Comment 4 for bug 1506390

Mark - Did you test this on a version of libvirt that was newer than 1.2.8?

There are permission issues even with libvirt 1.2.2:

Ubuntu: 14.04.3

libvirtd (libvirt) 1.2.2

/var/log/libvirt/libvirtd.log

2015-10-19 19:54:30.799+0000: 19818: warning : virLXCProcessMonitorInitNotify:615 : Cannot obtain pid NS inode for 20236: Unable to stat /proc/20236/ns/pid: Permission denied
2015-10-19 19:56:09.601+0000: 19818: warning : virLXCProcessReboot:124 : Unable to handle reboot of vm instance-00000001

2015-10-19 19:54:30.799+0000: 19818: error : virLXCProcessGetNsInode:582 : Unable to stat /proc/20236/ns/pid: Permission denied

There are known issues with Ubuntu and LXC containers related to the apparmor profile. The default installation of Devstack + Libvirt + LXC does not install the apparmor profiles, but I'm not sure if that's causing the issue or not. I was able to disable however I wasn't able to try with a newer version of libvirt yet.