Follow VIRTIO 1.1 spec, only writing out a single used ring for a batch of descriptors. Signed-off-by: Guo Zhi <qtxuning1999@xxxxxxxxxxx> --- drivers/vhost/vhost.c | 14 ++++++++++++-- drivers/vhost/vhost.h | 1 + 2 files changed, 13 insertions(+), 2 deletions(-) diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c index 40097826cff0..7b20fa5a46c3 100644 --- a/drivers/vhost/vhost.c +++ b/drivers/vhost/vhost.c @@ -2376,10 +2376,20 @@ static int __vhost_add_used_n(struct vhost_virtqueue *vq, vring_used_elem_t __user *used; u16 old, new; int start; + int copy_n = count; + /** + * If in order feature negotiated, devices can notify the use of a batch of buffers to + * the driver by only writing out a single used ring entry with the id corresponding + * to the head entry of the descriptor chain describing the last buffer in the batch. + */ + if (vhost_has_feature(vq, VIRTIO_F_IN_ORDER)) { + copy_n = 1; + heads = &heads[count - 1]; + } start = vq->last_used_idx & (vq->num - 1); used = vq->used->ring + start; - if (vhost_put_used(vq, heads, start, count)) { + if (vhost_put_used(vq, heads, start, copy_n)) { vq_err(vq, "Failed to write used"); return -EFAULT; } @@ -2410,7 +2420,7 @@ int vhost_add_used_n(struct vhost_virtqueue *vq, struct vring_used_elem *heads, start = vq->last_used_idx & (vq->num - 1); n = vq->num - start; - if (n < count) { + if (n < count && !vhost_has_feature(vq, VIRTIO_F_IN_ORDER)) { r = __vhost_add_used_n(vq, heads, n); if (r < 0) return r; diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h index d9109107af08..0d5c49a30421 100644 --- a/drivers/vhost/vhost.h +++ b/drivers/vhost/vhost.h @@ -236,6 +236,7 @@ enum { VHOST_FEATURES = (1ULL << VIRTIO_F_NOTIFY_ON_EMPTY) | (1ULL << VIRTIO_RING_F_INDIRECT_DESC) | (1ULL << VIRTIO_RING_F_EVENT_IDX) | + (1ULL << VIRTIO_F_IN_ORDER) | (1ULL << VHOST_F_LOG_ALL) | (1ULL << VIRTIO_F_ANY_LAYOUT) | (1ULL << VIRTIO_F_VERSION_1) -- 2.17.1