* Re: [PATCH] PCI: Add vf reset notification for pf
2024-02-04 6:12 [PATCH] PCI: Add vf reset notification for pf Emily Deng
@ 2024-02-04 7:08 ` Keith Busch
2024-02-04 11:20 ` Leon Romanovsky
` (2 subsequent siblings)
3 siblings, 0 replies; 6+ messages in thread
From: Keith Busch @ 2024-02-04 7:08 UTC (permalink / raw)
To: Emily Deng
Cc: amd-gfx, bhelgaas, alex.williamson, linux-pci, linux-kernel, kvm
On Sun, Feb 04, 2024 at 02:12:57PM +0800, Emily Deng wrote:
> @@ -926,6 +926,7 @@ struct pci_driver {
> int (*sriov_configure)(struct pci_dev *dev, int num_vfs); /* On PF */
> int (*sriov_set_msix_vec_count)(struct pci_dev *vf, int msix_vec_count); /* On PF */
> u32 (*sriov_get_vf_total_msix)(struct pci_dev *pf);
> + void (*sriov_vf_reset_notification)(struct pci_dev *pf, struct pci_dev *vf);
You've created a new callback, but there is no user. Could you resubmit
this with an in-kernel use case?
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH] PCI: Add vf reset notification for pf
2024-02-04 6:12 [PATCH] PCI: Add vf reset notification for pf Emily Deng
2024-02-04 7:08 ` Keith Busch
@ 2024-02-04 11:20 ` Leon Romanovsky
2024-02-05 3:47 ` Deng, Emily
2024-02-05 11:28 ` Christian König
2024-02-05 12:22 ` Zhi Wang
3 siblings, 1 reply; 6+ messages in thread
From: Leon Romanovsky @ 2024-02-04 11:20 UTC (permalink / raw)
To: Emily Deng
Cc: amd-gfx, bhelgaas, alex.williamson, linux-pci, linux-kernel, kvm
On Sun, Feb 04, 2024 at 02:12:57PM +0800, Emily Deng wrote:
> When a vf has been reset, the pf wants to get notification to remove the vf
> out of schedule.
It is very questionable if this is right thing to do. The idea of SR-IOV
is that VFs represent a physical device and they should be treated
separately from the PF.
In addition to that Keith said, this patch needs better justification.
Thanks
>
> Solution:
> Add the callback function in pci_driver sriov_vf_reset_notification. When
> vf reset happens, then call this callback function.
>
> Signed-off-by: Emily Deng <Emily.Deng@amd.com>
> ---
> drivers/pci/pci.c | 8 ++++++++
> include/linux/pci.h | 1 +
> 2 files changed, 9 insertions(+)
>
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index 60230da957e0..aca937b05531 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -4780,6 +4780,14 @@ EXPORT_SYMBOL_GPL(pcie_flr);
> */
> int pcie_reset_flr(struct pci_dev *dev, bool probe)
> {
> + struct pci_dev *pf_dev;
> +
> + if (dev->is_virtfn) {
> + pf_dev = dev->physfn;
> + if (pf_dev->driver->sriov_vf_reset_notification)
> + pf_dev->driver->sriov_vf_reset_notification(pf_dev, dev);
> + }
> +
> if (dev->dev_flags & PCI_DEV_FLAGS_NO_FLR_RESET)
> return -ENOTTY;
>
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index c69a2cc1f412..4fa31d9b0aa7 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -926,6 +926,7 @@ struct pci_driver {
> int (*sriov_configure)(struct pci_dev *dev, int num_vfs); /* On PF */
> int (*sriov_set_msix_vec_count)(struct pci_dev *vf, int msix_vec_count); /* On PF */
> u32 (*sriov_get_vf_total_msix)(struct pci_dev *pf);
> + void (*sriov_vf_reset_notification)(struct pci_dev *pf, struct pci_dev *vf);
> const struct pci_error_handlers *err_handler;
> const struct attribute_group **groups;
> const struct attribute_group **dev_groups;
> --
> 2.36.1
>
>
^ permalink raw reply [flat|nested] 6+ messages in thread* RE: [PATCH] PCI: Add vf reset notification for pf
2024-02-04 11:20 ` Leon Romanovsky
@ 2024-02-05 3:47 ` Deng, Emily
0 siblings, 0 replies; 6+ messages in thread
From: Deng, Emily @ 2024-02-05 3:47 UTC (permalink / raw)
To: Leon Romanovsky
Cc: bhelgaas@google.com, alex.williamson@redhat.com,
linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org,
kvm@vger.kernel.org
[AMD Official Use Only - General]
The use case is the vfio-pci driver, which is used to support a user mode PF driver. Will also sent out the vfio-pci driver patch. And add more comments in the patch. Thanks.
