Virtualization - Oct 2023 - [PATCH vfio 10/11] vfio/virtio: Expose admin commands over virtio device

On Tue, Oct 10, 2023 at 12:59:37PM -0300, Jason Gunthorpe
wrote:
> On Tue, Oct 10, 2023 at 11:14:56AM -0400, Michael S. Tsirkin wrote:
> 
> > I suggest 3 but call it on the VF. commands will switch to PF
> > internally as needed. For example, intel might be interested in
exposing
> > admin commands through a memory BAR of VF itself.
> 
> FWIW, we have been pushing back on such things in VFIO, so it will
> have to be very carefully security justified.
> 
> Probably since that is not standard it should just live in under some
> intel-only vfio driver behavior, not in virtio land.
Btw, what is that intel thing everyone is talking about?  And why
would the virtio core support vendor specific behavior like that?

On Tue, Oct 10, 2023 at 11:13:30PM -0700, Christoph Hellwig
wrote:
> On Tue, Oct 10, 2023 at 12:59:37PM -0300, Jason Gunthorpe wrote:
> > On Tue, Oct 10, 2023 at 11:14:56AM -0400, Michael S. Tsirkin wrote:
> > 
> > > I suggest 3 but call it on the VF. commands will switch to PF
> > > internally as needed. For example, intel might be interested in
exposing
> > > admin commands through a memory BAR of VF itself.
> > 
> > FWIW, we have been pushing back on such things in VFIO, so it will
> > have to be very carefully security justified.
> > 
> > Probably since that is not standard it should just live in under some
> > intel-only vfio driver behavior, not in virtio land.
> 
> Btw, what is that intel thing everyone is talking about?  And why
> would the virtio core support vendor specific behavior like that?
It's not a thing it's Zhu Lingshan :) intel is just one of the vendors
that implemented vdpa support and so Zhu Lingshan from intel is working
on vdpa and has also proposed virtio spec extensions for migration.
intel's driver is called ifcvf.  vdpa composes all this stuff that is
added to vfio in userspace, so it's a different approach.

-- 
MST