Allow the migrate and migrate_incoming commands to pass the migration
configuration options all at once, dispensing the use of
migrate-set-parameters and migrate-set-capabilities.

The motivation of this is to simplify the interface with the
management layer and avoid the usage of several command invocations to
configure a migration. It also avoids stale parameters from a previous
migration to influence the current migration.

The options that are changed during the migration can still be set
with the existing commands.

The order of precedence is:

'config' argument > migrate-set-parameters > -global migration cmdline
> defaults (migration_properties)

I.e. the config takes precedence over all, values not present in the
config assume the default values. The -global migration command line
option allows the defaults to be overridden for debug.

Reviewed-by: Peter Xu <[email protected]>
Signed-off-by: Fabiano Rosas <[email protected]>
---
 migration/migration-hmp-cmds.c |  5 +++--
 migration/migration.c          | 28 +++++++++++++++++++++++++---
 migration/options.c            | 19 +++++++++++++++++++
 migration/options.h            |  4 +++-
 qapi/migration.json            | 10 ++++++++++
 system/vl.c                    |  3 ++-
 6 files changed, 62 insertions(+), 7 deletions(-)

diff --git a/migration/migration-hmp-cmds.c b/migration/migration-hmp-cmds.c
index 7e5ac57da5..e9c3541352 100644
--- a/migration/migration-hmp-cmds.c
+++ b/migration/migration-hmp-cmds.c
@@ -672,7 +672,7 @@ void hmp_migrate_incoming(Monitor *mon, const QDict *qdict)
     }
     QAPI_LIST_PREPEND(caps, g_steal_pointer(&channel));
 
-    qmp_migrate_incoming(NULL, true, caps, true, false, &err);
+    qmp_migrate_incoming(NULL, true, caps, NULL, true, false, &err);
     qapi_free_MigrationChannelList(caps);
 
 end:
@@ -1070,7 +1070,8 @@ void hmp_migrate(Monitor *mon, const QDict *qdict)
     }
     QAPI_LIST_PREPEND(caps, g_steal_pointer(&channel));
 
-    qmp_migrate(NULL, true, caps, false, false, true, resume, &err);
+    qmp_migrate(NULL, true, caps, NULL, false, false, true, resume,
+                &err);
     if (hmp_handle_error(mon, err)) {
         return;
     }
diff --git a/migration/migration.c b/migration/migration.c
index 90b381b1fe..d23ab2905a 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -1930,13 +1930,24 @@ void migrate_del_blocker(Error **reasonp)
 
 void qmp_migrate_incoming(const char *uri, bool has_channels,
                           MigrationChannelList *channels,
-                          bool has_exit_on_error, bool exit_on_error,
-                          Error **errp)
+                          MigrationParameters *config, bool has_exit_on_error,
+                          bool exit_on_error, Error **errp)
 {
     Error *local_err = NULL;
     static bool once = true;
+    MigrationState *s = migrate_get_current();
     MigrationIncomingState *mis = migration_incoming_get_current();
 
+    if (config) {
+        /*
+         * If a config was provided, all options set previously by
+         * migrate-set-parameters get ignored.
+         */
+        if (!migrate_params_override(s, config, errp)) {
+            return;
+        }
+    }
+
     if (!once) {
         error_setg(errp, "The incoming migration has already been started");
         return;
@@ -2208,7 +2219,8 @@ static gboolean qmp_migrate_finish_cb(QIOChannel *channel,
 }
 
 void qmp_migrate(const char *uri, bool has_channels,
-                 MigrationChannelList *channels, bool has_detach, bool detach,
+                 MigrationChannelList *channels,
+                 bool has_detach, bool detach, MigrationParameters *config,
                  bool has_resume, bool resume, Error **errp)
 {
     bool resume_requested;
@@ -2219,6 +2231,16 @@ void qmp_migrate(const char *uri, bool has_channels,
     MigrationChannel *channelv[MIGRATION_CHANNEL_TYPE__MAX] = { NULL };
     MigrationChannel *cpr_channel = NULL;
 
