Jason Wang
2021-Mar-16 08:08 UTC
[RFC v2 13/13] vhost: Use VRING_AVAIL_F_NO_INTERRUPT at device call on shadow virtqueue
? 2021/3/16 ??3:48, Eugenio P?rez ??:> Signed-off-by: Eugenio P?rez <eperezma at redhat.com> > --- > hw/virtio/vhost-shadow-virtqueue.c | 28 +++++++++++++++++++++++++++- > 1 file changed, 27 insertions(+), 1 deletion(-) > > diff --git a/hw/virtio/vhost-shadow-virtqueue.c b/hw/virtio/vhost-shadow-virtqueue.c > index 7df98fc43f..e3879a4622 100644 > --- a/hw/virtio/vhost-shadow-virtqueue.c > +++ b/hw/virtio/vhost-shadow-virtqueue.c > @@ -71,10 +71,35 @@ typedef struct VhostShadowVirtqueue { > /* Next head to consume from device */ > uint16_t used_idx; > > + /* Cache for the exposed notification flag */ > + bool notification; > + > /* Descriptors copied from guest */ > vring_desc_t descs[]; > } VhostShadowVirtqueue; > > +static void vhost_shadow_vq_set_notification(VhostShadowVirtqueue *svq, > + bool enable) > +{ > + uint16_t notification_flag; > + > + if (svq->notification == enable) { > + return; > + } > + > + notification_flag = virtio_tswap16(svq->vdev, VRING_AVAIL_F_NO_INTERRUPT); > + > + svq->notification = enable; > + if (enable) { > + svq->vring.avail->flags &= ~notification_flag; > + } else { > + svq->vring.avail->flags |= notification_flag; > + } > + > + /* Make sure device reads our flag */ > + smp_mb();This is a hint, so we don't need memory barrier here. Thanks> +} > + > static void vhost_vring_write_descs(VhostShadowVirtqueue *svq, > const struct iovec *iovec, > size_t num, bool more_descs, bool write) > @@ -251,7 +276,7 @@ static void vhost_shadow_vq_handle_call_no_test(EventNotifier *n) > do { > unsigned i = 0; > > - /* TODO: Use VRING_AVAIL_F_NO_INTERRUPT */ > + vhost_shadow_vq_set_notification(svq, false); > while (true) { > g_autofree VirtQueueElement *elem = vhost_shadow_vq_get_buf(svq); > if (!elem) { > @@ -269,6 +294,7 @@ static void vhost_shadow_vq_handle_call_no_test(EventNotifier *n) > svq->masked_notifier.signaled = true; > event_notifier_set(svq->masked_notifier.n); > } > + vhost_shadow_vq_set_notification(svq, true); > } while (vhost_shadow_vq_more_used(svq)); > > if (masked_notifier) {