virtio-bus: have callers tolerate new host notifier api

Have vhost and dataplane use the new api for transports that
have been converted.

Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

hw/block/dataplane/virtio-blk.c

@@ -79,7 +79,8 @@ void virtio_blk_data_plane_create(VirtIODevice *vdev, VirtIOBlkConf *conf,
     }
 
     /* Don't try if transport does not support notifiers. */
-    if (!k->set_guest_notifiers || !k->set_host_notifier) {
+    if (!k->set_guest_notifiers ||
+        (!k->set_host_notifier && !k->ioeventfd_started)) {
         error_setg(errp,
                    "device is incompatible with dataplane "
                    "(transport does not support notifiers)");
@@ -157,7 +158,10 @@ void virtio_blk_data_plane_start(VirtIOBlockDataPlane *s)
     s->guest_notifier = virtio_queue_get_guest_notifier(s->vq);
 
     /* Set up virtqueue notify */
+    r = virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), 0, true);
+    if (r == -ENOSYS) {
         r = k->set_host_notifier(qbus->parent, 0, true);
+    }
     if (r != 0) {
         fprintf(stderr, "virtio-blk failed to set host notifier (%d)\n", r);
         goto fail_host_notifier;
@@ -193,6 +197,7 @@ void virtio_blk_data_plane_stop(VirtIOBlockDataPlane *s)
     BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(s->vdev)));
     VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
     VirtIOBlock *vblk = VIRTIO_BLK(s->vdev);
+    int r;
 
     if (!vblk->dataplane_started || s->stopping) {
         return;
@@ -217,7 +222,10 @@ void virtio_blk_data_plane_stop(VirtIOBlockDataPlane *s)
 
     aio_context_release(s->ctx);
 
+    r = virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), 0, false);
+    if (r == -ENOSYS) {
         k->set_host_notifier(qbus->parent, 0, false);
+    }
 
     /* Clean up guest notifier (irq) */
     k->set_guest_notifiers(qbus->parent, 1, false);

hw/scsi/virtio-scsi-dataplane.c

@@ -31,7 +31,8 @@ void virtio_scsi_set_iothread(VirtIOSCSI *s, IOThread *iothread)
     s->ctx = iothread_get_aio_context(vs->conf.iothread);
 
     /* Don't try if transport does not support notifiers. */
-    if (!k->set_guest_notifiers || !k->set_host_notifier) {
+    if (!k->set_guest_notifiers ||
+        (!k->set_host_notifier && !k->ioeventfd_started)) {
         fprintf(stderr, "virtio-scsi: Failed to set iothread "
                    "(transport does not support notifiers)");
         exit(1);
@@ -73,7 +74,10 @@ static int virtio_scsi_vring_init(VirtIOSCSI *s, VirtQueue *vq, int n,
     int rc;
 
     /* Set up virtqueue notify */
+    rc = virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), n, true);
+    if (rc == -ENOSYS) {
         rc = k->set_host_notifier(qbus->parent, n, true);
+    }
     if (rc != 0) {
         fprintf(stderr, "virtio-scsi: Failed to set host notifier (%d)\n",
                 rc);
@@ -159,8 +163,11 @@ fail_vrings:
     virtio_scsi_clear_aio(s);
     aio_context_release(s->ctx);
     for (i = 0; i < vs->conf.num_queues + 2; i++) {
+        rc = virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), i, false);
+        if (rc == -ENOSYS) {
             k->set_host_notifier(qbus->parent, i, false);
         }
+    }
     k->set_guest_notifiers(qbus->parent, vs->conf.num_queues + 2, false);
 fail_guest_notifiers:
     s->dataplane_fenced = true;
@@ -174,7 +181,7 @@ void virtio_scsi_dataplane_stop(VirtIOSCSI *s)
     BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(s)));
     VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
     VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(s);
-    int i;
+    int i, rc;
 
     if (!s->dataplane_started || s->dataplane_stopping) {
         return;
@@ -198,8 +205,11 @@ void virtio_scsi_dataplane_stop(VirtIOSCSI *s)
     aio_context_release(s->ctx);
 
     for (i = 0; i < vs->conf.num_queues + 2; i++) {
+        rc = virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), i, false);
+        if (rc == -ENOSYS) {
             k->set_host_notifier(qbus->parent, i, false);
         }
+    }
 
     /* Clean up guest notifier (irq) */
     k->set_guest_notifiers(qbus->parent, vs->conf.num_queues + 2, false);

hw/virtio/vhost.c

@@ -1110,14 +1110,18 @@ int vhost_dev_enable_notifiers(struct vhost_dev *hdev, VirtIODevice *vdev)
     VirtioBusState *vbus = VIRTIO_BUS(qbus);
     VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(vbus);
     int i, r, e;
-    if (!k->set_host_notifier) {
+    if (!k->set_host_notifier || !k->ioeventfd_started) {
         fprintf(stderr, "binding does not support host notifiers\n");
         r = -ENOSYS;
         goto fail;
     }
 
     for (i = 0; i < hdev->nvqs; ++i) {
+        r = virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), hdev->vq_index + i,
+                                         true);
+        if (r == -ENOSYS) {
             r = k->set_host_notifier(qbus->parent, hdev->vq_index + i, true);
+        }
         if (r < 0) {
             fprintf(stderr, "vhost VQ %d notifier binding failed: %d\n", i, -r);
             goto fail_vq;
@@ -1127,7 +1131,11 @@ int vhost_dev_enable_notifiers(struct vhost_dev *hdev, VirtIODevice *vdev)
     return 0;
 fail_vq:
     while (--i >= 0) {
+        e = virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), hdev->vq_index + i,
+                                         false);
+        if (e == -ENOSYS) {
             e = k->set_host_notifier(qbus->parent, hdev->vq_index + i, false);
+        }
         if (e < 0) {
             fprintf(stderr, "vhost VQ %d notifier cleanup error: %d\n", i, -r);
             fflush(stderr);
@@ -1151,7 +1159,11 @@ void vhost_dev_disable_notifiers(struct vhost_dev *hdev, VirtIODevice *vdev)
     int i, r;
 
     for (i = 0; i < hdev->nvqs; ++i) {
+        r = virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), hdev->vq_index + i,
+                                         false);
+        if (r == -ENOSYS) {
             r = k->set_host_notifier(qbus->parent, hdev->vq_index + i, false);
+        }
         if (r < 0) {
             fprintf(stderr, "vhost VQ %d notifier cleanup failed: %d\n", i, -r);
             fflush(stderr);