qemu/qmp: implement function to hotplug serial ports

Implement function to hotplug virtio serial ports, the serial ports
are visible in the guest at the directory /dev/virtio-ports.

Signed-off-by: Julio Montes <julio.montes@intel.com>

qemu/qmp.go

@@ -986,3 +986,17 @@ func (q *QMP) ExecuteCharDevUnixSocketAdd(ctx context.Context, id, path string,
 	}
 	return q.executeCommand(ctx, "chardev-add", args, nil)
 }
+
+// ExecuteVirtSerialPortAdd adds a virtserialport.
+// id is an identifier for the virtserialport, name is a name for the virtserialport and
+// it will be visible in the VM, chardev is the character device id previously added.
+func (q *QMP) ExecuteVirtSerialPortAdd(ctx context.Context, id, name, chardev string) error {
+	args := map[string]interface{}{
+		"driver":  VirtioSerialPort,
+		"id":      id,
+		"name":    name,
+		"chardev": chardev,
+	}
+
+	return q.executeCommand(ctx, "device_add", args, nil)
+}

qemu/qmp_test.go

@@ -1057,3 +1057,20 @@ func TestExecuteCharDevUnixSocketAdd(t *testing.T) {
 	q.Shutdown()
 	<-disconnectedCh
 }
+
+// Checks virtio serial port hotplug
+func TestExecuteVirtSerialPortAdd(t *testing.T) {
+	connectedCh := make(chan *QMPVersion)
+	disconnectedCh := make(chan struct{})
+	buf := newQMPTestCommandBuffer(t)
+	buf.AddCommand("device_add", nil, "return", nil)
+	cfg := QMPConfig{Logger: qmpTestLogger{}}
+	q := startQMPLoop(buf, cfg, connectedCh, disconnectedCh)
+	checkVersion(t, connectedCh)
+	err := q.ExecuteVirtSerialPortAdd(context.Background(), "foo", "foo.channel", "foo")
+	if err != nil {
+		t.Fatalf("Unexpected error %v", err)
+	}
+	q.Shutdown()
+	<-disconnectedCh
+}