[RFC PATCH 04/17] COLO info: use colo info to tell migration target colo is enabled

[Yang Hongyang <yanghy@cn.fujitsu.com>]

migrate colo info to migration target to tell the target colo is
enabled.

Signed-off-by: Yang Hongyang <yanghy@cn.fujitsu.com>
---
 Makefile.objs                      |  1 +
 include/migration/migration-colo.h |  3 ++
 migration-colo-comm.c              | 68 ++++++++++++++++++++++++++++++++++++++
 vl.c                               |  4 +++
 4 files changed, 76 insertions(+)
 create mode 100644 migration-colo-comm.c

diff --git a/Makefile.objs b/Makefile.objs
index cab5824..1836a68 100644
--- a/Makefile.objs
+++ b/Makefile.objs
@@ -50,6 +50,7 @@ common-obj-$(CONFIG_POSIX) += os-posix.o
 common-obj-$(CONFIG_LINUX) += fsdev/
 
 common-obj-y += migration.o migration-tcp.o
+common-obj-y += migration-colo-comm.o
 common-obj-$(CONFIG_COLO) += migration-colo.o
 common-obj-y += vmstate.o
 common-obj-y += qemu-file.o
diff --git a/include/migration/migration-colo.h b/include/migration/migration-colo.h
index 35b384c..e3735d8 100644
--- a/include/migration/migration-colo.h
+++ b/include/migration/migration-colo.h
@@ -12,6 +12,9 @@
 #define QEMU_MIGRATION_COLO_H
 
 #include "qemu-common.h"
+#include "migration/migration.h"
+
+void colo_info_mig_init(void);
 
 bool colo_supported(void);
 
diff --git a/migration-colo-comm.c b/migration-colo-comm.c
new file mode 100644
index 0000000..ccbc246
--- /dev/null
+++ b/migration-colo-comm.c
@@ -0,0 +1,68 @@
+/*
+ *  COarse-grain LOck-stepping Virtual Machines for Non-stop Service (COLO)
+ *  (a.k.a. Fault Tolerance or Continuous Replication)
+ *
+ *  Copyright (C) 2014 FUJITSU LIMITED
+ *
+ * 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 <migration/migration-colo.h>
+
+#define DEBUG_COLO
+
+#ifdef DEBUG_COLO
+#define DPRINTF(fmt, ...) \
+    do { fprintf(stdout, "COLO: " fmt, ## __VA_ARGS__); } while (0)
+#else
+#define DPRINTF(fmt, ...) \
+    do { } while (0)
+#endif
+
+static bool colo_requested;
+
+/* save */
+
+static bool migrate_use_colo(void)
+{
+    MigrationState *s = migrate_get_current();
+    return s->enabled_capabilities[MIGRATION_CAPABILITY_COLO];
+}
+
+static void colo_info_save(QEMUFile *f, void *opaque)
+{
+    qemu_put_byte(f, migrate_use_colo());
+}
+
+/* restore */
+
+static int colo_info_load(QEMUFile *f, void *opaque, int version_id)
+{
+    int value = qemu_get_byte(f);
+
+    if (value && !colo_supported()) {
+        fprintf(stderr, "COLO is not supported\n");
+        return -EINVAL;
+    }
+
+    if (value && !colo_requested) {
+        DPRINTF("COLO requested!\n");
+    }
+
+    colo_requested = value;
+
+    return 0;
+}
+
+static SaveVMHandlers savevm_colo_info_handlers = {
+    .save_state = colo_info_save,
+    .load_state = colo_info_load,
+};
+
+void colo_info_mig_init(void)
+{
+    register_savevm_live(NULL, "colo info", -1, 1,
+                         &savevm_colo_info_handlers, NULL);
+}
diff --git a/vl.c b/vl.c
index fe451aa..1a282d8 100644
--- a/vl.c
+++ b/vl.c
@@ -89,6 +89,7 @@ int main(int argc, char **argv)
 #include "sysemu/dma.h"
 #include "audio/audio.h"
 #include "migration/migration.h"
+#include "migration/migration-colo.h"
 #include "sysemu/kvm.h"
 #include "qapi/qmp/qjson.h"
 #include "qemu/option.h"
@@ -4339,6 +4340,9 @@ int main(int argc, char **argv, char **envp)
 
     blk_mig_init();
     ram_mig_init();
+    if (colo_supported()) {
+        colo_info_mig_init();
+    }
 
     /* open the virtual block devices */
     if (snapshot)
-- 
1.9.1