Microphone input dies in guest when switching evdev input justin@justin-3900x:~$ lsb_release -a No LSB modules are available. Distributor ID: Ubuntu Description: Ubuntu 20.04 LTS Release: 20.04 Codename: focal justin@justin-3900x:~$ apt list --installed | egrep '*qemu*|*kvm*' WARNING: apt does not have a stable CLI interface. Use with caution in scripts. ipxe-qemu-256k-compat-efi-roms/focal,focal,now 1.0.0+git-20150424.a25a16d-0ubuntu4 all [installed,automatic] ipxe-qemu/focal,focal,now 1.0.0+git-20190109.133f4c4-0ubuntu3 all [installed,automatic] libvirt-daemon-driver-qemu/focal,now 6.0.0-0ubuntu8 amd64 [installed,automatic] qemu-block-extra/focal-updates,focal-security,now 1:4.2-3ubuntu6.1 amd64 [installed,automatic] qemu-kvm/focal-updates,focal-security,now 1:4.2-3ubuntu6.1 amd64 [installed] qemu-system-common/focal-updates,focal-security,now 1:4.2-3ubuntu6.1 amd64 [installed,automatic] qemu-system-data/focal-updates,focal-updates,focal-security,focal-security,now 1:4.2-3ubuntu6.1 all [installed,automatic] qemu-system-gui/focal-updates,focal-security,now 1:4.2-3ubuntu6.1 amd64 [installed,automatic] qemu-system-x86/focal-updates,focal-security,now 1:4.2-3ubuntu6.1 amd64 [installed] qemu-utils/focal-updates,focal-security,now 1:4.2-3ubuntu6.1 amd64 [installed,automatic] qemu/focal-updates,focal-security,now 1:4.2-3ubuntu6.1 amd64 [installed] justin@justin-3900x:~$ This did not happen in Eoan (qemu 4.0.0). I was able to switch in/out of a VM with my audio coming through fine. I enabled Eoan in my sources.list, downgraded all my qemu packages, and the issue was resolved. This happens on the latest Windows 10 guest when a sound device is listening for the microphone. /var/log/libvirt/qemu/.log spews this error out when I switch with evdev (which is just the keyboard and mouse, the audio is passed through I assume spice): audio: live=228193 hw->conv_buf->size=1920 A bug was just triggered in audio_get_avail Context: audio: live=228675 sw->hw->conv_buf->size=1920 A bug was just triggered in audio_pcm_hw_get_live_in Context: audio: live=228675 hw->conv_buf->size=1920 A bug was just triggered in audio_get_avail Context: audio: live=229156 sw->hw->conv_buf->size=1920 A bug was just triggered in audio_pcm_hw_get_live_in Context: audio: live=229156 hw->conv_buf->size=1920 A bug was just triggered in audio_get_avail Context: audio: live=229638 sw->hw->conv_buf->size=1920 A bug was just triggered in audio_pcm_hw_get_live_in Context: audio: live=229638 hw->conv_buf->size=1920 A bug was just triggered in audio_get_avail Context: audio: live=230119 sw->hw->conv_buf->size=1920 A bug was just triggered in audio_pcm_hw_get_live_in Context: audio: live=230119 hw->conv_buf->size=1920 A bug was just triggered in audio_get_avail Context: audio: live=230600 sw->hw->conv_buf->size=1920 A bug was just triggered in audio_pcm_hw_get_live_in Context: audio: live=230600 hw->conv_buf->size=1920 A bug was just triggered in audio_get_avail Context: audio: live=231081 sw->hw->conv_buf->size=1920 I have this exact issue with any VM using Spice audio redirection. My setup has Linux (Fedora 32) as host and guest. The Guest microphone freezes mid way through most video conferences, which is quite a pain. I see the exact same error messages: A bug was just triggered in audio_get_avail Context: audio: live=172895567 sw->hw->conv_buf->size=1920 A bug was just triggered in audio_pcm_hw_get_live_in Context: audio: live=172895567 hw->conv_buf->size=1920 Closing the spice client (Boxes or Virtmanager) and reconnecting sometimes restores microphone. I have tried AC97 and HD Audio as virtual hardware and have the same results, AC97 may be proving to be a little less failure prone, but I have not had enough events to be sure. I upgraded to Ubuntu 20.10 (Groovy Gorilla) and the issue was resolved. Here's a list of relevant package versions: root@justin-3900x:/home/justin# apt list --installed | grep virt (etc...) WARNING: apt does not have a stable CLI interface. Use with caution in