From: Jason Wang <jasowang@redhat.com>

Date: Fri, 25 Sep 2015 13:21:28 +0800

Subject: [PATCH] virtio: introduce virtqueue_unmap_sg()

Factor out sg unmapping logic. This will be reused by the patch that

can discard descriptor.

Cc: Michael S. Tsirkin <mst@redhat.com>

Cc: Andrew James <andrew.james@hpe.com>

Signed-off-by: Jason Wang <jasowang@redhat.com>

Reviewed-by: Michael S. Tsirkin <mst@redhat.com>

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

(cherry picked from commit ce317461573bac12b10d67699b4ddf1f97cf066c)

---

 hw/virtio/virtio.c | 14 ++++++++++----

 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c

index 788b556..242aecb 100644

--- a/hw/virtio/virtio.c

+++ b/hw/virtio/virtio.c

@@ -243,14 +243,12 @@ int virtio_queue_empty(VirtQueue *vq)

     return vring_avail_idx(vq) == vq->last_avail_idx;

 }

-void virtqueue_fill(VirtQueue *vq, const VirtQueueElement *elem,

-                    unsigned int len, unsigned int idx)

+static void virtqueue_unmap_sg(VirtQueue *vq, const VirtQueueElement *elem,

+                               unsigned int len)

 {

     unsigned int offset;

     int i;

-    trace_virtqueue_fill(vq, elem, len, idx);

-

     offset = 0;

     for (i = 0; i < elem->in_num; i++) {

         size_t size = MIN(len - offset, elem->in_sg[i].iov_len);

@@ -266,6 +264,14 @@ void virtqueue_fill(VirtQueue *vq, const VirtQueueElement *elem,

         cpu_physical_memory_unmap(elem->out_sg[i].iov_base,

                                   elem->out_sg[i].iov_len,

                                   0, elem->out_sg[i].iov_len);

+}

+

+void virtqueue_fill(VirtQueue *vq, const VirtQueueElement *elem,

+                    unsigned int len, unsigned int idx)

+{

+    trace_virtqueue_fill(vq, elem, len, idx);

+

+    virtqueue_unmap_sg(vq, elem, len);

     idx = (idx + vring_used_idx(vq)) % vq->vring.num;