[PATCH] vfio: add vfio_device_get_region_fd()

[John Levon <john.levon@nutanix.com>]

This keeps the existence of ->region_fds private to hw/vfio/device.c.

Signed-off-by: John Levon <john.levon@nutanix.com>
---
 include/hw/vfio/vfio-device.h | 12 ++++++++++++
 hw/vfio/device.c              |  7 +++++++
 hw/vfio/region.c              |  5 +----
 3 files changed, 20 insertions(+), 4 deletions(-)

diff --git a/include/hw/vfio/vfio-device.h b/include/hw/vfio/vfio-device.h
index d45e5a68a2..1926adb0a3 100644
--- a/include/hw/vfio/vfio-device.h
+++ b/include/hw/vfio/vfio-device.h
@@ -256,6 +256,18 @@ 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,
                                      uint32_t subtype, struct vfio_region_info **info);
+
+/**
+ * Return the fd for mapping this region. This is either the device's fd (for
+ * e.g. kernel vfio), or a per-region fd (for vfio-user).
+ *
+ * @vbasedev: #VFIODevice to use
+ * @index: region index
+ *
+ * Returns the fd.
+ */
+int vfio_device_get_region_fd(VFIODevice *vbasedev, int index);
+
 bool vfio_device_has_region_cap(VFIODevice *vbasedev, int region, uint16_t cap_type);
 
 int vfio_device_get_irq_info(VFIODevice *vbasedev, int index,
diff --git a/hw/vfio/device.c b/hw/vfio/device.c
index d32600eda1..d91c695b69 100644
--- a/hw/vfio/device.c
+++ b/hw/vfio/device.c
@@ -243,6 +243,13 @@ retry:
     return 0;
 }
 
+int vfio_device_get_region_fd(VFIODevice *vbasedev, int index)
+{
+        return vbasedev->region_fds ?
+               vbasedev->region_fds[index] :
+               vbasedev->fd;
+}
+
 int vfio_device_get_region_info_type(VFIODevice *vbasedev, uint32_t type,
                                      uint32_t subtype, struct vfio_region_info **info)
 {
diff --git a/hw/vfio/region.c b/hw/vfio/region.c
index f5b8e3cbf1..d04c57db63 100644
--- a/hw/vfio/region.c
+++ b/hw/vfio/region.c
@@ -273,10 +273,7 @@ int vfio_region_mmap(VFIORegion *region)
             goto no_mmap;
         }
 
-        /* Use the per-region fd if set, or the shared fd. */
-        fd = region->vbasedev->region_fds ?
-             region->vbasedev->region_fds[region->nr] :
-             region->vbasedev->fd,
+        fd = vfio_device_get_region_fd(region->vbasedev, region->nr);
 
         map_align = (void *)ROUND_UP((uintptr_t)map_base, (uintptr_t)align);
         munmap(map_base, map_align - map_base);
-- 
2.43.0