issues with vm after upgrade

Daniel P. Berrange dan at berrange.com
Tue Aug 3 13:12:06 UTC 2021


On Tue, Aug 03, 2021 at 02:54:39PM +0200, daggs wrote:
> Greetings Martin,
> 
> > Sent: Tuesday, August 03, 2021 at 11:37 AM
> > From: "Martin Kletzander" <mkletzan at redhat.com>
> > To: "daggs" <daggs at gmx.com>
> > Cc: libvirt-users at redhat.com
> > Subject: Re: issues with vm after upgrade
> >
> > On Mon, Aug 02, 2021 at 04:33:20PM +0200, daggs wrote:
> > >Greetings Martin,
> > >
> > >> Sent: Monday, August 02, 2021 at 12:17 PM
> > >> From: "Martin Kletzander" <mkletzan at redhat.com>
> > >> To: "daggs" <daggs at gmx.com>
> > >> Cc: libvirt-users at redhat.com
> > >> Subject: Re: issues with vm after upgrade
> > >>
> > >> On Sat, Jul 31, 2021 at 12:19:59PM +0200, daggs wrote:
> > >> >Greetings,
> > >> >
> > >> >a few weeks ago I've upgraded my system, this resulted with qemu and libvirt being upgraded to 6.0.0 and ~7.5.0 respectfully.
> > >> >I have two vms running on my system, router and streamer.
> > >> >the router vm works great, the streamer vm doesn't.
> > >> >after the streamer vm start, the monitor screen gets black and thats it. no relevant error are found in the log, see: http://dpaste.com/ERWDEJQPC
> > >> >the xml ca be found at https://dpaste.com/FQDN6NTN2
> > >> >in contrast the following oneliner works: qemu-system-x86_64 \
> > >> >-machine pc-q35-5.0,accel=kvm,usb=off,smm=on,dump-guest-core=off \
> > >> >-cpu host,migratable=on \
> > >> >-m 15360 \
> > >> >-smp 4,sockets=1,dies=1,cores=2,threads=2 \
> > >> >-drive file=/home/streamer/streamer.img.qcow2.new,if=virtio,format=qcow2 \
> > >> >-device vfio-pci,host=0000:00:02.0,romfile=/home/streamer/gpu-8086:5912-uefi.rom,multifunction=on \
> > >> >-device vfio-pci,host=0000:00:1f.3,multifunction=on \
> > >> >-usb \
> > >> >-device usb-host,vendorid=0x046d,productid=0xc52e \
> > >> >-device usb-host,vendorid=0x2548,productid=0x1002 \
> > >> >-display none \
> > >> >-netdev tap,id=hostnet0,ifname=virtsw-streamer,script=no,downscript=no \
> > >> >-device e1000e,netdev=hostnet0,id=net0,mac=52:54:00:5a:4c:8c \
> > >> >-blockdev '{"driver":"file","filename":"/usr/share/edk2-ovmf/OVMF_CODE.secboot.fd","node-name":"libvirt-pflash0-storage","auto-read-only":true,"discard":"unmap"}' \
> > >> >-blockdev '{"driver":"file","filename":"/var/lib/libvirt/qemu/nvram/streamer-vm-q35_VARS.fd","node-name":"libvirt-pflash1-storage","auto-read-only":true,"discard":"unmap"}'
> > >> >
> > >> >another issue encountered caused by this param: "-audiodev id=audio1,driver=none" which is auto added to the qemu line.
> > >> >if I add the line to the above oneliner, the guest doesn't detects the pt sound card. without it it does and it works.
> > >> >
> > >>
> > >> The links have expired, so I cannot look at the XML.  However do you
> > >> have any <audio/> in the XML at all?  I believe that without it we are
> > >> disabling any audio backends since no audio HW was requested.
> > >>
> > >
> > >here are the links:
> > >1. xml: https://dpaste.com/D6JANX3Z3
> > >2. log: https://dpaste.com/FMUDZY9PD
> > >
> > >as for the audio entry, "    <audio id='1' type='none'/>" is in the xml
> > >I didn't added it
> > >
> >
> > So let get this straight.  You want the VM to use the HW GPU that you
> > assigned to it and also use the audio on that GPU (e.g. HDMI or DP
> > output).  When you add the "-audiodev driver=none" the VM cannot see the
> > audio device on that GPU card?  Or is that unrelated?
> >
> > There were some strict definitions added for audio devices lately, I
> > presume to make sure that no data gets leaked in/out the VM and in order
> > to get audio anywhere else than from/to VNC/spice you'd need to
> > configure that.  It should not affect device assignment as far as I
> > understand it, although there might be some misunderstanding.
> >
> 
> I'll try to explain, I'm passing the computer's O/B gpu and O/B sound card to the vm so I can use them inside the vm which serves as streamer.
> all was working well until I've upgraded both qemu and libvirt (target versions are started in the original mail)
> since then, the vm doesn't boot at all.
> I was able to bisect the qemu cmd libvirt generates partially and go the vm up. this points to a config issue.
> as part of the testing I've found out that when the vm boots, it has no sound card.
> following your suggestion, I've found that the xml has this: <audio id='1' type='none'/> I have never added it to the xml so I assume that it was added as part of the upgrade.
> based on this I assume that there is another config which prevents my vm from booting.
> unfortunately, I don't have the xml prior to the upgrade to diff them.

The <audio> element just refers to the *host* backend used for audio
playback. It would not affect guest hardware. Further, this has always
existed - it just wasn't exposed in the XML previously.


With regards,
Daniel
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