On Fri, Apr 1, 2022 at 2:14 AM Eugenio Pérez <epere...@redhat.com> wrote:
>
> Only the first one of them were properly enqueued back.
>
> Fixes: 100890f7ca ("vhost: Shadow virtqueue buffers forwarding")
> Signed-off-by: Eugenio Pérez <epere...@redhat.com>
> ---
> hw/virtio/vhost-shadow-virtqueue.c | 17 +++++++++++++++--
> 1 file changed, 15 insertions(+), 2 deletions(-)
>
> diff --git a/hw/virtio/vhost-shadow-virtqueue.c
> b/hw/virtio/vhost-shadow-virtqueue.c
> index b232803d1b..c17506df20 100644
> --- a/hw/virtio/vhost-shadow-virtqueue.c
> +++ b/hw/virtio/vhost-shadow-virtqueue.c
> @@ -333,13 +333,25 @@ static void
> vhost_svq_disable_notification(VhostShadowVirtqueue *svq)
> svq->vring.avail->flags |= cpu_to_le16(VRING_AVAIL_F_NO_INTERRUPT);
> }
>
> +static uint16_t vhost_svq_last_desc_of_chain(VhostShadowVirtqueue *svq,
> + uint16_t i)
> +{
> + vring_desc_t *descs = svq->vring.desc;
> +
> + while (le16_to_cpu(descs[i].flags) & VRING_DESC_F_NEXT) {
> + i = le16_to_cpu(descs[i].next);
This seems to be a guest trigger-able infinite loop?
Thanks
> + }
> +
> + return i;
> +}
> +
> static VirtQueueElement *vhost_svq_get_buf(VhostShadowVirtqueue *svq,
> uint32_t *len)
> {
> vring_desc_t *descs = svq->vring.desc;
> const vring_used_t *used = svq->vring.used;
> vring_used_elem_t used_elem;
> - uint16_t last_used;
> + uint16_t last_used, last_used_chain;
>
> if (!vhost_svq_more_used(svq)) {
> return NULL;
> @@ -365,7 +377,8 @@ static VirtQueueElement
> *vhost_svq_get_buf(VhostShadowVirtqueue *svq,
> return NULL;
> }
>
> - descs[used_elem.id].next = svq->free_head;
> + last_used_chain = vhost_svq_last_desc_of_chain(svq, used_elem.id);
> + descs[last_used_chain].next = svq->free_head;
> svq->free_head = used_elem.id;
>
> *len = used_elem.len;
> --
> 2.27.0
>
