Add new APIs with errp, to allow handlers report good
error messages. We'll convert existing handlers soon.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Reviewed-by: Peter Xu <peterx@redhat.com>
---
 include/migration/vmstate.h | 17 ++++++++++++++---
 migration/vmstate.c         |  4 ++++
 2 files changed, 18 insertions(+), 3 deletions(-)

diff --git a/include/migration/vmstate.h b/include/migration/vmstate.h
index 85838a49aee..77d58d27d41 100644
--- a/include/migration/vmstate.h
+++ b/include/migration/vmstate.h
@@ -32,12 +32,16 @@
 typedef struct VMStateInfo VMStateInfo;
 typedef struct VMStateField VMStateField;
 
-/* VMStateInfo allows customized migration of objects that don't fit in
+/*
+ * VMStateInfo allows customized migration of objects that don't fit in
  * any category in VMStateFlags. Additional information is always passed
- * into get and put in terms of field and vmdesc parameters. However
+ * into load and save in terms of field and vmdesc parameters. However
  * these two parameters should only be used in cases when customized
  * handling is needed, such as QTAILQ. For primitive data types such as
- * integer, field and vmdesc parameters should be ignored inside get/put.
+ * integer, field and vmdesc parameters should be ignored inside load/save.
+ *
+ * @get and @put are deprecated copies of @load and @save. For new interfaces
+ * use @load and @save.
  */
 struct VMStateInfo {
     const char *name;
@@ -46,6 +50,13 @@ struct VMStateInfo {
     int coroutine_mixed_fn (*put)(QEMUFile *f, void *pv, size_t size,
                                   const VMStateField *field,
                                   JSONWriter *vmdesc);
+    bool coroutine_mixed_fn (*load)(QEMUFile *f, void *pv, size_t size,
+                                    const VMStateField *field,
+                                    Error **errp);
+    bool coroutine_mixed_fn (*save)(QEMUFile *f, void *pv, size_t size,
+                                    const VMStateField *field,
+                                    JSONWriter *vmdesc,
+                                    Error **errp);
 };
 
 enum VMStateFlags {
diff --git a/migration/vmstate.c b/migration/vmstate.c
index 8825aa3b1f1..f16626d7d11 100644
--- a/migration/vmstate.c
+++ b/migration/vmstate.c
@@ -170,6 +170,8 @@ static bool vmstate_load_field(QEMUFile *f, void *pv, size_t size,
     } else if (field->flags & VMS_VSTRUCT) {
         return vmstate_load_state(f, field->vmsd, pv, field->struct_version_id,
                                   errp) >= 0;
+    } else if (field->info->load) {
+        return field->info->load(f, pv, size, field, errp);
     }
 
     if (field->info->get(f, pv, size, field) < 0) {
@@ -495,6 +497,8 @@ static bool vmstate_save_field(QEMUFile *f, void *pv, size_t size,
         return vmstate_save_state_v(f, field->vmsd, pv, vmdesc,
                                     field->struct_version_id,
                                     errp) >= 0;
+    } else if (field->info->save) {
+        return field->info->save(f, pv, size, field, vmdesc, errp);
     }
 
     if (field->info->put(f, pv, size, field, vmdesc) < 0) {
-- 
2.52.0