[COLO-Frame,(Base),v21,12/17] COLO: Add 'x-colo-lost-heartbeat' command to trigger failover

diff --git a/docs/qmp-commands.txt b/docs/qmp-commands.txt
index 13ab523..5296b30 100644
--- a/docs/qmp-commands.txt
+++ b/docs/qmp-commands.txt
@@ -554,6 +554,16 @@  Example:
 -> { "execute": "migrate_set_downtime", "arguments": { "value": 0.1 } }
 <- { "return": {} }
 
+x-colo-lost-heartbeat
+--------------------
+
+Tell COLO that heartbeat is lost, a failover or takeover is needed.
+
+Example:
+
+-> { "execute": "x-colo-lost-heartbeat" }
+<- { "return": {} }
+
 client_migrate_info
 -------------------
 
diff --git a/hmp-commands.hx b/hmp-commands.hx
index 06bef47..8819281 100644
--- a/hmp-commands.hx
+++ b/hmp-commands.hx
@@ -1040,6 +1040,21 @@  migration (or once already in postcopy).
 ETEXI
 
     {
+        .name       = "x_colo_lost_heartbeat",
+        .args_type  = "",
+        .params     = "",
+        .help       = "Tell COLO that heartbeat is lost,\n\t\t\t"
+                      "a failover or takeover is needed.",
+        .cmd = hmp_x_colo_lost_heartbeat,
+    },
+
+STEXI
+@item x_colo_lost_heartbeat
+@findex x_colo_lost_heartbeat
+Tell COLO that heartbeat is lost, a failover or takeover is needed.
+ETEXI
+
+    {
         .name       = "client_migrate_info",
         .args_type  = "protocol:s,hostname:s,port:i?,tls-port:i?,cert-subject:s?",
         .params     = "protocol hostname port tls-port cert-subject",
diff --git a/hmp.c b/hmp.c
index 759f4f4..909ec43 100644
--- a/hmp.c
+++ b/hmp.c
@@ -1450,6 +1450,14 @@  void hmp_migrate_start_postcopy(Monitor *mon, const QDict *qdict)
     hmp_handle_error(mon, &err);
 }
 
+void hmp_x_colo_lost_heartbeat(Monitor *mon, const QDict *qdict)
+{
+    Error *err = NULL;
+
+    qmp_x_colo_lost_heartbeat(&err);
+    hmp_handle_error(mon, &err);
+}
+
 void hmp_set_password(Monitor *mon, const QDict *qdict)
 {
     const char *protocol  = qdict_get_str(qdict, "protocol");
diff --git a/hmp.h b/hmp.h
index 184769c..05daf7c 100644
--- a/hmp.h
+++ b/hmp.h
@@ -72,6 +72,7 @@  void hmp_migrate_set_parameter(Monitor *mon, const QDict *qdict);
 void hmp_migrate_set_cache_size(Monitor *mon, const QDict *qdict);
 void hmp_client_migrate_info(Monitor *mon, const QDict *qdict);
 void hmp_migrate_start_postcopy(Monitor *mon, const QDict *qdict);
+void hmp_x_colo_lost_heartbeat(Monitor *mon, const QDict *qdict);
 void hmp_set_password(Monitor *mon, const QDict *qdict);
 void hmp_expire_password(Monitor *mon, const QDict *qdict);
 void hmp_eject(Monitor *mon, const QDict *qdict);
diff --git a/include/migration/colo.h b/include/migration/colo.h
index b40676c..e9ac2c3 100644
--- a/include/migration/colo.h
+++ b/include/migration/colo.h
@@ -17,6 +17,7 @@ 
 #include "migration/migration.h"
 #include "qemu/coroutine_int.h"
 #include "qemu/thread.h"
+#include "qemu/main-loop.h"
 
 bool colo_supported(void);
 void colo_info_init(void);
@@ -29,4 +30,6 @@  bool migration_incoming_enable_colo(void);
 void migration_incoming_exit_colo(void);
 void *colo_process_incoming_thread(void *opaque);
 bool migration_incoming_in_colo_state(void);
+
+COLOMode get_colo_mode(void);
 #endif
diff --git a/include/migration/failover.h b/include/migration/failover.h
new file mode 100644
index 0000000..3274735
--- /dev/null
+++ b/include/migration/failover.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) 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.
+ */
+
+#ifndef QEMU_FAILOVER_H
+#define QEMU_FAILOVER_H
+
+#include "qemu-common.h"
+
+void failover_request_active(Error **errp);
+
+#endif
diff --git a/migration/Makefile.objs b/migration/Makefile.objs
index 4bbe9ab..3f3e237 100644
--- a/migration/Makefile.objs
+++ b/migration/Makefile.objs
@@ -1,7 +1,7 @@ 
 common-obj-y += migration.o socket.o fd.o exec.o
 common-obj-y += tls.o
-common-obj-$(CONFIG_COLO) += colo.o
 common-obj-y += colo-comm.o
+common-obj-$(CONFIG_COLO) += colo.o colo-failover.o
 common-obj-y += vmstate.o
 common-obj-y += qemu-file.o
 common-obj-y += qemu-file-channel.o
diff --git a/migration/colo-comm.c b/migration/colo-comm.c
index 3af9333..a69a5f7 100644
--- a/migration/colo-comm.c
+++ b/migration/colo-comm.c
@@ -21,6 +21,17 @@  typedef struct {
 
