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vhost: toggle device callbacks using used event idx

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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.

Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
This commit is contained in:
Eugenio Pérez 2022-10-20 17:52:49 +02:00 committed by Jason Wang
parent f0c48e05bd
commit 01f8beacea
1 changed files with 15 additions and 3 deletions
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18
hw/virtio/vhost-shadow-virtqueue.c
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@ -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;
} 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,