[RFC 3/3] vfio/pci: Expose PCIe PASID capability to userspace

[Yi Liu]

This exposes PCIe PASID capability to userspace and where to emulate this
capability if wants to further expose it to VM.

And this only exposes PASID capability for devices which has PCIe PASID
extended struture in its configuration space. While for VFs, userspace
is still unable to see this capability as SR-IOV spec forbides VF to
implement PASID capability extended structure. It is a TODO in future.
Related discussion can be found in below links:

https://lore.kernel.org/kvm/20200407095801.648b1371@xxxxxxxxx/
https://lore.kernel.org/kvm/BL1PR11MB5271A60035EF591A5BE8AC878C01A@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx/

Signed-off-by: Yi Liu <yi.l.liu@xxxxxxxxx>
---
 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 7e2e62ab0869..dfae5ad5ebc0 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,
 	[PCI_EXT_CAP_ID_DVSEC]	=	0xFF,
 };
 
-- 
2.34.1