qemu: add vhostfd and disable-modern to vsock hotplug

`vhostfd` is used to specify the vhost-vsock device fd, and it holds
the context ID previously opened.

`disable-modern` is to disable the use of "modern" devices, by using virtio 0.9
instead of virtio 1.0. Particularly, this is useful when running the VM in a
nested environment.

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

qemu/qmp.go

@@ -883,11 +883,17 @@ func (q *QMP) ExecHotplugMemory(ctx context.Context, qomtype, id, mempath string
 }
 
 // ExecutePCIVSockAdd adds a vhost-vsock-pci bus
-func (q *QMP) ExecutePCIVSockAdd(ctx context.Context, id, guestCID string) error {
+func (q *QMP) ExecutePCIVSockAdd(ctx context.Context, id, guestCID, vhostfd string, disableModern bool) error {
 	args := map[string]interface{}{
 		"driver":    VHostVSockPCI,
 		"id":        id,
 		"guest-cid": guestCID,
+		"vhostfd":   vhostfd,
 	}
+
+	if disableModern {
+		args["disable-modern"] = disableModern
+	}
+
 	return q.executeCommand(ctx, "device_add", args, nil)
 }

qemu/qmp_test.go

@@ -955,7 +955,7 @@ func TestExecutePCIVSockAdd(t *testing.T) {
 	cfg := QMPConfig{Logger: qmpTestLogger{}}
 	q := startQMPLoop(buf, cfg, connectedCh, disconnectedCh)
 	checkVersion(t, connectedCh)
-	err := q.ExecutePCIVSockAdd(context.Background(), "vsock-pci0", "3")
+	err := q.ExecutePCIVSockAdd(context.Background(), "vsock-pci0", "3", "1", true)
 	if err != nil {
 		t.Fatalf("Unexpected error %v", err)
 	}