[PULL 09/12] migration/colo.c: Flush ram cache only after receiving device state

["Dr. David Alan Gilbert (git)" <dgilbert@redhat.com>]

From: Lukas Straub <lukasstraub2@web.de>

If we suceed in receiving ram state, but fail receiving the device
state, there will be a mismatch between the two.

Fix this by flushing the ram cache only after the vmstate has been
received.

Signed-off-by: Lukas Straub <lukasstraub2@web.de>
Message-Id: <3289d007d494cb0e2f05b1cf4ae6a78d300fede3.1589193382.git.lukasstraub2@web.de>
Reviewed-by: zhanghailiang <zhang.zhanghailiang@huawei.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
---
 migration/colo.c | 1 +
 migration/ram.c  | 5 +----
 migration/ram.h  | 1 +
 3 files changed, 3 insertions(+), 4 deletions(-)

diff --git a/migration/colo.c b/migration/colo.c
index d00b3b9d6b..4105999634 100644
--- a/migration/colo.c
+++ b/migration/colo.c
@@ -748,6 +748,7 @@ static void colo_incoming_process_checkpoint(MigrationIncomingState *mis,
 
     qemu_mutex_lock_iothread();
     vmstate_loading = true;
+    colo_flush_ram_cache();
     ret = qemu_load_device_state(fb);
     if (ret < 0) {
         error_setg(errp, "COLO: load device state failed");
diff --git a/migration/ram.c b/migration/ram.c
index 859f835f1a..41cc530d9d 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -3360,7 +3360,7 @@ static bool postcopy_is_running(void)
  * Flush content of RAM cache into SVM's memory.
  * Only flush the pages that be dirtied by PVM or SVM or both.
  */
-static void colo_flush_ram_cache(void)
+void colo_flush_ram_cache(void)
 {
     RAMBlock *block = NULL;
     void *dst_host;
@@ -3632,9 +3632,6 @@ static int ram_load(QEMUFile *f, void *opaque, int version_id)
     }
     trace_ram_load_complete(ret, seq_iter);
 
-    if (!ret  && migration_incoming_in_colo_state()) {
-        colo_flush_ram_cache();
-    }
     return ret;
 }
 
diff --git a/migration/ram.h b/migration/ram.h
index 5ceaff7cb4..2eeaacfa13 100644
--- a/migration/ram.h
+++ b/migration/ram.h
@@ -65,6 +65,7 @@ int ram_dirty_bitmap_reload(MigrationState *s, RAMBlock *rb);
 
 /* ram cache */
 int colo_init_ram_cache(void);
+void colo_flush_ram_cache(void);
 void colo_release_ram_cache(void);
 void colo_incoming_start_dirty_log(void);
 
-- 
2.26.2