qmp: support command 'query-qmp-schema'

The upper hyervisor manager application maybe need to wait some
QMP event to control boot sequence, but the event we wanted maybe
not exist in some older version, so we need query all QMP ABI and
check the event is supported or not.

related: kata-containers/runtime#1918

Signed-off-by: Ning Bo <ning.bo9@zte.com.cn>

qemu/qmp_test.go

@@ -1588,3 +1588,38 @@ func TestMainLoopEventBeforeGreeting(t *testing.T) {
 	q.Shutdown()
 	<-disconnectedCh
 }
+
+func TestQMPExecQueryQmpSchema(t *testing.T) {
+	connectedCh := make(chan *QMPVersion)
+	disconnectedCh := make(chan struct{})
+	buf := newQMPTestCommandBuffer(t)
+	schemaInfo := []SchemaInfo{
+		{
+			MetaType: "command",
+			Name:     "object-add",
+		},
+		{
+			MetaType: "event",
+			Name:     "VSOCK_RUNNING",
+		},
+	}
+	buf.AddCommand("query-qmp-schema", nil, "return", schemaInfo)
+	cfg := QMPConfig{
+		Logger:      qmpTestLogger{},
+		MaxCapacity: 1024,
+	}
+	q := startQMPLoop(buf, cfg, connectedCh, disconnectedCh)
+	checkVersion(t, connectedCh)
+	info, err := q.ExecQueryQmpSchema(context.Background())
+	if err != nil {
+		t.Fatalf("Unexpected error: %v\n", err)
+	}
+	if len(schemaInfo) != 2 {
+		t.Fatalf("Expected schema infos length equals to 2\n")
+	}
+	if reflect.DeepEqual(info, schemaInfo) == false {
+		t.Fatalf("Expected %v equals to %v\n", info, schemaInfo)
+	}
+	q.Shutdown()
+	<-disconnectedCh
+}