifcvf_intr_handler, 0,
>>> -				       vf->vring[i].msix_name,
>>> -				       &vf->vring[i]);
>>> -		if (ret) {
>>> -			IFCVF_ERR(pdev,
>>> -				  "Failed to request irq for vq %d\n", i);
>>> -			ifcvf_free_irq(adapter, i);
>>> +	ifcvf_set_config_vector(vf, config_vector);
>>> -			return ret;
>>> -		}
>>> +	return 0;
>>> +}
>>> +
>>> +static int ifcvf_request_irq(struct ifcvf_adapter *adapter)
>>> +{
>>
>> As replied above, I think having two modes should be sufficient and the code
>> could be greatly simplified.
>>
>> Thanks
>>
> Well it is claimed there are platforms where we are short
> on vectors. 3 versus 2 seems a 50% saving. You disagree?
>
>>> +	struct ifcvf_hw *vf = &adapter->vf;
>>> +	int nvectors, ret, max_intr;
>>> -		vf->vring[i].irq = irq;
>>> +	nvectors = ifcvf_alloc_vectors(adapter);
>>> +	if (!(nvectors > 0))
>>> +		return nvectors;
>>> +
>>> +	vf->msix_vector_status = MSIX_VECTOR_PER_VQ_AND_CONFIG;
>>> +	max_intr = vf->nr_vring + 1;
>>> +	if (nvectors < max_intr)
>>> +		vf->msix_vector_status = MSIX_VECTOR_SHARED_VQ_AND_CONFIG;
>>> +
>>> +	if (nvectors == 1) {
>>> +		vf->msix_vector_status = MSIX_VECTOR_DEV_SHARED;
>>> +		ret = ifcvf_request_dev_shared_irq(adapter);
>>> +
>>> +		return ret;
>>>    	}
>>> +	ret = ifcvf_request_vq_irq(adapter);
>>> +	if (ret)
>>> +		return ret;
>>> +
>>> +	ret = ifcvf_request_config_irq(adapter);
>>> +
>>> +	if (ret)
>>> +		return ret;
>>> +
>>>    	return 0;
>>>    }
>>> @@ -441,7 +611,10 @@ static int ifcvf_vdpa_get_vq_irq(struct vdpa_device *vdpa_dev,
>>>    {
>>>    	struct ifcvf_hw *vf = vdpa_to_vf(vdpa_dev);
>>> -	return vf->vring[qid].irq;
>>> +	if (vf->vqs_shared_irq < 0)
>>> +		return vf->vring[qid].irq;
>>> +	else
>>> +		return -EINVAL;
>>>    }
>>>    static struct vdpa_notification_area ifcvf_get_vq_notification(struct vdpa_device *vdpa_dev,

Re: [PATCH V4 4/4] vDPA/ifcvf: implement shared IRQ feature

[Jason Wang]

On Mon, Feb 14, 2022 at 10:25 PM Michael S. Tsirkin <mst@redhat.com> wrote:
>
> On Mon, Feb 14, 2022 at 03:19:25PM +0800, Jason Wang wrote:
> >
> > 在 2022/2/3 下午3:27, Zhu Lingshan 写道:
> > > On some platforms/devices, there may not be enough MSI vector
> > > slots allocated for virtqueues and config changes. In such a case,
> > > the interrupt sources(virtqueues, config changes) must share
> > > an IRQ/vector, to avoid initialization failures, keep
> > > the device functional.
> > >
> > > This commit handles three cases:
> > > (1) number of the allocated vectors == the number of virtqueues + 1
> > > (config changes), every virtqueue and the config interrupt has
> > > a separated vector/IRQ, the best and the most likely case.
> > > (2) number of the allocated vectors is less than the best case, but
> > > greater than 1. In this case, all virtqueues share a vector/IRQ,
> > > the config interrupt has a separated vector/IRQ
> > > (3) only one vector is allocated, in this case, the virtqueues and
> > > the config interrupt share a vector/IRQ. The worst and most
> > > unlikely case.
> > >
> > > Otherwise, it needs to fail.
> > >
> > > This commit introduces some helper functions:
> > > ifcvf_set_vq_vector() and ifcvf_set_config_vector() sets virtqueue
> > > vector and config vector in the device config space, so that
> > > the device can send interrupt DMA.
> > >
> > > This commit adds some fields in struct ifcvf_hw and re-placed
> > > the existed fields to be aligned with the cacheline.
> > >
> > > Signed-off-by: Zhu Lingshan <lingshan.zhu@intel.com>
> > > ---
> > >   drivers/vdpa/ifcvf/ifcvf_base.c |  47 ++++--
> > >   drivers/vdpa/ifcvf/ifcvf_base.h |  23 ++-
> > >   drivers/vdpa/ifcvf/ifcvf_main.c | 243 +++++++++++++++++++++++++++-----
> > >   3 files changed, 256 insertions(+), 57 deletions(-)
> > >
> > > diff --git a/drivers/vdpa/ifcvf/ifcvf_base.c b/drivers/vdpa/ifcvf/ifcvf_base.c
> > > index 397692ae671c..18dcb63ab1e3 100644
> > > --- a/drivers/vdpa/ifcvf/ifcvf_base.c
> > > +++ b/drivers/vdpa/ifcvf/ifcvf_base.c
> > > @@ -15,6 +15,36 @@ struct ifcvf_adapter *vf_to_adapter(struct ifcvf_hw *hw)
> > >     return container_of(hw, struct ifcvf_adapter, vf);
> > >   }
> > > +int ifcvf_set_vq_vector(struct ifcvf_hw *hw, u16 qid, int vector)
> > > +{
> > > +   struct virtio_pci_common_cfg __iomem *cfg = hw->common_cfg;
> > > +   struct ifcvf_adapter *ifcvf = vf_to_adapter(hw);
> > > +
> > > +   ifc_iowrite16(qid, &cfg->queue_select);
> > > +   ifc_iowrite16(vector, &cfg->queue_msix_vector);
> > > +   if (ifc_ioread16(&cfg->queue_msix_vector) == VIRTIO_MSI_NO_VECTOR) {
> > > +           IFCVF_ERR(ifcvf->pdev, "No msix vector for queue %u\n", qid);
> > > +                   return -EINVAL;
> > > +   }
> >
> >
> > Let's leave this check for the caller, E.g can caller try to assign
> > NO_VECTOR during uni-nit?
>
>
> Hmm I'm not sure I agree. Caller will have to write queue select
> again, and that's an extra IO, which is a waste.
> And having function checking itself just seems better contained.

It's as simple as just return what we read here like virtio_pci did:

u16 vp_modern_queue_vector(struct virtio_pci_modern_device *mdev,
                           u16 index, u16 vector)
{
        struct virtio_pci_common_cfg __iomem *cfg = mdev->common;

        vp_iowrite16(index, &cfg->queue_select);
        vp_iowrite16(vector, &cfg->queue_msix_vector);
        /* Flush the write out to device */
        return vp_ioread16(&cfg->queue_msix_vector);
}
EXPORT_SYMBOL_GPL(vp_modern_queue_vector);

Then the caller can decide to check it with NO_VECTOR if needed.
Current code will break the callers that want to set NO_VECTOR.

>
> >
> > > +
> > > +   return 0;
> > > +}
> > > +
> > > +int ifcvf_set_config_vector(struct ifcvf_hw *hw, int vector)
> > > +{
> > > +   struct virtio_pci_common_cfg __iomem *cfg = hw->common_cfg;
> > > +   struct ifcvf_adapter *ifcvf = vf_to_adapter(hw);
> > > +
> > > +   cfg = hw->common_cfg;
> > > +   ifc_iowrite16(vector,  &cfg->msix_config);
> > > +   if (ifc_ioread16(&cfg->msix_config) == VIRTIO_MSI_NO_VECTOR) {
> > > +           IFCVF_ERR(ifcvf->pdev, "No msix vector for device config\n");
> > > +           return -EINVAL;
> > > +   }
> >
> >
> > Similar question as above.
> >
> >
> > > +
> > > +   return 0;
> > > +}
> > > +
> > >   static void __iomem *get_cap_addr(struct ifcvf_hw *hw,
> > >                               struct virtio_pci_cap *cap)
> > >   {
> > > @@ -140,6 +170,8 @@ int ifcvf_init_hw(struct ifcvf_hw *hw, struct pci_dev *pdev)
> > >               hw->common_cfg, hw->notify_base, hw->isr,
> > >               hw->dev_cfg, hw->notify_off_multiplier);
> > > +   hw->vqs_shared_irq = -EINVAL;
> > > +
> > >     return 0;
> > >   }
> > > @@ -321,12 +353,6 @@ static int ifcvf_hw_enable(struct ifcvf_hw *hw)
> > >     ifcvf = vf_to_adapter(hw);
> > >     cfg = hw->common_cfg;
> > > -   ifc_iowrite16(IFCVF_MSI_CONFIG_OFF, &cfg->msix_config);
> > > -
> > > -   if (ifc_ioread16(&cfg->msix_config) == VIRTIO_MSI_NO_VECTOR) {
> > > -           IFCVF_ERR(ifcvf->pdev, "No msix vector for device config\n");
> > > -           return -EINVAL;
> > > -   }
> > >     for (i = 0; i < hw->nr_vring; i++) {
> > >             if (!hw->vring[i].ready)
> > > @@ -340,15 +366,6 @@ static int ifcvf_hw_enable(struct ifcvf_hw *hw)
> > >             ifc_iowrite64_twopart(hw->vring[i].used, &cfg->queue_used_lo,
> > >                                  &cfg->queue_used_hi);
> > >             ifc_iowrite16(hw->vring[i].size, &cfg->queue_size);
> > > -           ifc_iowrite16(i + IFCVF_MSI_QUEUE_OFF, &cfg->queue_msix_vector);
> > > -
> > > -           if (ifc_ioread16(&cfg->queue_msix_vector) ==
> > > -               VIRTIO_MSI_NO_VECTOR) {
> > > -                   IFCVF_ERR(ifcvf->pdev,
> > > -                             "No msix vector for queue %u\n", i);
> > > -                   return -EINVAL;
> > > -           }
> > > -
> > >             ifcvf_set_vq_state(hw, i, hw->vring[i].last_avail_idx);
> > >             ifc_iowrite16(1, &cfg->queue_enable);
> > >     }
> > > diff --git a/drivers/vdpa/ifcvf/ifcvf_base.h b/drivers/vdpa/ifcvf/ifcvf_base.h
> > > index 949b4fb9d554..9cfe088c82e9 100644
> > > --- a/drivers/vdpa/ifcvf/ifcvf_base.h
> > > +++ b/drivers/vdpa/ifcvf/ifcvf_base.h
> > > @@ -27,8 +27,6 @@
> > >   #define IFCVF_QUEUE_ALIGNMENT     PAGE_SIZE
> > >   #define IFCVF_QUEUE_MAX           32768
> > > -#define IFCVF_MSI_CONFIG_OFF       0
> > > -#define IFCVF_MSI_QUEUE_OFF        1
> > >   #define IFCVF_PCI_MAX_RESOURCE    6
> > >   #define IFCVF_LM_CFG_SIZE         0x40
> > > @@ -42,6 +40,13 @@
> > >   #define ifcvf_private_to_vf(adapter) \
> > >     (&((struct ifcvf_adapter *)adapter)->vf)
> > > +/* all vqs and config interrupt has its own vector */
> > > +#define MSIX_VECTOR_PER_VQ_AND_CONFIG              1
> > > +/* all vqs share a vector, and config interrupt has a separate vector */
> > > +#define MSIX_VECTOR_SHARED_VQ_AND_CONFIG   2
> > > +/* all vqs and config interrupt share a vector */
> > > +#define MSIX_VECTOR_DEV_SHARED                     3
> >
> >
> > I think there's no much value to differ 2 from 3 consider config interrupt
> > should be rare.
>
>
> Yes but if we do not have a dedicated vector then we need an
> extra device IO (in fact, a read) on each interrupt.

