[Qemu-devel] [PATCH RFC v3 02/27] migration: Introduce capability 'colo' to migration

[zhanghailiang]

This capability allows Primary VM (PVM) to be continuously checkpointed
to secondary VM.

Signed-off-by: zhanghailiang <address@hidden>
Signed-off-by: Yang Hongyang <address@hidden>
Signed-off-by: Gonglei <address@hidden>
Signed-off-by: Lai Jiangshan <address@hidden>
---
 include/migration/migration.h |  1 +
 migration/migration.c         | 15 +++++++++++++++
 qapi-schema.json              |  5 ++++-
 3 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/include/migration/migration.h b/include/migration/migration.h
index f37348b..3f5c705 100644
--- a/include/migration/migration.h
+++ b/include/migration/migration.h
@@ -154,6 +154,7 @@ 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/migration.c b/migration/migration.c
index b3adbc6..8403c8a 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -276,6 +276,15 @@ void 
qmp_migrate_set_capabilities(MigrationCapabilityStatusList *params,
     }
 
     for (cap = params; cap; cap = cap->next) {
+#ifndef CONFIG_COLO
+        if (cap->value->capability == MIGRATION_CAPABILITY_COLO &&
+            cap->value->state) {
+            error_setg(errp, "COLO is not currently supported, please"
+                             " configure with --enable-colo option in order to"
+                             " support COLO feature");
+            continue;
+        }
+#endif
         s->enabled_capabilities[cap->value->capability] = cap->value->state;
     }
 }
@@ -585,6 +594,12 @@ 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 e16f8eb..8c59e50 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -494,10 +494,13 @@
 # @auto-converge: If enabled, QEMU will automatically throttle down the guest
 #          to speed up convergence of RAM migration. (since 1.6)
 #
+# @colo: If enabled, the migration will never end, and the VM will instead be
+#          continuously checkpointed. (since 2.3)
+#
 # 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
-- 
1.7.12.4