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Subject: Re: [PATCH 4/4] x86/cpu/topology: Implement the CPU type sysfs
 interface
To:     Ricardo Neri <ricardo.neri-calderon@linux.intel.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        x86@kernel.org, Borislav Petkov <bp@suse.de>,
        Ingo Molnar <mingo@kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
Cc:     Tony Luck <tony.luck@intel.com>, Len Brown <len.brown@intel.com>,
        "Ravi V. Shankar" <ravi.v.shankar@intel.com>,
        linux-kernel@vger.kernel.org, Andi Kleen <ak@linux.intel.com>,
        Dave Hansen <dave.hansen@intel.com>,
        Kan Liang <kan.liang@linux.intel.com>,
        Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
References: <20201003011745.7768-1-ricardo.neri-calderon@linux.intel.com>
 <20201003011745.7768-5-ricardo.neri-calderon@linux.intel.com>
From:   Randy Dunlap <rdunlap@infradead.org>
Message-ID: <03d465a6-f49d-8b83-8fed-111e9eb6e5c5@infradead.org>
Date:   Fri, 2 Oct 2020 20:33:09 -0700
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On 10/2/20 6:17 PM, Ricardo Neri wrote:
> +u32 arch_get_cpu_type(int cpu)
> +{
> +	struct cpuinfo_x86 *c = &cpu_data(cpu);
> +
> +	if (cpu < 0 || cpu >= nr_cpu_ids)
> +		return 0;
> +
> +	return c->x86_cpu_type;> +}

Hi,

Consider using
#include <linux/nospec.h>
and array_index_nospec() to avoid speculation problems on cpu_data.

cheers.
-- 
~Randy