Bug 1977891

(In reply to smitterl from comment #0)
> Description of problem:
> virsh define adds an invalid audio element to the domain definition.
> Therefore, the domain can't start or be used after migration.
> 
> 
> Version-Release number of selected component (if applicable):
> libvirt-7.4.0-1.module+el8.5.0+11218+83343022.x86_64
> libvirt-7.4.0-1.module+el8.5.0+11218+83343022.s390x
> 
> How reproducible:
> 100%
> 
> Steps to Reproduce:
> vm.xml is a valid domain definition, name 'vm', not containing any element
> <audio>
> 1. virsh define vm.xml
> 2. virsh dumpxml vm|grep audio
> 
> Actual results:
>     <audio id='1' type='none'/>
> 
> 
> 
> Expected results:
> empty
> 
> Additional info:
> 1. The domain can't start afterwards as element is invalid

What do you mean by "invalid" here ?  Can you give the actual error message you receive.

A <audio type='none'/> is valid in all my own tests


> 2. When I migrate a machine to another host with
> libvirt-7.4.0-1.module+el8.5.0+11218+83343022.s390x, the running destination
> vm contains that audio element too. The domain can't be migrated back.

Can you give the error you get from migration ?

(In reply to Daniel Berrangé from comment #5)
> (In reply to smitterl from comment #0)
> > Description of problem:
> > virsh define adds an invalid audio element to the domain definition.
> > Therefore, the domain can't start or be used after migration.
> > 
> > 
> > Version-Release number of selected component (if applicable):
> > libvirt-7.4.0-1.module+el8.5.0+11218+83343022.x86_64
> > libvirt-7.4.0-1.module+el8.5.0+11218+83343022.s390x
> > 
> > How reproducible:
> > 100%
> > 
> > Steps to Reproduce:
> > vm.xml is a valid domain definition, name 'vm', not containing any element
> > <audio>
> > 1. virsh define vm.xml
> > 2. virsh dumpxml vm|grep audio
> > 
> > Actual results:
> >     <audio id='1' type='none'/>
> > 
> > 
> > 
> > Expected results:
> > empty
> > 
> > Additional info:
> > 1. The domain can't start afterwards as element is invalid
> 
> What do you mean by "invalid" here ?  Can you give the actual error message
> you receive.
> 
> A <audio type='none'/> is valid in all my own tests
> 
> 
> > 2. When I migrate a machine to another host with
> > libvirt-7.4.0-1.module+el8.5.0+11218+83343022.s390x, the running destination
> > vm contains that audio element too. The domain can't be migrated back.
> 
> Can you give the error you get from migration ?

I updated the description and title. I got confused between the different hosts and versions I worked with, sorry. As you said offline, migrating back from AV 8.5 to AV 8.4 doesn't work.

Look like this issue https://gitlab.com/libvirt/libvirt/-/issues/179

Dan - would you please take care of this one. Thanks.

Additional information: the audio element cannot be detached from the running machine. I get an error
`# virsh detach-device avocado-vt-remote-vm1 audio.xml --live
error: Failed to detach device from audio.xml
error: Operation not supported: live detach of device 'audio' is not supported
`
Therefore, I can't think of a workaround to fix the vm setup before migrating back but I might be missing something.

The 'virsh migrate' command allows you to provide a replacement XML document to use for the guest config on the target host. It is probably possible to take the current guest XML 'virsh dumpxml --migratable guestname', remove the <audio> element(s) and then pass this document to 'virsh migrate'.

(In reply to Daniel Berrangé from comment #10)
> The 'virsh migrate' command allows you to provide a replacement XML document
> to use for the guest config on the target host. It is probably possible to
> take the current guest XML 'virsh dumpxml --migratable guestname', remove
> the <audio> element(s) and then pass this document to 'virsh migrate'.

