On Thu, Oct 20, 2022 at 11:53 PM Eugenio Pérez <[email protected]> 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 <[email protected]>
> ---
> 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);
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
>
