func: static int vhost_user_start(VhostUserState *s)
  
  {
  
      VhostNetOptions options;
  
  
  
      if (vhost_user_running(s)) {
  
          return 0;
  
      }
  
  
  
      options.backend_type = VHOST_BACKEND_TYPE_USER;
  
      options.net_backend = &s->nc;
  
      options.opaque = s->chr;
  
  
  
      s->vhost_net = vhost_net_init(&options);
  
  
  
      return vhost_user_running(s) ? 0 : -1;
  
  }
  