another upgrade another vm issue

[daggs]

Greetings Laine,

> Sent: Saturday, October 30, 2021 at 5:40 PM
> From: "Laine Stump" <laine at redhat.com>
> To: "libvirt-users at redhat.com" <libvirt-users at redhat.com>
> Cc: "daggs" <daggs at gmx.com>
> Subject: Re: another upgrade another vm issue
>
> 
> 
> 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.
> 
> 

the kernel didn't changed.
downgrading both libvirt and eqmu was the first thing I did when the issue was encountered. the problem persisted.
I've isolated the last good execution of the vm prior to the upgrade, diffed the command line, it is the same one.
I'll verify that the working one is the the right one and will test again.
I'll go to vfio-users after I've make sure that nothing differs with the env.

thanks, for the help.

Dagg.