COLO: migrate COLO related info to secondary node

We can determine whether or not VM in destination should go into COLO mode
by referring to the info that was migrated.

We skip this section if COLO is not enabled (i.e.
migrate_set_capability colo off), so that, It doesn't break compatibility
with migration no matter whether users configure the --enable-colo/disable-colo
on the source/destination side or not;

Signed-off-by: zhanghailiang <zhang.zhanghailiang@huawei.com>
Signed-off-by: Li Zhijian <lizhijian@cn.fujitsu.com>
Signed-off-by: Gonglei <arei.gonglei@huawei.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Amit Shah <amit@amitshah.net>

include/migration/colo.h

@@ -14,7 +14,9 @@
 #define QEMU_COLO_H
 
 #include "qemu-common.h"
+#include "migration/migration.h"
 
 bool colo_supported(void);
+void colo_info_init(void);
 
 #endif

migration/Makefile.objs

@@ -1,6 +1,7 @@
 common-obj-y += migration.o socket.o fd.o exec.o
 common-obj-y += tls.o
 common-obj-$(CONFIG_COLO) += colo.o
+common-obj-y += colo-comm.o
 common-obj-y += vmstate.o
 common-obj-y += qemu-file.o
 common-obj-y += qemu-file-channel.o

migration/colo-comm.c

@@ -0,0 +1,51 @@
+/*
+ * COarse-grain LOck-stepping Virtual Machines for Non-stop Service (COLO)
+ * (a.k.a. Fault Tolerance or Continuous Replication)
+ *
+ * Copyright (c) 2016 HUAWEI TECHNOLOGIES CO., LTD.
+ * Copyright (c) 2016 FUJITSU LIMITED
+ * Copyright (c) 2016 Intel Corporation
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or
+ * later. See the COPYING file in the top-level directory.
+ *
+ */
+
+#include "qemu/osdep.h"
+#include <migration/colo.h>
+#include "trace.h"
+
+typedef struct {
+     bool colo_requested;
+} COLOInfo;
+
+static COLOInfo colo_info;
+
+static void colo_info_pre_save(void *opaque)
+{
+    COLOInfo *s = opaque;
+
+    s->colo_requested = migrate_colo_enabled();
+}
+
+static bool colo_info_need(void *opaque)
+{
+   return migrate_colo_enabled();
+}
+
+static const VMStateDescription colo_state = {
+    .name = "COLOState",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .pre_save = colo_info_pre_save,
+    .needed = colo_info_need,
+    .fields = (VMStateField[]) {
+        VMSTATE_BOOL(colo_requested, COLOInfo),
+        VMSTATE_END_OF_LIST()
+    },
+};
+
+void colo_info_init(void)
+{
+    vmstate_register(NULL, 0, &colo_state, &colo_info);
+}

vl.c

@@ -90,6 +90,7 @@ int main(int argc, char **argv)
 #include "audio/audio.h"
 #include "migration/migration.h"
 #include "sysemu/cpus.h"
+#include "migration/colo.h"
 #include "sysemu/kvm.h"
 #include "qapi/qmp/qjson.h"
 #include "qemu/option.h"
@@ -4426,6 +4427,8 @@ int main(int argc, char **argv, char **envp)
 #endif
     }
 
+    colo_info_init();
+
     if (net_init_clients() < 0) {
         exit(1);
     }