scsi: Add function to send device_add qmp command for a scsi device

device_add qmp command for scsi devices accepts additional parameters like
scsi-id and lun. Implement function to add scsi devices. Devices
with drivers "scsi-hd", "scsi-cd" and "scsi-disk" are accepted.

Signed-off-by: Archana Shinde <archana.m.shinde@intel.com>

qemu/qmp.go

@@ -672,6 +672,45 @@ func (q *QMP) ExecuteDeviceAdd(ctx context.Context, blockdevID, devID, driver, b
 	return q.executeCommand(ctx, "device_add", args, nil)
 }
 
+// ExecuteSCSIDeviceAdd adds the guest portion of a block device to a QEMU instance
+// using a SCSI driver with the device_add command.  blockdevID should match the
+// blockdevID passed to a previous call to ExecuteBlockdevAdd.  devID is the id of
+// the device to add.  Both strings must be valid QMP identifiers.  driver is the name of the
+// scsi driver,e.g., scsi-hd, and bus is the name of a SCSI controller bus.
+// scsiID is the SCSI id, lun is logical unit number. scsiID and lun are optional, a negative value
+// for scsiID and lun is ignored.
+func (q *QMP) ExecuteSCSIDeviceAdd(ctx context.Context, blockdevID, devID, driver, bus string, scsiID, lun int) error {
+	// TBD: Add drivers for scsi passthrough like scsi-generic and scsi-block
+	drivers := []string{"scsi-hd", "scsi-cd", "scsi-disk"}
+
+	isSCSIDriver := false
+	for _, d := range drivers {
+		if driver == d {
+			isSCSIDriver = true
+			break
+		}
+	}
+
+	if !isSCSIDriver {
+		return fmt.Errorf("Invalid SCSI driver provided %s", driver)
+	}
+
+	args := map[string]interface{}{
+		"id":     devID,
+		"driver": driver,
+		"drive":  blockdevID,
+		"bus":    bus,
+	}
+	if scsiID >= 0 {
+		args["scsi-id"] = scsiID
+	}
+	if lun >= 0 {
+		args["lun"] = lun
+	}
+
+	return q.executeCommand(ctx, "device_add", args, nil)
+}
+
 // ExecuteBlockdevDel deletes a block device by sending a x-blockdev-del command
 // for qemu versions < 2.9. It sends the updated blockdev-del command for qemu>=2.9.
 // blockdevID is the id of the block device to be deleted.  Typically, this will

qemu/qmp_test.go

@@ -389,6 +389,31 @@ func TestQMPDeviceAdd(t *testing.T) {
 	<-disconnectedCh
 }
 
+// Checks that the device_add command for scsi is correctly sent.
+//
+// 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 TestQMPSCSIDeviceAdd(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)
+	blockdevID := fmt.Sprintf("drive_%s", volumeUUID)
+	devID := fmt.Sprintf("device_%s", volumeUUID)
+	err := q.ExecuteSCSIDeviceAdd(context.Background(), blockdevID, devID,
+		"scsi-hd", "scsi0.0", 1, 2)
+	if err != nil {
+		t.Fatalf("Unexpected error %v", err)
+	}
+	q.Shutdown()
+	<-disconnectedCh
+}
+
 // Checks that the x-blockdev-del command is correctly sent.
 //
 // We start a QMPLoop, send the x-blockdev-del command and stop the loop.