[PATCH v1 1/1] PCI/ATS: For VF PCIe device use PF PASID Capability

[PATCH v1 1/1] PCI/ATS: For VF PCIe device use PF PASID Capability

[sathyanarayanan.kuppuswamy]

From: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>

Per PCIe r5.0, sec 9.3.7.14, if a PF implements the PASID Capability,
the PF PASID configuration is shared by its VFs. VFs must not implement
their own PASID Capability. But, commit 751035b8dc06 ("PCI/ATS: Cache
PASID Capability offset") when adding support for PASID Capability
offset caching, modified the pci_max_pasids() and pci_pasid_features()
APIs to use PASID Capability offset of VF device instead of using
PASID Capability offset of associated PF device. This change leads to
IOMMU bind failures when pci_max_pasids() and pci_pasid_features()
functions are invoked by PCIe VF devices.

So modify pci_max_pasids() and pci_pasid_features() functions to use
correct PASID Capability offset.

Fixes: 751035b8dc06 ("PCI/ATS: Cache PASID Capability offset")
Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
---
 drivers/pci/ats.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/ats.c b/drivers/pci/ats.c
index 982b46f0a54d..b6f064c885c3 100644
--- a/drivers/pci/ats.c
+++ b/drivers/pci/ats.c
@@ -424,11 +424,12 @@ void pci_restore_pasid_state(struct pci_dev *pdev)
 int pci_pasid_features(struct pci_dev *pdev)
 {
 	u16 supported;
-	int pasid = pdev->pasid_cap;
+	int pasid;
 
 	if (pdev->is_virtfn)
 		pdev = pci_physfn(pdev);
 
+	pasid = pdev->pasid_cap;
 	if (!pasid)
 		return -EINVAL;
 
@@ -451,11 +452,12 @@ int pci_pasid_features(struct pci_dev *pdev)
 int pci_max_pasids(struct pci_dev *pdev)
 {
 	u16 supported;
-	int pasid = pdev->pasid_cap;
+	int pasid;
 
 	if (pdev->is_virtfn)
 		pdev = pci_physfn(pdev);
 
+	pasid = pdev->pasid_cap;
 	if (!pasid)
 		return -EINVAL;
 
-- 
2.21.0

Re: [PATCH v1 1/1] PCI/ATS: For VF PCIe device use PF PASID Capability

[Bjorn Helgaas]

On Wed, Jan 29, 2020 at 11:14:00AM -0800, sathyanarayanan.kuppuswamy@linux.intel.com wrote:
> From: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
> 
> Per PCIe r5.0, sec 9.3.7.14, if a PF implements the PASID Capability,
> the PF PASID configuration is shared by its VFs. VFs must not implement
> their own PASID Capability. But, commit 751035b8dc06 ("PCI/ATS: Cache
> PASID Capability offset") when adding support for PASID Capability
> offset caching, modified the pci_max_pasids() and pci_pasid_features()
> APIs to use PASID Capability offset of VF device instead of using
> PASID Capability offset of associated PF device. This change leads to
> IOMMU bind failures when pci_max_pasids() and pci_pasid_features()
> functions are invoked by PCIe VF devices.
> 
> So modify pci_max_pasids() and pci_pasid_features() functions to use
> correct PASID Capability offset.
> 
> Fixes: 751035b8dc06 ("PCI/ATS: Cache PASID Capability offset")
> Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>

Applied to for-linus for v5.6, thanks!  I also added a stable tag
since 751035b8dc06 appeared in v5.5.

> ---
>  drivers/pci/ats.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/pci/ats.c b/drivers/pci/ats.c
> index 982b46f0a54d..b6f064c885c3 100644
> --- a/drivers/pci/ats.c
> +++ b/drivers/pci/ats.c
> @@ -424,11 +424,12 @@ void pci_restore_pasid_state(struct pci_dev *pdev)
>  int pci_pasid_features(struct pci_dev *pdev)
>  {
>  	u16 supported;
> -	int pasid = pdev->pasid_cap;
> +	int pasid;
>  
>  	if (pdev->is_virtfn)
>  		pdev = pci_physfn(pdev);
>  
> +	pasid = pdev->pasid_cap;
>  	if (!pasid)
>  		return -EINVAL;
>  
> @@ -451,11 +452,12 @@ int pci_pasid_features(struct pci_dev *pdev)
>  int pci_max_pasids(struct pci_dev *pdev)
>  {
>  	u16 supported;
> -	int pasid = pdev->pasid_cap;
> +	int pasid;
>  
>  	if (pdev->is_virtfn)
>  		pdev = pci_physfn(pdev);
>  
> +	pasid = pdev->pasid_cap;
>  	if (!pasid)
>  		return -EINVAL;
>  
> -- 
> 2.21.0
>