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Date:   Mon, 27 Jul 2020 10:23:44 +0200
From:   peterz@infradead.org
To:     Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
Cc:     Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@kernel.org>, Borislav Petkov <bp@suse.de>,
        Andy Lutomirski <luto@kernel.org>, x86@kernel.org,
        Dave Hansen <dave.hansen@intel.com>,
        Tony Luck <tony.luck@intel.com>,
        Cathy Zhang <cathy.zhang@intel.com>,
        Fenghua Yu <fenghua.yu@intel.com>,
        "H. Peter Anvin" <hpa@zytor.com>,
        Kyung Min Park <kyung.min.park@intel.com>,
        "Ravi V. Shankar" <ravi.v.shankar@intel.com>,
        Sean Christopherson <sean.j.christopherson@intel.com>,
        linux-kernel@vger.kernel.org,
        Ricardo Neri <ricardo.neri@intel.com>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        linux-edac@vger.kernel.org
Subject: Re: [PATCH 4/4] x86/cpu: Use SERIALIZE in sync_core() when available
Message-ID: <20200727082344.GE119549@hirez.programming.kicks-ass.net>
References: <20200727043132.15082-1-ricardo.neri-calderon@linux.intel.com>
 <20200727043132.15082-5-ricardo.neri-calderon@linux.intel.com>
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On Sun, Jul 26, 2020 at 09:31:32PM -0700, Ricardo Neri wrote:
> @@ -75,6 +77,12 @@ static inline void sync_core(void)
>  	 * Like all of Linux's memory ordering operations, this is a
>  	 * compiler barrier as well.
>  	 */
> +
> +	if (boot_cpu_has(X86_FEATURE_SERIALIZE)) {
> +		serialize();
> +		return;
> +	}
> +
>  	iret_to_self();

I was sorta expecting something like:

	alternative(IRET_TO_SELF, SERIALIZE, X86_FEATURE_SERIALIZE);

But instead you used boot_cpu_has() which is a dynamic test.