 static COLOInfo colo_info;
 
+COLOMode get_colo_mode(void)
+{
+    if (migration_in_colo_state()) {
+        return COLO_MODE_PRIMARY;
+    } else if (migration_incoming_in_colo_state()) {
+        return COLO_MODE_SECONDARY;
+    } else {
+        return COLO_MODE_UNKNOWN;
+    }
+}
+
 static void colo_info_pre_save(void *opaque)
 {
     COLOInfo *s = opaque;
diff --git a/migration/colo-failover.c b/migration/colo-failover.c
new file mode 100644
index 0000000..e31fc10
--- /dev/null
+++ b/migration/colo-failover.c
@@ -0,0 +1,42 @@ 
+/*
+ * 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 "migration/failover.h"
+#include "qmp-commands.h"
+#include "qapi/qmp/qerror.h"
+
+static QEMUBH *failover_bh;
+
+static void colo_failover_bh(void *opaque)
+{
+    qemu_bh_delete(failover_bh);
+    failover_bh = NULL;
+    /* TODO: Do failover work */
+}
+
+void failover_request_active(Error **errp)
+{
+    failover_bh = qemu_bh_new(colo_failover_bh, NULL);
+    qemu_bh_schedule(failover_bh);
+}
+
+void qmp_x_colo_lost_heartbeat(Error **errp)
+{
+    if (get_colo_mode() == COLO_MODE_UNKNOWN) {
+        error_setg(errp, QERR_FEATURE_DISABLED, "colo");
+        return;
+    }
+
+    failover_request_active(errp);
+}
diff --git a/migration/colo.c b/migration/colo.c
index 7c7d169..45b13cd 100644
--- a/migration/colo.c
+++ b/migration/colo.c
@@ -18,6 +18,7 @@ 
 #include "trace.h"
 #include "qemu/error-report.h"
 #include "qapi/error.h"
+#include "migration/failover.h"
 
 #define COLO_BUFFER_BASE_SIZE (4 * 1024 * 1024)
 
diff --git a/qapi-schema.json b/qapi-schema.json
index b6950be..6367685 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -822,6 +822,35 @@ 
             'vmstate-send', 'vmstate-size', 'vmstate-received',
             'vmstate-loaded' ] }
 
+##
+# @COLOMode
+#
+# The colo mode
+#
+# @unknown: unknown mode
+#
+# @primary: master side
+#
+# @secondary: slave side
+#
+# Since: 2.8
+##
+{ 'enum': 'COLOMode',
+  'data': [ 'unknown', 'primary', 'secondary'] }
+
+##
+# @x-colo-lost-heartbeat
+#
+# Tell qemu that heartbeat is lost, request it to do takeover procedures.
+# If this command is sent to the PVM, the Primary side will exit COLO mode.
+# If sent to the Secondary, the Secondary side will run failover work,
+# then takes over server operation to become the service VM.
+#
+# Since: 2.8
+##
+{ 'command': 'x-colo-lost-heartbeat' }
+
+##
 # @MouseInfo:
 #
 # Information about a mouse device.
diff --git a/stubs/migration-colo.c b/stubs/migration-colo.c
index 7b72395..7811764 100644
--- a/stubs/migration-colo.c
+++ b/stubs/migration-colo.c
@@ -12,6 +12,7 @@ 
 
 #include "qemu/osdep.h"
 #include "migration/colo.h"
+#include "qmp-commands.h"
 
 bool colo_supported(void)
 {
@@ -36,3 +37,10 @@  void *colo_process_incoming_thread(void *opaque)
 {
     return NULL;
 }
+
+void qmp_x_colo_lost_heartbeat(Error **errp)
+{
+    error_setg(errp, "COLO is not supported, please rerun configure"
+                     " with --enable-colo option in order to support"
+                     " COLO feature");
+}