another upgrade another vm issue

[Laine Stump]

On 10/30/21 6:57 AM, daggs wrote:
> Greetings Michal,
> 
>> Sent: Friday, October 29, 2021 at 11:36 AM
>> From: "Michal Prívozník" <mprivozn at redhat.com>
>> To: "daggs" <daggs at gmx.com>, libvirt-users at redhat.com
>> Subject: Re: another upgrade another vm issue
>>
>> On 10/28/21 8:40 PM, daggs wrote:
>>> Greetings,
>>>
>>> so I've upgraded my server and yet again, one of my vm lost a functionally.
>>> there is no usable sound card.
>>> xml: https://dpaste.com/CVR5M75VH
>>> in vm: https://snipboard.io/aZ7Dcf.jpg
>>>
>>> outputs:
>>> utils_server /home/igor # qemu-system-x86_64 --version
>>> QEMU emulator version 6.0.0
>>> Copyright (c) 2003-2021 Fabrice Bellard and the QEMU Project developers
>>> utils_server /home/igor # libvirtd --version
>>> libvirtd (libvirt) 7.8.0
>>> utils_server /home/igor #
>>>
>>> any ideas?
>>>
>>> Thanks.
>>>
>>>
>>
>> I suspect it's related to:
>>
>>    <audio id='1' type='none'/>
>>
>> in the domain XML. Selecting a backend might help.
>>
>>    https://libvirt.org/formatdomain.html#audio-backends
>>
>> Michal
>>
>>
> 
> I've diffed the current xml with the one last known to work, they both have the same entry

Can you possibly downgrade QEMU, libvirt, and the host kernel 
independently to see if downgrading just one (or two) of them fixes the 
problem?

(I would normally have suggested diffing the qemu commandline from the 
logs in /var/log/libvirt/qemu/${guestname}.log to see if the VFIO 
portion was unchanged (and thus counting out libvirt from the possible 
causes of the problem), but the commandlines have recently switched to 
using JSON syntax, so they will probably be different anyway).

Since your audio device is assigned with VFIO, and libvirt has nothing 
more to do with that than just unbinding the host driver and binding the 
vfio-pci driver, then putting the info on the commandline for QEMU, I'd 
put money on the problem being either in QEMU or the kernel, in which 
case you'd probably get more useful advice from the 
vfio-users at redhat.com mailing list than here.