Re: (proposal) RE: [PATCH v7 00/16] vfio: expose virtual Shared Virtual Addressing to VMs

Jason Gunthorpe
2020-11-03T15:22:39Z

On Tue, Nov 03, 2020 at 03:35:32PM +0100, joro@8bytes.org wrote:
> On Tue, Nov 03, 2020 at 10:06:42AM -0400, Jason Gunthorpe wrote:
> > The point is that other places beyond VFIO need this
>
> Which and why?
>
> > Sure, but sometimes it is necessary, and in those cases the answer
> > can't be "rewrite a SVA driver to use vfio"
>
> This is getting to abstract. Can you come up with an example where
> handling this in VFIO or an endpoint device kernel driver does not work?

This whole thread was brought up by IDXD which has a SVA driver and
now wants to add a vfio-mdev driver too. SVA devices that want to be
plugged into VMs are going to be common - this architecture that a SVA
driver cannot cover the kvm case seems problematic.

Yes, everything can have a SVA driver and a vfio-mdev, it works just
fine, but it is not very clean or simple.

Jason