[Bug 1703506] Re: SMT not supported by QEMU on AMD Ryzen CPU

[Andrii]

Found the same problem using Gnome boxes, as I understand it uses QEMU.

Error I see in gnome boxes when I'm trying to install windows 10 vm:
SYSTEM THREAD EXCEPTION NOT HANDLED

Fresh install of Ubuntu 22.04
CPU: AMD Ryzen 7 1700

The solution posted by asd fghjkl (ryzen27) worked for me too:

sudo nano /etc/modprobe.d/kvm.conf
add "options kvm ignore_msrs=1" (without quotes)
reboot

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https://bugs.launchpad.net/bugs/1703506

Title:
  SMT not supported by QEMU on AMD Ryzen CPU

Status in QEMU:
  Expired

Bug description:
  HyperThreading/SMT is supported by AMD Ryzen CPUs but results in this
  message when setting the topology to threads=2:

  qemu-system-x86_64: AMD CPU doesn't support hyperthreading. Please
  configure -smp options properly.

  Checking in a Windows 10 guest reveals that SMT is not enabled, and
  from what I understand, QEMU converts the topology from threads to
  cores internally on AMD CPUs. This appears to cause performance
  problems in the guest perhaps because programs are assuming that these
  threads are actual cores.

  Software: Linux 4.12, qemu 2.9.0 host with KVM enabled, Windows 10 pro
  guest

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