# File lib/vagrant-libvirt/config.rb, line 453
      def usb_controller(options = {})
        if options[:model].nil?
          raise 'USB controller model must be specified.'
        end

        if @usbctl_dev == UNSET_VALUE
            @usbctl_dev = {}
        end

        @usbctl_dev[:model] = options[:model]
        @usbctl_dev[:ports] = options[:ports]
      end