COLO: Load dirty pages into SVM's RAM cache firstly

We should not load PVM's state directly into SVM, because there maybe some
errors happen when SVM is receving data, which will break SVM.

We need to ensure receving all data before load the state into SVM. We use
an extra memory to cache these data (PVM's ram). The ram cache in secondary side
is initially the same as SVM/PVM's memory. And in the process of checkpoint,
we cache the dirty pages of PVM into this ram cache firstly, so this ram cache
always the same as PVM's memory at every checkpoint, then we flush this cached ram
to SVM after we receive all PVM's state.

Signed-off-by: zhanghailiang <zhang.zhanghailiang@huawei.com>
Signed-off-by: Li Zhijian <lizhijian@cn.fujitsu.com>
Signed-off-by: Zhang Chen <zhangckid@gmail.com>
Signed-off-by: Zhang Chen <chen.zhang@intel.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>

1 files changed, 7 insertions, 0 deletions

diff --git a/migration/migration.c b/migration/migration.c
index 215e81a190..7696729340 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -444,6 +444,11 @@ static void process_incoming_migration_co(void *opaque)
             exit(EXIT_FAILURE);
         }
 
+        if (colo_init_ram_cache() < 0) {
+            error_report("Init ram cache failed");
+            exit(EXIT_FAILURE);
+        }
+
         qemu_thread_create(&mis->colo_incoming_thread, "COLO incoming",
              colo_process_incoming_thread, mis, QEMU_THREAD_JOINABLE);
         mis->have_colo_incoming_thread = true;
@@ -451,6 +456,8 @@ static void process_incoming_migration_co(void *opaque)
 
         /* Wait checkpoint incoming thread exit before free resource */
         qemu_thread_join(&mis->colo_incoming_thread);
+        /* We hold the global iothread lock, so it is safe here */
+        colo_release_ram_cache();
     }
 
     if (ret < 0) {