Comment 0 for bug 1972075

Also filed upstream: https://gitlab.com/libvirt/libvirt/-/merge_requests/151

I recently upgraded from Ubuntu 21.10 to 22.04. I have an existing VM with virtio video and gl-accelerated Spice display which previously worked.

After the upgrade, virt-manager and virt-viewer display a blank screen. In the qemu libvirt logs, I observe many repetitions of:

```
qemu_spice_gl_scanout_texture: failed to get fd for texture
```

dmesg contains these AppArmor errors:

```
[250001.100362] audit: type=1400 audit(1651958128.696:706): apparmor="DENIED" operation="open" profile="libvirt-98a090a8-2fdf-463c-959b-810e5bc88b0d" name="/sys/devices/pci0000:00/0000:00:02.0/revision" pid=132725 comm="qemu-system-x86" requested_mask="r" denied_mask="r" fsuid=64055 ouid=0
[250001.100367] audit: type=1400 audit(1651958128.696:707): apparmor="DENIED" operation="open" profile="libvirt-98a090a8-2fdf-463c-959b-810e5bc88b0d" name="/sys/devices/pci0000:00/0000:00:02.0/config" pid=132725 comm="qemu-system-x86" requested_mask="r" denied_mask="r" fsuid=64055 ouid=0
```

Modifying the AppArmor config for this VM to permit access to the `revision` and `config` sysfs paths fixed this issue for me. The VM display is visible and virgl is working.