Assistance with vhost-user-snd on Xen Dom0 / QEMU DomU

[jeliccN]

Hi everyone,

I’m reaching out to ask for help debugging an issue I’m experiencing with vhost-user-snd on a Xen Type-1 hypervisor (Dom0) with a QEMU guest (DomU) running on an i.MX8QM-MEK board.

I’m running the backend on the host as follows:

vhost-device-sound --socket /tmp/vhost-sound.socket --backend pipewire &

And starting the guest with these QEMU parameters:

-chardev socket,id=snd_chardev,path=/tmp/vhost-sound.socket
-device vhost-user-snd,chardev=snd_chardev,id=snd,iommu_platform=true

I’m using QEMU 9.0.2 with vhost-user-snd support. I’ve extended VhostUserMemoryRegion with the parameters xen_mmap_flags and xen_mmap_data, as required by the backend, and I enabled backend Xen support during the build with --features xen.

However, I’m still have a major issue with SET_MEM_TABLE and ADD_MEM_REGION. I tried both operations, but they require passing a file descriptor (fd), and I’m unsure how to provide or bypass this in the Xen case.

I would appreciate your guidance, as I haven’t been able to find documentation or specifications describing exactly what is required on both the QEMU and backend sides to make vhost communication work and get vhost-user-snd running properly.

Thank you very much for your time and help!

[vireshk]

https://linaro.atlassian.net/wiki/spaces/HVAC/pages/29474095128/2024-08+kernel+prototype

I have a I2C based setup you may want to try. We use xen-vhost-frontend (which uses vhost-frontend - non-upstream).

[jeliccN]

Thank you for the response. I will try the same approach for the sound setup as well. This is very helpful.