vhost: move iova_tree set to vhost_svq_start

Since we don't know if we will use SVQ at qemu initialization, let's
allocate iova_tree only if needed. To do so, accept it at SVQ start, not
at initialization.

This will avoid to create it if the device does not support SVQ.

Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Message-Id: <20221215113144.322011-5-eperezma@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

3 files changed, 8 insertions, 11 deletions

diff --git a/hw/virtio/vhost-shadow-virtqueue.c b/hw/virtio/vhost-shadow-virtqueue.c
index 3b05bab..4307296 100644
--- a/hw/virtio/vhost-shadow-virtqueue.c
+++ b/hw/virtio/vhost-shadow-virtqueue.c
@@ -642,9 +642,10 @@ void vhost_svq_set_svq_kick_fd(VhostShadowVirtqueue *svq, int svq_kick_fd)
  * @svq: Shadow Virtqueue
  * @vdev: VirtIO device
  * @vq: Virtqueue to shadow
+ * @iova_tree: Tree to perform descriptors translations
  */
 void vhost_svq_start(VhostShadowVirtqueue *svq, VirtIODevice *vdev,
-                     VirtQueue *vq)
+                     VirtQueue *vq, VhostIOVATree *iova_tree)
 {
     size_t desc_size, driver_size, device_size;
 
@@ -655,6 +656,7 @@ void vhost_svq_start(VhostShadowVirtqueue *svq, VirtIODevice *vdev,
     svq->last_used_idx = 0;
     svq->vdev = vdev;
     svq->vq = vq;
+    svq->iova_tree = iova_tree;
 
     svq->vring.num = virtio_queue_get_num(vdev, virtio_get_queue_index(vq));
     driver_size = vhost_svq_driver_area_size(svq);
@@ -712,18 +714,15 @@ void vhost_svq_stop(VhostShadowVirtqueue *svq)
  * Creates vhost shadow virtqueue, and instructs the vhost device to use the
  * shadow methods and file descriptors.
  *
- * @iova_tree: Tree to perform descriptors translations
  * @ops: SVQ owner callbacks
  * @ops_opaque: ops opaque pointer
  */
-VhostShadowVirtqueue *vhost_svq_new(VhostIOVATree *iova_tree,
-                                    const VhostShadowVirtqueueOps *ops,
+VhostShadowVirtqueue *vhost_svq_new(const VhostShadowVirtqueueOps *ops,
                                     void *ops_opaque)
 {
     VhostShadowVirtqueue *svq = g_new0(VhostShadowVirtqueue, 1);
 
     event_notifier_init_fd(&svq->svq_kick, VHOST_FILE_UNBIND);
-    svq->iova_tree = iova_tree;
     svq->ops = ops;
     svq->ops_opaque = ops_opaque;
     return svq;
diff --git a/hw/virtio/vhost-shadow-virtqueue.h b/hw/virtio/vhost-shadow-virtqueue.h
index d04c34a..926a489 100644
--- a/hw/virtio/vhost-shadow-virtqueue.h
+++ b/hw/virtio/vhost-shadow-virtqueue.h
@@ -126,11 +126,10 @@ size_t vhost_svq_driver_area_size(const VhostShadowVirtqueue *svq);
 size_t vhost_svq_device_area_size(const VhostShadowVirtqueue *svq);
 
 void vhost_svq_start(VhostShadowVirtqueue *svq, VirtIODevice *vdev,
-                     VirtQueue *vq);
+                     VirtQueue *vq, VhostIOVATree *iova_tree);
 void vhost_svq_stop(VhostShadowVirtqueue *svq);
 
-VhostShadowVirtqueue *vhost_svq_new(VhostIOVATree *iova_tree,
-                                    const VhostShadowVirtqueueOps *ops,
+VhostShadowVirtqueue *vhost_svq_new(const VhostShadowVirtqueueOps *ops,
                                     void *ops_opaque);
 
 void vhost_svq_free(gpointer vq);
diff --git a/hw/virtio/vhost-vdpa.c b/hw/virtio/vhost-vdpa.c
index 65f8963..014c69a 100644
--- a/hw/virtio/vhost-vdpa.c
+++ b/hw/virtio/vhost-vdpa.c
@@ -430,8 +430,7 @@ static int vhost_vdpa_init_svq(struct vhost_dev *hdev, struct vhost_vdpa *v,
     for (unsigned n = 0; n < hdev->nvqs; ++n) {
         VhostShadowVirtqueue *svq;
 
-        svq = vhost_svq_new(v->iova_tree, v->shadow_vq_ops,
-                            v->shadow_vq_ops_opaque);
+        svq = vhost_svq_new(v->shadow_vq_ops, v->shadow_vq_ops_opaque);
         g_ptr_array_add(shadow_vqs, svq);
     }
 
@@ -1063,7 +1062,7 @@ static bool vhost_vdpa_svqs_start(struct vhost_dev *dev)
             goto err;
         }
 
-        vhost_svq_start(svq, dev->vdev, vq);
+        vhost_svq_start(svq, dev->vdev, vq, v->iova_tree);
         ok = vhost_vdpa_svq_map_rings(dev, svq, &addr, &err);
         if (unlikely(!ok)) {
             goto err_map;