RE: [RFC v1 0/2] vfio/pci: expose device's PASID capability to VMs

[Liu, Yi L]

Hi Alex,

Any comment on this series?

Regards,
Yi Liu

> From: Liu, Yi L
> Sent: Wednesday, January 29, 2020 8:19 PM
> To: alex.williamson@xxxxxxxxxx; eric.auger@xxxxxxxxxx
> Subject: [RFC v1 0/2] vfio/pci: expose device's PASID capability to VMs
> 
> Shared Virtual Addressing (SVA), a.k.a, Shared Virtual Memory (SVM) on Intel
> platforms allows address space sharing between device DMA and applications. SVA
> can reduce programming complexity and enhance security.
> 
> To enable SVA, device needs to have PASID capability, which is a key capability for
> SVA. This patchset exposes the device's PASID capability to guest instead of hiding it
> from guest.
> 
> The second patch emulates PASID capability for VFs (Virtual Function) since VFs don't
> implement such capability per PCIe spec. This patch emulates such capability and
> expose to VM if the capability is enabled in PF (Physical Function).
> 
> However, there is an open for PASID emulation. If PF driver disables PASID capability
> at runtime, then it may be an issue. e.g. PF should not disable PASID capability if
> there is guest using this capability on any VF related to this PF. To solve it, may need
> to introduce a generic communication framework between vfio-pci driver and PF
> drivers. Please feel free to give your suggestions on it.
> 
> Liu Yi L (2):
>   vfio/pci: Expose PCIe PASID capability to guest
>   vfio/pci: Emulate PASID/PRI capability for VFs
> 
>  drivers/vfio/pci/vfio_pci_config.c | 321
> ++++++++++++++++++++++++++++++++++++-
>  1 file changed, 318 insertions(+), 3 deletions(-)
> 
> --
> 2.7.4