Ok, right.

>
> >
> > > +
> > >   static inline u8 ifc_ioread8(u8 __iomem *addr)
> > >   {
> > >     return ioread8(addr);
> > > @@ -97,25 +102,27 @@ struct ifcvf_hw {
> > >     u8 __iomem *isr;
> > >     /* Live migration */
> > >     u8 __iomem *lm_cfg;
> > > -   u16 nr_vring;
> >
> >
> > Any reason for moving nv_vring, config_size, and other stuffs?
> >
> >
> > >     /* Notification bar number */
> > >     u8 notify_bar;
> > > +   u8 msix_vector_status;
> > > +   /* virtio-net or virtio-blk device config size */
> > > +   u32 config_size;
> > >     /* Notificaiton bar address */
> > >     void __iomem *notify_base;
> > >     phys_addr_t notify_base_pa;
> > >     u32 notify_off_multiplier;
> > > +   u32 dev_type;
> > >     u64 req_features;
> > >     u64 hw_features;
> > > -   u32 dev_type;
> > >     struct virtio_pci_common_cfg __iomem *common_cfg;
> > >     void __iomem *dev_cfg;
> > >     struct vring_info vring[IFCVF_MAX_QUEUES];
> > >     void __iomem * const *base;
> > >     char config_msix_name[256];
> > >     struct vdpa_callback config_cb;
> > > -   unsigned int config_irq;
> > > -   /* virtio-net or virtio-blk device config size */
> > > -   u32 config_size;
> > > +   int config_irq;
> > > +   int vqs_shared_irq;
> > > +   u16 nr_vring;
> > >   };
> > >   struct ifcvf_adapter {
> > > @@ -160,4 +167,6 @@ int ifcvf_set_vq_state(struct ifcvf_hw *hw, u16 qid, u16 num);
> > >   struct ifcvf_adapter *vf_to_adapter(struct ifcvf_hw *hw);
> > >   int ifcvf_probed_virtio_net(struct ifcvf_hw *hw);
> > >   u32 ifcvf_get_config_size(struct ifcvf_hw *hw);
> > > +int ifcvf_set_vq_vector(struct ifcvf_hw *hw, u16 qid, int vector);
> > > +int ifcvf_set_config_vector(struct ifcvf_hw *hw, int vector);
> > >   #endif /* _IFCVF_H_ */
> > > diff --git a/drivers/vdpa/ifcvf/ifcvf_main.c b/drivers/vdpa/ifcvf/ifcvf_main.c
> > > index 44c89ab0b6da..ca414399f040 100644
> > > --- a/drivers/vdpa/ifcvf/ifcvf_main.c
> > > +++ b/drivers/vdpa/ifcvf/ifcvf_main.c
> > > @@ -17,6 +17,7 @@
> > >   #define DRIVER_AUTHOR   "Intel Corporation"
> > >   #define IFCVF_DRIVER_NAME       "ifcvf"
> > > +/* handles config interrupt */
> >
> >
> > This seems unrelated to the shared IRQ logic and it looks useless since it's
> > easily to deduce it from the function name below.
> >
> >
> > >   static irqreturn_t ifcvf_config_changed(int irq, void *arg)
> > >   {
> > >     struct ifcvf_hw *vf = arg;
> > > @@ -27,6 +28,7 @@ static irqreturn_t ifcvf_config_changed(int irq, void *arg)
> > >     return IRQ_HANDLED;
> > >   }
> > > +/* handles vqs interrupt */
> >
> >
> > So did this.
> >
> >
> > >   static irqreturn_t ifcvf_intr_handler(int irq, void *arg)
> > >   {
> > >     struct vring_info *vring = arg;
> > > @@ -37,24 +39,78 @@ static irqreturn_t ifcvf_intr_handler(int irq, void *arg)
> > >     return IRQ_HANDLED;
> > >   }
> > > +/* handls vqs shared interrupt */
> > > +static irqreturn_t ifcvf_vq_shared_intr_handler(int irq, void *arg)
> > > +{
> > > +   struct ifcvf_hw *vf = arg;
> > > +   struct vring_info *vring;
> > > +   int i;
> > > +
> > > +   for (i = 0; i < vf->nr_vring; i++) {
> > > +           vring = &vf->vring[i];
> > > +           if (vring->cb.callback)
> > > +                   vf->vring->cb.callback(vring->cb.private);
> > > +   }
> > > +
> > > +   return IRQ_HANDLED;
> > > +}
> > > +
> > > +/* handles a shared interrupt for vqs and config */
> > > +static irqreturn_t ifcvf_dev_shared_intr_handler(int irq, void *arg)
>
> shared is not a good name given IRQ_SHARED is not set.
> maybe "common"? "reused"?
>
> > > +{
> > > +   struct ifcvf_hw *vf = arg;
> > > +   u8 isr;
> > > +
> > > +   isr = ifc_ioread8(vf->isr);
> >
> >
> > We need to exactly what vp_interrupt do here. Checking against vf->isr first
> > and return IRQ_NONE if it is not set.
>
> no, vf->isr is not set for VQ interrupts.

I actually wonder what's the actual behaviour of IFCVF.

> If need to actually poke
> at the VQ to know.
>
> > Always return IRQ_HANDLED will break the device who shares an irq with
> > IFCVF.
>
>
> It's a MSI, not INT#. So interrupt is not shared as such - it's only
> sharing vector between config and vq.

Right, I thought it was a shared one as virito_pci did.

