linux-kernel - Re: [PATCH v2 10/16] x86/mce: Separate global and per-CPU quirks

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Message-ID: <20250219160641.GD337534@yaz-khff2.amd.com>
Date: Wed, 19 Feb 2025 11:06:41 -0500
From: Yazen Ghannam <yazen.ghannam@....com>
To: "Zhuo, Qiuxu" <qiuxu.zhuo@...el.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 10/16] x86/mce: Separate global and per-CPU quirks

On Tue, Feb 18, 2025 at 06:03:42AM +0000, Zhuo, Qiuxu wrote:
> > From: Yazen Ghannam <yazen.ghannam@....com>
> > [...]
> > --- a/arch/x86/kernel/cpu/mce/intel.c
> > +++ b/arch/x86/kernel/cpu/mce/intel.c
> > @@ -468,8 +468,23 @@ static void intel_imc_init(struct cpuinfo_x86 *c)
> >  	}
> >  }
> > 
> > +static void intel_apply_quirks(struct cpuinfo_x86 *c) {
> > +	/*
> > +	 * SDM documents that on family 6 bank 0 should not be written
> > +	 * because it aliases to another special BIOS controlled
> > +	 * register.
> > +	 * But it's not aliased anymore on model 0x1a+
> > +	 * Don't ignore bank 0 completely because there could be a
> > +	 * valid event later, merely don't write CTL0.
> 
> Is it better to add the following description here? So that it's clear
> we don't apply the quirks for older CPUs.
> 
>     Older CPUs (prior to family 6) can't reach this point and already return early 
>     due to the check of __mcheck_cpu_ancient_init().
> 

I don't know. As you said, the older CPUs don't enter this code, so why
refer to them at all?

> > +	 */
> > +	if (c->x86_vfm < INTEL_NEHALEM_EP &&
> > this_cpu_read(mce_num_banks))
> > +		this_cpu_ptr(mce_banks_array)[0].init = false; }
> > +
> [...]
> 
> LGTM. Thanks.
> 
>     Reviewed-by: Qiuxu Zhuo <qiuxu.zhuo@...el.com>
> 

Thanks,
Yazen