qemu/qmp: add vfio mediated device support

In addition to normal VFIO device, this patch adds VFIO mediated device
as a supplement to do hot plug on PCI(E) bridges.

Signed-off-by: Zhao Xinda <xinda.zhao@intel.com>

qemu/qmp.go

@@ -837,6 +837,24 @@ func (q *QMP) ExecutePCIVFIODeviceAdd(ctx context.Context, devID, bdf, addr, bus
 	return q.executeCommand(ctx, "device_add", args, nil)
 }
 
+// ExecutePCIVFIOMediatedDeviceAdd adds a VFIO mediated device to a QEMU instance using the device_add command.
+// This function can be used to hot plug VFIO mediated devices on PCI(E) bridges, unlike
+// ExecuteVFIODeviceAdd this function receives the bus and the device address on its parent bus.
+// bus is optional. devID is the id of the device to add. Must be valid QMP identifier. sysfsdev is the VFIO
+// mediated device.
+func (q *QMP) ExecutePCIVFIOMediatedDeviceAdd(ctx context.Context, devID, sysfsdev, addr, bus string) error {
+	args := map[string]interface{}{
+		"id":       devID,
+		"driver":   "vfio-pci",
+		"sysfsdev": sysfsdev,
+		"addr":     addr,
+	}
+	if bus != "" {
+		args["bus"] = bus
+	}
+	return q.executeCommand(ctx, "device_add", args, nil)
+}
+
 // ExecuteCPUDeviceAdd adds a CPU to a QEMU instance using the device_add command.
 // driver is the CPU model, cpuID must be a unique ID to identify the CPU, socketID is the socket number within
 // node/board the CPU belongs to, coreID is the core number within socket the CPU belongs to, threadID is the

qemu/qmp_test.go

@@ -892,6 +892,30 @@ func TestQMPPCIDeviceAdd(t *testing.T) {
 	<-disconnectedCh
 }
 
+// Checks that PCI VFIO mediated devices are correctly added using device_add.
+//
+// We start a QMPLoop, send the device_add command and stop the loop.
+//
+// The device_add command should be correctly sent and the QMP loop should
+// exit gracefully.
+func TestQMPPCIVFIOMediatedDeviceAdd(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)
+	sysfsDev := "/sys/bus/pci/devices/0000:00:02.0/a297db4a-f4c2-11e6-90f6-d3b88d6c9525"
+	devID := fmt.Sprintf("device_%s", volumeUUID)
+	err := q.ExecutePCIVFIOMediatedDeviceAdd(context.Background(), devID, sysfsDev, "0x1", "")
+	if err != nil {
+		t.Fatalf("Unexpected error %v", err)
+	}
+	q.Shutdown()
+	<-disconnectedCh
+}
+
 // Checks that CPU are correctly added using device_add
 func TestQMPCPUDeviceAdd(t *testing.T) {
 	connectedCh := make(chan *QMPVersion)