virtio-blk: always use dataplane path if ioeventfd is active

Override start_ioeventfd and stop_ioeventfd to start/stop the
whole dataplane logic.  This has some positive side effects:

- no need anymore for virtio_add_queue_aio (i.e. a revert of
  commit 0ff841f6d138904d514efa1d885bcaf54583852d)

- no need anymore to switch from generic ioeventfd handlers to
  dataplane

It detects some errors better:

    $ qemu-system-x86_64 -object iothread,id=io \
          -drive id=null,file=null-aio://,if=none,format=raw \
          -device virtio-blk-pci,ioeventfd=off,iothread=io,drive=null
    qemu-system-x86_64: -device virtio-blk-pci,ioeventfd=off,iothread=io,drive=null:
    ioeventfd is required for iothread

while previously it would have started just fine.

Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.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, 7 insertions, 8 deletions

diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c
index 37fe72bdcd..0c5fd27593 100644
--- a/hw/block/virtio-blk.c
+++ b/hw/block/virtio-blk.c
@@ -611,7 +611,7 @@ static void virtio_blk_handle_output(VirtIODevice *vdev, VirtQueue *vq)
         /* 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);
+        virtio_device_start_ioeventfd(vdev);
         if (!s->dataplane_disabled) {
             return;
         }
@@ -687,11 +687,9 @@ static void virtio_blk_reset(VirtIODevice *vdev)
         virtio_blk_free_request(req);
     }
 
-    if (s->dataplane) {
-        virtio_blk_data_plane_stop(s->dataplane);
-    }
     aio_context_release(ctx);
 
+    assert(!s->dataplane_started);
     blk_set_enable_write_cache(s->blk, s->original_wce);
 }
 
@@ -789,9 +787,8 @@ static void virtio_blk_set_status(VirtIODevice *vdev, uint8_t status)
 {
     VirtIOBlock *s = VIRTIO_BLK(vdev);
 
-    if (s->dataplane && !(status & (VIRTIO_CONFIG_S_DRIVER |
-                                    VIRTIO_CONFIG_S_DRIVER_OK))) {
-        virtio_blk_data_plane_stop(s->dataplane);
+    if (!(status & (VIRTIO_CONFIG_S_DRIVER | VIRTIO_CONFIG_S_DRIVER_OK))) {
+        assert(!s->dataplane_started);
     }
 
     if (!(status & VIRTIO_CONFIG_S_DRIVER_OK)) {
@@ -919,7 +916,7 @@ static void virtio_blk_device_realize(DeviceState *dev, Error **errp)
     s->sector_mask = (s->conf.conf.logical_block_size / BDRV_SECTOR_SIZE) - 1;
 
     for (i = 0; i < conf->num_queues; i++) {
-        virtio_add_queue_aio(vdev, 128, virtio_blk_handle_output);
+        virtio_add_queue(vdev, 128, virtio_blk_handle_output);
     }
     virtio_blk_data_plane_create(vdev, conf, &s->dataplane, &err);
     if (err != NULL) {
@@ -1002,6 +999,8 @@ static void virtio_blk_class_init(ObjectClass *klass, void *data)
     vdc->reset = virtio_blk_reset;
     vdc->save = virtio_blk_save_device;
     vdc->load = virtio_blk_load_device;
+    vdc->start_ioeventfd = virtio_blk_data_plane_start;
+    vdc->stop_ioeventfd = virtio_blk_data_plane_stop;
 }
 
 static const TypeInfo virtio_blk_info = {