IIUC, you are referring to the --xml argument. I tried this but it didn't work either:

# cat migratable.xml |grep audio
>>empty
# virsh dumpxml avocado-vt-vm1|grep audio
    <audio id='1' type='none'/>
# virsh migrate avocado-vt-vm1 --live --verbose --postcopy qemu+ssh://<my-dest-ip>/system --xml migratable.xml 
error: unsupported configuration: unknown audio type 'none'

(--persistent-xml migratable --persistent raise the same error)

Upstream patch proposed https://listman.redhat.com/archives/libvir-list/2021-July/msg00158.html

*** Bug 1981431 has been marked as a duplicate of this bug. ***

Pkgs on source host:
libvirt-daemon-7.6.0-1.module+el8.5.0+12097+2c77910b.x86_64
qemu-kvm-6.0.0-26.module+el8.5.0+12044+525f0ebc.x86_64

Pkgs on target host:
libvirt-7.0.0-14.3.module+el8.4.0+11878+84e54169.x86_64
qemu-kvm-5.2.0-16.module+el8.4.0+11923+e8b883e4.4.x86_64

1. define a guest with the vnc graphics, start the guest, check guest xml
# virsh dumpxml avocado-vt-vm1
...
 <graphics type='vnc' port='5900' autoport='yes' listen='127.0.0.1'>
      <listen type='address' address='127.0.0.1'/>
    </graphics>
    <audio id='1' type='none'/>    <=== default audio device for vnc graphics has been added
...

2. check the migratable xml
# virsh dumpxml avocado-vt-vm1 --migratable |grep "<audio"
(no output)

3. migrate the guest to target host
# virsh migrate avocado-vt-vm1 qemu+ssh://$hostname/system --verbose --live --p2p
Migration: [100 %]error: internal error: qemu unexpectedly closed the monitor: 2021-08-09T12:29:54.186850Z qemu-kvm: Unknown savevm section or instance 'audio' 0. Make sure that your current VM setup matches your saved VM setup, including any hotplugged devices
2021-08-09T12:29:54.187115Z qemu-kvm: load of migration failed: Invalid argument

Hi, Daniel
Please help to check the above testing result. Thanks

(In reply to Lili Zhu from comment #21)
> 3. migrate the guest to target host
> # virsh migrate avocado-vt-vm1 qemu+ssh://$hostname/system --verbose --live
> --p2p
> Migration: [100 %]error: internal error: qemu unexpectedly closed the
> monitor: 2021-08-09T12:29:54.186850Z qemu-kvm: Unknown savevm section or
> instance 'audio' 0. Make sure that your current VM setup matches your saved
> VM setup, including any hotplugged devices
> 2021-08-09T12:29:54.187115Z qemu-kvm: load of migration failed: Invalid
> argument
> 
> Hi, Daniel
> Please help to check the above testing result. Thanks

This is an unexpected problem in QEMU which causes vmstate changes when QEMU has no sound frontend device present. I filed bug 1991671 to track this problem.

We'll keep this libvirt bug open until we see the QEMU one solved

Pkgs on source host:
libvirt-7.6.0-2.module+el8.5.0+12219+a5ea13d2.x86_64
qemu-kvm-6.0.0-28.module+el8.5.0+12271+fffa967b.x86_64

Pkgs on target host:
libvirt-7.0.0-14.1.module+el8.4.0+11095+d46acebf.x86_64
qemu-kvm-5.2.0-16.module+el8.4.0+10806+b7d97207.x86_64

1. define a guest with the vnc graphics, start the guest, check guest xml
# virsh dumpxml avocado-vt-vm1
...
 <graphics type='vnc' port='5900' autoport='yes' listen='127.0.0.1'>
      <listen type='address' address='127.0.0.1'/>
    </graphics>
    <audio id='1' type='none'/>    <=== default audio device for vnc graphics has been added
...

2. check the migratable xml
# virsh dumpxml avocado-vt-vm1 --migratable |grep "<audio"
(no output)

3. migrate the guest to target host
# virsh migrate avocado-vt-vm1 qemu+ssh://$hostname/system --verbose --live --p2p
Migration: [100 %]

4.

As the testing result matches with the expected result, mark the bug as verified.

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory (virt:av bug fix and enhancement update), and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHBA-2021:4684