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Date:   Wed, 26 Jun 2019 22:34:52 +0200 (CEST)
From:   Thomas Gleixner <tglx@linutronix.de>
To:     Fenghua Yu <fenghua.yu@intel.com>
cc:     Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
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Subject: Re: [PATCH v9 13/17] x86/split_lock: Disable split lock detection
 by kernel parameter "nosplit_lock_detect"
In-Reply-To: <1560897679-228028-14-git-send-email-fenghua.yu@intel.com>
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References: <1560897679-228028-1-git-send-email-fenghua.yu@intel.com> <1560897679-228028-14-git-send-email-fenghua.yu@intel.com>
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On Tue, 18 Jun 2019, Fenghua Yu wrote:
>  
>  static void split_lock_update_msr(void)
>  {
> -	/* Enable split lock detection */
> -	this_cpu_or(msr_test_ctl_cached, MSR_TEST_CTL_SPLIT_LOCK_DETECT);
> +	if (split_lock_detect_enabled) {
> +		/* Enable split lock detection */
> +		this_cpu_or(msr_test_ctl_cached, MSR_TEST_CTL_SPLIT_LOCK_DETECT);
> +	} else {
> +		/* Disable split lock detection */

Could you please comment the non obvious things and not the obvious ones?

> +		this_cpu_and(msr_test_ctl_cached, ~MSR_TEST_CTL_SPLIT_LOCK_DETECT);

It's entirely clear that the if (enabled) path enables it or am I missing
something?

Thanks,

	tglx