Re: [PATCH] vhost: accept VIRTIO_F_ORDER_PLATFORM as a valid SVQ feature

[Eugenio Perez Martin]

On Tue, Feb 14, 2023 at 7:31 AM Jason Wang <jasowang@redhat.com> wrote:
>
> On Tue, Feb 14, 2023 at 3:19 AM Eugenio Pérez <eperezma@redhat.com> wrote:
> >
> > VIRTIO_F_ORDER_PLATFORM indicates that memory accesses by the driver and
> > the device are ordered in a way described by the platform.  Since vDPA
> > devices may be backed by a hardware devices, let's allow
> > VIRTIO_F_ORDER_PLATFORM.
> >
> > Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
> > ---
> >  hw/virtio/vhost-shadow-virtqueue.c | 1 +
> >  1 file changed, 1 insertion(+)
> >
> > diff --git a/hw/virtio/vhost-shadow-virtqueue.c 
> > b/hw/virtio/vhost-shadow-virtqueue.c
> > index 4307296358..6bb1998f12 100644
> > --- a/hw/virtio/vhost-shadow-virtqueue.c
> > +++ b/hw/virtio/vhost-shadow-virtqueue.c
> > @@ -34,6 +34,7 @@ bool vhost_svq_valid_features(uint64_t features, Error 
> > **errp)
> >          switch (b) {
> >          case VIRTIO_F_ANY_LAYOUT:
> >          case VIRTIO_RING_F_EVENT_IDX:
> > +        case VIRTIO_F_ORDER_PLATFORM:
>
> Do we need to add this bit to vdpa_feature_bits[] as well?
>

If we want to pass it to the guest, yes we should. I'll send another
patch for it.

But I think that should be done on top / in parallel actually.

Open question: Should all vdpa hardware devices offer it? Or this is
only needed on specific archs?

Thanks!