+    if (config) {
+        /*
+         * If a config was provided, all options set previously by
+         * migrate-set-parameters get ignored.
+         */
+        if (!migrate_params_override(s, config, errp)) {
+            return;
+        }
+    }
+
     /*
      * Having preliminary checks for uri and channel
      */
diff --git a/migration/options.c b/migration/options.c
index d1d8e5c181..ccc25ad008 100644
--- a/migration/options.c
+++ b/migration/options.c
@@ -1389,6 +1389,25 @@ void migrate_params_store_defaults(MigrationState *s)
     s->initial_params = QAPI_CLONE(MigrationParameters, &s->parameters);
 }
 
+bool migrate_params_override(MigrationState *s, MigrationParameters *new,
+                             Error **errp)
+{
+    ERRP_GUARD();
+
+    assert(bql_locked());
+
+    /* reset to initial parameters */
+    migrate_params_apply(s->initial_params);
+
+    /* apply the new ones on top */
+    qmp_migrate_set_parameters(new, errp);
+    if (*errp) {
+        return false;
+    }
+
+    return true;
+}
+
 void qmp_migrate_set_parameters(MigrationParameters *params, Error **errp)
 {
     MigrationState *s = migrate_get_current();
diff --git a/migration/options.h b/migration/options.h
index 47f84bf180..29dee6f444 100644
--- a/migration/options.h
+++ b/migration/options.h
@@ -84,6 +84,8 @@ void migrate_capability_set_compat(MigrationParameters 
*params, int i,
                                    bool val);
 void migrate_capabilities_set_compat(MigrationParameters *params,
                                      MigrationCapabilityStatusList *caps);
-bool migrate_caps_check(const MigrationParameters *const new, Error **errp);
+bool migrate_caps_check(const MigrationParameters *new, Error **errp);
 void migrate_params_store_defaults(MigrationState *s);
+bool migrate_params_override(MigrationState *s, MigrationParameters *new,
+                             Error **errp);
 #endif
diff --git a/qapi/migration.json b/qapi/migration.json
index 76a1e03f2f..bd799d67e4 100644
--- a/qapi/migration.json
+++ b/qapi/migration.json
@@ -1546,6 +1546,10 @@
 #     will fail unless migration is in "postcopy-paused" state.
 #     (default: false, since 3.0)
 #
+# @config: migration configuration options.  When present, any
+#     migration configuration previously set with
+#     @migrate-set-parameters is ignored.  (since 11.0)
+#
 # Features:
 #
 # @deprecated: Argument @detach is deprecated.
@@ -1610,6 +1614,7 @@
   'data': {'*uri': 'str',
            '*channels': [ 'MigrationChannel' ],
            '*detach': { 'type': 'bool', 'features': [ 'deprecated' ] },
+           '*config': 'MigrationParameters',
            '*resume': 'bool' } }
 
 ##
@@ -1629,6 +1634,10 @@
 #     :qapi:event:`MIGRATION` event, and error details could be
 #     retrieved with `query-migrate`.  (since 9.1)
 #
+# @config: migration configuration options.  When present, any
+#     migration configuration previously set with
+#     @migrate-set-parameters is ignored.  (since 11.0)
+#
 # Since: 2.3
 #
 # .. admonition:: Notes
@@ -1682,6 +1691,7 @@
 { 'command': 'migrate-incoming',
              'data': {'*uri': 'str',
                       '*channels': [ 'MigrationChannel' ],
+                      '*config': 'MigrationParameters',
                       '*exit-on-error': 'bool' } }
 
 ##
diff --git a/system/vl.c b/system/vl.c
index 5091fe52d9..d09dc9a61c 100644
--- a/system/vl.c
+++ b/system/vl.c
@@ -2829,7 +2829,8 @@ void qmp_x_exit_preconfig(Error **errp)
                 g_new0(MigrationChannelList, 1);
 
             channels->value = incoming_channels[MIGRATION_CHANNEL_TYPE_MAIN];
-            qmp_migrate_incoming(NULL, true, channels, true, true, &local_err);
+            qmp_migrate_incoming(NULL, true, channels, NULL, true, true,
+                                 &local_err);
             if (local_err) {
                 error_reportf_err(local_err, "-incoming %s: ", incoming);
                 exit(1);
-- 
2.51.0


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