[PATCH 13/33] vhost: move vrings mapping to the top of vhost_virtqueue_start()

[Vladimir Sementsov-Ogievskiy]

This simplifies further refactoring and final introduction
of vhost backend live migration.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsement...@yandex-team.ru>
---
 hw/virtio/vhost.c | 47 +++++++++++++++++++++++------------------------
 1 file changed, 23 insertions(+), 24 deletions(-)

diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
index bc1821eadd..97113174b9 100644
--- a/hw/virtio/vhost.c
+++ b/hw/virtio/vhost.c
@@ -1288,30 +1288,6 @@ int vhost_virtqueue_start(struct vhost_dev *dev,
         /* Queue might not be ready for start */
         return 0;
     }
-
-    vq->num = state.num = virtio_queue_get_num(vdev, idx);
-    r = dev->vhost_ops->vhost_set_vring_num(dev, &state);
-    if (r) {
-        VHOST_OPS_DEBUG(r, "vhost_set_vring_num failed");
-        return r;
-    }
-
-    state.num = virtio_queue_get_last_avail_idx(vdev, idx);
-    r = dev->vhost_ops->vhost_set_vring_base(dev, &state);
-    if (r) {
-        VHOST_OPS_DEBUG(r, "vhost_set_vring_base failed");
-        return r;
-    }
-
-    if (vhost_needs_vring_endian(vdev)) {
-        r = vhost_virtqueue_set_vring_endian_legacy(dev,
-                                                    virtio_is_big_endian(vdev),
-                                                    vhost_vq_index);
-        if (r) {
-            return r;
-        }
-    }
-
     vq->desc_size = l = virtio_queue_get_desc_size(vdev, idx);
     vq->desc_phys = a;
     vq->desc = vhost_memory_map(dev, a, l, false);
@@ -1334,6 +1310,29 @@ int vhost_virtqueue_start(struct vhost_dev *dev,
         goto fail;
     }
 
+    vq->num = state.num = virtio_queue_get_num(vdev, idx);
+    r = dev->vhost_ops->vhost_set_vring_num(dev, &state);
+    if (r) {
+        VHOST_OPS_DEBUG(r, "vhost_set_vring_num failed");
+        goto fail;
+    }
+
+    state.num = virtio_queue_get_last_avail_idx(vdev, idx);
+    r = dev->vhost_ops->vhost_set_vring_base(dev, &state);
+    if (r) {
+        VHOST_OPS_DEBUG(r, "vhost_set_vring_base failed");
+        goto fail;
+    }
+
+    if (vhost_needs_vring_endian(vdev)) {
+        r = vhost_virtqueue_set_vring_endian_legacy(dev,
+                                                    virtio_is_big_endian(vdev),
+                                                    vhost_vq_index);
+        if (r) {
+            goto fail;
+        }
+    }
+
     r = vhost_virtqueue_set_addr(dev, vq, vhost_vq_index, dev->log_enabled);
     if (r < 0) {
         goto fail;
-- 
2.48.1