--- /dev/null
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Sergio Lopez <slp@redhat.com>
+Date: Mon, 16 Sep 2019 13:24:12 +0200
+Subject: [PATCH] virtio-blk: schedule virtio_notify_config to run on main
+ context
+
+virtio_notify_config() needs to acquire the global mutex, which isn't
+allowed from an iothread, and may lead to a deadlock like this:
+
+ - main thead
+ * Has acquired: qemu_global_mutex.
+ * Is trying the acquire: iothread AioContext lock via
+ AIO_WAIT_WHILE (after aio_poll).
+
+ - iothread
+ * Has acquired: AioContext lock.
+ * Is trying to acquire: qemu_global_mutex (via
+ virtio_notify_config->prepare_mmio_access).
+
+If virtio_blk_resize() is called from an iothread, schedule
+virtio_notify_config() to be run in the main context BH.
+
+[Removed unnecessary newline as suggested by Kevin Wolf
+<kwolf@redhat.com>.
+--Stefan]
+
+Signed-off-by: Sergio Lopez <slp@redhat.com>
+Reviewed-by: Kevin Wolf <kwolf@redhat.com>
+Message-id: 20190916112411.21636-1-slp@redhat.com
+Message-Id: <20190916112411.21636-1-slp@redhat.com>
+Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
+---
+ hw/block/virtio-blk.c | 16 +++++++++++++++-
+ 1 file changed, 15 insertions(+), 1 deletion(-)
+
+diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c
+index cbb3729158..0d9adcdaff 100644
+--- a/hw/block/virtio-blk.c
++++ b/hw/block/virtio-blk.c
+@@ -16,6 +16,7 @@
+ #include "qemu/iov.h"
+ #include "qemu/module.h"
+ #include "qemu/error-report.h"
++#include "qemu/main-loop.h"
+ #include "trace.h"
+ #include "hw/block/block.h"
+ #include "sysemu/blockdev.h"
+@@ -1082,11 +1083,24 @@ static int virtio_blk_load_device(VirtIODevice *vdev, QEMUFile *f,
+ return 0;
+ }
+
++static void virtio_resize_cb(void *opaque)
++{
++ VirtIODevice *vdev = opaque;
++
++ assert(qemu_get_current_aio_context() == qemu_get_aio_context());
++ virtio_notify_config(vdev);
++}
++
+ static void virtio_blk_resize(void *opaque)
+ {
+ VirtIODevice *vdev = VIRTIO_DEVICE(opaque);
+
+- virtio_notify_config(vdev);
++ /*
++ * virtio_notify_config() needs to acquire the global mutex,
++ * so it can't be called from an iothread. Instead, schedule
++ * it to be run in the main context BH.
++ */
++ aio_bh_schedule_oneshot(qemu_get_aio_context(), virtio_resize_cb, vdev);
+ }
+
+ static const BlockDevOps virtio_block_ops = {
+--
+2.20.1
+