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, 6 deletions

diff --git a/hw/pci-host/piix.c b/hw/pci-host/piix.c
index f1712b8..ed2424c 100644
--- a/hw/pci-host/piix.c
+++ b/hw/pci-host/piix.c
@@ -582,6 +582,7 @@ static const VMStateDescription vmstate_piix3_rcr = {
     .name = "PIIX3/rcr",
     .version_id = 1,
     .minimum_version_id = 1,
+    .needed = piix3_rcr_needed,
     .fields = (VMStateField[]) {
         VMSTATE_UINT8(rcr, PIIX3State),
         VMSTATE_END_OF_LIST()
@@ -600,12 +601,9 @@ static const VMStateDescription vmstate_piix3 = {
                               PIIX_NUM_PIRQS, 3),
         VMSTATE_END_OF_LIST()
     },
-    .subsections = (VMStateSubsection[]) {
-        {
-            .vmsd = &vmstate_piix3_rcr,
-            .needed = piix3_rcr_needed,
-        },
-        { 0 }
+    .subsections = (const VMStateDescription*[]) {
+        &vmstate_piix3_rcr,
+        NULL
     }
 };