[Qemu-devel] [PATCH 1/2] virtio-serial: Check if virtio queue is ready before consuming data

[Amit Shah]

If a virtio-serial port is removed before the guest comes up and
initialises the virtqueues, qemu exits with the message

Guest moved used index from 0 to 61440

This happens because we try to clear any pending buffers from the
virtqueue.

Ensure the virtqueue is initialised before calling any virtqueue
operations.

Signed-off-by: Amit Shah <address@hidden>
---
 hw/virtio-serial-bus.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/hw/virtio-serial-bus.c b/hw/virtio-serial-bus.c
index 7f9d28f..b89daa6 100644
--- a/hw/virtio-serial-bus.c
+++ b/hw/virtio-serial-bus.c
@@ -139,6 +139,9 @@ static void flush_queued_data(VirtIOSerialPort *port, bool 
discard)
 {
     assert(port);
 
+    if (!virtio_queue_ready(port->ovq)) {
+        return;
+    }
     do_flush_queued_data(port, port->ovq, &port->vser->vdev, discard);
 }
 
-- 
1.7.0.1