Re: [PATCH 2/3] vdpa: Add dummy receive callbacks

[Eugenio Perez Martin]

On Mon, Nov 22, 2021 at 4:55 AM Jason Wang <jasowang@redhat.com> wrote:
>
> On Fri, Nov 19, 2021 at 6:20 PM Eugenio Pérez <eperezma@redhat.com> wrote:
> >
> > Qemu falls back on userland handlers even if vhost-user and vhost-vdpa
> > cases. These assumes a tap device can handle the packets.
> >
> > If a vdpa device fail to start, it can trigger a sigsegv because of
> > that. Add dummy receivers that return no progress so it can keep
> > running.
> >
> > Fixes: 1e0a84ea49 ("vhost-vdpa: introduce vhost-vdpa net client")
> > Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
> > ---
> >  net/vhost-vdpa.c | 16 ++++++++++++++++
> >  1 file changed, 16 insertions(+)
> >
> > diff --git a/net/vhost-vdpa.c b/net/vhost-vdpa.c
> > index 2e3c22a8c7..4c75b78304 100644
> > --- a/net/vhost-vdpa.c
> > +++ b/net/vhost-vdpa.c
> > @@ -170,9 +170,25 @@ static bool vhost_vdpa_check_peer_type(NetClientState 
> > *nc, ObjectClass *oc,
> >      return true;
> >  }
> >
> > +/** Dummy receive in case qemu falls back to userland tap networking */
> > +static ssize_t vhost_vdpa_receive_iov(NetClientState *nc,
> > +                                      const struct iovec *iov, int iovcnt)
> > +{
> > +    return 0;
> > +}
> > +
> > +/** Dummy receive in case qemu falls back to userland tap networking */
> > +static ssize_t vhost_vdpa_receive_raw(NetClientState *nc, const uint8_t 
> > *buf,
> > +                                      size_t size)
> > +{
> > +    return 0;
> > +}
>
> It looks to me the .receive_raw is not need, in nc_sendv_compat() we had:
>
> =>  if (flags & QEMU_NET_PACKET_FLAG_RAW && nc->info->receive_raw) {
>         ret = nc->info->receive_raw(nc, buffer, offset);
>     } else {
>         ret = nc->info->receive(nc, buffer, offset);
>     }
>

Right, I will delete the _raw part.

Thanks!

> Thanks
>
> > +
> >  static NetClientInfo net_vhost_vdpa_info = {
> >          .type = NET_CLIENT_DRIVER_VHOST_VDPA,
> >          .size = sizeof(VhostVDPAState),
> > +        .receive_iov = vhost_vdpa_receive_iov,
> > +        .receive_raw = vhost_vdpa_receive_raw,
> >          .cleanup = vhost_vdpa_cleanup,
> >          .has_vnet_hdr = vhost_vdpa_has_vnet_hdr,
> >          .has_ufo = vhost_vdpa_has_ufo,
> > --
> > 2.27.0
> >
>