diff mbox series

PCI: Add vf reset notification for pf

Message ID 20240204061257.1408243-1-Emily.Deng@amd.com
State New
Headers
Series PCI: Add vf reset notification for pf |

Commit Message

Emily Deng Feb. 4, 2024, 6:12 a.m. UTC 
  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(+)

Comments

Keith Busch Feb. 4, 2024, 7:08 a.m. UTC | #1 
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?
Leon Romanovsky Feb. 4, 2024, 11:20 a.m. UTC | #2 
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
> 
>
Emily Deng Feb. 5, 2024, 3:47 a.m. UTC | #3 
[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
>>
>>
Christian König Feb. 5, 2024, 11:28 a.m. UTC | #4 
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;
Zhi Wang Feb. 5, 2024, 12:22 p.m. UTC | #5 
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.
diff mbox series

Patch

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;