migration: Use normal VMStateDescriptions for Subsections

We create optional sections with this patch.  But we already have
optional subsections.  Instead of having two mechanism that do the
same, we can just generalize it.

For subsections we just change:

- Add a needed function to VMStateDescription
- Remove VMStateSubsection (after removal of the needed function
  it is just a VMStateDescription)
- Adjust the whole tree, moving the needed function to the corresponding
  VMStateDescription

Signed-off-by: Juan Quintela <quintela@redhat.com>

1 files changed, 4 insertions, 7 deletions

diff --git a/hw/display/qxl.c b/hw/display/qxl.c
index b220e2d..722146e 100644
--- a/hw/display/qxl.c
+++ b/hw/display/qxl.c
@@ -2220,6 +2220,7 @@ static VMStateDescription qxl_vmstate_monitors_config = {
     .name               = "qxl/monitors-config",
     .version_id         = 1,
     .minimum_version_id = 1,
+    .needed = qxl_monitors_config_needed,
     .fields = (VMStateField[]) {
         VMSTATE_UINT64(guest_monitors_config, PCIQXLDevice),
         VMSTATE_END_OF_LIST()
@@ -2253,13 +2254,9 @@ static VMStateDescription qxl_vmstate = {
         VMSTATE_UINT64(guest_cursor, PCIQXLDevice),
         VMSTATE_END_OF_LIST()
     },
-    .subsections = (VMStateSubsection[]) {
-        {
-            .vmsd = &qxl_vmstate_monitors_config,
-            .needed = qxl_monitors_config_needed,
-        }, {
-            /* empty */
-        }
+    .subsections = (const VMStateDescription*[]) {
+        &qxl_vmstate_monitors_config,
+        NULL
     }
 };