Instead of iterating over all QOM devices to find the VFIODevice
associated with a memory region, it is faster to just use the
vfio_device_list to lookup the VFIODevice.

Cc: Alex Williamson <alex@shazbot.org>
Cc: Cédric Le Goater <clg@redhat.com>
Signed-off-by: Vivek Kasireddy <vivek.kasireddy@intel.com>
---
 hw/vfio/device.c              | 12 ++++++++++++
 include/hw/vfio/vfio-device.h |  9 +++++++++
 2 files changed, 21 insertions(+)

diff --git a/hw/vfio/device.c b/hw/vfio/device.c
index 973fc35b59..afeff0f034 100644
--- a/hw/vfio/device.c
+++ b/hw/vfio/device.c
@@ -644,3 +644,15 @@ static VFIODeviceIOOps vfio_device_io_ops_ioctl = {
     .region_read = vfio_device_io_region_read,
     .region_write = vfio_device_io_region_write,
 };
+
+VFIODevice *vfio_device_lookup(MemoryRegion *mr)
+{
+    VFIODevice *vbasedev;
+
+    QLIST_FOREACH(vbasedev, &vfio_device_list, next) {
+        if (vbasedev->dev == mr->dev) {
+            return vbasedev;
+        }
+    }
+    return NULL;
+}
diff --git a/include/hw/vfio/vfio-device.h b/include/hw/vfio/vfio-device.h
index 596c7f5a10..ccf2fd887c 100644
--- a/include/hw/vfio/vfio-device.h
+++ b/include/hw/vfio/vfio-device.h
@@ -318,6 +318,15 @@ int vfio_device_get_irq_info(VFIODevice *vbasedev, int index,
  * Returns the region index or -1 on error.
  */
 int vfio_get_region_index_from_mr(MemoryRegion *mr);
+
+/**
+ * Return the VFIO device associated with a given MemoryRegion.
+ *
+ * @mr: MemoryRegion to use
+ *
+ * Returns the VFIO device if found or NULL.
+ */
+VFIODevice *vfio_device_lookup(MemoryRegion *mr);
 #endif
 
 /* Returns 0 on success, or a negative errno. */
-- 
2.50.1