virtio-blk: use aio handler for data plane

In addition to handling IO in vcpu thread and in io thread, dataplane
introduces yet another mode: handling it by AioContext.

This reuses the same handler as previous modes, which triggers races as
these were not designed to be reentrant.  Use a separate handler just
for aio, and disable regular handlers when dataplane is active.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

1 files changed, 17 insertions, 10 deletions

diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c
index 151fe788db..3f88f8cf59 100644
--- a/hw/block/virtio-blk.c
+++ b/hw/block/virtio-blk.c
@@ -578,20 +578,11 @@ void virtio_blk_handle_request(VirtIOBlockReq *req, MultiReqBuffer *mrb)
     }
 }
 
-static void virtio_blk_handle_output(VirtIODevice *vdev, VirtQueue *vq)
+void virtio_blk_handle_vq(VirtIOBlock *s, VirtQueue *vq)
 {
-    VirtIOBlock *s = VIRTIO_BLK(vdev);
     VirtIOBlockReq *req;
     MultiReqBuffer mrb = {};
 
-    /* Some guests kick before setting VIRTIO_CONFIG_S_DRIVER_OK so start
-     * dataplane here instead of waiting for .set_status().
-     */
-    if (s->dataplane && !s->dataplane_started) {
-        virtio_blk_data_plane_start(s->dataplane);
-        return;
-    }
-
     blk_io_plug(s->blk);
 
     while ((req = virtio_blk_get_request(s))) {
@@ -605,6 +596,22 @@ static void virtio_blk_handle_output(VirtIODevice *vdev, VirtQueue *vq)
     blk_io_unplug(s->blk);
 }
 
+static void virtio_blk_handle_output(VirtIODevice *vdev, VirtQueue *vq)
+{
+    VirtIOBlock *s = (VirtIOBlock *)vdev;
+
+    if (s->dataplane) {
+        /* Some guests kick before setting VIRTIO_CONFIG_S_DRIVER_OK so start
+         * dataplane here instead of waiting for .set_status().
+         */
+        virtio_blk_data_plane_start(s->dataplane);
+        if (!s->dataplane_disabled) {
+            return;
+        }
+    }
+    virtio_blk_handle_vq(s, vq);
+}
+
 static void virtio_blk_dma_restart_bh(void *opaque)
 {
     VirtIOBlock *s = opaque;