Re: [BUG] Linux kernel crash in amd_smn_init during PVH Dom0 boot on AMD EPYC

[Jason Andryuk <jason.andryuk@amd.com>]

On 2026-08-19 03:09, Arthur Borsboom wrote:
> It has taken me about 1,5 day of work to find out why the screen
> remained black, to determine where the problem was, how to retrieve
> potential info by a serial-over-LAN console, subscribe to the mailing
> list, and create this bug report to help.

Yes, this is annoying :/

> On Wed, 19 Aug 2026 at 08:50, Jan Beulich <jbeulich@suse.com> wrote:
>>
>> On 18.08.2026 23:47, Arthur Borsboom wrote:
>>> Hi,
>>>
>>> I am encountering an early Linux kernel crash when booting a PVH
>>> Dom0 on an AMD EPYC system (Family 19h Model 97). PV boot on the
>>> same system works fine. The crash occurs during amd_smn_init due
>>> to a divide-by-zero exception.

That looks like the same issue I am trying to fix.

>>> There is a potentially related bug report discussing a Linux patch
>>> addressing AMD SMN initialization under Xen PVH:
>>>
>>> https://patchew.org/linux/20260623211904.3674-1-jason.andryuk@amd.com/
>>>
>>> It seems there was an ongoing discussion between Linux devs who
>>> seem to have the need to align with Xen devs for a proper/future-proof fix.
>>> I am submitting this report to share raw hardware trace data and
>>> help move this forward.

Yes, there was some discussion, but we have agreed on an approach.
>> [1] https://patchew.org/linux/20260814214255.83127-1-jason.andryuk@amd.com/20260814214255.83127-2-jason.andryuk@amd.com/
This v2 is basically what was suggested by a maintainer, so it should be 
picked up - hopefully soon.

Regards,
Jason