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

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;

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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


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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


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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,

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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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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

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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
>

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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
>

_______________________________________________
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,

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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,
>

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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,
> >

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