cannot run libvirt in an 'lxc create -t ubuntu' container

if you try to start a qemu/kvm guest from inside a container crated by lxc create -t ubuntu, it will fail with something like:
error: Failed to start domain my.img
error: unable to allow device /dev/full: Operation not permitted

$ lxc-create -t ubuntu -n lv1
$ lxc-start -n lv1 -d
$ lxc-console -n lv1
# login here
% apt-get install qemu-kvm wget
% apt-get install dbus # bug 918343
% apt-get install libvirt-bin
% wget http://launchpad.net/cirros/trunk/0.3.0/+download/cirros-0.3.0-x86_64-disk.img -O disk.zimg
% qemu-img convert disk.zimg -O qcow2 /tmp/disk.img
% wget https://bugs.launchpad.net/ubuntu/+source/lxc/+bug/918946/+attachment/2683440/+files/libvirt.xml
% virsh define libvirt.xml
% virsh start mytest

from a working qemu guest, I see:
# cat /sys/fs/cgroup/devices/libvirt/qemu/myname/devices.list
c 136:* rw
c 1:3 rw
c 1:7 rw
c 1:5 rw
c 1:8 rw
c 1:9 rw
c 5:2 rw
c 254:0 rw

So I think we need to add access to that list of devices. (haven't testd this all the way yet).

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: lxc 0.7.5-3ubuntu5
ProcVersionSignature: User Name 3.2.0-8.15-virtual 3.2.0
Uname: Linux 3.2.0-8-virtual x86_64
ApportVersion: 1.90-0ubuntu1
Architecture: amd64
Date: Thu Jan 19 21:52:06 2012
Ec2AMI: ami-0000012b
Ec2AMIManifest: FIXME
Ec2AvailabilityZone: nova
Ec2InstanceType: m1.small
Ec2Kernel: unavailable
Ec2Ramdisk: unavailable
ProcEnviron:
 PATH=(custom, user)
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: lxc
UpgradeStatus: No upgrade log present (probably fresh install)