[PULL,20/40] migration: mode parameter

diff --git a/qapi/migration.json b/qapi/migration.json
index e6610af428..47c02a9346 100644
--- a/qapi/migration.json
+++ b/qapi/migration.json
@@ -631,6 +631,15 @@ 
   'data': [ 'none', 'zlib',
             { 'name': 'zstd', 'if': 'CONFIG_ZSTD' } ] }
 
+##
+# @MigMode:
+#
+# @normal: the original form of migration. (since 8.2)
+#
+##
+{ 'enum': 'MigMode',
+  'data': [ 'normal' ] }
+
 ##
 # @BitmapMigrationBitmapAliasTransform:
 #
@@ -849,6 +858,9 @@ 
 # @vcpu-dirty-limit: Dirtyrate limit (MB/s) during live migration.
 #     Defaults to 1.  (Since 8.1)
 #
+# @mode: Migration mode. See description in @MigMode. Default is 'normal'.
+#        (Since 8.2)
+#
 # Features:
 #
 # @deprecated: Member @block-incremental is deprecated.  Use
@@ -881,7 +893,8 @@ 
            'multifd-zlib-level', 'multifd-zstd-level',
            'block-bitmap-mapping',
            { 'name': 'x-vcpu-dirty-limit-period', 'features': ['unstable'] },
-           'vcpu-dirty-limit'] }
+           'vcpu-dirty-limit',
+           'mode'] }
 
 ##
 # @MigrateSetParameters:
@@ -1033,6 +1046,9 @@ 
 # @vcpu-dirty-limit: Dirtyrate limit (MB/s) during live migration.
 #     Defaults to 1.  (Since 8.1)
 #
+# @mode: Migration mode. See description in @MigMode. Default is 'normal'.
+#        (Since 8.2)
+#
 # Features:
 #
 # @deprecated: Member @block-incremental is deprecated.  Use
@@ -1085,7 +1101,8 @@ 
             '*block-bitmap-mapping': [ 'BitmapMigrationNodeAlias' ],
             '*x-vcpu-dirty-limit-period': { 'type': 'uint64',
                                             'features': [ 'unstable' ] },
-            '*vcpu-dirty-limit': 'uint64'} }
+            '*vcpu-dirty-limit': 'uint64',
+            '*mode': 'MigMode'} }
 
 ##
 # @migrate-set-parameters:
@@ -1257,6 +1274,9 @@ 
 # @vcpu-dirty-limit: Dirtyrate limit (MB/s) during live migration.
 #     Defaults to 1.  (Since 8.1)
 #
+# @mode: Migration mode. See description in @MigMode. Default is 'normal'.
+#        (Since 8.2)
+#
 # Features:
 #
 # @deprecated: Member @block-incremental is deprecated.  Use
@@ -1306,7 +1326,8 @@ 
             '*block-bitmap-mapping': [ 'BitmapMigrationNodeAlias' ],
             '*x-vcpu-dirty-limit-period': { 'type': 'uint64',
                                             'features': [ 'unstable' ] },
-            '*vcpu-dirty-limit': 'uint64'} }
+            '*vcpu-dirty-limit': 'uint64',
+            '*mode': 'MigMode'} }
 
 ##
 # @query-migrate-parameters:
diff --git a/include/hw/qdev-properties-system.h b/include/hw/qdev-properties-system.h
index e4f8a13afc..91f7a2452d 100644
--- a/include/hw/qdev-properties-system.h
+++ b/include/hw/qdev-properties-system.h
@@ -7,6 +7,7 @@  extern const PropertyInfo qdev_prop_chr;
 extern const PropertyInfo qdev_prop_macaddr;
 extern const PropertyInfo qdev_prop_reserved_region;
 extern const PropertyInfo qdev_prop_multifd_compression;
+extern const PropertyInfo qdev_prop_mig_mode;
 extern const PropertyInfo qdev_prop_losttickpolicy;
 extern const PropertyInfo qdev_prop_blockdev_on_error;
 extern const PropertyInfo qdev_prop_bios_chs_trans;
@@ -42,6 +43,9 @@  extern const PropertyInfo qdev_prop_cpus390entitlement;
 #define DEFINE_PROP_MULTIFD_COMPRESSION(_n, _s, _f, _d) \
     DEFINE_PROP_SIGNED(_n, _s, _f, _d, qdev_prop_multifd_compression, \
                        MultiFDCompression)
+#define DEFINE_PROP_MIG_MODE(_n, _s, _f, _d) \
+    DEFINE_PROP_SIGNED(_n, _s, _f, _d, qdev_prop_mig_mode, \
+                       MigMode)
 #define DEFINE_PROP_LOSTTICKPOLICY(_n, _s, _f, _d) \
     DEFINE_PROP_SIGNED(_n, _s, _f, _d, qdev_prop_losttickpolicy, \
                         LostTickPolicy)
diff --git a/include/migration/misc.h b/include/migration/misc.h
index 673ac490fb..1bc8902e6d 100644
--- a/include/migration/misc.h
+++ b/include/migration/misc.h
@@ -15,6 +15,7 @@ 
 #define MIGRATION_MISC_H
 
 #include "qemu/notify.h"
+#include "qapi/qapi-types-migration.h"
 #include "qapi/qapi-types-net.h"
 
