linux-kernel - Re: [PATCH v2 4/4] x86/mce: Add Zhaoxin LMCE support

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Date:   Tue, 10 Sep 2019 14:36:57 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Tony W Wang-oc <TonyWWang-oc@...oxin.com>
Cc:     "tony.luck@...el.com" <tony.luck@...el.com>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "mingo@...hat.com" <mingo@...hat.com>,
        "hpa@...or.com" <hpa@...or.com>, "x86@...nel.org" <x86@...nel.org>,
        "linux-edac@...r.kernel.org" <linux-edac@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "yazen.ghannam@....com" <yazen.ghannam@....com>,
        "vishal.l.verma@...el.com" <vishal.l.verma@...el.com>,
        "qiuxu.zhuo@...el.com" <qiuxu.zhuo@...el.com>,
        David Wang <DavidWang@...oxin.com>,
        "Cooper Yan(BJ-RD)" <CooperYan@...oxin.com>,
        "Qiyuan Wang(BJ-RD)" <QiyuanWang@...oxin.com>,
        "Herry Yang(BJ-RD)" <HerryYang@...oxin.com>
Subject: Re: [PATCH v2 4/4] x86/mce: Add Zhaoxin LMCE support

On Tue, Sep 10, 2019 at 08:20:07AM +0000, Tony W Wang-oc wrote:
> Zhaoxin newer CPUs support LMCE that compatible with Intel's
> "Machine-Check Architecture", so add support for Zhaoxin LMCE
> in mce/core.c.
> 
> Signed-off-by: Tony W Wang-oc <TonyWWang-oc@...oxin.com>
> ---
> v1->v2:
>  - Fix redefinition of "mce_zhaoxin_feature_clear"
> 
>  arch/x86/include/asm/mce.h     |  2 ++
>  arch/x86/kernel/cpu/mce/core.c | 25 +++++++++++++++++++++++--
>  2 files changed, 25 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/x86/include/asm/mce.h b/arch/x86/include/asm/mce.h
> index 0986a11..01840ec 100644
> --- a/arch/x86/include/asm/mce.h
> +++ b/arch/x86/include/asm/mce.h
> @@ -352,8 +352,10 @@ static inline void mce_hygon_feature_init(struct cpuinfo_x86 *c)	{ return mce_am
>  
>  #ifdef CONFIG_CPU_SUP_ZHAOXIN
>  void mce_zhaoxin_feature_init(struct cpuinfo_x86 *c);
> +void mce_zhaoxin_feature_clear(struct cpuinfo_x86 *c);
>  #else
>  static inline void mce_zhaoxin_feature_init(struct cpuinfo_x86 *c) { }
> +static inline void mce_zhaoxin_feature_clear(struct cpuinfo_x86 *c) { }
>  #endif
>  
>  #endif /* _ASM_X86_MCE_H */
> diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c
> index 8a36833..595d3af7ac 100644
> --- a/arch/x86/kernel/cpu/mce/core.c
> +++ b/arch/x86/kernel/cpu/mce/core.c
> @@ -1129,6 +1129,17 @@ static bool __mc_check_crashing_cpu(int cpu)
>  		u64 mcgstatus;
>  
>  		mcgstatus = mce_rdmsrl(MSR_IA32_MCG_STATUS);
> +
> +		if (boot_cpu_data.x86_vendor == X86_VENDOR_ZHAOXIN) {
> +			if (mcgstatus & MCG_STATUS_LMCES) {
> +				return false;
> +			} else {
> +				if (mcgstatus & MCG_STATUS_RIPV)
> +					mce_wrmsrl(MSR_IA32_MCG_STATUS, 0);
> +				return true;
> +			}
> +		}

Simplify:

                if (boot_cpu_data.x86_vendor == X86_VENDOR_ZHAOXIN) {
                        if (mcgstatus & MCG_STATUS_LMCES)
                                return false;
		}

		<--- Now here, on your CPUs which don't set MCG_STATUS_LMCES,
it will fallback to clearing the status register. I.e., what you do in the else
clause.

-- 
Regards/Gruss,
    Boris.

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