Add support for hot-plugging IBM VFIO-AP devices

Add ExecuteAPVFIOMediatedDeviceAdd to qmp.go, which executes a hotplug
for an IBM Adjunct processor (AP) VFIO device (see also
https://www.kernel.org/doc/html/latest/s390/vfio-ap.html )
Also includes the respective unittest and adds the VfioAP DeviceDriver
constant to qemu.go.

Pushing again due to incidental CI failure

Fixes: #133

Signed-off-by: Jakob-Naucke <jakob.naucke@ibm.com>
Reviewed-by: alicefr <afrosi@redhat.com>

qemu/qemu.go

@@ -123,6 +123,9 @@ const (
 	// VfioCCW is the vfio driver with CCW transport.
 	VfioCCW DeviceDriver = "vfio-ccw"
 
+	// VfioAP is the vfio driver with AP transport.
+	VfioAP DeviceDriver = "vfio-ap"
+
 	// VHostVSockPCI is a generic Vsock vhost device with PCI transport.
 	VHostVSockPCI DeviceDriver = "vhost-vsock-pci"
 

qemu/qmp.go

@@ -1217,6 +1217,15 @@ func (q *QMP) ExecutePCIVFIOMediatedDeviceAdd(ctx context.Context, devID, sysfsd
 	return q.executeCommand(ctx, "device_add", args, nil)
 }
 
+// ExecuteAPVFIOMediatedDeviceAdd adds a VFIO mediated AP device to a QEMU instance using the device_add command.
+func (q *QMP) ExecuteAPVFIOMediatedDeviceAdd(ctx context.Context, sysfsdev string) error {
+	args := map[string]interface{}{
+		"driver":   VfioAP,
+		"sysfsdev": sysfsdev,
+	}
+	return q.executeCommand(ctx, "device_add", args, nil)
+}
+
 // isSocketIDSupported returns if the cpu driver supports the socket id option
 func isSocketIDSupported(driver string) bool {
 	if driver == "host-s390x-cpu" || driver == "host-powerpc64-cpu" {

qemu/qmp_test.go

@@ -1100,6 +1100,23 @@ func TestQMPPCIVFIOPCIeDeviceAdd(t *testing.T) {
 	<-disconnectedCh
 }
 
+func TestQMPAPVFIOMediatedDeviceAdd(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/devices/vfio_ap/matrix/a297db4a-f4c2-11e6-90f6-d3b88d6c9525"
+	err := q.ExecuteAPVFIOMediatedDeviceAdd(context.Background(), sysfsDev)
+	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) {
 	drivers := []string{"host-x86_64-cpu", "host-s390x-cpu", "host-powerpc64-cpu"}