>
>
> >
> > > +   if (isr & VIRTIO_PCI_ISR_CONFIG)
> > > +           ifcvf_config_changed(irq, arg);
> > > +
> > > +   return ifcvf_vq_shared_intr_handler(irq, arg);
> > > +}
> > > +
> > >   static void ifcvf_free_irq_vectors(void *data)
> > >   {
> > >     pci_free_irq_vectors(data);
> > >   }
> > > -static void ifcvf_free_irq(struct ifcvf_adapter *adapter, int queues)
> > > +static void ifcvf_free_vq_irq(struct ifcvf_adapter *adapter, int queues)
> > >   {
> > >     struct pci_dev *pdev = adapter->pdev;
> > >     struct ifcvf_hw *vf = &adapter->vf;
> > >     int i;
> > > +   if (vf->msix_vector_status == MSIX_VECTOR_PER_VQ_AND_CONFIG) {
> > > +           for (i = 0; i < queues; i++) {
> > > +                   devm_free_irq(&pdev->dev, vf->vring[i].irq, &vf->vring[i]);
> > > +                   vf->vring[i].irq = -EINVAL;
> > > +           }
> > > +   } else {
> > > +           devm_free_irq(&pdev->dev, vf->vqs_shared_irq, vf);
> > > +           vf->vqs_shared_irq = -EINVAL;
> > > +   }
> > > +}
> > > -   for (i = 0; i < queues; i++) {
> > > -           devm_free_irq(&pdev->dev, vf->vring[i].irq, &vf->vring[i]);
> > > -           vf->vring[i].irq = -EINVAL;
> > > +static void ifcvf_free_config_irq(struct ifcvf_adapter *adapter)
> > > +{
> > > +   struct pci_dev *pdev = adapter->pdev;
> > > +   struct ifcvf_hw *vf = &adapter->vf;
> > > +
> > > +   /* If the irq is shared by all vqs and the config interrupt,
> > > +    * it is already freed in ifcvf_free_vq_irq, so here only
> > > +    * need to free config irq when msix_vector_status != MSIX_VECTOR_DEV_SHARED
> > > +    */
> > > +   if (vf->msix_vector_status != MSIX_VECTOR_DEV_SHARED) {
> > > +           devm_free_irq(&pdev->dev, vf->config_irq, vf);
> > > +           vf->config_irq = -EINVAL;
> > >     }
> > > +}
> > > +
> > > +static void ifcvf_free_irq(struct ifcvf_adapter *adapter, int queues)
> > > +{
> > > +   struct pci_dev *pdev = adapter->pdev;
> > > -   devm_free_irq(&pdev->dev, vf->config_irq, vf);
> > > +   ifcvf_free_vq_irq(adapter, queues);
> > > +   ifcvf_free_config_irq(adapter);
> > >     ifcvf_free_irq_vectors(pdev);
> > >   }
> > > @@ -86,58 +142,172 @@ static int ifcvf_alloc_vectors(struct ifcvf_adapter *adapter)
> > >     return ret;
> > >   }
> > > -static int ifcvf_request_irq(struct ifcvf_adapter *adapter)
> > > +static int ifcvf_request_per_vq_irq(struct ifcvf_adapter *adapter)
> > >   {
> > >     struct pci_dev *pdev = adapter->pdev;
> > >     struct ifcvf_hw *vf = &adapter->vf;
> > > -   int vector, nvectors, i, ret, irq;
> > > -   u16 max_intr;
> > > +   int i, vector, ret, irq;
> > > -   nvectors = ifcvf_alloc_vectors(adapter);
> > > -   if (!(nvectors > 0))
> > > -           return nvectors;
> > > +   for (i = 0; i < vf->nr_vring; i++) {
> > > +           snprintf(vf->vring[i].msix_name, 256, "ifcvf[%s]-%d\n", pci_name(pdev), i);
> > > +           vector = i;
> > > +           irq = pci_irq_vector(pdev, vector);
> > > +           ret = devm_request_irq(&pdev->dev, irq,
> > > +                                  ifcvf_intr_handler, 0,
> > > +                                  vf->vring[i].msix_name,
> > > +                                  &vf->vring[i]);
> > > +           if (ret) {
> > > +                   IFCVF_ERR(pdev, "Failed to request irq for vq %d\n", i);
> > > +                   ifcvf_free_vq_irq(adapter, i);
> > > +           } else {
> > > +                   vf->vring[i].irq = irq;
> > > +                   ifcvf_set_vq_vector(vf, i, vector);
> > > +           }
> > > +   }
> > > -   max_intr = vf->nr_vring + 1;
> > > +   vf->vqs_shared_irq = -EINVAL;
> > > +
> > > +   return 0;
> > > +}
> > > +
> > > +static int ifcvf_request_shared_vq_irq(struct ifcvf_adapter *adapter)
> > > +{
> > > +   struct pci_dev *pdev = adapter->pdev;
> > > +   struct ifcvf_hw *vf = &adapter->vf;
> > > +   int i, vector, ret, irq;
> > > +
> > > +   vector = 0;
> > > +   /* reuse msix_name[256] space of vring0 to store shared vqs interrupt name */
> >
> >
> > I think we can remove this comment since the code is straightforward.
> >
> >
> > > +   snprintf(vf->vring[0].msix_name, 256, "ifcvf[%s]-vqs-shared-irq\n", pci_name(pdev));
> > > +   irq = pci_irq_vector(pdev, vector);
> > > +   ret = devm_request_irq(&pdev->dev, irq,
> > > +                          ifcvf_vq_shared_intr_handler, 0,
> > > +                          vf->vring[0].msix_name, vf);
> > > +   if (ret) {
> > > +           IFCVF_ERR(pdev, "Failed to request shared irq for vf\n");
> > > +
> > > +           return ret;
> > > +   }
> > > +
> > > +   vf->vqs_shared_irq = irq;
> > > +   for (i = 0; i < vf->nr_vring; i++) {
> > > +           vf->vring[i].irq = -EINVAL;
> > > +           ifcvf_set_vq_vector(vf, i, vector);
> > > +   }
> > > +
> > > +   return 0;
> > > +
> > > +}
> > > +
> > > +static int ifcvf_request_dev_shared_irq(struct ifcvf_adapter *adapter)
> > > +{
> > > +   struct pci_dev *pdev = adapter->pdev;
> > > +   struct ifcvf_hw *vf = &adapter->vf;
> > > +   int i, vector, ret, irq;
> > > +
> > > +   vector = 0;
> > > +   /* reuse msix_name[256] space of vring0 to store shared device interrupt name */
> > > +   snprintf(vf->vring[0].msix_name, 256, "ifcvf[%s]-dev-shared-irq\n", pci_name(pdev));
> > > +   irq = pci_irq_vector(pdev, vector);
> > > +   ret = devm_request_irq(&pdev->dev, irq,
> > > +                          ifcvf_dev_shared_intr_handler, 0,
> > > +                          vf->vring[0].msix_name, vf);
> > > +   if (ret) {
> > > +           IFCVF_ERR(pdev, "Failed to request shared irq for vf\n");
> > > -   ret = pci_alloc_irq_vectors(pdev, max_intr,
> > > -                               max_intr, PCI_IRQ_MSIX);
> > > -   if (ret < 0) {
> > > -           IFCVF_ERR(pdev, "Failed to alloc IRQ vectors\n");
> > >             return ret;
> > >     }
> > > +   vf->vqs_shared_irq = irq;
> > > +   for (i = 0; i < vf->nr_vring; i++) {
> > > +           vf->vring[i].irq = -EINVAL;
> > > +           ifcvf_set_vq_vector(vf, i, vector);
> > > +   }
> > > +
> > > +   vf->config_irq = irq;
> > > +   ifcvf_set_config_vector(vf, vector);
> > > +
> > > +   return 0;
> > > +
> > > +}
> > > +
> > > +static int ifcvf_request_vq_irq(struct ifcvf_adapter *adapter)
> > > +{
> > > +   struct ifcvf_hw *vf = &adapter->vf;
> > > +   int ret;
> > > +
> > > +   if (vf->msix_vector_status == MSIX_VECTOR_PER_VQ_AND_CONFIG)
> > > +           ret = ifcvf_request_per_vq_irq(adapter);
> > > +   else
> > > +           ret = ifcvf_request_shared_vq_irq(adapter);
> > > +
> > > +   return ret;
> > > +}
> > > +
> > > +static int ifcvf_request_config_irq(struct ifcvf_adapter *adapter)
> > > +{
> > > +   struct pci_dev *pdev = adapter->pdev;
> > > +   struct ifcvf_hw *vf = &adapter->vf;
> > > +   int config_vector, ret;
> > > +
> > > +   if (vf->msix_vector_status == MSIX_VECTOR_DEV_SHARED)
> > > +           return 0;
> > > +
> > > +   if (vf->msix_vector_status == MSIX_VECTOR_PER_VQ_AND_CONFIG)
> > > +           /* vector 0 ~ vf->nr_vring for vqs, num vf->nr_vring vector for config interrupt */
> > > +           config_vector = vf->nr_vring;
> > > +
> > > +   if (vf->msix_vector_status ==  MSIX_VECTOR_SHARED_VQ_AND_CONFIG)
> > > +           /* vector 0 for vqs and 1 for config interrupt */
> > > +           config_vector = 1;
> > > +
> > >     snprintf(vf->config_msix_name, 256, "ifcvf[%s]-config\n",
> > >              pci_name(pdev));
> > > -   vector = 0;
> > > -   vf->config_irq = pci_irq_vector(pdev, vector);
> > > +   vf->config_irq = pci_irq_vector(pdev, config_vector);
> > >     ret = devm_request_irq(&pdev->dev, vf->config_irq,
> > >                            ifcvf_config_changed, 0,
> > >                            vf->config_msix_name, vf);
> > >     if (ret) {
> > >             IFCVF_ERR(pdev, "Failed to request config irq\n");
> > > +           ifcvf_free_vq_irq(adapter, vf->nr_vring);
> > >             return ret;
> > >     }
> > > -   for (i = 0; i < vf->nr_vring; i++) {
> > > -           snprintf(vf->vring[i].msix_name, 256, "ifcvf[%s]-%d\n",
> > > -                    pci_name(pdev), i);
> > > -           vector = i + IFCVF_MSI_QUEUE_OFF;
> > > -           irq = pci_irq_vector(pdev, vector);
> > > -           ret = devm_request_irq(&pdev->dev, irq,
> > > -                                  ifcvf_intr_handler, 0,
> > > -                                  vf->vring[i].msix_name,
> > > -                                  &vf->vring[i]);
> > > -           if (ret) {
> > > -                   IFCVF_ERR(pdev,
> > > -                             "Failed to request irq for vq %d\n", i);
> > > -                   ifcvf_free_irq(adapter, i);
> > > +   ifcvf_set_config_vector(vf, config_vector);
> > > -                   return ret;
> > > -           }
> > > +   return 0;
> > > +}
> > > +
> > > +static int ifcvf_request_irq(struct ifcvf_adapter *adapter)
> > > +{
> >
> >
> > As replied above, I think having two modes should be sufficient and the code
> > could be greatly simplified.
> >
> > Thanks
> >
>
> Well it is claimed there are platforms where we are short
> on vectors. 3 versus 2 seems a 50% saving. You disagree?

I think we can 2 vectors (a dedicated for config).

Thanks

>
> > > +   struct ifcvf_hw *vf = &adapter->vf;
> > > +   int nvectors, ret, max_intr;
> > > -           vf->vring[i].irq = irq;
> > > +   nvectors = ifcvf_alloc_vectors(adapter);
> > > +   if (!(nvectors > 0))
> > > +           return nvectors;
> > > +
> > > +   vf->msix_vector_status = MSIX_VECTOR_PER_VQ_AND_CONFIG;
> > > +   max_intr = vf->nr_vring + 1;
> > > +   if (nvectors < max_intr)
> > > +           vf->msix_vector_status = MSIX_VECTOR_SHARED_VQ_AND_CONFIG;
> > > +
> > > +   if (nvectors == 1) {
> > > +           vf->msix_vector_status = MSIX_VECTOR_DEV_SHARED;
> > > +           ret = ifcvf_request_dev_shared_irq(adapter);
> > > +
> > > +           return ret;
> > >     }
> > > +   ret = ifcvf_request_vq_irq(adapter);
> > > +   if (ret)
> > > +           return ret;
> > > +
> > > +   ret = ifcvf_request_config_irq(adapter);
> > > +
> > > +   if (ret)
> > > +           return ret;
> > > +
> > >     return 0;
> > >   }
> > > @@ -441,7 +611,10 @@ static int ifcvf_vdpa_get_vq_irq(struct vdpa_device *vdpa_dev,
> > >   {
> > >     struct ifcvf_hw *vf = vdpa_to_vf(vdpa_dev);
> > > -   return vf->vring[qid].irq;
> > > +   if (vf->vqs_shared_irq < 0)
> > > +           return vf->vring[qid].irq;
> > > +   else
> > > +           return -EINVAL;
> > >   }
> > >   static struct vdpa_notification_area ifcvf_get_vq_notification(struct vdpa_device *vdpa_dev,
>

Re: [PATCH V4 4/4] vDPA/ifcvf: implement shared IRQ feature

[Zhu, Lingshan]

On 2/15/2022 11:34 AM, Jason Wang wrote:
> On Mon, Feb 14, 2022 at 10:25 PM Michael S. Tsirkin <mst@redhat.com> wrote:
>> On Mon, Feb 14, 2022 at 03:19:25PM +0800, Jason Wang wrote:
>>> 在 2022/2/3 下午3:27, Zhu Lingshan 写道:
>>>> On some platforms/devices, there may not be enough MSI vector
>>>> slots allocated for virtqueues and config changes. In such a case,
>>>> the interrupt sources(virtqueues, config changes) must share
>>>> an IRQ/vector, to avoid initialization failures, keep
>>>> the device functional.
>>>>
>>>> This commit handles three cases:
>>>> (1) number of the allocated vectors == the number of virtqueues + 1
>>>> (config changes), every virtqueue and the config interrupt has
>>>> a separated vector/IRQ, the best and the most likely case.
>>>> (2) number of the allocated vectors is less than the best case, but
>>>> greater than 1. In this case, all virtqueues share a vector/IRQ,
>>>> the config interrupt has a separated vector/IRQ
>>>> (3) only one vector is allocated, in this case, the virtqueues and
>>>> the config interrupt share a vector/IRQ. The worst and most
>>>> unlikely case.
>>>>
>>>> Otherwise, it needs to fail.
>>>>
>>>> This commit introduces some helper functions:
>>>> ifcvf_set_vq_vector() and ifcvf_set_config_vector() sets virtqueue
>>>> vector and config vector in the device config space, so that
>>>> the device can send interrupt DMA.
>>>>
>>>> This commit adds some fields in struct ifcvf_hw and re-placed
>>>> the existed fields to be aligned with the cacheline.
>>>>
>>>> Signed-off-by: Zhu Lingshan <lingshan.zhu@intel.com>
>>>> ---
>>>>    drivers/vdpa/ifcvf/ifcvf_base.c |  47 ++++--
>>>>    drivers/vdpa/ifcvf/ifcvf_base.h |  23 ++-
>>>>    drivers/vdpa/ifcvf/ifcvf_main.c | 243 +++++++++++++++++++++++++++-----
>>>>    3 files changed, 256 insertions(+), 57 deletions(-)
>>>>
>>>> diff --git a/drivers/vdpa/ifcvf/ifcvf_base.c b/drivers/vdpa/ifcvf/ifcvf_base.c
>>>> index 397692ae671c..18dcb63ab1e3 100644
>>>> --- a/drivers/vdpa/ifcvf/ifcvf_base.c
>>>> +++ b/drivers/vdpa/ifcvf/ifcvf_base.c
>>>> @@ -15,6 +15,36 @@ struct ifcvf_adapter *vf_to_adapter(struct ifcvf_hw *hw)
>>>>      return container_of(hw, struct ifcvf_adapter, vf);
>>>>    }
>>>> +int ifcvf_set_vq_vector(struct ifcvf_hw *hw, u16 qid, int vector)
>>>> +{
>>>> +   struct virtio_pci_common_cfg __iomem *cfg = hw->common_cfg;
>>>> +   struct ifcvf_adapter *ifcvf = vf_to_adapter(hw);
>>>> +
>>>> +   ifc_iowrite16(qid, &cfg->queue_select);
>>>> +   ifc_iowrite16(vector, &cfg->queue_msix_vector);
>>>> +   if (ifc_ioread16(&cfg->queue_msix_vector) == VIRTIO_MSI_NO_VECTOR) {
>>>> +           IFCVF_ERR(ifcvf->pdev, "No msix vector for queue %u\n", qid);
>>>> +                   return -EINVAL;
>>>> +   }
>>>
>>> Let's leave this check for the caller, E.g can caller try to assign
>>> NO_VECTOR during uni-nit?
>>
>> Hmm I'm not sure I agree. Caller will have to write queue select
>> again, and that's an extra IO, which is a waste.
>> And having function checking itself just seems better contained.
> It's as simple as just return what we read here like virtio_pci did:
>
> u16 vp_modern_queue_vector(struct virtio_pci_modern_device *mdev,
>                             u16 index, u16 vector)
> {
>          struct virtio_pci_common_cfg __iomem *cfg = mdev->common;
>
>          vp_iowrite16(index, &cfg->queue_select);
>          vp_iowrite16(vector, &cfg->queue_msix_vector);
>          /* Flush the write out to device */
>          return vp_ioread16(&cfg->queue_msix_vector);
> }
> EXPORT_SYMBOL_GPL(vp_modern_queue_vector);
>
> Then the caller can decide to check it with NO_VECTOR if needed.
> Current code will break the callers that want to set NO_VECTOR.
OK, we can let the caller check the return value, then re-use 
set_xxx_vector in hw_disable()

