Re: [PATCH v2 07/16] x86/mce/amd: Simplify DFR handler setup

Borislav Petkov
2024-04-30T18:06:54Z

On Mon, Apr 29, 2024 at 08:34:37PM +0200, Robert Richter wrote:
> After looking a while into it I think the issue was the following:
>
> IBS offset was not enabled by firmware, but MCE already was (due to
> earlier setup). And mce was (maybe) not on all cpus and only one cpu
> per socket enabled. The IBS vector should be enabled on all cpus. Now
> firmware allocated offset 1 for mce (instead of offset 0 as for
> k8). This caused the hardcoded value (offset 1 for IBS) to be already
> taken. Also, hardcoded values couldn't be used at all as this would
> have not been worked on k8 (for mce). Another issue was to find the
> next free offset as you couldn't examine just the current cpu. So even
> if the offset on the current was available, another cpu might have
> that offset already in use. Yet another problem was that programmed
> offsets for mce and ibs overlapped each other and the kernel had to
> reassign them (the ibs offset).
>
> I hope a remember correctly here with all details.

I think you're remembering it correct because after I read this, a very
very old and dormant brain cell did light up in my head and said, oh
yeah, that definitely rings a bell!

:-P

Yazen, this is the type of mess I was talking about.

--
Regards/Gruss,
Boris.