Re: [RFC PATCH 09/12] vdpa: Extract vhost_vdpa_net_svq_add from vhost_vdpa_net_handle_ctrl_avail

[Eugenio Perez Martin]

On Mon, Jul 18, 2022 at 10:53 AM Jason Wang <jasowang@redhat.com> wrote:
>
>
> 在 2022/7/16 19:34, Eugenio Pérez 写道:
> > So we can reuse to inject state messages.
> >
> > Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
> > ---
> >   net/vhost-vdpa.c | 89 +++++++++++++++++++++++++++---------------------
> >   1 file changed, 51 insertions(+), 38 deletions(-)
> >
> > diff --git a/net/vhost-vdpa.c b/net/vhost-vdpa.c
> > index 211bd0468b..aaae51a778 100644
> > --- a/net/vhost-vdpa.c
> > +++ b/net/vhost-vdpa.c
> > @@ -334,6 +334,54 @@ static bool vhost_vdpa_net_cvq_map_elem(VhostVDPAState 
> > *s,
> >       return true;
> >   }
> >
> > +static virtio_net_ctrl_ack vhost_vdpa_net_svq_add(VhostShadowVirtqueue 
> > *svq,
> > +                                               const struct iovec 
> > *dev_buffers)
>
>
> The name should be tweaked since it is used only for cvq.
>

Right, I'll change.

>
> > +{
> > +    /* in buffer used for device model */
> > +    virtio_net_ctrl_ack status;
> > +    const struct iovec in = {
> > +        .iov_base = &status,
> > +        .iov_len = sizeof(status),
> > +    };
> > +    size_t dev_written;
> > +    int r;
> > +    void *unused = (void *)1;
> > +
> > +    r = vhost_svq_add(svq, &dev_buffers[0], 1, &dev_buffers[1], 1, unused);
> > +    if (unlikely(r != 0)) {
> > +        if (unlikely(r == -ENOSPC)) {
> > +            qemu_log_mask(LOG_GUEST_ERROR, "%s: No space on device 
> > queue\n",
> > +                          __func__);
> > +        }
> > +        return VIRTIO_NET_ERR;
> > +    }
> > +
> > +    /*
> > +     * We can poll here since we've had BQL from the time we sent the
> > +     * descriptor. Also, we need to take the answer before SVQ pulls by 
> > itself,
> > +     * when BQL is released
> > +     */
>
>
> This reminds me that, do we need a upper limit of the time on the
> polling here. (Avoid taking BQL for too long time).
>

Sending a new version of rx filters here.

But we have other parts where we can have BQL forever because we trust
the device, like vring enable syscalls for example.

Thanks!