在 2022/7/7 02:39, Eugenio Pérez 写道:
> We will allow SVQ user to store opaque data for each element, so its
> easier if we store this kind of information just at avail.
>
> Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Note that kernel driver doesn't have this optimization so far. I wonder
if this is not a must, let's post this on top of the shadow CVQ stuffs.
Thanks
> ---
> hw/virtio/vhost-shadow-virtqueue.h | 3 +++
> hw/virtio/vhost-shadow-virtqueue.c | 14 ++++++++------
> 2 files changed, 11 insertions(+), 6 deletions(-)
>
> diff --git a/hw/virtio/vhost-shadow-virtqueue.h b/hw/virtio/vhost-shadow-virtqueue.h
> index e434dc63b0..0e434e9fd0 100644
> --- a/hw/virtio/vhost-shadow-virtqueue.h
> +++ b/hw/virtio/vhost-shadow-virtqueue.h
> @@ -17,6 +17,9 @@
>
> typedef struct SVQElement {
> VirtQueueElement *elem;
> +
> + /* Last descriptor of the chain */
> + uint32_t last_chain_id;
> } SVQElement;
>
> typedef struct VhostShadowVirtqueue VhostShadowVirtqueue;
> diff --git a/hw/virtio/vhost-shadow-virtqueue.c b/hw/virtio/vhost-shadow-virtqueue.c
> index cf1745fd4d..c5e49e51c5 100644
> --- a/hw/virtio/vhost-shadow-virtqueue.c
> +++ b/hw/virtio/vhost-shadow-virtqueue.c
> @@ -239,7 +239,9 @@ static bool vhost_svq_add(VhostShadowVirtqueue *svq, const struct iovec *out_sg,
> size_t out_num, const struct iovec *in_sg,
> size_t in_num, VirtQueueElement *elem)
> {
> + SVQElement *svq_elem;
> unsigned qemu_head;
> + size_t n;
> bool ok = vhost_svq_add_split(svq, out_sg, out_num, in_sg, in_num,
> &qemu_head);
> if (unlikely(!ok)) {
> @@ -247,7 +249,10 @@ static bool vhost_svq_add(VhostShadowVirtqueue *svq, const struct iovec *out_sg,
> return false;
> }
>
> - svq->ring_id_maps[qemu_head].elem = elem;
> + n = out_num + in_num;
> + svq_elem = &svq->ring_id_maps[qemu_head];
> + svq_elem->elem = elem;
> + svq_elem->last_chain_id = vhost_svq_last_desc_of_chain(svq, n, qemu_head);
> return true;
> }
>
> @@ -400,7 +405,7 @@ static SVQElement vhost_svq_get_buf(VhostShadowVirtqueue *svq, uint32_t *len)
> const vring_used_t *used = svq->vring.used;
> vring_used_elem_t used_elem;
> SVQElement svq_elem = vhost_svq_empty_elem();
> - uint16_t last_used, last_used_chain, num;
> + uint16_t last_used;
>
> if (!vhost_svq_more_used(svq)) {
> return svq_elem;
> @@ -428,11 +433,8 @@ static SVQElement vhost_svq_get_buf(VhostShadowVirtqueue *svq, uint32_t *len)
> return svq_elem;
> }
>
> - num = svq_elem.elem->in_num + svq_elem.elem->out_num;
> - last_used_chain = vhost_svq_last_desc_of_chain(svq, num, used_elem.id);
> - svq->desc_next[last_used_chain] = svq->free_head;
> + svq->desc_next[svq_elem.last_chain_id] = svq->free_head;
> svq->free_head = used_elem.id;
> -
> *len = used_elem.len;
> return svq_elem;
> }