[libvirt-users] Block device IO limits

Hi all, is there a way to limit the throughput (or the number of operations per seconds) of a block device? I ask because I've a couple of misconfigured VMs that are performing a lot of disk activity (swapping I'd bet but I haven't access to their OS). Since their storage is on a NFS share they are slowing down other VMs on the same share. Thank you. Davide.