Comment 2 for bug 1015154

Any news on this?
I've hit the same thing

Ubuntu server 12.04
Attempting to create socket connection between VM host and a pre-existing guest.
Following this guide
http://wiki.libvirt.org/page/Qemu_guest_agent

New channel defined in VM

<channel type='unix'>
   <source mode='bind' path='/var/lib/libvirt/qemu/app-dev-tony.agent'/>
   <target type='virtio' name='org.qemu.guest_agent.0'/>
</channel>

When starting VM, get the following

error: Failed to start domain app-dev-tony
error: internal error Process exited while reading console log output: char device redirected to /dev/pts/3
bind(unix:/var/lib/libvirt/qemu/app-dev-tony.agent): Permission denied
chardev: opening backend "socket" failed: Permission denied