linux-kernel - RE: [PATCH v2 07/16] x86/mce: Define BSP-only init

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Message-ID: <CY8PR11MB7134DA72B48006B403A6516D89C42@CY8PR11MB7134.namprd11.prod.outlook.com>
Date: Thu, 20 Feb 2025 01:37:37 +0000
From: "Zhuo, Qiuxu" <qiuxu.zhuo@...el.com>
To: Yazen Ghannam <yazen.ghannam@....com>
CC: "x86@...nel.org" <x86@...nel.org>, "Luck, Tony" <tony.luck@...el.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-edac@...r.kernel.org" <linux-edac@...r.kernel.org>,
	"Smita.KoralahalliChannabasappa@....com"
	<Smita.KoralahalliChannabasappa@....com>
Subject: RE: [PATCH v2 07/16] x86/mce: Define BSP-only init

> From: Yazen Ghannam <yazen.ghannam@....com>
> [...]
> > > --- a/arch/x86/kernel/cpu/mce/core.c
> > > +++ b/arch/x86/kernel/cpu/mce/core.c
> > > [...]
> > > +/* Called only on the boot CPU. */
> > > +void cpu_mca_init(struct cpuinfo_x86 *c) {
> > > +	u64 cap;
> > > +
> > > +	if (!mce_available(c))
> > > +		return;
> > > +
> > > +	mce_flags.overflow_recov =
> > > cpu_feature_enabled(X86_FEATURE_OVERFLOW_RECOV);
> > > +	mce_flags.succor	 =
> > > cpu_feature_enabled(X86_FEATURE_SUCCOR);
> > > +	mce_flags.smca		 =
> > > cpu_feature_enabled(X86_FEATURE_SMCA);
> >
> > 1. Before this patch set, the above code was executed only if the following
> >     condition was true. Do we still need this check?
> >
> >     if (c->x86_vendor == X86_VENDOR_AMD || c->x86_vendor ==
> X86_VENDOR_HYGON)
> >     {
> >           The above code.
> >      }
> 
> I don't think so. Feature checks should be independent of vendor, so the
> vendor checks are redundant.

Without the vendor check, the Intel CPUs will also run this code (which they should
*NOT* ) and may mistakenly set those global AMD-specific flags, which may result in
Intel CPUs performing AMD-specific error handling during the machine check.

-Qiuxu