Re: [PATCH vfio 11/11] vfio/virtio: Introduce a vfio driver over virtio devices

["Michael S. Tsirkin" <mst@redhat.com>]

On Fri, Sep 22, 2023 at 09:25:01AM -0300, Jason Gunthorpe wrote:
> On Fri, Sep 22, 2023 at 11:02:50AM +0800, Jason Wang wrote:
> > On Fri, Sep 22, 2023 at 3:53 AM Jason Gunthorpe <jgg@nvidia.com> wrote:
> > >
> > > On Thu, Sep 21, 2023 at 03:34:03PM -0400, Michael S. Tsirkin wrote:
> > >
> > > > that's easy/practical.  If instead VDPA gives the same speed with just
> > > > shadow vq then keeping this hack in vfio seems like less of a problem.
> > > > Finally if VDPA is faster then maybe you will reconsider using it ;)
> > >
> > > It is not all about the speed.
> > >
> > > VDPA presents another large and complex software stack in the
> > > hypervisor that can be eliminated by simply using VFIO.
> > 
> > vDPA supports standard virtio devices so how did you define
> > complexity?
> 
> As I said, VFIO is already required for other devices in these VMs. So
> anything incremental over base-line vfio-pci is complexity to
> minimize.
> 
> Everything vdpa does is either redundant or unnecessary compared to
> VFIO in these environments.
> 
> Jason

Yes but you know. There are all kind of environments.  I guess you
consider yours the most mainstream and important, and are sure it will
always stay like this.  But if there's a driver that does what you need
then you use that. You really should be explaining what vdpa
*does not* do that you need.

But anyway, if Alex wants to maintain this it's not too bad,
but I would like to see more code move into a library
living under the virtio directory. As it is structured now
it will make virtio core development harder.

-- 
MST