This patch exposes PCIe PASID capability to guest for assigned devices.
Existing vfio_pci driver hides it from guest by setting the capability
length as 0 in pci_ext_cap_length[].

And this patch only exposes PASID capability for devices which has PCIe
PASID extended struture in its configuration space. So VFs, will will
not see PASID capability on VFs as VF doesn't implement PASID extended
structure in its configuration space. For VF, it is a TODO in future.
Related discussion can be found in below link:

https://lkml.org/lkml/2020/4/7/693

Cc: Kevin Tian <[email protected]>
CC: Jacob Pan <[email protected]>
Cc: Alex Williamson <[email protected]>
Cc: Eric Auger <[email protected]>
Cc: Jean-Philippe Brucker <[email protected]>
Cc: Joerg Roedel <[email protected]>
Cc: Lu Baolu <[email protected]>
Signed-off-by: Liu Yi L <[email protected]>
---
v1 -> v2:
*) added in v2, but it was sent in a separate patchseries before
---
 drivers/vfio/pci/vfio_pci_config.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/vfio/pci/vfio_pci_config.c 
b/drivers/vfio/pci/vfio_pci_config.c
index 8746c94..56d126b 100644
--- a/drivers/vfio/pci/vfio_pci_config.c
+++ b/drivers/vfio/pci/vfio_pci_config.c
@@ -95,7 +95,7 @@ static const u16 pci_ext_cap_length[PCI_EXT_CAP_ID_MAX + 1] = 
{
        [PCI_EXT_CAP_ID_LTR]    =       PCI_EXT_CAP_LTR_SIZEOF,
        [PCI_EXT_CAP_ID_SECPCI] =       0,      /* not yet */
        [PCI_EXT_CAP_ID_PMUX]   =       0,      /* not yet */
-       [PCI_EXT_CAP_ID_PASID]  =       0,      /* not yet */
+       [PCI_EXT_CAP_ID_PASID]  =       PCI_EXT_CAP_PASID_SIZEOF,
 };
 
 /*
-- 
2.7.4

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