linux-headers: sync VIRTIO_MEM_F_UNPLUGGED_INACCESSIBLE

Let's synchronize the new feature flag, available in Linux since
v5.16-rc1.

Reviewed-by: Michal Privoznik <[email protected]>
Signed-off-by: David Hildenbrand <[email protected]>
Message-Id: <20211217134039[email protected]>
Reviewed-by: Michael S. Tsirkin <[email protected]>
Signed-off-by: Michael S. Tsirkin <[email protected]>

diff --git a/include/standard-headers/linux/virtio_mem.h b/include/standard-headers/linux/virtio_mem.h
index 05e5ade75d3d8d2533c63d4fb4fe1c9026d86751..18c74c527c8ab19ff3d7f1b8601fdc665d4df68d 100644 (file)
--- a/include/standard-headers/linux/virtio_mem.h
+++ b/include/standard-headers/linux/virtio_mem.h
@@ -68,9 +68,10 @@
  * explicitly triggered (VIRTIO_MEM_REQ_UNPLUG).
  *
  * There are no guarantees what will happen if unplugged memory is
- * read/written. Such memory should, in general, not be touched. E.g.,
- * even writing might succeed, but the values will simply be discarded at
- * random points in time.
+ * read/written. In general, unplugged memory should not be touched, because
+ * the resulting action is undefined. There is one exception: without
+ * VIRTIO_MEM_F_UNPLUGGED_INACCESSIBLE, unplugged memory inside the usable
+ * region can be read, to simplify creation of memory dumps.
  *
  * It can happen that the device cannot process a request, because it is
  * busy. The device driver has to retry later.
@@ -87,6 +88,8 @@
 
 /* node_id is an ACPI PXM and is valid */
 #define VIRTIO_MEM_F_ACPI_PXM          0
+/* unplugged memory must not be accessed */
+#define VIRTIO_MEM_F_UNPLUGGED_INACCESSIBLE    1
 
 
 /* --- virtio-mem: guest -> host requests --- */