scripts. gir1.2-libvirt-glib-1.0/groovy,now 3.0.0-1 amd64 [installed,automatic] libgovirt-common/groovy,groovy,now 0.3.7-1 all [installed,automatic] libgovirt2/groovy,now 0.3.7-1 amd64 [installed,automatic] libqt5virtualkeyboard5/groovy,now 5.14.2+dfsg-2 amd64 [installed,automatic] libsys-virt-perl/groovy,now 6.3.0-1 amd64 [installed,automatic] libvirt-clients/groovy-updates,now 6.6.0-1ubuntu3.1 amd64 [installed,automatic] libvirt-daemon-driver-qemu/groovy-updates,now 6.6.0-1ubuntu3.1 amd64 [installed,automatic] libvirt-daemon-driver-storage-zfs/groovy-updates,now 6.6.0-1ubuntu3.1 amd64 [installed] libvirt-daemon-system-systemd/groovy-updates,now 6.6.0-1ubuntu3.1 amd64 [installed,automatic] libvirt-daemon-system/groovy-updates,now 6.6.0-1ubuntu3.1 amd64 [installed,automatic] libvirt-daemon/groovy-updates,now 6.6.0-1ubuntu3.1 amd64 [installed,automatic] libvirt-glib-1.0-0/groovy,now 3.0.0-1 amd64 [installed,automatic] libvirt0/groovy-updates,now 6.6.0-1ubuntu3.1 amd64 [installed,automatic] python3-libvirt/groovy,now 6.1.0-1 amd64 [installed,automatic] qml-module-qtquick-virtualkeyboard/groovy,now 5.14.2+dfsg-2 amd64 [installed,automatic] qtvirtualkeyboard-plugin/groovy,now 5.14.2+dfsg-2 amd64 [installed,automatic] ruby-fog-libvirt/groovy,groovy,now 0.6.0-1 all [installed,automatic] ruby-libvirt/groovy,now 0.7.1-1build1 amd64 [installed,automatic] vagrant-libvirt/groovy,groovy,now 0.1.2-1 all [installed,automatic] virt-manager/groovy,groovy,now 1:2.2.1-4ubuntu2 all [installed] virt-p2v/groovy,now 1.42.0-2 amd64 [installed,automatic] virt-viewer/groovy,now 7.0-2build1 amd64 [installed,automatic] virtinst/groovy,groovy,now 1:2.2.1-4ubuntu2 all [installed,automatic] qemu-kvm/groovy,now 1:5.0-5ubuntu9 amd64 [installed] ipxe-qemu-256k-compat-efi-roms/groovy,groovy,now 1.0.0+git-20150424.a25a16d-0ubuntu4 all [installed,automatic] ipxe-qemu/groovy,groovy,now 1.0.0+git-20190125.36a4c85-5ubuntu3 all [installed,automatic] libvirt-daemon-driver-qemu/groovy-updates,now 6.6.0-1ubuntu3.1 amd64 [installed,automatic] qemu-block-extra/groovy,now 1:5.0-5ubuntu9 amd64 [installed,automatic] qemu-efi-aarch64/groovy,groovy,now 2020.05-5 all [installed,automatic] qemu-efi-arm/groovy,groovy,now 2020.05-5 all [installed,automatic] qemu-kvm/groovy,now 1:5.0-5ubuntu9 amd64 [installed] qemu-system-arm/groovy,now 1:5.0-5ubuntu9 amd64 [installed] qemu-system-common/groovy,now 1:5.0-5ubuntu9 amd64 [installed,automatic] qemu-system-data/groovy,groovy,now 1:5.0-5ubuntu9 all [installed,automatic] qemu-system-gui/groovy,now 1:5.0-5ubuntu9 amd64 [installed,automatic] qemu-system-x86/groovy,now 1:5.0-5ubuntu9 amd64 [installed] qemu-user-static/groovy,now 1:5.0-5ubuntu9 amd64 [installed] qemu-utils/groovy,now 1:5.0-5ubuntu9 amd64 [installed,automatic] qemu/groovy,now 1:5.0-5ubuntu9 amd64 [installed] The QEMU project is currently moving its bug tracking to another system. For this we need to know which bugs are still valid and which could be closed already. Thus we are setting older bugs to "Incomplete" now. If the bug has already been fixed in the latest upstream version of QEMU, then please close this ticket as "Fix released". If it is not fixed yet and you think that this bug report here is still valid, then you have two options: 1) If you already have an account on gitlab.com, please open a new ticket for this problem in our new tracker here: https://gitlab.com/qemu-project/qemu/-/issues and then close this ticket here on Launchpad (or let it expire auto- matically after 60 days). Please mention the URL of this bug ticket on Launchpad in the new ticket on GitLab. 2) If you don't have an account on gitlab.com and don't intend to get one, but still would like to keep this ticket opened, then please switch the state back to "New" within the next 60 days (otherwise it will get closed as "Expired"). We will then eventually migrate the ticket auto- matically to the new system. Thank you and sorry for the inconvenience. Was fixed when moving to QEMU 5.x in Ubuntu 20.10. Was fixed when moving to QEMU 5.x in Ubuntu 20.10.