PCI passthrough broken on kernel 5.15-pve

[SplendidRecluse]

I just upgraded my system to the 5.15 Kernel release and observed that PCI passthrough stopped working.

The following two errors repeat many times per second until they fill the disk in /var/log/syslog:

Jun 13 15:23:42 pve QEMU[1762]: kvm: vfio_region_write(0000:08:00.0:region3+0x1f9f58, 0x0,8) failed: Device or resource busy
Jun 13 15:23:42 pve kernel: [  119.776597] vfio-pci 0000:08:00.0: BAR 3: can't reserve [mem 0xf0000000-0xf1ffffff 64bit pref]

If I boot into 5.13, passthrough works as expected. Does anyone know what might be causing this?

 

[dcsapak]

do you by any chance trying to passthrough the only gpu in your system? if yes, try to also disable simplefb (in addition to efifb,etc.) on your kernel cmdline, like its described in the know issues section here: https://pve.proxmox.com/wiki/Roadmap#Proxmox_VE_7.2