[vhost-user] how to get enabled vring num

Hi, All:
    I create qemu VM with 1 cpu and 1 NIC using vhost-user client mode with 2 pairs queue, when VM start, bu default only one pair queue is enabled unless use 'ethtool -L eth0 2' to enable.
    now I want to get vring num using vhost-user lib api---rte_vhost_get_vring_num, and send pkt to allqueues of VM(actully donnot know how many queue is enabled) by round robin, if i send pkt to a disabled queue, it will be fail.
    So, is there a api to get only enabled vring num rather than all vring num?


Thanks!