qemu: add migration incoming defer support

qemu commandline supports -incoming defer
and qmp supports migrate-incoming uri.

Signed-off-by: Peng Tao <bergwolf@hyper.sh>

qemu/qemu.go

@@ -1397,6 +1397,8 @@ const (
 	MigrationFD = 1
 	// MigrationExec is the migration incoming type based on commands.
 	MigrationExec = 2
+	// MigrationDefer is the defer incoming type
+	MigrationDefer = 3
 )
 
 // Incoming controls migration source preparation
@@ -1779,6 +1781,8 @@ func (config *Config) appendIncoming() {
 	case MigrationFD:
 		chFDs := config.appendFDs([]*os.File{config.Incoming.FD})
 		uri = fmt.Sprintf("fd:%d", chFDs[0])
+	case MigrationDefer:
+		uri = "defer"
 	default:
 		return
 	}

qemu/qemu_test.go

@@ -725,6 +725,16 @@ func TestAppendIncomingExec(t *testing.T) {
 	testAppend(source, incomingStringExec, t)
 }
 
+var incomingStringDefer = "-S -incoming defer"
+
+func TestAppendIncomingDefer(t *testing.T) {
+	source := Incoming{
+		MigrationType: MigrationDefer,
+	}
+
+	testAppend(source, incomingStringDefer, t)
+}
+
 func TestBadName(t *testing.T) {
 	c := &Config{}
 	c.appendName()

qemu/qmp.go

@@ -1457,3 +1457,11 @@ func (q *QMP) ExecuteQueryMigration(ctx context.Context) (MigrationStatus, error
 
 	return status, nil
 }
+
+// ExecuteMigrationIncoming start migration from incoming uri.
+func (q *QMP) ExecuteMigrationIncoming(ctx context.Context, uri string) error {
+	args := map[string]interface{}{
+		"uri": uri,
+	}
+	return q.executeCommand(ctx, "migrate-incoming", args, nil)
+}

qemu/qmp_test.go

@@ -1349,6 +1349,23 @@ func TestExecuteVirtSerialPortAdd(t *testing.T) {
 	<-disconnectedCh
 }
 
+// Check migration incoming
+func TestExecuteMigrationIncoming(t *testing.T) {
+	connectedCh := make(chan *QMPVersion)
+	disconnectedCh := make(chan struct{})
+	buf := newQMPTestCommandBuffer(t)
+	buf.AddCommand("migrate-incoming", nil, "return", nil)
+	cfg := QMPConfig{Logger: qmpTestLogger{}}
+	q := startQMPLoop(buf, cfg, connectedCh, disconnectedCh)
+	checkVersion(t, connectedCh)
+	err := q.ExecuteMigrationIncoming(context.Background(), "uri")
+	if err != nil {
+		t.Fatalf("Unexpected error %v", err)
+	}
+	q.Shutdown()
+	<-disconnectedCh
+}
+
 // Checks migration status
 func TestExecuteQueryMigration(t *testing.T) {
 	connectedCh := make(chan *QMPVersion)