Thanks
>>>> +
>>>> +   return 0;
>>>> +}
>>>> +
>>>> +int ifcvf_set_config_vector(struct ifcvf_hw *hw, int vector)
>>>> +{
>>>> +   struct virtio_pci_common_cfg __iomem *cfg = hw->common_cfg;
>>>> +   struct ifcvf_adapter *ifcvf = vf_to_adapter(hw);
>>>> +
>>>> +   cfg = hw->common_cfg;
>>>> +   ifc_iowrite16(vector,  &cfg->msix_config);
>>>> +   if (ifc_ioread16(&cfg->msix_config) == VIRTIO_MSI_NO_VECTOR) {
>>>> +           IFCVF_ERR(ifcvf->pdev, "No msix vector for device config\n");
>>>> +           return -EINVAL;
>>>> +   }
>>>
>>> Similar question as above.
>>>
>>>
>>>> +
>>>> +   return 0;
>>>> +}
>>>> +
>>>>    static void __iomem *get_cap_addr(struct ifcvf_hw *hw,
>>>>                                struct virtio_pci_cap *cap)
>>>>    {
>>>> @@ -140,6 +170,8 @@ int ifcvf_init_hw(struct ifcvf_hw *hw, struct pci_dev *pdev)
>>>>                hw->common_cfg, hw->notify_base, hw->isr,
>>>>                hw->dev_cfg, hw->notify_off_multiplier);
>>>> +   hw->vqs_shared_irq = -EINVAL;
>>>> +
>>>>      return 0;
>>>>    }
>>>> @@ -321,12 +353,6 @@ static int ifcvf_hw_enable(struct ifcvf_hw *hw)
>>>>      ifcvf = vf_to_adapter(hw);
>>>>      cfg = hw->common_cfg;
>>>> -   ifc_iowrite16(IFCVF_MSI_CONFIG_OFF, &cfg->msix_config);
>>>> -
>>>> -   if (ifc_ioread16(&cfg->msix_config) == VIRTIO_MSI_NO_VECTOR) {
>>>> -           IFCVF_ERR(ifcvf->pdev, "No msix vector for device config\n");
>>>> -           return -EINVAL;
>>>> -   }
>>>>      for (i = 0; i < hw->nr_vring; i++) {
>>>>              if (!hw->vring[i].ready)
>>>> @@ -340,15 +366,6 @@ static int ifcvf_hw_enable(struct ifcvf_hw *hw)
>>>>              ifc_iowrite64_twopart(hw->vring[i].used, &cfg->queue_used_lo,
>>>>                                   &cfg->queue_used_hi);
>>>>              ifc_iowrite16(hw->vring[i].size, &cfg->queue_size);
>>>> -           ifc_iowrite16(i + IFCVF_MSI_QUEUE_OFF, &cfg->queue_msix_vector);
>>>> -
>>>> -           if (ifc_ioread16(&cfg->queue_msix_vector) ==
>>>> -               VIRTIO_MSI_NO_VECTOR) {
>>>> -                   IFCVF_ERR(ifcvf->pdev,
>>>> -                             "No msix vector for queue %u\n", i);
>>>> -                   return -EINVAL;
>>>> -           }
>>>> -
>>>>              ifcvf_set_vq_state(hw, i, hw->vring[i].last_avail_idx);
>>>>              ifc_iowrite16(1, &cfg->queue_enable);
>>>>      }
>>>> diff --git a/drivers/vdpa/ifcvf/ifcvf_base.h b/drivers/vdpa/ifcvf/ifcvf_base.h
>>>> index 949b4fb9d554..9cfe088c82e9 100644
>>>> --- a/drivers/vdpa/ifcvf/ifcvf_base.h
>>>> +++ b/drivers/vdpa/ifcvf/ifcvf_base.h
>>>> @@ -27,8 +27,6 @@
>>>>    #define IFCVF_QUEUE_ALIGNMENT     PAGE_SIZE
>>>>    #define IFCVF_QUEUE_MAX           32768
>>>> -#define IFCVF_MSI_CONFIG_OFF       0
>>>> -#define IFCVF_MSI_QUEUE_OFF        1
>>>>    #define IFCVF_PCI_MAX_RESOURCE    6
>>>>    #define IFCVF_LM_CFG_SIZE         0x40
>>>> @@ -42,6 +40,13 @@
>>>>    #define ifcvf_private_to_vf(adapter) \
>>>>      (&((struct ifcvf_adapter *)adapter)->vf)
>>>> +/* all vqs and config interrupt has its own vector */
>>>> +#define MSIX_VECTOR_PER_VQ_AND_CONFIG              1
>>>> +/* all vqs share a vector, and config interrupt has a separate vector */
>>>> +#define MSIX_VECTOR_SHARED_VQ_AND_CONFIG   2
>>>> +/* all vqs and config interrupt share a vector */
>>>> +#define MSIX_VECTOR_DEV_SHARED                     3
>>>
>>> I think there's no much value to differ 2 from 3 consider config interrupt
>>> should be rare.
>>
>> Yes but if we do not have a dedicated vector then we need an
>> extra device IO (in fact, a read) on each interrupt.
> Ok, right.
>
>>>> +
>>>>    static inline u8 ifc_ioread8(u8 __iomem *addr)
>>>>    {
>>>>      return ioread8(addr);
>>>> @@ -97,25 +102,27 @@ struct ifcvf_hw {
>>>>      u8 __iomem *isr;
>>>>      /* Live migration */
>>>>      u8 __iomem *lm_cfg;
>>>> -   u16 nr_vring;
>>>
>>> Any reason for moving nv_vring, config_size, and other stuffs?
>>>
>>>
>>>>      /* Notification bar number */
>>>>      u8 notify_bar;
>>>> +   u8 msix_vector_status;
>>>> +   /* virtio-net or virtio-blk device config size */
>>>> +   u32 config_size;
>>>>      /* Notificaiton bar address */
>>>>      void __iomem *notify_base;
>>>>      phys_addr_t notify_base_pa;
>>>>      u32 notify_off_multiplier;
>>>> +   u32 dev_type;
>>>>      u64 req_features;
>>>>      u64 hw_features;
>>>> -   u32 dev_type;
>>>>      struct virtio_pci_common_cfg __iomem *common_cfg;
>>>>      void __iomem *dev_cfg;
>>>>      struct vring_info vring[IFCVF_MAX_QUEUES];
>>>>      void __iomem * const *base;
>>>>      char config_msix_name[256];
>>>>      struct vdpa_callback config_cb;
>>>> -   unsigned int config_irq;
>>>> -   /* virtio-net or virtio-blk device config size */
>>>> -   u32 config_size;
>>>> +   int config_irq;
>>>> +   int vqs_shared_irq;
>>>> +   u16 nr_vring;
>>>>    };
>>>>    struct ifcvf_adapter {
>>>> @@ -160,4 +167,6 @@ int ifcvf_set_vq_state(struct ifcvf_hw *hw, u16 qid, u16 num);
>>>>    struct ifcvf_adapter *vf_to_adapter(struct ifcvf_hw *hw);
>>>>    int ifcvf_probed_virtio_net(struct ifcvf_hw *hw);
>>>>    u32 ifcvf_get_config_size(struct ifcvf_hw *hw);
>>>> +int ifcvf_set_vq_vector(struct ifcvf_hw *hw, u16 qid, int vector);
>>>> +int ifcvf_set_config_vector(struct ifcvf_hw *hw, int vector);
>>>>    #endif /* _IFCVF_H_ */
>>>> diff --git a/drivers/vdpa/ifcvf/ifcvf_main.c b/drivers/vdpa/ifcvf/ifcvf_main.c
>>>> index 44c89ab0b6da..ca414399f040 100644
>>>> --- a/drivers/vdpa/ifcvf/ifcvf_main.c
>>>> +++ b/drivers/vdpa/ifcvf/ifcvf_main.c
>>>> @@ -17,6 +17,7 @@
>>>>    #define DRIVER_AUTHOR   "Intel Corporation"
>>>>    #define IFCVF_DRIVER_NAME       "ifcvf"
>>>> +/* handles config interrupt */
>>>
>>> This seems unrelated to the shared IRQ logic and it looks useless since it's
>>> easily to deduce it from the function name below.
>>>
>>>
>>>>    static irqreturn_t ifcvf_config_changed(int irq, void *arg)
>>>>    {
>>>>      struct ifcvf_hw *vf = arg;
>>>> @@ -27,6 +28,7 @@ static irqreturn_t ifcvf_config_changed(int irq, void *arg)
>>>>      return IRQ_HANDLED;
>>>>    }
>>>> +/* handles vqs interrupt */
>>>
>>> So did this.
>>>
>>>
>>>>    static irqreturn_t ifcvf_intr_handler(int irq, void *arg)
>>>>    {
>>>>      struct vring_info *vring = arg;
>>>> @@ -37,24 +39,78 @@ static irqreturn_t ifcvf_intr_handler(int irq, void *arg)
>>>>      return IRQ_HANDLED;
>>>>    }
>>>> +/* handls vqs shared interrupt */
>>>> +static irqreturn_t ifcvf_vq_shared_intr_handler(int irq, void *arg)
>>>> +{
>>>> +   struct ifcvf_hw *vf = arg;
>>>> +   struct vring_info *vring;
>>>> +   int i;
>>>> +
>>>> +   for (i = 0; i < vf->nr_vring; i++) {
>>>> +           vring = &vf->vring[i];
>>>> +           if (vring->cb.callback)
>>>> +                   vf->vring->cb.callback(vring->cb.private);
>>>> +   }
>>>> +
>>>> +   return IRQ_HANDLED;
>>>> +}
>>>> +
>>>> +/* handles a shared interrupt for vqs and config */
>>>> +static irqreturn_t ifcvf_dev_shared_intr_handler(int irq, void *arg)
>> shared is not a good name given IRQ_SHARED is not set.
>> maybe "common"? "reused"?
>>
>>>> +{
>>>> +   struct ifcvf_hw *vf = arg;
>>>> +   u8 isr;
>>>> +
>>>> +   isr = ifc_ioread8(vf->isr);
>>>
>>> We need to exactly what vp_interrupt do here. Checking against vf->isr first
>>> and return IRQ_NONE if it is not set.
>> no, vf->isr is not set for VQ interrupts.
> I actually wonder what's the actual behaviour of IFCVF.
>
>> If need to actually poke
>> at the VQ to know.
>>
>>> Always return IRQ_HANDLED will break the device who shares an irq with
>>> IFCVF.
>>
>> It's a MSI, not INT#. So interrupt is not shared as such - it's only
>> sharing vector between config and vq.
> Right, I thought it was a shared one as virito_pci did.
>
>>
>>>> +   if (isr & VIRTIO_PCI_ISR_CONFIG)
>>>> +           ifcvf_config_changed(irq, arg);
>>>> +
>>>> +   return ifcvf_vq_shared_intr_handler(irq, arg);
>>>> +}
>>>> +
>>>>    static void ifcvf_free_irq_vectors(void *data)
>>>>    {
>>>>      pci_free_irq_vectors(data);
>>>>    }
>>>> -static void ifcvf_free_irq(struct ifcvf_adapter *adapter, int queues)
>>>> +static void ifcvf_free_vq_irq(struct ifcvf_adapter *adapter, int queues)
>>>>    {
>>>>      struct pci_dev *pdev = adapter->pdev;
>>>>      struct ifcvf_hw *vf = &adapter->vf;
>>>>      int i;
>>>> +   if (vf->msix_vector_status == MSIX_VECTOR_PER_VQ_AND_CONFIG) {
>>>> +           for (i = 0; i < queues; i++) {
>>>> +                   devm_free_irq(&pdev->dev, vf->vring[i].irq, &vf->vring[i]);
>>>> +                   vf->vring[i].irq = -EINVAL;
>>>> +           }
>>>> +   } else {
>>>> +           devm_free_irq(&pdev->dev, vf->vqs_shared_irq, vf);
>>>> +           vf->vqs_shared_irq = -EINVAL;
>>>> +   }
>>>> +}
>>>> -   for (i = 0; i < queues; i++) {
>>>> -           devm_free_irq(&pdev->dev, vf->vring[i].irq, &vf->vring[i]);
>>>> -           vf->vring[i].irq = -EINVAL;
>>>> +static void ifcvf_free_config_irq(struct ifcvf_adapter *adapter)
>>>> +{
>>>> +   struct pci_dev *pdev = adapter->pdev;
