As the title of this feature requests says, it will be really handy to have such feature and limit clients IOps when dealing with abusive clients, or it will be even better we can setup this limit in the KVM plans.

Limiting or throttling the IO of KVM QEMU instances is possible with cgroup blkio controller => https://www.linux-kvm.org/images/7/72/2011-forum-keep-a-limit-on-it-io-throttling-in-qemu.pdf

Also virsh has support for it too => https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/7/html/virtualization_deployment_and_administration_guide/sect-managing_guest_virtual_machines_with_virsh-disk_io_throttling