[Qemu-devel] [PATCH 05/11] vmstate: Create optional sections

[Juan Quintela <quintela@redhat.com>]

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>
---
 include/migration/vmstate.h |  2 ++
 migration/savevm.c          |  8 ++++++++
 migration/vmstate.c         | 11 +++++++++++
 trace-events                |  1 +
 4 files changed, 22 insertions(+)

diff --git a/include/migration/vmstate.h b/include/migration/vmstate.h
index 7153b1e..38de790 100644
--- a/include/migration/vmstate.h
+++ b/include/migration/vmstate.h
@@ -815,6 +815,8 @@ int vmstate_load_state(QEMUFile *f, const VMStateDescription *vmsd,
 void vmstate_save_state(QEMUFile *f, const VMStateDescription *vmsd,
                         void *opaque, QJSON *vmdesc);

+bool vmstate_save_needed(const VMStateDescription *vmsd, void *opaque);
+
 int vmstate_register_with_alias_id(DeviceState *dev, int instance_id,
                                    const VMStateDescription *vmsd,
                                    void *base, int alias_id,
diff --git a/migration/savevm.c b/migration/savevm.c
index 2091882..b018f30 100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -834,6 +834,11 @@ 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);
@@ -947,6 +952,9 @@ 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 6138d1a..e8ccf22 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)
 {
diff --git a/trace-events b/trace-events
index 52b7efa..bcdce29 100644
--- a/trace-events
+++ b/trace-events
@@ -1191,6 +1191,7 @@ qemu_loadvm_state_section_partend(uint32_t section_id) "%u"
 qemu_loadvm_state_section_startfull(uint32_t section_id, const char *idstr, uint32_t instance_id, uint32_t version_id) "%u(%s) %u %u"
 savevm_section_start(const char *id, unsigned int section_id) "%s, section_id %u"
 savevm_section_end(const char *id, unsigned int section_id, int ret) "%s, section_id %u -> %d"
+savevm_section_skip(const char *id, unsigned int section_id) "%s, section_id %u"
 savevm_state_begin(void) ""
 savevm_state_header(void) ""
 savevm_state_iterate(void) ""
-- 
2.4.3