>>>> +   struct ifcvf_hw *vf = &adapter->vf;
>>>> +
>>>> +   /* If the irq is shared by all vqs and the config interrupt,
>>>> +    * it is already freed in ifcvf_free_vq_irq, so here only
>>>> +    * need to free config irq when msix_vector_status != MSIX_VECTOR_DEV_SHARED
>>>> +    */
>>>> +   if (vf->msix_vector_status != MSIX_VECTOR_DEV_SHARED) {
>>>> +           devm_free_irq(&pdev->dev, vf->config_irq, vf);
>>>> +           vf->config_irq = -EINVAL;
>>>>      }
>>>> +}
>>>> +
>>>> +static void ifcvf_free_irq(struct ifcvf_adapter *adapter, int queues)
>>>> +{
>>>> +   struct pci_dev *pdev = adapter->pdev;
>>>> -   devm_free_irq(&pdev->dev, vf->config_irq, vf);
>>>> +   ifcvf_free_vq_irq(adapter, queues);
>>>> +   ifcvf_free_config_irq(adapter);
>>>>      ifcvf_free_irq_vectors(pdev);
>>>>    }
>>>> @@ -86,58 +142,172 @@ static int ifcvf_alloc_vectors(struct ifcvf_adapter *adapter)
>>>>      return ret;
>>>>    }
>>>> -static int ifcvf_request_irq(struct ifcvf_adapter *adapter)
>>>> +static int ifcvf_request_per_vq_irq(struct ifcvf_adapter *adapter)
>>>>    {
>>>>      struct pci_dev *pdev = adapter->pdev;
>>>>      struct ifcvf_hw *vf = &adapter->vf;
>>>> -   int vector, nvectors, i, ret, irq;
>>>> -   u16 max_intr;
>>>> +   int i, vector, ret, irq;
>>>> -   nvectors = ifcvf_alloc_vectors(adapter);
>>>> -   if (!(nvectors > 0))
>>>> -           return nvectors;
>>>> +   for (i = 0; i < vf->nr_vring; i++) {
>>>> +           snprintf(vf->vring[i].msix_name, 256, "ifcvf[%s]-%d\n", pci_name(pdev), i);
>>>> +           vector = i;
>>>> +           irq = pci_irq_vector(pdev, vector);
>>>> +           ret = devm_request_irq(&pdev->dev, irq,
>>>> +                                  ifcvf_intr_handler, 0,
>>>> +                                  vf->vring[i].msix_name,
>>>> +                                  &vf->vring[i]);
>>>> +           if (ret) {
>>>> +                   IFCVF_ERR(pdev, "Failed to request irq for vq %d\n", i);
>>>> +                   ifcvf_free_vq_irq(adapter, i);
>>>> +           } else {
>>>> +                   vf->vring[i].irq = irq;
>>>> +                   ifcvf_set_vq_vector(vf, i, vector);
>>>> +           }
>>>> +   }
>>>> -   max_intr = vf->nr_vring + 1;
>>>> +   vf->vqs_shared_irq = -EINVAL;
>>>> +
>>>> +   return 0;
>>>> +}
>>>> +
>>>> +static int ifcvf_request_shared_vq_irq(struct ifcvf_adapter *adapter)
>>>> +{
>>>> +   struct pci_dev *pdev = adapter->pdev;
>>>> +   struct ifcvf_hw *vf = &adapter->vf;
>>>> +   int i, vector, ret, irq;
>>>> +
>>>> +   vector = 0;
>>>> +   /* reuse msix_name[256] space of vring0 to store shared vqs interrupt name */
>>>
>>> I think we can remove this comment since the code is straightforward.
>>>
>>>
>>>> +   snprintf(vf->vring[0].msix_name, 256, "ifcvf[%s]-vqs-shared-irq\n", pci_name(pdev));
>>>> +   irq = pci_irq_vector(pdev, vector);
>>>> +   ret = devm_request_irq(&pdev->dev, irq,
>>>> +                          ifcvf_vq_shared_intr_handler, 0,
>>>> +                          vf->vring[0].msix_name, vf);
>>>> +   if (ret) {
>>>> +           IFCVF_ERR(pdev, "Failed to request shared irq for vf\n");
>>>> +
>>>> +           return ret;
>>>> +   }
>>>> +
>>>> +   vf->vqs_shared_irq = irq;
>>>> +   for (i = 0; i < vf->nr_vring; i++) {
>>>> +           vf->vring[i].irq = -EINVAL;
>>>> +           ifcvf_set_vq_vector(vf, i, vector);
>>>> +   }
>>>> +
>>>> +   return 0;
>>>> +
>>>> +}
>>>> +
>>>> +static int ifcvf_request_dev_shared_irq(struct ifcvf_adapter *adapter)
>>>> +{
>>>> +   struct pci_dev *pdev = adapter->pdev;
>>>> +   struct ifcvf_hw *vf = &adapter->vf;
>>>> +   int i, vector, ret, irq;
>>>> +
>>>> +   vector = 0;
>>>> +   /* reuse msix_name[256] space of vring0 to store shared device interrupt name */
>>>> +   snprintf(vf->vring[0].msix_name, 256, "ifcvf[%s]-dev-shared-irq\n", pci_name(pdev));
>>>> +   irq = pci_irq_vector(pdev, vector);
>>>> +   ret = devm_request_irq(&pdev->dev, irq,
>>>> +                          ifcvf_dev_shared_intr_handler, 0,
>>>> +                          vf->vring[0].msix_name, vf);
>>>> +   if (ret) {
>>>> +           IFCVF_ERR(pdev, "Failed to request shared irq for vf\n");
>>>> -   ret = pci_alloc_irq_vectors(pdev, max_intr,
>>>> -                               max_intr, PCI_IRQ_MSIX);
>>>> -   if (ret < 0) {
>>>> -           IFCVF_ERR(pdev, "Failed to alloc IRQ vectors\n");
>>>>              return ret;
>>>>      }
>>>> +   vf->vqs_shared_irq = irq;
>>>> +   for (i = 0; i < vf->nr_vring; i++) {
>>>> +           vf->vring[i].irq = -EINVAL;
>>>> +           ifcvf_set_vq_vector(vf, i, vector);
>>>> +   }
>>>> +
>>>> +   vf->config_irq = irq;
>>>> +   ifcvf_set_config_vector(vf, vector);
>>>> +
>>>> +   return 0;
>>>> +
>>>> +}
>>>> +
>>>> +static int ifcvf_request_vq_irq(struct ifcvf_adapter *adapter)
>>>> +{
>>>> +   struct ifcvf_hw *vf = &adapter->vf;
>>>> +   int ret;
>>>> +
>>>> +   if (vf->msix_vector_status == MSIX_VECTOR_PER_VQ_AND_CONFIG)
>>>> +           ret = ifcvf_request_per_vq_irq(adapter);
>>>> +   else
>>>> +           ret = ifcvf_request_shared_vq_irq(adapter);
>>>> +
>>>> +   return ret;
>>>> +}
>>>> +
>>>> +static int ifcvf_request_config_irq(struct ifcvf_adapter *adapter)
>>>> +{
>>>> +   struct pci_dev *pdev = adapter->pdev;
>>>> +   struct ifcvf_hw *vf = &adapter->vf;
>>>> +   int config_vector, ret;
>>>> +
>>>> +   if (vf->msix_vector_status == MSIX_VECTOR_DEV_SHARED)
>>>> +           return 0;
>>>> +
>>>> +   if (vf->msix_vector_status == MSIX_VECTOR_PER_VQ_AND_CONFIG)
>>>> +           /* vector 0 ~ vf->nr_vring for vqs, num vf->nr_vring vector for config interrupt */
>>>> +           config_vector = vf->nr_vring;
>>>> +
>>>> +   if (vf->msix_vector_status ==  MSIX_VECTOR_SHARED_VQ_AND_CONFIG)
>>>> +           /* vector 0 for vqs and 1 for config interrupt */
>>>> +           config_vector = 1;
>>>> +
>>>>      snprintf(vf->config_msix_name, 256, "ifcvf[%s]-config\n",
>>>>               pci_name(pdev));
>>>> -   vector = 0;
>>>> -   vf->config_irq = pci_irq_vector(pdev, vector);
>>>> +   vf->config_irq = pci_irq_vector(pdev, config_vector);
>>>>      ret = devm_request_irq(&pdev->dev, vf->config_irq,
>>>>                             ifcvf_config_changed, 0,
>>>>                             vf->config_msix_name, vf);
>>>>      if (ret) {
>>>>              IFCVF_ERR(pdev, "Failed to request config irq\n");
>>>> +           ifcvf_free_vq_irq(adapter, vf->nr_vring);
>>>>              return ret;
>>>>      }
>>>> -   for (i = 0; i < vf->nr_vring; i++) {
>>>> -           snprintf(vf->vring[i].msix_name, 256, "ifcvf[%s]-%d\n",
>>>> -                    pci_name(pdev), i);
>>>> -           vector = i + IFCVF_MSI_QUEUE_OFF;
>>>> -           irq = pci_irq_vector(pdev, vector);
>>>> -           ret = devm_request_irq(&pdev->dev, irq,
>>>> -                                  ifcvf_intr_handler, 0,
>>>> -                                  vf->vring[i].msix_name,
>>>> -                                  &vf->vring[i]);
>>>> -           if (ret) {
>>>> -                   IFCVF_ERR(pdev,
>>>> -                             "Failed to request irq for vq %d\n", i);
>>>> -                   ifcvf_free_irq(adapter, i);
>>>> +   ifcvf_set_config_vector(vf, config_vector);
>>>> -                   return ret;
>>>> -           }
>>>> +   return 0;
>>>> +}
>>>> +
>>>> +static int ifcvf_request_irq(struct ifcvf_adapter *adapter)
>>>> +{
>>>
>>> As replied above, I think having two modes should be sufficient and the code
>>> could be greatly simplified.
>>>
>>> Thanks
>>>
>> Well it is claimed there are platforms where we are short
>> on vectors. 3 versus 2 seems a 50% saving. You disagree?
> I think we can 2 vectors (a dedicated for config).
>
> Thanks
>
>>>> +   struct ifcvf_hw *vf = &adapter->vf;
>>>> +   int nvectors, ret, max_intr;
>>>> -           vf->vring[i].irq = irq;
>>>> +   nvectors = ifcvf_alloc_vectors(adapter);
>>>> +   if (!(nvectors > 0))
>>>> +           return nvectors;
>>>> +
>>>> +   vf->msix_vector_status = MSIX_VECTOR_PER_VQ_AND_CONFIG;
>>>> +   max_intr = vf->nr_vring + 1;
>>>> +   if (nvectors < max_intr)
>>>> +           vf->msix_vector_status = MSIX_VECTOR_SHARED_VQ_AND_CONFIG;
>>>> +
>>>> +   if (nvectors == 1) {
>>>> +           vf->msix_vector_status = MSIX_VECTOR_DEV_SHARED;
>>>> +           ret = ifcvf_request_dev_shared_irq(adapter);
>>>> +
>>>> +           return ret;
>>>>      }
>>>> +   ret = ifcvf_request_vq_irq(adapter);
>>>> +   if (ret)
>>>> +           return ret;
>>>> +
>>>> +   ret = ifcvf_request_config_irq(adapter);
>>>> +
>>>> +   if (ret)
>>>> +           return ret;
>>>> +
>>>>      return 0;
>>>>    }
>>>> @@ -441,7 +611,10 @@ static int ifcvf_vdpa_get_vq_irq(struct vdpa_device *vdpa_dev,
>>>>    {
>>>>      struct ifcvf_hw *vf = vdpa_to_vf(vdpa_dev);
>>>> -   return vf->vring[qid].irq;
>>>> +   if (vf->vqs_shared_irq < 0)
>>>> +           return vf->vring[qid].irq;
>>>> +   else
>>>> +           return -EINVAL;
>>>>    }
>>>>    static struct vdpa_notification_area ifcvf_get_vq_notification(struct vdpa_device *vdpa_dev,

