how to change nic's tx/rx ring size inside vm

Hi, all: my environment is qemu-kvm-6.0.0, 4.18.0-240, libvirt 7.4.0. vm is configured like this queues='4' rx_queue_size='1024' tx_queue_size='1024'. inside vm i can not change nic's ring size. changing tx leads to error 'Cannot set device ring parameters: Operation not supported'. changing rx leads to error 'rx unmodified, ignoring. no ring parameters changed, aborting' how to make it work and confirm what current value is? thanks