KVM windows guest on Ubuntu 12.10 - no sound

Recently I faced a problem that I could play sound from the KVM windows based guest machine (even though the virtual sound card AC'97 was properly detected and installed). I went through several article recommending to change the type of the card, configure qemu.conf to grant access to the audio. Unfortunately none of these really helped. Then after doing all the previously described things I tried disabling the apparmor and... Now it works...

Below I enclose more detailed procedure on what was needed in my case to make the audio from the guest kvm machine working.

1. Change the type of the card (might not be necessary). In my case the es1370 was chosen

2. Configure qemu.conf - please ensure that the following entries are present in the qemu.conf configuration file. The username and groupname shall be adapted to your system configuration


#  vim /etc/libvirt/qemu.conf 
...

#
vnc_allow_host_audio = 1

...

# The user ID for QEMU processes run by the system instance.

user = "krychu"

# The group ID for QEMU processes run by the system instance.

group = "krychu"

...

3. Disable apparmor. Disabling armor really made the sound working on my box. Actually I completely removed the apparmor from my system (I think it is not necessary, you might try only disabling it).

First I stopped the service:
#  service apparmor stop

Next I removed it from the startup scripts
#  update-rc.d -f apparmor remove

Since I do not use apparmor at the moment I eventually decided to remove it completely (if it happens that you installed apparmor-utils as well you should remove it as well)
#  apt-get remove apparmor apparmor-utils 


Reboot...