[v3,26/35] postcopy/outgoing: add -n options to disable background transfer

diff --git a/hmp-commands.hx b/hmp-commands.hx
index f2f1264..b054760 100644
--- a/hmp-commands.hx
+++ b/hmp-commands.hx
@@ -826,25 +826,27 @@  ETEXI
 
     {
         .name       = "migrate",
-        .args_type  = "detach:-d,blk:-b,inc:-i,postcopy:-p,uri:s",
-        .params     = "[-d] [-b] [-i] [-p] uri",
+        .args_type  = "detach:-d,blk:-b,inc:-i,postcopy:-p,nobg:-n,uri:s",
+        .params     = "[-d] [-b] [-i] [-p [-n]] uri",
         .help       = "migrate to URI (using -d to not wait for completion)"
 		      "\n\t\t\t -b for migration without shared storage with"
 		      " full copy of disk\n\t\t\t -i for migration without "
 		      "shared storage with incremental copy of disk "
 		      "(base image shared between src and destination)"
-		      "\n\t\t\t-p for migration with postcopy mode enabled",
+		      "\n\t\t\t-p for migration with postcopy mode enabled"
+		      "\n\t\t\t-n for no background transfer of postcopy mode",
         .mhandler.cmd = hmp_migrate,
     },
 
 
 STEXI
-@item migrate [-d] [-b] [-i] [-p] @var{uri}
+@item migrate [-d] [-b] [-i] [-p [-n]] @var{uri}
 @findex migrate
 Migrate to @var{uri} (using -d to not wait for completion).
 	-b for migration with full copy of disk
 	-i for migration with incremental copy of disk (base image is shared)
 	-p for migration with postcopy mode enabled
+	-n for migration with postcopy mode enabled without background transfer
 ETEXI
 
     {
diff --git a/hmp.c b/hmp.c
index 2ea3bc4..203b552 100644
--- a/hmp.c
+++ b/hmp.c
@@ -1036,11 +1036,13 @@  void hmp_migrate(Monitor *mon, const QDict *qdict)
     int blk = qdict_get_try_bool(qdict, "blk", 0);
     int inc = qdict_get_try_bool(qdict, "inc", 0);
     int postcopy = qdict_get_try_bool(qdict, "postcopy", 0);
+    int nobg = qdict_get_try_bool(qdict, "nobg", 0);
     const char *uri = qdict_get_str(qdict, "uri");
     Error *err = NULL;
 
     qmp_migrate(uri, !!blk, blk, !!inc, inc, false, false,
-                !!postcopy, postcopy, &err);
+                !!postcopy, postcopy, !!nobg, nobg,
+                &err);
     if (err) {
         monitor_printf(mon, "migrate: %s\n", error_get_pretty(err));
         error_free(err);
diff --git a/migration-postcopy.c b/migration-postcopy.c
index 399e233..5f98ae6 100644
--- a/migration-postcopy.c
+++ b/migration-postcopy.c
@@ -557,6 +557,13 @@  int postcopy_outgoing_ram_save_background(QEMUFile *f, void *postcopy)
         abort();
     }
 
+    if (s->ms->params.nobg) {
+        if (ram_bytes_remaining() == 0) {
+            postcopy_outgoing_ram_all_sent(f, s);
+        }
+        return 0;
+    }
+
     DPRINTF("outgoing background state: %d\n", s->state);
     i = 0;
     t0 = qemu_get_clock_ns(rt_clock);
diff --git a/migration.c b/migration.c
index 85f8f71..279dda5 100644
--- a/migration.c
+++ b/migration.c
@@ -510,7 +510,8 @@  void migrate_del_blocker(Error *reason)
 
 void qmp_migrate(const char *uri, bool has_blk, bool blk,
                  bool has_inc, bool inc, bool has_detach, bool detach,
-                 bool has_postcopy, bool postcopy, Error **errp)
+                 bool has_postcopy, bool postcopy, bool has_nobg, bool nobg,
+                 Error **errp)
 {
     MigrationState *s = migrate_get_current();
     MigrationParams params;
@@ -520,6 +521,7 @@  void qmp_migrate(const char *uri, bool has_blk, bool blk,
     params.blk = blk;
     params.shared = inc;
     params.postcopy = postcopy;
+    params.nobg = nobg;
 
     if (s->state == MIG_STATE_ACTIVE) {
         error_set(errp, QERR_MIGRATION_ACTIVE);
diff --git a/migration.h b/migration.h
index 9b3c03b..6724c19 100644
--- a/migration.h
+++ b/migration.h
@@ -25,6 +25,7 @@  struct MigrationParams {
     bool blk;
     bool shared;
     bool postcopy;
+    bool nobg;
 };
 
 typedef struct MigrationState MigrationState;
diff --git a/qapi-schema.json b/qapi-schema.json
index c969e5a..70d0577 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -2095,7 +2095,7 @@ 
 ##
 { 'command': 'migrate',
   'data': {'uri': 'str', '*blk': 'bool', '*inc': 'bool', '*detach': 'bool' ,
-           '*postcopy': 'bool'} }
+           '*postcopy': 'bool', '*nobg': 'bool'} }
 
 # @xen-save-devices-state:
 #
diff --git a/qmp-commands.hx b/qmp-commands.hx
index ece7a7e..defbeba 100644
--- a/qmp-commands.hx
+++ b/qmp-commands.hx
@@ -518,7 +518,7 @@  EQMP
 
     {
         .name       = "migrate",
-        .args_type  = "detach:-d,blk:-b,inc:-i,postcopy:-p,uri:s",
+        .args_type  = "detach:-d,blk:-b,inc:-i,postcopy:-p,nobg:-n,uri:s",
         .mhandler.cmd_new = qmp_marshal_input_migrate,
     },
 
@@ -533,6 +533,7 @@  Arguments:
 - "blk": block migration, full disk copy (json-bool, optional)
 - "inc": incremental disk copy (json-bool, optional)
 - "postcopy": postcopy migration (json-bool, optional)
+- "nobg": postcopy without background transfer (json-bool, optional)
 - "uri": Destination URI (json-string)
 
 Example:
diff --git a/savevm.c b/savevm.c
index 675f9a5..0a3acd8 100644
--- a/savevm.c
+++ b/savevm.c
@@ -1839,6 +1839,7 @@  static int qemu_savevm_state(QEMUFile *f)
         .blk = 0,
         .shared = 0,
         .postcopy = 0,
+        .nobg = 0,
     };
 
     if (qemu_savevm_state_blocked(NULL)) {