linux-kernel - Re: [PATCH v6 02/15] x86/mce: Define BSP-only init

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Message-ID: <98d80660-7140-43a2-b17c-07a0884996f8@suse.com>
Date: Wed, 10 Sep 2025 14:47:16 +0300
From: Nikolay Borisov <nik.borisov@...e.com>
To: Yazen Ghannam <yazen.ghannam@....com>, x86@...nel.org,
 Tony Luck <tony.luck@...el.com>, "Rafael J. Wysocki" <rafael@...nel.org>
Cc: linux-kernel@...r.kernel.org, linux-edac@...r.kernel.org,
 Smita.KoralahalliChannabasappa@....com, Qiuxu Zhuo <qiuxu.zhuo@...el.com>,
 linux-acpi@...r.kernel.org
Subject: Re: [PATCH v6 02/15] x86/mce: Define BSP-only init

On 9/8/25 18:40, Yazen Ghannam wrote:
> Currently, MCA initialization is executed identically on each CPU as
> they are brought online. However, a number of MCA initialization tasks
> only need to be done once.
> 
> Define a function to collect all 'global' init tasks and call this from
> the BSP only. Start with CPU features.
> 
> Reviewed-by: Qiuxu Zhuo <qiuxu.zhuo@...el.com>
> Tested-by: Tony Luck <tony.luck@...el.com>
> Reviewed-by: Tony Luck <tony.luck@...el.com>
> Signed-off-by: Yazen Ghannam <yazen.ghannam@....com>

<snip>

> @@ -2240,6 +2233,27 @@ DEFINE_IDTENTRY_RAW(exc_machine_check)
>   }
>   #endif
>   
> +void mca_bsp_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);
> +
> +	rdmsrq(MSR_IA32_MCG_CAP, cap);
> +
> +	/* Use accurate RIP reporting if available. */
> +	if ((cap & MCG_EXT_P) && MCG_EXT_CNT(cap) >= 9)
> +		mca_cfg.rip_msr = MSR_IA32_MCG_EIP;
> +
> +	if (cap & MCG_SER_P)
> +		mca_cfg.ser = 1;
> +}
> +

LGTM

Reviewed-by: Nikolay Borisov <nik.borisov@...e.com>

nit: One question though for those CPUs which consist of P+E cores, is 
it mandated that both types of cores will have identical MCE 
architecture, I assume the x86 world will be a lot more unified than 
Arm's big.LITTLE ?

>   /*
>    * Called for each booted CPU to set up machine checks.
>    * Must be called with preempt off:
>