linux-kernel - Re: [PATCH v12] x86/split_lock: Enable split lock detection by kernel

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Date:   Wed, 22 Jan 2020 20:04:05 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     "Luck, Tony" <tony.luck@...el.com>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...nel.org>,
        Fenghua Yu <fenghua.yu@...el.com>,
        Ingo Molnar <mingo@...hat.com>, H Peter Anvin <hpa@...or.com>,
        Ashok Raj <ashok.raj@...el.com>,
        Ravi V Shankar <ravi.v.shankar@...el.com>,
        linux-kernel <linux-kernel@...r.kernel.org>, x86 <x86@...nel.org>
Subject: Re: [PATCH v12] x86/split_lock: Enable split lock detection by kernel

On Wed, Jan 22, 2020 at 10:55:14AM -0800, Luck, Tony wrote:
> diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
> index e9b62498fe75..c3edd2bba184 100644
> --- a/arch/x86/include/asm/cpufeatures.h
> +++ b/arch/x86/include/asm/cpufeatures.h
> @@ -220,6 +220,7 @@
>  #define X86_FEATURE_ZEN			( 7*32+28) /* "" CPU is AMD family 0x17 (Zen) */
>  #define X86_FEATURE_L1TF_PTEINV		( 7*32+29) /* "" L1TF workaround PTE inversion */
>  #define X86_FEATURE_IBRS_ENHANCED	( 7*32+30) /* Enhanced IBRS */
> +#define X86_FEATURE_SPLIT_LOCK_DETECT	( 7*32+31) /* #AC for split lock */

That word is already full in tip:

...
#define X86_FEATURE_MSR_IA32_FEAT_CTL   ( 7*32+31) /* "" MSR IA32_FEAT_CTL configured */

use word 11 instead.

> +#define MSR_TEST_CTRL				0x00000033
> +#define MSR_TEST_CTRL_SPLIT_LOCK_DETECT_BIT	29
> +#define MSR_TEST_CTRL_SPLIT_LOCK_DETECT		BIT(MSR_TEST_CTRL_SPLIT_LOCK_DETECT_BIT)
> +
>  #define MSR_IA32_SPEC_CTRL		0x00000048 /* Speculation Control */
>  #define SPEC_CTRL_IBRS			BIT(0)	   /* Indirect Branch Restricted Speculation */
>  #define SPEC_CTRL_STIBP_SHIFT		1	   /* Single Thread Indirect Branch Predictor (STIBP) bit */
> @@ -70,6 +74,10 @@
>   */
>  #define MSR_IA32_UMWAIT_CONTROL_TIME_MASK	(~0x03U)
>  
> +#define MSR_IA32_CORE_CAPABILITIES			  0x000000cf
> +#define MSR_IA32_CORE_CAPABILITIES_SPLIT_LOCK_DETECT_BIT  5
> +#define MSR_IA32_CORE_CAPABILITIES_SPLIT_LOCK_DETECT	  BIT(MSR_IA32_CORE_CAPABILITIES_SPLIT_LOCK_DETECT_BIT)

Any chance making those shorter?

-- 
Regards/Gruss,
    Boris.

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