[Qemu-devel] [PATCH COLO-Frame (Base) v21 01/17] migration: Introduce capability 'x-colo' to migration

[zhanghailiang]

We add helper function colo_supported() to indicate whether
colo is supported or not, with which we use to control whether or not
showing 'x-colo' string to users, they can use qmp command
'query-migrate-capabilities' or hmp command 'info migrate_capabilities'
to learn if colo is supported.

The default value for COLO is disabled.

Cc: Juan Quintela <address@hidden>
Cc: Amit Shah <address@hidden>
Cc: Eric Blake <address@hidden>
Cc: Markus Armbruster <address@hidden>
Signed-off-by: zhanghailiang <address@hidden>
Signed-off-by: Li Zhijian <address@hidden>
Signed-off-by: Gonglei <address@hidden>
Reviewed-by: Eric Blake <address@hidden>
---
v20:
- fix the description of 'x-colo' in qmp-commands.hx
v16:
- fix compile broken due to missing osdep.h
v14:
- Fix the date of Copyright to 2016
v10:
- Rename capability 'colo' to experimental 'x-colo' (Eric's suggestion).
- Rename migrate_enable_colo() to migrate_colo_enabled() (Eric's suggestion).
---
 docs/qmp-commands.txt         |  5 ++++-
 include/migration/colo.h      | 20 ++++++++++++++++++++
 include/migration/migration.h |  1 +
 migration/Makefile.objs       |  1 +
 migration/colo.c              | 19 +++++++++++++++++++
 migration/migration.c         | 18 ++++++++++++++++++
 qapi-schema.json              |  6 +++++-
 stubs/Makefile.objs           |  1 +
 stubs/migration-colo.c        | 19 +++++++++++++++++++
 9 files changed, 88 insertions(+), 2 deletions(-)
 create mode 100644 include/migration/colo.h
 create mode 100644 migration/colo.c
 create mode 100644 stubs/migration-colo.c

diff --git a/docs/qmp-commands.txt b/docs/qmp-commands.txt
index 3220fb1..bf2b77d 100644
--- a/docs/qmp-commands.txt
+++ b/docs/qmp-commands.txt
@@ -2861,6 +2861,7 @@ Enable/Disable migration capabilities
 - "compress": use multiple compression threads to accelerate live migration
 - "events": generate events for each migration state change
 - "postcopy-ram": postcopy mode for live migration
+- "x-colo": COarse-Grain LOck Stepping for Non-stop Service
 
 Arguments:
 
@@ -2882,6 +2883,7 @@ Query current migration capabilities
          - "compress": Multiple compression threads state (json-bool)
          - "events": Migration state change event state (json-bool)
          - "postcopy-ram": postcopy ram state (json-bool)
+         - "x-colo": COarse-Grain LOck Stepping for Non-stop Service 
(json-bool)
 
 Arguments:
 
@@ -2895,7 +2897,8 @@ Example:
      {"state": false, "capability": "zero-blocks"},
      {"state": false, "capability": "compress"},
      {"state": true, "capability": "events"},
-     {"state": false, "capability": "postcopy-ram"}
+     {"state": false, "capability": "postcopy-ram"},
+     {"state": false, "capability": "x-colo"}
    ]}
 
 migrate-set-parameters
diff --git a/include/migration/colo.h b/include/migration/colo.h
new file mode 100644
index 0000000..59a632a
--- /dev/null
+++ b/include/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) 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_COLO_H
+#define QEMU_COLO_H
+
+#include "qemu-common.h"
+
+bool colo_supported(void);
+
+#endif
diff --git a/include/migration/migration.h b/include/migration/migration.h
index 2791b90..34f442b 100644
--- a/include/migration/migration.h
+++ b/include/migration/migration.h
@@ -298,6 +298,7 @@ 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_colo_enabled(void);
 
 int64_t xbzrle_cache_resize(int64_t new_size);
 
diff --git a/migration/Makefile.objs b/migration/Makefile.objs
index 30ad945..cff96f0 100644
--- a/migration/Makefile.objs
+++ b/migration/Makefile.objs
@@ -1,5 +1,6 @@
 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 += vmstate.o
 common-obj-y += qemu-file.o
 common-obj-y += qemu-file-channel.o
diff --git a/migration/colo.c b/migration/colo.c
new file mode 100644
index 0000000..d215057
--- /dev/null
+++ b/migration/colo.c
@@ -0,0 +1,19 @@
+/*
+ * 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"
+
+bool colo_supported(void)
+{
+    return false;
+}
diff --git a/migration/migration.c b/migration/migration.c
index 4d417b7..f7dd9c6 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -36,6 +36,7 @@
 #include "exec/address-spaces.h"
 #include "io/channel-buffer.h"
 #include "io/channel-tls.h"
+#include "migration/colo.h"
 
 #define MAX_THROTTLE  (32 << 20)      /* Migration transfer speed throttling */
 
@@ -531,6 +532,9 @@ MigrationCapabilityStatusList 
*qmp_query_migrate_capabilities(Error **errp)
 
     caps = NULL; /* silence compiler warning */
     for (i = 0; i < MIGRATION_CAPABILITY__MAX; i++) {
+        if (i == MIGRATION_CAPABILITY_X_COLO && !colo_supported()) {
+            continue;
+        }
         if (head == NULL) {
             head = g_malloc0(sizeof(*caps));
             caps = head;
@@ -733,6 +737,14 @@ void 
qmp_migrate_set_capabilities(MigrationCapabilityStatusList *params,
     }
 
     for (cap = params; cap; cap = cap->next) {
+        if (cap->value->capability == MIGRATION_CAPABILITY_X_COLO) {
+            if (!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;
     }
 
@@ -1712,6 +1724,12 @@ fail:
                       MIGRATION_STATUS_FAILED);
 }
 
+bool migrate_colo_enabled(void)
+{
+    MigrationState *s = migrate_get_current();
+    return s->enabled_capabilities[MIGRATION_CAPABILITY_X_COLO];
+}
+
 /*
  * Master migration thread on the source VM.
  * It drives the migration and pumps the data down the outgoing channel.
diff --git a/qapi-schema.json b/qapi-schema.json
index ded1179..bed3d9e 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -574,11 +574,15 @@
 #          been migrated, pulling the remaining pages along as needed. NOTE: If
 #          the migration fails during postcopy the VM will fail.  (since 2.6)
 #
+# @x-colo: If enabled, migration will never end, and the state of the VM on the
+#        primary side will be migrated continuously to the VM on secondary
+#        side. (since 2.8)
+#
 # Since: 1.2
 ##
 { 'enum': 'MigrationCapability',
   'data': ['xbzrle', 'rdma-pin-all', 'auto-converge', 'zero-blocks',
-           'compress', 'events', 'postcopy-ram'] }
+           'compress', 'events', 'postcopy-ram', 'x-colo'] }
 
 ##
 # @MigrationCapabilityStatus
diff --git a/stubs/Makefile.objs b/stubs/Makefile.objs
index c5850e8..005c03f 100644
--- a/stubs/Makefile.objs
+++ b/stubs/Makefile.objs
@@ -48,3 +48,4 @@ stub-obj-y += iohandler.o
 stub-obj-y += smbios_type_38.o
 stub-obj-y += ipmi.o
 stub-obj-y += pc_madt_cpu_entry.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..d215057
--- /dev/null
+++ b/stubs/migration-colo.c
@@ -0,0 +1,19 @@
+/*
+ * 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"
+
+bool colo_supported(void)
+{
+    return false;
+}
-- 
1.8.3.1