Re: [PATCH V4 4/4] vDPA/ifcvf: implement shared IRQ feature

[Michael S. Tsirkin]

On Tue, Feb 15, 2022 at 11:34:31AM +0800, Jason Wang wrote:
> On Mon, Feb 14, 2022 at 10:25 PM Michael S. Tsirkin <mst@redhat.com> wrote:
> >
> > On Mon, Feb 14, 2022 at 03:19:25PM +0800, Jason Wang wrote:
> > >
> > > 在 2022/2/3 下午3:27, Zhu Lingshan 写道:
> > > > On some platforms/devices, there may not be enough MSI vector
> > > > slots allocated for virtqueues and config changes. In such a case,
> > > > the interrupt sources(virtqueues, config changes) must share
> > > > an IRQ/vector, to avoid initialization failures, keep
> > > > the device functional.
> > > >
> > > > This commit handles three cases:
> > > > (1) number of the allocated vectors == the number of virtqueues + 1
> > > > (config changes), every virtqueue and the config interrupt has
> > > > a separated vector/IRQ, the best and the most likely case.
> > > > (2) number of the allocated vectors is less than the best case, but
> > > > greater than 1. In this case, all virtqueues share a vector/IRQ,
> > > > the config interrupt has a separated vector/IRQ
> > > > (3) only one vector is allocated, in this case, the virtqueues and
> > > > the config interrupt share a vector/IRQ. The worst and most
> > > > unlikely case.
> > > >
> > > > Otherwise, it needs to fail.
> > > >
> > > > This commit introduces some helper functions:
> > > > ifcvf_set_vq_vector() and ifcvf_set_config_vector() sets virtqueue
> > > > vector and config vector in the device config space, so that
> > > > the device can send interrupt DMA.
> > > >
> > > > This commit adds some fields in struct ifcvf_hw and re-placed
> > > > the existed fields to be aligned with the cacheline.
> > > >
> > > > Signed-off-by: Zhu Lingshan <lingshan.zhu@intel.com>
> > > > ---
> > > >   drivers/vdpa/ifcvf/ifcvf_base.c |  47 ++++--
> > > >   drivers/vdpa/ifcvf/ifcvf_base.h |  23 ++-
> > > >   drivers/vdpa/ifcvf/ifcvf_main.c | 243 +++++++++++++++++++++++++++-----
> > > >   3 files changed, 256 insertions(+), 57 deletions(-)
> > > >
> > > > diff --git a/drivers/vdpa/ifcvf/ifcvf_base.c b/drivers/vdpa/ifcvf/ifcvf_base.c
> > > > index 397692ae671c..18dcb63ab1e3 100644
> > > > --- a/drivers/vdpa/ifcvf/ifcvf_base.c
> > > > +++ b/drivers/vdpa/ifcvf/ifcvf_base.c
> > > > @@ -15,6 +15,36 @@ struct ifcvf_adapter *vf_to_adapter(struct ifcvf_hw *hw)
> > > >     return container_of(hw, struct ifcvf_adapter, vf);
> > > >   }
> > > > +int ifcvf_set_vq_vector(struct ifcvf_hw *hw, u16 qid, int vector)
> > > > +{
> > > > +   struct virtio_pci_common_cfg __iomem *cfg = hw->common_cfg;
> > > > +   struct ifcvf_adapter *ifcvf = vf_to_adapter(hw);
> > > > +
> > > > +   ifc_iowrite16(qid, &cfg->queue_select);
> > > > +   ifc_iowrite16(vector, &cfg->queue_msix_vector);
> > > > +   if (ifc_ioread16(&cfg->queue_msix_vector) == VIRTIO_MSI_NO_VECTOR) {
> > > > +           IFCVF_ERR(ifcvf->pdev, "No msix vector for queue %u\n", qid);
> > > > +                   return -EINVAL;
> > > > +   }
> > >
> > >
> > > Let's leave this check for the caller, E.g can caller try to assign
> > > NO_VECTOR during uni-nit?
> >
> >
> > Hmm I'm not sure I agree. Caller will have to write queue select
> > again, and that's an extra IO, which is a waste.
> > And having function checking itself just seems better contained.
> 
> It's as simple as just return what we read here like virtio_pci did:
> 
> u16 vp_modern_queue_vector(struct virtio_pci_modern_device *mdev,
>                            u16 index, u16 vector)
> {
>         struct virtio_pci_common_cfg __iomem *cfg = mdev->common;
> 
>         vp_iowrite16(index, &cfg->queue_select);
>         vp_iowrite16(vector, &cfg->queue_msix_vector);
>         /* Flush the write out to device */
>         return vp_ioread16(&cfg->queue_msix_vector);
> }
> EXPORT_SYMBOL_GPL(vp_modern_queue_vector);


That would be ok.

