Introduce virtio_bh_new_guarded(), similar to qemu_bh_new_guarded()
but using the transport memory guard, instead of the device one
(there can only be one virtio device per virtio bus).

Inspired-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
---
 include/hw/virtio/virtio.h |  7 +++++++
 hw/virtio/virtio.c         | 10 ++++++++++
 2 files changed, 17 insertions(+)

diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h
index b3c74a1bca..12419d6355 100644
--- a/include/hw/virtio/virtio.h
+++ b/include/hw/virtio/virtio.h
@@ -22,6 +22,7 @@
 #include "standard-headers/linux/virtio_config.h"
 #include "standard-headers/linux/virtio_ring.h"
 #include "qom/object.h"
+#include "block/aio.h"
 
 /*
  * A guest should never accept this. It implies negotiation is broken
@@ -527,4 +528,10 @@ static inline bool virtio_device_disabled(VirtIODevice *vdev)
 bool virtio_legacy_allowed(VirtIODevice *vdev);
 bool virtio_legacy_check_disabled(VirtIODevice *vdev);
 
+QEMUBH *virtio_bh_new_guarded_full(VirtIODevice *vdev,
+                                   QEMUBHFunc *cb, void *opaque,
+                                   const char *name);
+#define virtio_bh_new_guarded(vdev, cb, opaque) \
+    virtio_bh_new_guarded_full((vdev), (cb), (opaque), (stringify(cb)))
+
 #endif
diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
index fb6b4ccd83..e1735cf7fd 100644
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -4176,3 +4176,13 @@ static void virtio_register_types(void)
 }
 
 type_init(virtio_register_types)
+
+QEMUBH *virtio_bh_new_guarded_full(VirtIODevice *vdev,
+                                   QEMUBHFunc *cb, void *opaque,
+                                   const char *name)
+{
+    BusState *virtio_bus = qdev_get_parent_bus(DEVICE(vdev));
+    DeviceState *transport = virtio_bus->parent;
+
+    return qemu_bh_new_full(cb, opaque, name, &transport->mem_reentrancy_guard);
+}
-- 
2.41.0