Arch Linux

Ampera

Member

Registered: 2020-08-17

Posts: 1

Kernel 5.8.1 seems to have novel KVM issue

Before I go any further, this is a heads up, not a complaint. The issue is fixed for me, this is if you're in the position to do something about it, as I thought it useful to make it known. If specific details are needed to reproduce this, I can provide, I just have limited time right this second.

I installed Kernel 5.8.1 this weekend, and Monday morning, it seems like there is a novel issue with QEMU/KVM. Booting a known good Windows 10 VM results in the following bluescreen

https://amperaa.net/cdn/projects/scrot9.png

After a quick switch to the current linux-lts kernel, this issue was resolved. A quick google search shows this cropped up some time around march/may this year, and had something to do with a speculative execution bug with QEMU/KVM on Zen 2 machines.
I will say I am running on a Zen 2 chip, the 3950X to be exact. If anyone's got the same issue, or has the setup to confirm this, I'm sure someone would appreciate it, I'm just here to bring attention that there might be something wrong.

Have a good day.

EDIT: Was unaware of the image restriction. I've removed the image tags

I can write a bug for this one, but I didn't have time to collect details I believed necessary to do it, I just wanted to make a post to see if other people had the same issue, and to get it out there quickly before I returned to (funnily enough) my QA job.

EDIT2: Bug has been written, for reference https://bugs.archlinux.org/task/67620

Last edited by Ampera (2020-08-17 17:16:33)

loqs

Member

Registered: 2014-03-06

Posts: 18,924

Re: Kernel 5.8.1 seems to have novel KVM issue

Please see https://wiki.archlinux.org/index.php/Re … Guidelines
Please do not post oversized image https://wiki.archlinux.org/index.php/Co … s_and_code

ronnylov

Member

Registered: 2010-12-21

Posts: 65

Re: Kernel 5.8.1 seems to have novel KVM issue

I confirm this error. I just upgraded from Ryzen 7 1700 to Ryzen 7 3800X.
Getting the same bluescreen.

archixxx

Member

Registered: 2012-10-17

Posts: 40

Re: Kernel 5.8.1 seems to have novel KVM issue

I have a Ryzen 9 3800. I'm currently using this "cpu" settings in my Windows domain configuration for libvirtd (v6.5):

  ...
  <cpu mode='host-passthrough' check='none' migratable='on'>
    <topology sockets='1' dies='1' cores='6' threads='2'/>
    <feature policy='require' name='topoext'/>
    <feature policy='disable' name='amd-stibp'/>
  </cpu>
  ...

Archlinux wiki also mentions some other possible workarounds but the one above worked best for me: https://wiki.archlinux.org/index.php/PC … CK_FAILURE