[libvirt] Ability to nice KVM processes

Hey all, I'd quite like the ability to nice my KVM process, on a home basis this stops my Windows VM locking up my linux desktop when it's under load (or at least limits it) and in a commercial setting it might be nice to offer CPU priority to other customers or company backup-services over customer VPS instances for example. How does it sound? Any thoughts? A quick chat in #virt revealed that a method for adding generic KVM options has been under discussion for ages - I thought i'd throw my two cents in, what about some sort of expression with variables like: <cmdstring>{cmd} {options}</cmdstring> (default) for my nice proposition you could: <cmdstring>/usr/bin/nice {cmd} {options}</cmdstring> Obviously people could use this to add conflicting options which is concerning but perhaps that should be their own lookout - it seems to be a fairly advanced request. Thanks, Henri