I searched my hardware name and found that this hardware seems to have problem with drivers in dom0. So I had to try the sys-audio approach. Once I have passed the Audio PCI device to the sys-audio, I can hear the correct sound when I test in sys-audio aplay /usr/share/sounds/alsa/Front_Center.wav.
I cannot find any official tutorial about sys-audio other than Setting up an audio VM - #24 by hamenarin . Thus I tried things in the post, and it seems that VCHAN connection has deadlock or something similar and it is not anything easy to solve for a xen vchan noob like me.
Basically I run the salt script to create the sys-audio VM, installed qubes-audio-daemon qubes-core-admin-client to the fedora-34-xfce and make pulseaudio to boot automatically (qvm-start-daemon --all --watch is already autostart), fixed the policy errors, setting audiovm attribute of related VM correctly (I have set the audiovm of other unrelated appvms to be '', only the VM that I want to hear from to be sys-audio).
I tried to play an MP3 file in my appvm and have no luck. Moreover the MP3 player seems to block when playing.
So I tried manually to execute pulseaudio and pacat-simple-vchan -l <vmid> <vmname> in sys-audio.
I have no luck when I keep restarting pacat-simple-vchan; each time when I restarting pulseaudio, it seems that one CHUNK (0.1s or similar) of sound data of AppVM is consumed and the audio output plays the chunk again and again.
Is there any expert on sys-audio that can help me out?