Fix virtio_blk(4) failing to attach on some hypervisors.

Approved by:	so
Security:	EN-21:23.virtio_blk

1 files changed, 18 insertions, 2 deletions

diff --git a/sys/dev/virtio/block/virtio_blk.c b/sys/dev/virtio/block/virtio_blk.c
index 50642fb0b009..8a5558f4571d 100644
--- a/sys/dev/virtio/block/virtio_blk.c
+++ b/sys/dev/virtio/block/virtio_blk.c
@@ -126,6 +126,7 @@ static int	vtblk_detach(device_t);
 static int	vtblk_suspend(device_t);
 static int	vtblk_resume(device_t);
 static int	vtblk_shutdown(device_t);
+static int	vtblk_attach_completed(device_t);
 static int	vtblk_config_change(device_t);
 
 static int	vtblk_open(struct disk *);
@@ -255,6 +256,7 @@ static device_method_t vtblk_methods[] = {
 	DEVMETHOD(device_shutdown,	vtblk_shutdown),
 
 	/* VirtIO methods. */
+	DEVMETHOD(virtio_attach_completed, vtblk_attach_completed),
 	DEVMETHOD(virtio_config_change,	vtblk_config_change),
 
 	DEVMETHOD_END
@@ -378,8 +380,6 @@ vtblk_attach(device_t dev)
 		goto fail;
 	}
 
-	vtblk_create_disk(sc);
-
 	virtqueue_enable_intr(sc->vtblk_vq);
 
 fail:
@@ -462,6 +462,22 @@ vtblk_shutdown(device_t dev)
 }
 
 static int
+vtblk_attach_completed(device_t dev)
+{
+	struct vtblk_softc *sc;
+
+	sc = device_get_softc(dev);
+
+	/*
+	 * Create disk after attach as VIRTIO_BLK_T_GET_ID can only be
+	 * processed after the device acknowledged
+	 * VIRTIO_CONFIG_STATUS_DRIVER_OK.
+	 */
+	vtblk_create_disk(sc);
+	return (0);
+}
+
+static int
 vtblk_config_change(device_t dev)
 {
 	struct vtblk_softc *sc;