 /* migration/ram.c */
diff --git a/migration/options.h b/migration/options.h
index 237f2d6b4a..246c160aee 100644
--- a/migration/options.h
+++ b/migration/options.h
@@ -83,6 +83,7 @@  uint8_t migrate_max_cpu_throttle(void);
 uint64_t migrate_max_bandwidth(void);
 uint64_t migrate_avail_switchover_bandwidth(void);
 uint64_t migrate_max_postcopy_bandwidth(void);
+MigMode migrate_mode(void);
 int migrate_multifd_channels(void);
 MultiFDCompression migrate_multifd_compression(void);
 int migrate_multifd_zlib_level(void);
diff --git a/hw/core/qdev-properties-system.c b/hw/core/qdev-properties-system.c
index 7c6dfab128..b9179e8917 100644
--- a/hw/core/qdev-properties-system.c
+++ b/hw/core/qdev-properties-system.c
@@ -673,6 +673,20 @@  const PropertyInfo qdev_prop_multifd_compression = {
     .set_default_value = qdev_propinfo_set_default_value_enum,
 };
 
+/* --- MigMode --- */
+
+QEMU_BUILD_BUG_ON(sizeof(MigMode) != sizeof(int));
+
+const PropertyInfo qdev_prop_mig_mode = {
+    .name = "MigMode",
+    .description = "mig_mode values, "
+                   "normal",
+    .enum_table = &MigMode_lookup,
+    .get = qdev_propinfo_get_enum,
+    .set = qdev_propinfo_set_enum,
+    .set_default_value = qdev_propinfo_set_default_value_enum,
+};
+
 /* --- Reserved Region --- */
 
 /*
diff --git a/migration/migration-hmp-cmds.c b/migration/migration-hmp-cmds.c
index dfe98da355..a170440991 100644
--- a/migration/migration-hmp-cmds.c
+++ b/migration/migration-hmp-cmds.c
@@ -387,6 +387,11 @@  void hmp_info_migrate_parameters(Monitor *mon, const QDict *qdict)
         monitor_printf(mon, "%s: %" PRIu64 " MB/s\n",
             MigrationParameter_str(MIGRATION_PARAMETER_VCPU_DIRTY_LIMIT),
             params->vcpu_dirty_limit);
+
+        assert(params->has_mode);
+        monitor_printf(mon, "%s: %s\n",
+            MigrationParameter_str(MIGRATION_PARAMETER_MODE),
+            qapi_enum_lookup(&MigMode_lookup, params->mode));
     }
 
     qapi_free_MigrationParameters(params);
@@ -661,6 +666,10 @@  void hmp_migrate_set_parameter(Monitor *mon, const QDict *qdict)
         p->has_vcpu_dirty_limit = true;
         visit_type_size(v, param, &p->vcpu_dirty_limit, &err);
         break;
+    case MIGRATION_PARAMETER_MODE:
+        p->has_mode = true;
+        visit_type_MigMode(v, param, &p->mode, &err);
+        break;
     default:
         assert(0);
     }
diff --git a/migration/options.c b/migration/options.c
index 9a39826ca5..8d8ec73ad9 100644
--- a/migration/options.c
+++ b/migration/options.c
@@ -176,6 +176,9 @@  Property migration_properties[] = {
     DEFINE_PROP_UINT64("vcpu-dirty-limit", MigrationState,
                        parameters.vcpu_dirty_limit,
                        DEFAULT_MIGRATE_VCPU_DIRTY_LIMIT),
+    DEFINE_PROP_MIG_MODE("mode", MigrationState,
+                      parameters.mode,
+                      MIG_MODE_NORMAL),
 
     /* Migration capabilities */
     DEFINE_PROP_MIG_CAP("x-xbzrle", MIGRATION_CAPABILITY_XBZRLE),
@@ -827,6 +830,13 @@  uint64_t migrate_max_postcopy_bandwidth(void)
     return s->parameters.max_postcopy_bandwidth;
 }
 
+MigMode migrate_mode(void)
+{
+    MigrationState *s = migrate_get_current();
+
+    return s->parameters.mode;
+}
+
 int migrate_multifd_channels(void)
 {
     MigrationState *s = migrate_get_current();
@@ -999,6 +1009,8 @@  MigrationParameters *qmp_query_migrate_parameters(Error **errp)
     params->x_vcpu_dirty_limit_period = s->parameters.x_vcpu_dirty_limit_period;
     params->has_vcpu_dirty_limit = true;
     params->vcpu_dirty_limit = s->parameters.vcpu_dirty_limit;
+    params->has_mode = true;
+    params->mode = s->parameters.mode;
 
     return params;
 }
@@ -1034,6 +1046,7 @@  void migrate_params_init(MigrationParameters *params)
     params->has_announce_step = true;
     params->has_x_vcpu_dirty_limit_period = true;
     params->has_vcpu_dirty_limit = true;
+    params->has_mode = true;
 }
 
 /*
@@ -1331,6 +1344,10 @@  static void migrate_params_test_apply(MigrateSetParameters *params,
     if (params->has_vcpu_dirty_limit) {
         dest->vcpu_dirty_limit = params->vcpu_dirty_limit;
     }
+
+    if (params->has_mode) {
+        dest->mode = params->mode;
+    }
 }
 
 static void migrate_params_apply(MigrateSetParameters *params, Error **errp)
@@ -1471,6 +1488,10 @@  static void migrate_params_apply(MigrateSetParameters *params, Error **errp)
     if (params->has_vcpu_dirty_limit) {
         s->parameters.vcpu_dirty_limit = params->vcpu_dirty_limit;
     }
+
+    if (params->has_mode) {
+        s->parameters.mode = params->mode;
+    }
 }
 
 void qmp_migrate_set_parameters(MigrateSetParameters *params, Error **errp)