Below are basically information I would like to share with you all.
I tried upgrade BIOS to latest 4801 and I did instantly regretted that.
The latest 4801 and 4602 don’t work with QEMU/Passthrough - kernel panic or freeze every restart/shutdown.
If you try to downgrade BIOS from latest 4801 it’s not possible using official BUpdater or EZ BIOS update utility as both do not allow downgrade.
I used old AMI update tool “afudos 4406.cap /x /p /b /n /k” and it worked fine.
I found downgrading method this reddit article in the comments:
Recently I’ve build new PC on AMD 2600 on ASUS Prime X370-Pro and two Nvidia PCIex cards. Obviously I’ve updated BIOS to (then) latest version 4602.
PC worked just fine on Windows and Linux except running QEMU with passthrough PCIex card or USB controller. System/kernel was crashing every time on reboot, when I’ve tried to run VM.
Situation resolved then BIOS downgrade to earlier version 4406. Everthing worked fine after downgrade.
Today I’ve noticed new BIOS version 4801 and I wonder if anyone using Linux/QEMU/Passthrough tried it already?