On Mon, May 20, 2024 at 3:01 PM Jonah Palmer <jonah.pal...@oracle.com> wrote:
>
> Add VIRTIO_F_IN_ORDER feature support in virtqueue_split_pop and
> virtqueue_packed_pop.
>
> VirtQueueElements popped from the available/descritpor ring are added to
> the VirtQueue's used_elems array in-order and in the same fashion as
> they would be added the used and descriptor rings, respectively.
>
> This will allow us to keep track of the current order, what elements
> have been written, as well as an element's essential data after being
> processed.
>
> Tested-by: Lei Yang <leiy...@redhat.com>
> Signed-off-by: Jonah Palmer <jonah.pal...@oracle.com>
> ---
> hw/virtio/virtio.c | 17 ++++++++++++++++-
> 1 file changed, 16 insertions(+), 1 deletion(-)
>
> diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
> index 893a072c9d..7456d61bc8 100644
> --- a/hw/virtio/virtio.c
> +++ b/hw/virtio/virtio.c
> @@ -1506,7 +1506,7 @@ static void *virtqueue_alloc_element(size_t sz,
> unsigned out_num, unsigned in_nu
>
> static void *virtqueue_split_pop(VirtQueue *vq, size_t sz)
> {
> - unsigned int i, head, max;
> + unsigned int i, head, max, prev_avail_idx;
> VRingMemoryRegionCaches *caches;
> MemoryRegionCache indirect_desc_cache;
> MemoryRegionCache *desc_cache;
> @@ -1539,6 +1539,8 @@ static void *virtqueue_split_pop(VirtQueue *vq, size_t
> sz)
> goto done;
> }
>
> + prev_avail_idx = vq->last_avail_idx;
> +
> if (!virtqueue_get_head(vq, vq->last_avail_idx++, &head)) {
> goto done;
> }
> @@ -1630,6 +1632,12 @@ static void *virtqueue_split_pop(VirtQueue *vq, size_t
> sz)
> elem->in_sg[i] = iov[out_num + i];
> }
>
> + if (virtio_vdev_has_feature(vdev, VIRTIO_F_IN_ORDER)) {
I think vq->last_avail_idx - 1 could be more clear here.
Either way,
Reviewed-by: Eugenio Pérez <epere...@redhat.com>
> + vq->used_elems[prev_avail_idx].index = elem->index;
> + vq->used_elems[prev_avail_idx].len = elem->len;
> + vq->used_elems[prev_avail_idx].ndescs = elem->ndescs;
> + }
> +
> vq->inuse++;
>
> trace_virtqueue_pop(vq, elem, elem->in_num, elem->out_num);
> @@ -1758,6 +1766,13 @@ static void *virtqueue_packed_pop(VirtQueue *vq,
> size_t sz)
>
> elem->index = id;
> elem->ndescs = (desc_cache == &indirect_desc_cache) ? 1 : elem_entries;
> +
> + if (virtio_vdev_has_feature(vdev, VIRTIO_F_IN_ORDER)) {
> + vq->used_elems[vq->last_avail_idx].index = elem->index;
> + vq->used_elems[vq->last_avail_idx].len = elem->len;
> + vq->used_elems[vq->last_avail_idx].ndescs = elem->ndescs;
> + }
> +
> vq->last_avail_idx += elem->ndescs;
> vq->inuse += elem->ndescs;
>
> --
> 2.39.3
>
