PCI: Add vf reset notification for pf

[PATCH] PCI: Add vf reset notification for pf

Posted by Emily Deng 2 years ago

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;
-- 
2.36.1

Re: [PATCH] PCI: Add vf reset notification for pf

Posted by Zhi Wang 2 years ago

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.

Re: [PATCH] PCI: Add vf reset notification for pf

Posted by Christian König 2 years ago

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;

Re: [PATCH] PCI: Add vf reset notification for pf

Posted by Leon Romanovsky 2 years ago

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
> 
>

Re: [PATCH] PCI: Add vf reset notification for pf

Posted by Keith Busch 2 years ago

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?