> Then the caller can decide to check it with NO_VECTOR if needed.
> Current code will break the callers that want to set NO_VECTOR.
> 
> >
> > >
> > > > +
> > > > +   return 0;
> > > > +}
> > > > +
> > > > +int ifcvf_set_config_vector(struct ifcvf_hw *hw, int vector)
> > > > +{
> > > > +   struct virtio_pci_common_cfg __iomem *cfg = hw->common_cfg;
> > > > +   struct ifcvf_adapter *ifcvf = vf_to_adapter(hw);
> > > > +
> > > > +   cfg = hw->common_cfg;
> > > > +   ifc_iowrite16(vector,  &cfg->msix_config);
> > > > +   if (ifc_ioread16(&cfg->msix_config) == VIRTIO_MSI_NO_VECTOR) {
> > > > +           IFCVF_ERR(ifcvf->pdev, "No msix vector for device config\n");
> > > > +           return -EINVAL;
> > > > +   }
> > >
> > >
> > > Similar question as above.
> > >
> > >
> > > > +
> > > > +   return 0;
> > > > +}
> > > > +
> > > >   static void __iomem *get_cap_addr(struct ifcvf_hw *hw,
> > > >                               struct virtio_pci_cap *cap)
> > > >   {
> > > > @@ -140,6 +170,8 @@ int ifcvf_init_hw(struct ifcvf_hw *hw, struct pci_dev *pdev)
> > > >               hw->common_cfg, hw->notify_base, hw->isr,
> > > >               hw->dev_cfg, hw->notify_off_multiplier);
> > > > +   hw->vqs_shared_irq = -EINVAL;
> > > > +
> > > >     return 0;
> > > >   }
> > > > @@ -321,12 +353,6 @@ static int ifcvf_hw_enable(struct ifcvf_hw *hw)
> > > >     ifcvf = vf_to_adapter(hw);
> > > >     cfg = hw->common_cfg;
> > > > -   ifc_iowrite16(IFCVF_MSI_CONFIG_OFF, &cfg->msix_config);
> > > > -
> > > > -   if (ifc_ioread16(&cfg->msix_config) == VIRTIO_MSI_NO_VECTOR) {
> > > > -           IFCVF_ERR(ifcvf->pdev, "No msix vector for device config\n");
> > > > -           return -EINVAL;
> > > > -   }
> > > >     for (i = 0; i < hw->nr_vring; i++) {
> > > >             if (!hw->vring[i].ready)
> > > > @@ -340,15 +366,6 @@ static int ifcvf_hw_enable(struct ifcvf_hw *hw)
> > > >             ifc_iowrite64_twopart(hw->vring[i].used, &cfg->queue_used_lo,
> > > >                                  &cfg->queue_used_hi);
> > > >             ifc_iowrite16(hw->vring[i].size, &cfg->queue_size);
> > > > -           ifc_iowrite16(i + IFCVF_MSI_QUEUE_OFF, &cfg->queue_msix_vector);
> > > > -
> > > > -           if (ifc_ioread16(&cfg->queue_msix_vector) ==
> > > > -               VIRTIO_MSI_NO_VECTOR) {
> > > > -                   IFCVF_ERR(ifcvf->pdev,
> > > > -                             "No msix vector for queue %u\n", i);
> > > > -                   return -EINVAL;
> > > > -           }
> > > > -
> > > >             ifcvf_set_vq_state(hw, i, hw->vring[i].last_avail_idx);
> > > >             ifc_iowrite16(1, &cfg->queue_enable);
> > > >     }
> > > > diff --git a/drivers/vdpa/ifcvf/ifcvf_base.h b/drivers/vdpa/ifcvf/ifcvf_base.h
> > > > index 949b4fb9d554..9cfe088c82e9 100644
> > > > --- a/drivers/vdpa/ifcvf/ifcvf_base.h
> > > > +++ b/drivers/vdpa/ifcvf/ifcvf_base.h
> > > > @@ -27,8 +27,6 @@
> > > >   #define IFCVF_QUEUE_ALIGNMENT     PAGE_SIZE
> > > >   #define IFCVF_QUEUE_MAX           32768
> > > > -#define IFCVF_MSI_CONFIG_OFF       0
> > > > -#define IFCVF_MSI_QUEUE_OFF        1
> > > >   #define IFCVF_PCI_MAX_RESOURCE    6
> > > >   #define IFCVF_LM_CFG_SIZE         0x40
> > > > @@ -42,6 +40,13 @@
> > > >   #define ifcvf_private_to_vf(adapter) \
> > > >     (&((struct ifcvf_adapter *)adapter)->vf)
> > > > +/* all vqs and config interrupt has its own vector */
> > > > +#define MSIX_VECTOR_PER_VQ_AND_CONFIG              1
> > > > +/* all vqs share a vector, and config interrupt has a separate vector */
> > > > +#define MSIX_VECTOR_SHARED_VQ_AND_CONFIG   2
> > > > +/* all vqs and config interrupt share a vector */
> > > > +#define MSIX_VECTOR_DEV_SHARED                     3
> > >
> > >
> > > I think there's no much value to differ 2 from 3 consider config interrupt
> > > should be rare.
> >
> >
> > Yes but if we do not have a dedicated vector then we need an
> > extra device IO (in fact, a read) on each interrupt.
> 
> Ok, right.
> 
> >
> > >
> > > > +
> > > >   static inline u8 ifc_ioread8(u8 __iomem *addr)
> > > >   {
> > > >     return ioread8(addr);
> > > > @@ -97,25 +102,27 @@ struct ifcvf_hw {
> > > >     u8 __iomem *isr;
> > > >     /* Live migration */
> > > >     u8 __iomem *lm_cfg;
> > > > -   u16 nr_vring;
> > >
> > >
> > > Any reason for moving nv_vring, config_size, and other stuffs?
> > >
> > >
> > > >     /* Notification bar number */
> > > >     u8 notify_bar;
> > > > +   u8 msix_vector_status;
> > > > +   /* virtio-net or virtio-blk device config size */
> > > > +   u32 config_size;
> > > >     /* Notificaiton bar address */
> > > >     void __iomem *notify_base;
> > > >     phys_addr_t notify_base_pa;
> > > >     u32 notify_off_multiplier;
> > > > +   u32 dev_type;
> > > >     u64 req_features;
> > > >     u64 hw_features;
> > > > -   u32 dev_type;
> > > >     struct virtio_pci_common_cfg __iomem *common_cfg;
> > > >     void __iomem *dev_cfg;
> > > >     struct vring_info vring[IFCVF_MAX_QUEUES];
> > > >     void __iomem * const *base;
> > > >     char config_msix_name[256];
> > > >     struct vdpa_callback config_cb;
> > > > -   unsigned int config_irq;
> > > > -   /* virtio-net or virtio-blk device config size */
> > > > -   u32 config_size;
> > > > +   int config_irq;
> > > > +   int vqs_shared_irq;
> > > > +   u16 nr_vring;
> > > >   };
> > > >   struct ifcvf_adapter {
> > > > @@ -160,4 +167,6 @@ int ifcvf_set_vq_state(struct ifcvf_hw *hw, u16 qid, u16 num);
> > > >   struct ifcvf_adapter *vf_to_adapter(struct ifcvf_hw *hw);
> > > >   int ifcvf_probed_virtio_net(struct ifcvf_hw *hw);
> > > >   u32 ifcvf_get_config_size(struct ifcvf_hw *hw);
> > > > +int ifcvf_set_vq_vector(struct ifcvf_hw *hw, u16 qid, int vector);
> > > > +int ifcvf_set_config_vector(struct ifcvf_hw *hw, int vector);
> > > >   #endif /* _IFCVF_H_ */
> > > > diff --git a/drivers/vdpa/ifcvf/ifcvf_main.c b/drivers/vdpa/ifcvf/ifcvf_main.c
> > > > index 44c89ab0b6da..ca414399f040 100644
> > > > --- a/drivers/vdpa/ifcvf/ifcvf_main.c
> > > > +++ b/drivers/vdpa/ifcvf/ifcvf_main.c
> > > > @@ -17,6 +17,7 @@
> > > >   #define DRIVER_AUTHOR   "Intel Corporation"
> > > >   #define IFCVF_DRIVER_NAME       "ifcvf"
> > > > +/* handles config interrupt */
> > >
> > >
> > > This seems unrelated to the shared IRQ logic and it looks useless since it's
> > > easily to deduce it from the function name below.
> > >
> > >
> > > >   static irqreturn_t ifcvf_config_changed(int irq, void *arg)
> > > >   {
> > > >     struct ifcvf_hw *vf = arg;
> > > > @@ -27,6 +28,7 @@ static irqreturn_t ifcvf_config_changed(int irq, void *arg)
> > > >     return IRQ_HANDLED;
> > > >   }
> > > > +/* handles vqs interrupt */
> > >
> > >
> > > So did this.
> > >
> > >
> > > >   static irqreturn_t ifcvf_intr_handler(int irq, void *arg)
> > > >   {
> > > >     struct vring_info *vring = arg;
> > > > @@ -37,24 +39,78 @@ static irqreturn_t ifcvf_intr_handler(int irq, void *arg)
> > > >     return IRQ_HANDLED;
> > > >   }
> > > > +/* handls vqs shared interrupt */
> > > > +static irqreturn_t ifcvf_vq_shared_intr_handler(int irq, void *arg)
> > > > +{
> > > > +   struct ifcvf_hw *vf = arg;
> > > > +   struct vring_info *vring;
> > > > +   int i;
> > > > +
> > > > +   for (i = 0; i < vf->nr_vring; i++) {
> > > > +           vring = &vf->vring[i];
> > > > +           if (vring->cb.callback)
> > > > +                   vf->vring->cb.callback(vring->cb.private);
> > > > +   }
> > > > +
> > > > +   return IRQ_HANDLED;
> > > > +}
> > > > +
> > > > +/* handles a shared interrupt for vqs and config */
> > > > +static irqreturn_t ifcvf_dev_shared_intr_handler(int irq, void *arg)
> >
> > shared is not a good name given IRQ_SHARED is not set.
> > maybe "common"? "reused"?
> >
> > > > +{
> > > > +   struct ifcvf_hw *vf = arg;
> > > > +   u8 isr;
> > > > +
> > > > +   isr = ifc_ioread8(vf->isr);
> > >
> > >
> > > We need to exactly what vp_interrupt do here. Checking against vf->isr first
> > > and return IRQ_NONE if it is not set.
> >
> > no, vf->isr is not set for VQ interrupts.
> 
> I actually wonder what's the actual behaviour of IFCVF.
> 
> > If need to actually poke
> > at the VQ to know.
> >
> > > Always return IRQ_HANDLED will break the device who shares an irq with
> > > IFCVF.
> >
> >
> > It's a MSI, not INT#. So interrupt is not shared as such - it's only
> > sharing vector between config and vq.
> 
> Right, I thought it was a shared one as virito_pci did.
> 
> >
> >
> > >
> > > > +   if (isr & VIRTIO_PCI_ISR_CONFIG)
> > > > +           ifcvf_config_changed(irq, arg);
> > > > +
> > > > +   return ifcvf_vq_shared_intr_handler(irq, arg);
> > > > +}
> > > > +
> > > >   static void ifcvf_free_irq_vectors(void *data)
> > > >   {
> > > >     pci_free_irq_vectors(data);
> > > >   }
> > > > -static void ifcvf_free_irq(struct ifcvf_adapter *adapter, int queues)
> > > > +static void ifcvf_free_vq_irq(struct ifcvf_adapter *adapter, int queues)
> > > >   {
> > > >     struct pci_dev *pdev = adapter->pdev;
> > > >     struct ifcvf_hw *vf = &adapter->vf;
> > > >     int i;
> > > > +   if (vf->msix_vector_status == MSIX_VECTOR_PER_VQ_AND_CONFIG) {
> > > > +           for (i = 0; i < queues; i++) {
> > > > +                   devm_free_irq(&pdev->dev, vf->vring[i].irq, &vf->vring[i]);
> > > > +                   vf->vring[i].irq = -EINVAL;
> > > > +           }
> > > > +   } else {
> > > > +           devm_free_irq(&pdev->dev, vf->vqs_shared_irq, vf);
> > > > +           vf->vqs_shared_irq = -EINVAL;
> > > > +   }
> > > > +}
> > > > -   for (i = 0; i < queues; i++) {
> > > > -           devm_free_irq(&pdev->dev, vf->vring[i].irq, &vf->vring[i]);
> > > > -           vf->vring[i].irq = -EINVAL;
> > > > +static void ifcvf_free_config_irq(struct ifcvf_adapter *adapter)
> > > > +{
