Hi Alex,
> From: Alex Williamson
> Sent: Saturday, September 12, 2020 6:13 AM
>
> On Thu, 10 Sep 2020 03:45:30 -0700
> Liu Yi L wrote:
>
> > 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[].
>
> This exposes the PASID capability, but it's still read-only, so this largely
> just helps
> userspace know where to emulate the capability, right? Thanks,
oh, yes. This path only makes it visible to userspace. perhaps, I should
refine the commit message and the patch name. right?
Regards,
Yi Liu
> Alex
>
> > And this patch only exposes PASID capability for devices which has
> > PCIe PASID extended struture in its configuration space. VFs will not
> > expose the PASID capability as they do not implement the PASID
> > extended structure in their config space. It is a TODO in future.
> > Related discussion can be found in below link:
> >
> > https://lore.kernel.org/kvm/20200407095801.648b1...@w520.home/
> >
> > Cc: Kevin Tian
> > CC: Jacob Pan
> > Cc: Alex Williamson
> > Cc: Eric Auger
> > Cc: Jean-Philippe Brucker
> > Cc: Joerg Roedel
> > Cc: Lu Baolu
> > Signed-off-by: Liu Yi L
> > Reviewed-by: Eric Auger
> > ---
> > v5 -> v6:
> > *) add review-by from Eric Auger.
> >
> > 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 d98843f..07ff2e6 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,
> > };
> >
> > /*
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