Comment 5 for bug 292587

The patch cited wasn't upstream until kvm-75. Hardy had kvm-62, which should [1] have virtio support. I didn't switch to virtio until intrepid myself, I can't comment on if it's reproducible there. As important as being able to soft reboot your guests is, you can workaround this with a forced power off. Meeting the SRU for "obviously safe" sounds simple with how minimal the patch is, but I'd side that the workarounds are safer than risking a kvm patch, with how important KVM is.

Jaunty ships shortly, and this bug is fixed there.

[1] http://www.linux-kvm.org/page/Virtio