On Fri, Oct 21, 2022 at 09:45:14AM +0200, Eugenio Perez Martin wrote:
> On Fri, Oct 21, 2022 at 5:40 AM Jason Wang <jasow...@redhat.com> wrote:
> >
> > On Thu, Oct 20, 2022 at 11:53 PM Eugenio Pérez <epere...@redhat.com> wrote:
> > >
> > > Actually use the new field of the used ring and tell the device if SVQ
> > > wants to be notified.
> > >
> > > The code is not reachable at the moment.
> > >
> > > Signed-off-by: Eugenio Pérez <epere...@redhat.com>
> > > ---
> > > hw/virtio/vhost-shadow-virtqueue.c | 18 +++++++++++++++---
> > > 1 file changed, 15 insertions(+), 3 deletions(-)
> > >
> > > diff --git a/hw/virtio/vhost-shadow-virtqueue.c
> > > b/hw/virtio/vhost-shadow-virtqueue.c
> > > index a518f84772..f5c0fad3fc 100644
> > > --- a/hw/virtio/vhost-shadow-virtqueue.c
> > > +++ b/hw/virtio/vhost-shadow-virtqueue.c
> > > @@ -369,15 +369,27 @@ static bool
> > > vhost_svq_more_used(VhostShadowVirtqueue *svq)
> > > */
> > > static bool vhost_svq_enable_notification(VhostShadowVirtqueue *svq)
> > > {
> > > - svq->vring.avail->flags &= ~cpu_to_le16(VRING_AVAIL_F_NO_INTERRUPT);
> > > - /* Make sure the flag is written before the read of used_idx */
> > > + if (virtio_vdev_has_feature(svq->vdev, VIRTIO_RING_F_EVENT_IDX)) {
> > > + uint16_t *used_event = (uint16_t
> > > *)&svq->vring.avail->ring[svq->vring.num];
> > > + *used_event = svq->shadow_used_idx;
> >
> > Do we need to care about the endian here?
> >
> > E.g vduse has:
> >
> > *((uint16_t *)&vq->vring.used->ring[vq->vring.num]) = htole16(val);
> >
>
> Good catch, I forgot about endianness.
>
> I'll review the series, thanks!
It's generally a waste that we don't use endian-ness annotations
the way linux does.
> > Thanks
> >
> > > + } else {
> > > + svq->vring.avail->flags &=
> > > ~cpu_to_le16(VRING_AVAIL_F_NO_INTERRUPT);
> > > + }
> > > +
> > > + /* Make sure the event is enabled before the read of used_idx */
> > > smp_mb();
> > > return !vhost_svq_more_used(svq);
> > > }
> > >
> > > static void vhost_svq_disable_notification(VhostShadowVirtqueue *svq)
> > > {
> > > - svq->vring.avail->flags |= cpu_to_le16(VRING_AVAIL_F_NO_INTERRUPT);
> > > + /*
> > > + * No need to disable notification in the event idx case, since used
> > > event
> > > + * index is already an index too far away.
> > > + */
> > > + if (!virtio_vdev_has_feature(svq->vdev, VIRTIO_RING_F_EVENT_IDX)) {
> > > + svq->vring.avail->flags |=
> > > cpu_to_le16(VRING_AVAIL_F_NO_INTERRUPT);
> > > + }
> > > }
> > >
> > > static uint16_t vhost_svq_last_desc_of_chain(const VhostShadowVirtqueue
> > > *svq,
> > > --
> > > 2.31.1
> > >
> >
