virtio_ring: remove unnecessary to_vvq call in vring hot path

It passes '_vq' to virtqueue_use_indirect(), which still calls
to_vvq to get 'vq', let's directly pass 'vq'. It can avoid
unnecessary call of to_vvq in hot path.

Signed-off-by: Xianting Tian <xianting.tian@linux.alibaba.com>
Message-Id: <20220328105817.1028065-1-xianting.tian@linux.alibaba.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>

drivers/virtio/virtio_ring.c

@@ -205,11 +205,9 @@ struct vring_virtqueue {
 
 #define to_vvq(_vq) container_of(_vq, struct vring_virtqueue, vq)
 
-static inline bool virtqueue_use_indirect(struct virtqueue *_vq,
+static inline bool virtqueue_use_indirect(struct vring_virtqueue *vq,
 					  unsigned int total_sg)
 {
-	struct vring_virtqueue *vq = to_vvq(_vq);
-
 	/*
 	 * If the host supports indirect descriptor tables, and we have multiple
 	 * buffers, then go indirect. FIXME: tune this threshold
@@ -499,7 +497,7 @@ static inline int virtqueue_add_split(struct virtqueue *_vq,
 
 	head = vq->free_head;
 
-	if (virtqueue_use_indirect(_vq, total_sg))
+	if (virtqueue_use_indirect(vq, total_sg))
 		desc = alloc_indirect_split(_vq, total_sg, gfp);
 	else {
 		desc = NULL;
@@ -1178,7 +1176,7 @@ static inline int virtqueue_add_packed(struct virtqueue *_vq,
 
 	BUG_ON(total_sg == 0);
 
-	if (virtqueue_use_indirect(_vq, total_sg)) {
+	if (virtqueue_use_indirect(vq, total_sg)) {
 		err = virtqueue_add_indirect_packed(vq, sgs, total_sg, out_sgs,
 						    in_sgs, data, gfp);
 		if (err != -ENOMEM) {