Emily Deng
Best Wishes
>-----Original Message-----
>From: Leon Romanovsky <leon@kernel.org>
>Sent: Sunday, February 4, 2024 7:21 PM
>To: Deng, Emily <Emily.Deng@amd.com>
>Cc: amd-gfx@lists.freedesktop.org; bhelgaas@google.com;
>alex.williamson@redhat.com; linux-pci@vger.kernel.org; linux-
>kernel@vger.kernel.org; kvm@vger.kernel.org
>Subject: Re: [PATCH] PCI: Add vf reset notification for pf
>
>On Sun, Feb 04, 2024 at 02:12:57PM +0800, Emily Deng wrote:
>> When a vf has been reset, the pf wants to get notification to remove
>> the vf out of schedule.
>
>It is very questionable if this is right thing to do. The idea of SR-IOV is that
>VFs represent a physical device and they should be treated separately from
>the PF.
>
>In addition to that Keith said, this patch needs better justification.
>
>Thanks
>
>>
>> Solution:
>> Add the callback function in pci_driver sriov_vf_reset_notification.
>> When vf reset happens, then call this callback function.
>>
>> Signed-off-by: Emily Deng <Emily.Deng@amd.com>
>> ---
>> drivers/pci/pci.c | 8 ++++++++
>> include/linux/pci.h | 1 +
>> 2 files changed, 9 insertions(+)
>>
>> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index
>> 60230da957e0..aca937b05531 100644
>> --- a/drivers/pci/pci.c
>> +++ b/drivers/pci/pci.c
>> @@ -4780,6 +4780,14 @@ EXPORT_SYMBOL_GPL(pcie_flr);
>> */
>> int pcie_reset_flr(struct pci_dev *dev, bool probe) {
>> + struct pci_dev *pf_dev;
>> +
>> + if (dev->is_virtfn) {
>> + pf_dev = dev->physfn;
>> + if (pf_dev->driver->sriov_vf_reset_notification)
>> + pf_dev->driver->sriov_vf_reset_notification(pf_dev,
>dev);
>> + }
>> +
>> if (dev->dev_flags & PCI_DEV_FLAGS_NO_FLR_RESET)
>> return -ENOTTY;
>>
>> diff --git a/include/linux/pci.h b/include/linux/pci.h index
>> c69a2cc1f412..4fa31d9b0aa7 100644
>> --- a/include/linux/pci.h
>> +++ b/include/linux/pci.h
>> @@ -926,6 +926,7 @@ struct pci_driver {
>> int (*sriov_configure)(struct pci_dev *dev, int num_vfs); /* On PF */
>> int (*sriov_set_msix_vec_count)(struct pci_dev *vf, int
>msix_vec_count); /* On PF */
>> u32 (*sriov_get_vf_total_msix)(struct pci_dev *pf);
>> + void (*sriov_vf_reset_notification)(struct pci_dev *pf, struct
>> +pci_dev *vf);
>> const struct pci_error_handlers *err_handler;
>> const struct attribute_group **groups;
>> const struct attribute_group **dev_groups;
>> --
>> 2.36.1
>>
>>
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] PCI: Add vf reset notification for pf
2024-02-04 6:12 [PATCH] PCI: Add vf reset notification for pf Emily Deng
2024-02-04 7:08 ` Keith Busch
2024-02-04 11:20 ` Leon Romanovsky
@ 2024-02-05 11:28 ` Christian König
2024-02-05 12:22 ` Zhi Wang
3 siblings, 0 replies; 6+ messages in thread
From: Christian König @ 2024-02-05 11:28 UTC (permalink / raw)
To: Emily Deng, amd-gfx, bhelgaas, alex.williamson, linux-pci,
linux-kernel, kvm
Am 04.02.24 um 07:12 schrieb Emily Deng:
> When a vf has been reset, the pf wants to get notification to remove the vf
> out of schedule.
>
> Solution:
> Add the callback function in pci_driver sriov_vf_reset_notification. When
> vf reset happens, then call this callback function.
Well that doesn't make much sense. As other already noted as well a VF
should be an encapsulated representation of a physical devices
functionality.
AMD implemented that a bit different with a hypervisor to control which
PF functionality a VF exposes, but that doesn't mean that we can leak
this AMD specific handling into the common Linux PCI subsystem.
