[Pkg-libvirt-maintainers] Bug#630212: libvirt-bin: libvirt doesn't spawn qemu with supplementary groups

[Alex Bennee]

Package: libvirt-bin
Version: 0.8.3-5+squeeze1
Severity: important
Tags: upstream


If you configure libvirt to spawn qemu with it's own user you can run into
problems getting KVM to work. This is because although the qemu user belongs
to the kvm and disk groups without calling initgroups the spawned process
won't be able to access /dev/kvm (root:kvm) and much hilarity/head scratching
will ensue.

This problem has been documented upstream and has been patched in recent releases:

https://bugzilla.redhat.com/show_bug.cgi?id=664406

In the end the workaround I applied was to nail the /dev/kvm device to:

ls -l /dev/kvm
crw-rw---- 1 root qemu 10, 232 Jun 12 11:51 /dev/kvm

And nailed it up with:

cat /etc/udev/rules.d/99-local-permissions.rules
# Make kvm available to qemu
KERNEL=="kvm", GROUP="qemu", MODE="0660"

-- System Information:
Debian Release: 6.0.1
  APT prefers stable
  APT policy: (990, 'stable'), (500, 'stable-updates')
Architecture: i386 (i686)

Kernel: Linux 2.6.32-5-686 (SMP w/1 CPU core)
Locale: LANG=en_GB.UTF-8, LC_CTYPE=en_GB.UTF-8 (charmap=UTF-8) (ignored: LC_ALL set to en_GB.UTF-8)
Shell: /bin/sh linked to /bin/dash