trace: add virtio_set_status() trace event

The virtio device lifecycle can be observed by looking at the sequence
of set status operations.  This is especially important for catching the
reset operation (status value 0), which resets the device and all
virtqueues.

Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>

1 files changed, 10 insertions, 0 deletions

diff --git a/hw/virtio.c b/hw/virtio.c
index 13aa0faf27..946d911580 100644
--- a/hw/virtio.c
+++ b/hw/virtio.c
@@ -498,6 +498,16 @@ void virtio_update_irq(VirtIODevice *vdev)
     virtio_notify_vector(vdev, VIRTIO_NO_VECTOR);
 }
 
+void virtio_set_status(VirtIODevice *vdev, uint8_t val)
+{
+    trace_virtio_set_status(vdev, val);
+
+    if (vdev->set_status) {
+        vdev->set_status(vdev, val);
+    }
+    vdev->status = val;
+}
+
 void virtio_reset(void *opaque)
 {
     VirtIODevice *vdev = opaque;