virtio: support setting memory region based host notifier

This patch introduces the support for setting memory region
based host notifiers for virtio device. This is helpful when
using a hardware accelerator for a virtio device, because
hardware heavily depends on the notification, this will allow
the guest driver in the VM to notify the hardware directly.

Signed-off-by: Tiwei Bie <tiwei.bie@intel.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

1 files changed, 13 insertions, 0 deletions

diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
index 006d3d1148..1debb0147b 100644
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -2454,6 +2454,19 @@ EventNotifier *virtio_queue_get_host_notifier(VirtQueue *vq)
     return &vq->host_notifier;
 }
 
+int virtio_queue_set_host_notifier_mr(VirtIODevice *vdev, int n,
+                                      MemoryRegion *mr, bool assign)
+{
+    BusState *qbus = qdev_get_parent_bus(DEVICE(vdev));
+    VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
+
+    if (k->set_host_notifier_mr) {
+        return k->set_host_notifier_mr(qbus->parent, n, mr, assign);
+    }
+
+    return -1;
+}
+
 void virtio_device_set_child_bus_name(VirtIODevice *vdev, char *bus_name)
 {
     g_free(vdev->bus_name);