[RFC,v4,02/28] migration: Introduce capability 'colo' to migration

diff --git a/include/migration/migration-colo.h b/include/migration/migration-colo.h
new file mode 100644
index 0000000..6fdbb94
--- /dev/null
+++ b/include/migration/migration-colo.h
@@ -0,0 +1,20 @@ 
+/*
+ * COarse-grain LOck-stepping Virtual Machines for Non-stop Service (COLO)
+ * (a.k.a. Fault Tolerance or Continuous Replication)
+ *
+ * Copyright (c) 2015 HUAWEI TECHNOLOGIES CO.,LTD.
+ * Copyright (c) 2015 FUJITSU LIMITED
+ * Copyright (c) 2015 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.
+ */
+
+#ifndef QEMU_MIGRATION_COLO_H
+#define QEMU_MIGRATION_COLO_H
+
+#include "qemu-common.h"
+
+bool colo_supported(void);
+
+#endif
diff --git a/include/migration/migration.h b/include/migration/migration.h
index bf09968..59acb62 100644
--- a/include/migration/migration.h
+++ b/include/migration/migration.h
@@ -149,6 +149,7 @@  int xbzrle_decode_buffer(uint8_t *src, int slen, uint8_t *dst, int dlen);
 
 int migrate_use_xbzrle(void);
 int64_t migrate_xbzrle_cache_size(void);
+bool migrate_enable_colo(void);
 
 int64_t xbzrle_cache_resize(int64_t new_size);
 
diff --git a/migration/Makefile.objs b/migration/Makefile.objs
index d929e96..5a25d39 100644
--- a/migration/Makefile.objs
+++ b/migration/Makefile.objs
@@ -1,4 +1,5 @@ 
 common-obj-y += migration.o tcp.o
+common-obj-$(CONFIG_COLO) += colo.o
 common-obj-y += vmstate.o
 common-obj-y += qemu-file.o qemu-file-buf.o qemu-file-unix.o qemu-file-stdio.o
 common-obj-y += xbzrle.o
diff --git a/migration/colo.c b/migration/colo.c
new file mode 100644
index 0000000..babfe4f
--- /dev/null
+++ b/migration/colo.c
@@ -0,0 +1,18 @@ 
+/*
+ * COarse-grain LOck-stepping Virtual Machines for Non-stop Service (COLO)
+ * (a.k.a. Fault Tolerance or Continuous Replication)
+ *
+ * Copyright (c) 2015 HUAWEI TECHNOLOGIES CO.,LTD.
+ * Copyright (c) 2015 FUJITSU LIMITED
+ * Copyright (c) 2015 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 "migration/migration-colo.h"
+
+bool colo_supported(void)
+{
+    return true;
+}
diff --git a/migration/colo.c. b/migration/colo.c.
new file mode 100644
index 0000000..e69de29
diff --git a/migration/migration.c b/migration/migration.c
index bc42490..7009ddd 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -25,6 +25,7 @@ 
 #include "qemu/thread.h"
 #include "qmp-commands.h"
 #include "trace.h"
+#include "migration/migration-colo.h"
 
 #define MAX_THROTTLE  (32 << 20)      /* Migration speed throttling */
 
@@ -154,6 +155,9 @@  MigrationCapabilityStatusList *qmp_query_migrate_capabilities(Error **errp)
 
     caps = NULL; /* silence compiler warning */
     for (i = 0; i < MIGRATION_CAPABILITY_MAX; i++) {
+        if (i == MIGRATION_CAPABILITY_COLO && !colo_supported()) {
+            continue;
+        }
         if (head == NULL) {
             head = g_malloc0(sizeof(*caps));
             caps = head;
@@ -279,6 +283,13 @@  void qmp_migrate_set_capabilities(MigrationCapabilityStatusList *params,
     }
 
     for (cap = params; cap; cap = cap->next) {
+        if (cap->value->capability == MIGRATION_CAPABILITY_COLO &&
+            cap->value->state && !colo_supported()) {
+            error_setg(errp, "COLO is not currently supported, please"
+                             " configure with --enable-colo option in order to"
+                             " support COLO feature");
+            continue;
+        }
         s->enabled_capabilities[cap->value->capability] = cap->value->state;
     }
 }
@@ -605,6 +616,12 @@  int64_t migrate_xbzrle_cache_size(void)
     return s->xbzrle_cache_size;
 }
 
+bool migrate_enable_colo(void)
+{
+    MigrationState *s = migrate_get_current();
+    return s->enabled_capabilities[MIGRATION_CAPABILITY_COLO];
+}
+
 /* migration thread support */
 
 static void *migration_thread(void *opaque)
diff --git a/qapi-schema.json b/qapi-schema.json
index ac9594d..193cad4 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -518,10 +518,13 @@ 
 # @auto-converge: If enabled, QEMU will automatically throttle down the guest
 #          to speed up convergence of RAM migration. (since 1.6)
 #
+# @colo: If enabled, migration will never end, and the state of VM in primary side
+#        will be migrated continuously to VM in secondary side. (since 2.4)
+#
 # Since: 1.2
 ##
 { 'enum': 'MigrationCapability',
-  'data': ['xbzrle', 'rdma-pin-all', 'auto-converge', 'zero-blocks'] }
+  'data': ['xbzrle', 'rdma-pin-all', 'auto-converge', 'zero-blocks', 'colo'] }
 
 ##
 # @MigrationCapabilityStatus
diff --git a/stubs/Makefile.objs b/stubs/Makefile.objs
index 8beff4c..65a7171 100644
--- a/stubs/Makefile.objs
+++ b/stubs/Makefile.objs
@@ -39,3 +39,4 @@  stub-obj-$(CONFIG_WIN32) += fd-register.o
 stub-obj-y += cpus.o
 stub-obj-y += kvm.o
 stub-obj-y += qmp_pc_dimm_device_list.o
+stub-obj-y += migration-colo.o
diff --git a/stubs/migration-colo.c b/stubs/migration-colo.c
new file mode 100644
index 0000000..ccbaea8
--- /dev/null
+++ b/stubs/migration-colo.c
@@ -0,0 +1,18 @@ 
+/*
+ * COarse-grain LOck-stepping Virtual Machines for Non-stop Service (COLO)
+ * (a.k.a. Fault Tolerance or Continuous Replication)
+ *
+ * Copyright (c) 2015 HUAWEI TECHNOLOGIES CO.,LTD.
+ * Copyright (c) 2015 FUJITSU LIMITED
+ * Copyright (c) 2015 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 "migration/migration-colo.h"
+
+bool colo_supported(void)
+{
+    return false;
+}