[REGRESSION] GPU passes into VM improperly after c376a3456d8b or a98db518dde2

[70sp]

Hello,

I have been dealing with a regression launching a Windows QEMU/KVM virtual machine with a GPU passed through.

The issue consists of launching a QEMU/KVM VM, which gets stuck for about 2 minutes on booting with a white screen and then having NVIDIA’s code 43 in Windows.

I’m certain, that the issue is not caused by anything in Windows or related software in Linux, because I tried reinstalling my whole PC including the Windows VM. I tried to reproduce the bug on an out-of-the-box Arch Linux install and the bug is still present.

The first bad commit is either a98db518dde246e01ead53617dc0a30d6aaa3752 or c376a3456d8bef43ec556a98c0a04c35086c2737. I don’t know for sure which one introduced it, because during bisection I had to skip a98db518dde246e01ead53617dc0a30d6aaa3752 due to it being unable to launch the virtual machine resulting in a different error (didn’t even start booting). In kernels before these commits, the VM works flawlessly.

I have tested it on latest mainline kernel and the issue is still present. I have been experiencing the issue since kernel 6.13, so I just switched to the 6.12 LTS kernel instead which doesn’t have this issue.

Configuration of my Linux install and hardware: https://pastebin.com/rcsyyYiK
.config: https://pastebin.com/RTQCBduD
dmesg errors: https://pastebin.com/84jPP81E
lspci: https://pastebin.com/qi29BSWi

#regzbot introduced: a98db518dde246e01ead53617dc0a30d6aaa3752..c376a3456d8bef43ec556a98c0a04c35086c2737

Best Regards,
Šimon Pospíchal