Re: [PATCH v2 3/4] vdpa: handle VIRTIO_NET_CTRL_ANNOUNCE in vhost_vdpa_net_handle_ctrl_avail

[Eugenio Perez Martin]

On Wed, Nov 30, 2022 at 8:02 AM Jason Wang <jasowang@redhat.com> wrote:
>
> On Fri, Nov 25, 2022 at 1:33 AM Eugenio Pérez <eperezma@redhat.com> wrote:
> >
> > Since this capability is emulated by qemu shadowed CVQ cannot forward it
> > to the device. Process all that command within qemu.
> >
> > Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
> > ---
> >  net/vhost-vdpa.c | 15 ++++++++++++---
> >  1 file changed, 12 insertions(+), 3 deletions(-)
> >
> > diff --git a/net/vhost-vdpa.c b/net/vhost-vdpa.c
> > index 2b4b85d8f8..8172aa8449 100644
> > --- a/net/vhost-vdpa.c
> > +++ b/net/vhost-vdpa.c
> > @@ -489,9 +489,18 @@ static int 
> > vhost_vdpa_net_handle_ctrl_avail(VhostShadowVirtqueue *svq,
> >      out.iov_len = iov_to_buf(elem->out_sg, elem->out_num, 0,
> >                               s->cvq_cmd_out_buffer,
> >                               vhost_vdpa_net_cvq_cmd_len());
> > -    dev_written = vhost_vdpa_net_cvq_add(s, out.iov_len, sizeof(status));
> > -    if (unlikely(dev_written < 0)) {
> > -        goto out;
> > +    if (*(uint8_t *)s->cvq_cmd_out_buffer == VIRTIO_NET_CTRL_ANNOUNCE) {
> > +        /*
> > +         * Guest announce capability is emulated by qemu, so dont forward 
> > to
>
> s/dont/don't/
>

I'll correct it, thanks!

> > +         * the device.
> > +         */
> > +        dev_written = sizeof(status);
> > +        *s->status = VIRTIO_NET_OK;
>
> I wonder if we should avoid negotiating ANNOUNCE with vDPA parents if
> we do this?
>

I can re-check, but the next patch should avoid it. Even if
negotiated, the parent should never set the announce status bit, since
we never tell the device is a destination device.

But it's better to be on the safe side, I'll recheck.

Thanks!

> Thanks
>
> > +    } else {
> > +        dev_written = vhost_vdpa_net_cvq_add(s, out.iov_len, 
> > sizeof(status));
> > +        if (unlikely(dev_written < 0)) {
> > +            goto out;
> > +        }
> >      }
> >
> >      if (unlikely(dev_written < sizeof(status))) {
> > --
> > 2.31.1
> >
>