linux-kernel - Re: [PATCH] Handle Ice Lake MONITOR erratum

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Message-ID: <aAfvalru47h7Qffk@gmail.com>
Date: Tue, 22 Apr 2025 21:35:06 +0200
From: Ingo Molnar <mingo@...nel.org>
To: Dave Hansen <dave.hansen@...el.com>
Cc: Dave Hansen <dave.hansen@...ux.intel.com>, linux-kernel@...r.kernel.org,
	x86@...nel.org, andrew.cooper3@...rix.com,
	Len Brown <len.brown@...el.com>,
	Peter Zijlstra <peterz@...radead.org>,
	"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
	Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
	stable@...r.kernel.org
Subject: Re: [PATCH] Handle Ice Lake MONITOR erratum


* Dave Hansen <dave.hansen@...el.com> wrote:

> On 4/21/25 23:46, Ingo Molnar wrote:
> >>  /*
> >> + * These CPUs have buggy MWAIT/MONITOR implementations that
> >> + * usually manifest as hangs or stalls at boot.
> >> + */
> >> +#define MWAIT_VFM(_vfm)	\
> >> +	X86_MATCH_VFM_FEATURE(_vfm, X86_FEATURE_MWAIT, 0)
> >> +static const struct x86_cpu_id monitor_bug_list[] = {
> >> +	MWAIT_VFM(INTEL_ATOM_GOLDMONT),
> >> +	MWAIT_VFM(INTEL_LUNARLAKE_M),
> >> +	MWAIT_VFM(INTEL_ICELAKE_X),	/* Erratum ICX143 */
> >> +	{},
> >> +};
> > While it's just an internal helper, macro names should still be 
> > intuitive:
> > 
> >   s/MWAIT_VFM
> >    /VFM_MWAIT_BUG
> 
> The current convention is to end with the thing that's being matched,
> like "_FEATURE" or "_VFM" in the X86_MATCH*() macros. That's why I
> ordered it the way I did.
> 
> As for including "BUG", the _macro_ doesn't match CPUs with the bug.
> It's just matching CPUs with the specified VFM that have MWAIT. It could
> (theoretically) get used for non-bug things so I don't think it's
> intuitive to put "BUG" in the name.

Oh, that makes sense - objection withdrawn.

Thanks,

	Ingo