[PATCH v2 1/7] Introduce 'track-writes-ram' migration capability.

[Andrey Gruzdev]

Signed-off-by: Andrey Gruzdev <andrey.gruzdev@virtuozzo.com>
---
 migration/migration.c | 96 +++++++++++++++++++++++++++++++++++++++++++
 migration/migration.h |  1 +
 qapi/migration.json   |  7 +++-
 3 files changed, 103 insertions(+), 1 deletion(-)

diff --git a/migration/migration.c b/migration/migration.c
index 87a9b59f83..ff0364dde0 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -56,6 +56,7 @@
 #include "net/announce.h"
 #include "qemu/queue.h"
 #include "multifd.h"
+#include "sysemu/cpus.h"
 
 #ifdef CONFIG_VFIO
 #include "hw/vfio/vfio-common.h"
@@ -1165,6 +1166,91 @@ static bool migrate_caps_check(bool *cap_list,
         }
     }
 
+    if (cap_list[MIGRATION_CAPABILITY_TRACK_WRITES_RAM]) {
+        if (cap_list[MIGRATION_CAPABILITY_POSTCOPY_RAM]) {
+            error_setg(errp,
+                    "Track-writes is not compatible with postcopy-ram");
+            return false;
+        }
+
+        if (cap_list[MIGRATION_CAPABILITY_DIRTY_BITMAPS]) {
+            error_setg(errp,
+                    "Track-writes is not compatible with dirty-bitmaps");
+            return false;
+        }
+
+        if (cap_list[MIGRATION_CAPABILITY_POSTCOPY_BLOCKTIME]) {
+            error_setg(errp,
+                    "Track-writes is not compatible with postcopy-blocktime");
+            return false;
+        }
+
+        if (cap_list[MIGRATION_CAPABILITY_LATE_BLOCK_ACTIVATE]) {
+            error_setg(errp,
+                    "Track-writes is not compatible with late-block-activate");
+            return false;
+        }
+
+        if (cap_list[MIGRATION_CAPABILITY_RETURN_PATH]) {
+            error_setg(errp,
+                    "Track-writes is not compatible with return-path");
+            return false;
+        }
+
+        if (cap_list[MIGRATION_CAPABILITY_MULTIFD]) {
+            error_setg(errp, "Track-writes is not compatible with multifd");
+            return false;
+        }
+
+        if (cap_list[MIGRATION_CAPABILITY_PAUSE_BEFORE_SWITCHOVER]) {
+            error_setg(errp,
+                    "Track-writes is not compatible with 
pause-before-switchover");
+            return false;
+        }
+
+        if (cap_list[MIGRATION_CAPABILITY_AUTO_CONVERGE]) {
+            error_setg(errp,
+                    "Track-writes is not compatible with auto-converge");
+            return false;
+        }
+
+        if (cap_list[MIGRATION_CAPABILITY_RELEASE_RAM]) {
+            error_setg(errp,
+                    "Track-writes is not compatible with release-ram");
+            return false;
+        }
+
+        if (cap_list[MIGRATION_CAPABILITY_RDMA_PIN_ALL]) {
+            error_setg(errp,
+                    "Track-writes is not compatible with rdma-pin-all");
+            return false;
+        }
+
+        if (cap_list[MIGRATION_CAPABILITY_COMPRESS]) {
+            error_setg(errp,
+                    "Track-writes is not compatible with compression");
+            return false;
+        }
+
+        if (cap_list[MIGRATION_CAPABILITY_XBZRLE]) {
+            error_setg(errp,
+                    "Track-writes is not compatible with XBZLRE");
+            return false;
+        }
+
+        if (cap_list[MIGRATION_CAPABILITY_X_COLO]) {
+            error_setg(errp,
+                    "Track-writes is not compatible with x-colo");
+            return false;
+        }
+
+        if (cap_list[MIGRATION_CAPABILITY_VALIDATE_UUID]) {
+            error_setg(errp,
+                    "Track-writes is not compatible with validate-uuid");
+            return false;
+        }
+    }
+
     return true;
 }
 
@@ -2490,6 +2576,15 @@ bool migrate_use_block_incremental(void)
     return s->parameters.block_incremental;
 }
 
+bool migrate_track_writes_ram(void)
+{
+    MigrationState *s;
+
+    s = migrate_get_current();
+
+    return s->enabled_capabilities[MIGRATION_CAPABILITY_TRACK_WRITES_RAM];
+}
+
 /* migration thread support */
 /*
  * Something bad happened to the RP stream, mark an error
@@ -3783,6 +3878,7 @@ static Property migration_properties[] = {
     DEFINE_PROP_MIG_CAP("x-block", MIGRATION_CAPABILITY_BLOCK),
     DEFINE_PROP_MIG_CAP("x-return-path", MIGRATION_CAPABILITY_RETURN_PATH),
     DEFINE_PROP_MIG_CAP("x-multifd", MIGRATION_CAPABILITY_MULTIFD),
+    DEFINE_PROP_MIG_CAP("x-track-writes-ram", 
MIGRATION_CAPABILITY_TRACK_WRITES_RAM),
 
     DEFINE_PROP_END_OF_LIST(),
 };
diff --git a/migration/migration.h b/migration/migration.h
index d096b77f74..339ae720e0 100644
--- a/migration/migration.h
+++ b/migration/migration.h
@@ -341,6 +341,7 @@ int migrate_compress_wait_thread(void);
 int migrate_decompress_threads(void);
 bool migrate_use_events(void);
 bool migrate_postcopy_blocktime(void);
+bool migrate_track_writes_ram(void);
 
 /* Sending on the return path - generic and then for each message type */
 void migrate_send_rp_shut(MigrationIncomingState *mis,
diff --git a/qapi/migration.json b/qapi/migration.json
index 3c75820527..03fe0547f1 100644
--- a/qapi/migration.json
+++ b/qapi/migration.json
@@ -442,6 +442,11 @@
 # @validate-uuid: Send the UUID of the source to allow the destination
 #                 to ensure it is the same. (since 4.2)
 #
+# @track-writes-ram: If enabled, the migration stream will be a snapshot
+#                    of the VM exactly at the point when the migration
+#                    procedure starts. The VM RAM is saved with running VM.
+#                    (since 5.2)
+#
 # Since: 1.2
 ##
 { 'enum': 'MigrationCapability',
@@ -449,7 +454,7 @@
            'compress', 'events', 'postcopy-ram', 'x-colo', 'release-ram',
            'block', 'return-path', 'pause-before-switchover', 'multifd',
            'dirty-bitmaps', 'postcopy-blocktime', 'late-block-activate',
-           'x-ignore-shared', 'validate-uuid' ] }
+           'x-ignore-shared', 'validate-uuid', 'track-writes-ram'] }
 
 ##
 # @MigrationCapabilityStatus:
-- 
2.25.1