Error starting domain, pcie-root-port, in use by ich9-intel-hda

Software & Operating Systems VFIO
1

A system update broke qemu/kvm virtualization yesterday. I’m on manjaro and I’ve been using jackaudio for a while. I see the following error:

Screenshot_2022-01-05_08-52-54
Screenshot_2022-01-05_08-52-541253×718 153 KB

The necro thread is here: https://forum.level1techs.com/t/qemu-native-jack-audio-support/156494

The magic sauce for creating a patchbay connection for my windows guest looked like this:

  <qemu:commandline>
...
    <qemu:arg value="-audiodev"/>
    <qemu:arg value="jack,id=win10large,in.format=s32,out.format=s32,in.frequency=48000,out.frequency=48000"/>
    <qemu:arg value="-device"/>
    <qemu:arg value="ich9-intel-hda"/>
    <qemu:arg value="-device"/>
    <qemu:arg value="hda-duplex,audiodev=win10large"/>
...
  </qemu:commandline>

It looked like there is a new PCI Controller in the Hardware list in Virt-Manager. I think virt-manager does it’s best to list hardware based on the xml specification of the virtual machine. Some change seemed like it was made.

/var/log/pacman.log : [2022-01-04T06:03:24-0500] [ALPM] upgraded qemu (6.1.0-5 → 6.2.0-2)

I began looking for documentation to change slots or functions of the ich9-intel-hda device.

Jack is the host backend for the guest’s ich9-intel-hda device. The relevant libvirt.org section is https://libvirt.org/formatdomain.html#sound-devices, which states “Valid values are specific to the underlying hypervisor”.

My hypervisor is qemu/kvm. Qemu.org shows a new 6.1.1 and 6.2.0 release in December 2021. I suspect the 6.1.1 release would not have broken my virtual machine, but I’m an the mercy of my package maintainers at manjaro who within days of the 6.2.0 release updated the repo.

The next breadcrumb comes at https://www.qemu.org/docs/master/system/device-emulation.html

$ qemu-system-x86_64 --device ich9-intel-hda,help
ich9-intel-hda options:
  acpi-index=<uint32>    -  (default: 0)
  addr=<int32>           - Slot and optional function number, example: 06.0 or 06 (default: -1)
  debug=<uint32>         -  (default: 0)
  failover_pair_id=<str>
...

The final working xml portion for jackaudio is now:

    <qemu:arg value="-audiodev"/>
    <qemu:arg value="jack,id=win10large,in.format=s32,out.format=s32,in.frequency=48000,out.frequency=48000"/>
    <qemu:arg value="-device"/>
    <qemu:arg value="ich9-intel-hda,bus=pcie.0,addr=0x1b"/>
    <qemu:arg value="-device"/>
    <qemu:arg value="hda-duplex,audiodev=win10large"/>

Lurking around the gitlab for qemu I found this patch that may be related:
https://gitlab.com/qemu-project/qemu/-/commit/9e2423ef58f37e1d9def4ef33b054cb7e86da1f7

2

The screenshot posted has nothing to do with jack, you have not set the cpu feature flag topoext which you need for a hyper-threaded guest.

You do know that the virtual HDA device only can operate in S16 mode? By using these parameters you’re forcing an extra conversion to get it to float (what Jack uses) degrading quality even further then the limited HDA device limits you to already.

As for the PCI in use issues, this is documented, libvirt moved to using JSON configuration for devices and due to the way QEMU handles parsing the configuration this causes PCI device ID conflicts. You need to convert your configuration arguments to using the JSON format also, or better yet, simply use the libvirt native tags instead of custom commands as it supports jack these days.

<audio id="1" type="jack" />
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