> > > > +   struct pci_dev *pdev = adapter->pdev;
> > > > +   struct ifcvf_hw *vf = &adapter->vf;
> > > > +
> > > > +   /* If the irq is shared by all vqs and the config interrupt,
> > > > +    * it is already freed in ifcvf_free_vq_irq, so here only
> > > > +    * need to free config irq when msix_vector_status != MSIX_VECTOR_DEV_SHARED
> > > > +    */
> > > > +   if (vf->msix_vector_status != MSIX_VECTOR_DEV_SHARED) {
> > > > +           devm_free_irq(&pdev->dev, vf->config_irq, vf);
> > > > +           vf->config_irq = -EINVAL;
> > > >     }
> > > > +}
> > > > +
> > > > +static void ifcvf_free_irq(struct ifcvf_adapter *adapter, int queues)
> > > > +{
> > > > +   struct pci_dev *pdev = adapter->pdev;
> > > > -   devm_free_irq(&pdev->dev, vf->config_irq, vf);
> > > > +   ifcvf_free_vq_irq(adapter, queues);
> > > > +   ifcvf_free_config_irq(adapter);
> > > >     ifcvf_free_irq_vectors(pdev);
> > > >   }
> > > > @@ -86,58 +142,172 @@ static int ifcvf_alloc_vectors(struct ifcvf_adapter *adapter)
> > > >     return ret;
> > > >   }
> > > > -static int ifcvf_request_irq(struct ifcvf_adapter *adapter)
> > > > +static int ifcvf_request_per_vq_irq(struct ifcvf_adapter *adapter)
> > > >   {
> > > >     struct pci_dev *pdev = adapter->pdev;
> > > >     struct ifcvf_hw *vf = &adapter->vf;
> > > > -   int vector, nvectors, i, ret, irq;
> > > > -   u16 max_intr;
> > > > +   int i, vector, ret, irq;
> > > > -   nvectors = ifcvf_alloc_vectors(adapter);
> > > > -   if (!(nvectors > 0))
> > > > -           return nvectors;
> > > > +   for (i = 0; i < vf->nr_vring; i++) {
> > > > +           snprintf(vf->vring[i].msix_name, 256, "ifcvf[%s]-%d\n", pci_name(pdev), i);
> > > > +           vector = i;
> > > > +           irq = pci_irq_vector(pdev, vector);
> > > > +           ret = devm_request_irq(&pdev->dev, irq,
> > > > +                                  ifcvf_intr_handler, 0,
> > > > +                                  vf->vring[i].msix_name,
> > > > +                                  &vf->vring[i]);
> > > > +           if (ret) {
> > > > +                   IFCVF_ERR(pdev, "Failed to request irq for vq %d\n", i);
> > > > +                   ifcvf_free_vq_irq(adapter, i);
> > > > +           } else {
> > > > +                   vf->vring[i].irq = irq;
> > > > +                   ifcvf_set_vq_vector(vf, i, vector);
> > > > +           }
> > > > +   }
> > > > -   max_intr = vf->nr_vring + 1;
> > > > +   vf->vqs_shared_irq = -EINVAL;
> > > > +
> > > > +   return 0;
> > > > +}
> > > > +
> > > > +static int ifcvf_request_shared_vq_irq(struct ifcvf_adapter *adapter)
> > > > +{
> > > > +   struct pci_dev *pdev = adapter->pdev;
> > > > +   struct ifcvf_hw *vf = &adapter->vf;
> > > > +   int i, vector, ret, irq;
> > > > +
> > > > +   vector = 0;
> > > > +   /* reuse msix_name[256] space of vring0 to store shared vqs interrupt name */
> > >
> > >
> > > I think we can remove this comment since the code is straightforward.
> > >
> > >
> > > > +   snprintf(vf->vring[0].msix_name, 256, "ifcvf[%s]-vqs-shared-irq\n", pci_name(pdev));
> > > > +   irq = pci_irq_vector(pdev, vector);
> > > > +   ret = devm_request_irq(&pdev->dev, irq,
> > > > +                          ifcvf_vq_shared_intr_handler, 0,
> > > > +                          vf->vring[0].msix_name, vf);
> > > > +   if (ret) {
> > > > +           IFCVF_ERR(pdev, "Failed to request shared irq for vf\n");
> > > > +
> > > > +           return ret;
> > > > +   }
> > > > +
> > > > +   vf->vqs_shared_irq = irq;
> > > > +   for (i = 0; i < vf->nr_vring; i++) {
> > > > +           vf->vring[i].irq = -EINVAL;
> > > > +           ifcvf_set_vq_vector(vf, i, vector);
> > > > +   }
> > > > +
> > > > +   return 0;
> > > > +
> > > > +}
> > > > +
> > > > +static int ifcvf_request_dev_shared_irq(struct ifcvf_adapter *adapter)
> > > > +{
> > > > +   struct pci_dev *pdev = adapter->pdev;
> > > > +   struct ifcvf_hw *vf = &adapter->vf;
> > > > +   int i, vector, ret, irq;
> > > > +
> > > > +   vector = 0;
> > > > +   /* reuse msix_name[256] space of vring0 to store shared device interrupt name */
> > > > +   snprintf(vf->vring[0].msix_name, 256, "ifcvf[%s]-dev-shared-irq\n", pci_name(pdev));
> > > > +   irq = pci_irq_vector(pdev, vector);
> > > > +   ret = devm_request_irq(&pdev->dev, irq,
> > > > +                          ifcvf_dev_shared_intr_handler, 0,
> > > > +                          vf->vring[0].msix_name, vf);
> > > > +   if (ret) {
> > > > +           IFCVF_ERR(pdev, "Failed to request shared irq for vf\n");
> > > > -   ret = pci_alloc_irq_vectors(pdev, max_intr,
> > > > -                               max_intr, PCI_IRQ_MSIX);
> > > > -   if (ret < 0) {
> > > > -           IFCVF_ERR(pdev, "Failed to alloc IRQ vectors\n");
> > > >             return ret;
> > > >     }
> > > > +   vf->vqs_shared_irq = irq;
> > > > +   for (i = 0; i < vf->nr_vring; i++) {
> > > > +           vf->vring[i].irq = -EINVAL;
> > > > +           ifcvf_set_vq_vector(vf, i, vector);
> > > > +   }
> > > > +
> > > > +   vf->config_irq = irq;
> > > > +   ifcvf_set_config_vector(vf, vector);
> > > > +
> > > > +   return 0;
> > > > +
> > > > +}
> > > > +
> > > > +static int ifcvf_request_vq_irq(struct ifcvf_adapter *adapter)
> > > > +{
> > > > +   struct ifcvf_hw *vf = &adapter->vf;
> > > > +   int ret;
> > > > +
> > > > +   if (vf->msix_vector_status == MSIX_VECTOR_PER_VQ_AND_CONFIG)
> > > > +           ret = ifcvf_request_per_vq_irq(adapter);
> > > > +   else
> > > > +           ret = ifcvf_request_shared_vq_irq(adapter);
> > > > +
> > > > +   return ret;
> > > > +}
> > > > +
> > > > +static int ifcvf_request_config_irq(struct ifcvf_adapter *adapter)
> > > > +{
> > > > +   struct pci_dev *pdev = adapter->pdev;
> > > > +   struct ifcvf_hw *vf = &adapter->vf;
> > > > +   int config_vector, ret;
> > > > +
> > > > +   if (vf->msix_vector_status == MSIX_VECTOR_DEV_SHARED)
> > > > +           return 0;
> > > > +
> > > > +   if (vf->msix_vector_status == MSIX_VECTOR_PER_VQ_AND_CONFIG)
> > > > +           /* vector 0 ~ vf->nr_vring for vqs, num vf->nr_vring vector for config interrupt */
> > > > +           config_vector = vf->nr_vring;
> > > > +
> > > > +   if (vf->msix_vector_status ==  MSIX_VECTOR_SHARED_VQ_AND_CONFIG)
> > > > +           /* vector 0 for vqs and 1 for config interrupt */
> > > > +           config_vector = 1;
> > > > +
> > > >     snprintf(vf->config_msix_name, 256, "ifcvf[%s]-config\n",
> > > >              pci_name(pdev));
> > > > -   vector = 0;
> > > > -   vf->config_irq = pci_irq_vector(pdev, vector);
> > > > +   vf->config_irq = pci_irq_vector(pdev, config_vector);
> > > >     ret = devm_request_irq(&pdev->dev, vf->config_irq,
> > > >                            ifcvf_config_changed, 0,
> > > >                            vf->config_msix_name, vf);
> > > >     if (ret) {
> > > >             IFCVF_ERR(pdev, "Failed to request config irq\n");
> > > > +           ifcvf_free_vq_irq(adapter, vf->nr_vring);
> > > >             return ret;
> > > >     }
> > > > -   for (i = 0; i < vf->nr_vring; i++) {
> > > > -           snprintf(vf->vring[i].msix_name, 256, "ifcvf[%s]-%d\n",
> > > > -                    pci_name(pdev), i);
> > > > -           vector = i + IFCVF_MSI_QUEUE_OFF;
> > > > -           irq = pci_irq_vector(pdev, vector);
> > > > -           ret = devm_request_irq(&pdev->dev, irq,
> > > > -                                  ifcvf_intr_handler, 0,
> > > > -                                  vf->vring[i].msix_name,
> > > > -                                  &vf->vring[i]);
> > > > -           if (ret) {
> > > > -                   IFCVF_ERR(pdev,
> > > > -                             "Failed to request irq for vq %d\n", i);
> > > > -                   ifcvf_free_irq(adapter, i);
> > > > +   ifcvf_set_config_vector(vf, config_vector);
> > > > -                   return ret;
> > > > -           }
> > > > +   return 0;
> > > > +}
> > > > +
> > > > +static int ifcvf_request_irq(struct ifcvf_adapter *adapter)
> > > > +{
> > >
> > >
> > > As replied above, I think having two modes should be sufficient and the code
> > > could be greatly simplified.
> > >
> > > Thanks
> > >
> >
> > Well it is claimed there are platforms where we are short
> > on vectors. 3 versus 2 seems a 50% saving. You disagree?
> 
> I think we can 2 vectors (a dedicated for config).
> 
> Thanks
> 
> >
> > > > +   struct ifcvf_hw *vf = &adapter->vf;
> > > > +   int nvectors, ret, max_intr;
> > > > -           vf->vring[i].irq = irq;
> > > > +   nvectors = ifcvf_alloc_vectors(adapter);
> > > > +   if (!(nvectors > 0))
> > > > +           return nvectors;
> > > > +
> > > > +   vf->msix_vector_status = MSIX_VECTOR_PER_VQ_AND_CONFIG;
> > > > +   max_intr = vf->nr_vring + 1;
> > > > +   if (nvectors < max_intr)
> > > > +           vf->msix_vector_status = MSIX_VECTOR_SHARED_VQ_AND_CONFIG;
> > > > +
> > > > +   if (nvectors == 1) {
> > > > +           vf->msix_vector_status = MSIX_VECTOR_DEV_SHARED;
> > > > +           ret = ifcvf_request_dev_shared_irq(adapter);
> > > > +
> > > > +           return ret;
> > > >     }
> > > > +   ret = ifcvf_request_vq_irq(adapter);
> > > > +   if (ret)
> > > > +           return ret;
> > > > +
> > > > +   ret = ifcvf_request_config_irq(adapter);
> > > > +
> > > > +   if (ret)
> > > > +           return ret;
> > > > +
> > > >     return 0;
> > > >   }
> > > > @@ -441,7 +611,10 @@ static int ifcvf_vdpa_get_vq_irq(struct vdpa_device *vdpa_dev,
> > > >   {
> > > >     struct ifcvf_hw *vf = vdpa_to_vf(vdpa_dev);
> > > > -   return vf->vring[qid].irq;
> > > > +   if (vf->vqs_shared_irq < 0)
> > > > +           return vf->vring[qid].irq;
> > > > +   else
> > > > +           return -EINVAL;
> > > >   }
> > > >   static struct vdpa_notification_area ifcvf_get_vq_notification(struct vdpa_device *vdpa_dev,
> >