vmstate: Create optional sections

To make sections optional, we need to do it at the beggining of the code.

Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

2 files changed, 19 insertions, 0 deletions

diff --git a/migration/savevm.c b/migration/savevm.c
index 1a9b00b320..e779c96ef9 100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -836,6 +836,11 @@ void qemu_savevm_state_complete(QEMUFile *f)
         if ((!se->ops || !se->ops->save_state) && !se->vmsd) {
             continue;
         }
+        if (se->vmsd && !vmstate_save_needed(se->vmsd, se->opaque)) {
+            trace_savevm_section_skip(se->idstr, se->section_id);
+            continue;
+        }
+
         trace_savevm_section_start(se->idstr, se->section_id);
 
         json_start_object(vmdesc, NULL);
@@ -949,6 +954,9 @@ static int qemu_save_device_state(QEMUFile *f)
         if ((!se->ops || !se->ops->save_state) && !se->vmsd) {
             continue;
         }
+        if (se->vmsd && !vmstate_save_needed(se->vmsd, se->opaque)) {
+            continue;
+        }
 
         save_section_header(f, se, QEMU_VM_SECTION_FULL);
 
diff --git a/migration/vmstate.c b/migration/vmstate.c
index 6138d1acb7..e8ccf22f67 100644
--- a/migration/vmstate.c
+++ b/migration/vmstate.c
@@ -276,6 +276,17 @@ static void vmsd_desc_field_end(const VMStateDescription *vmsd, QJSON *vmdesc,
     json_end_object(vmdesc);
 }
 
+
+bool vmstate_save_needed(const VMStateDescription *vmsd, void *opaque)
+{
+    if (vmsd->needed && !vmsd->needed(opaque)) {
+        /* optional section not needed */
+        return false;
+    }
+    return true;
+}
+
+
 void vmstate_save_state(QEMUFile *f, const VMStateDescription *vmsd,
                         void *opaque, QJSON *vmdesc)
 {