Add documentation for vfio_device_get_region_info() and clarify the
expectations around its usage.

Cc: Alex Williamson <alex.williamson@redhat.com>
Cc: Cédric Le Goater <clg@redhat.com>
Signed-off-by: Vivek Kasireddy <vivek.kasireddy@intel.com>
---
 include/hw/vfio/vfio-device.h | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/include/hw/vfio/vfio-device.h b/include/hw/vfio/vfio-device.h
index 0fe6c60ba2..bb28123faf 100644
--- a/include/hw/vfio/vfio-device.h
+++ b/include/hw/vfio/vfio-device.h
@@ -257,6 +257,19 @@ void vfio_device_prepare(VFIODevice *vbasedev, VFIOContainer *bcontainer,
 
 void vfio_device_unprepare(VFIODevice *vbasedev);
 
+/**
+ * Return the region info for a given region index. The region info includes
+ * details such as size, offset, and capabilities. Note that the returned
+ * info pointer is either a cached copy or newly allocated by
+ * vfio_device_get_region_info(), so the caller is not expected to allocate
+ * or free it.
+ *
+ * @vbasedev: #VFIODevice to use
+ * @index: region index
+ * @info: pointer to store the region info
+ *
+ * Returns 0 on success or a negative value on error.
+ */
 int vfio_device_get_region_info(VFIODevice *vbasedev, int index,
                                 struct vfio_region_info **info);
 int vfio_device_get_region_info_type(VFIODevice *vbasedev, uint32_t type,
-- 
2.50.1