Additional to that a technical blocker is that when a VF is passed into
a VM you don't have access to the PF any more to make this reset
notification.
Regards,
Christian.
>
> Signed-off-by: Emily Deng <Emily.Deng@amd.com>
> ---
> drivers/pci/pci.c | 8 ++++++++
> include/linux/pci.h | 1 +
> 2 files changed, 9 insertions(+)
>
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index 60230da957e0..aca937b05531 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -4780,6 +4780,14 @@ EXPORT_SYMBOL_GPL(pcie_flr);
> */
> int pcie_reset_flr(struct pci_dev *dev, bool probe)
> {
> + struct pci_dev *pf_dev;
> +
> + if (dev->is_virtfn) {
> + pf_dev = dev->physfn;
> + if (pf_dev->driver->sriov_vf_reset_notification)
> + pf_dev->driver->sriov_vf_reset_notification(pf_dev, dev);
> + }
> +
> if (dev->dev_flags & PCI_DEV_FLAGS_NO_FLR_RESET)
> return -ENOTTY;
>
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index c69a2cc1f412..4fa31d9b0aa7 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -926,6 +926,7 @@ struct pci_driver {
> int (*sriov_configure)(struct pci_dev *dev, int num_vfs); /* On PF */
> int (*sriov_set_msix_vec_count)(struct pci_dev *vf, int msix_vec_count); /* On PF */
> u32 (*sriov_get_vf_total_msix)(struct pci_dev *pf);
> + void (*sriov_vf_reset_notification)(struct pci_dev *pf, struct pci_dev *vf);
> const struct pci_error_handlers *err_handler;
> const struct attribute_group **groups;
> const struct attribute_group **dev_groups;
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH] PCI: Add vf reset notification for pf
2024-02-04 6:12 [PATCH] PCI: Add vf reset notification for pf Emily Deng
` (2 preceding siblings ...)
2024-02-05 11:28 ` Christian König
@ 2024-02-05 12:22 ` Zhi Wang
3 siblings, 0 replies; 6+ messages in thread
From: Zhi Wang @ 2024-02-05 12:22 UTC (permalink / raw)
To: Emily Deng
Cc: amd-gfx, bhelgaas, alex.williamson, linux-pci, linux-kernel, kvm
On Sun, 4 Feb 2024 14:12:57 +0800
Emily Deng <Emily.Deng@amd.com> wrote:
> When a vf has been reset, the pf wants to get notification to remove
> the vf out of schedule.
>
> Solution:
> Add the callback function in pci_driver sriov_vf_reset_notification.
> When vf reset happens, then call this callback function.
>
> Signed-off-by: Emily Deng <Emily.Deng@amd.com>
> ---
> drivers/pci/pci.c | 8 ++++++++
> include/linux/pci.h | 1 +
> 2 files changed, 9 insertions(+)
>
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index 60230da957e0..aca937b05531 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -4780,6 +4780,14 @@ EXPORT_SYMBOL_GPL(pcie_flr);
> */
> int pcie_reset_flr(struct pci_dev *dev, bool probe)
> {
> + struct pci_dev *pf_dev;
> +
> + if (dev->is_virtfn) {
> + pf_dev = dev->physfn;
> + if (pf_dev->driver->sriov_vf_reset_notification)
> +
> pf_dev->driver->sriov_vf_reset_notification(pf_dev, dev);
> + }
> +
> if (dev->dev_flags & PCI_DEV_FLAGS_NO_FLR_RESET)
> return -ENOTTY;
>
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index c69a2cc1f412..4fa31d9b0aa7 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -926,6 +926,7 @@ struct pci_driver {
> int (*sriov_configure)(struct pci_dev *dev, int num_vfs);
> /* On PF */ int (*sriov_set_msix_vec_count)(struct pci_dev *vf, int
> msix_vec_count); /* On PF */ u32 (*sriov_get_vf_total_msix)(struct
> pci_dev *pf);
> + void (*sriov_vf_reset_notification)(struct pci_dev *pf,
> struct pci_dev *vf); const struct pci_error_handlers *err_handler;
> const struct attribute_group **groups;
> const struct attribute_group **dev_groups;
Hi:
I would suggest you can provide a cover letter including a complete
picture that tells the background, detailed problem statement, the
solutions and plus the users. As this seems very like a generic change,
it needs a better justification to convince folks why this is the best
solution. Without a complete picture, the solution just looks like a
workaround.
Thanks,
Zhi.
^ permalink raw reply [flat|nested] 6+ messages in thread