linux-kernel - Re: [PATCH v3 07/18] x86/intel_rdt: Add Haswell feature discovery

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Date:   Sun, 9 Oct 2016 18:28:23 +0200
From:   Borislav Petkov <bp@...e.de>
To:     Fenghua Yu <fenghua.yu@...el.com>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        "H. Peter Anvin" <h.peter.anvin@...el.com>,
        Ingo Molnar <mingo@...e.hu>, Tony Luck <tony.luck@...el.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Stephane Eranian <eranian@...gle.com>,
        Dave Hansen <dave.hansen@...el.com>,
        Nilay Vaish <nilayvaish@...il.com>, Shaohua Li <shli@...com>,
        David Carrillo-Cisneros <davidcc@...gle.com>,
        Ravi V Shankar <ravi.v.shankar@...el.com>,
        Sai Prakhya <sai.praneeth.prakhya@...el.com>,
        Vikas Shivappa <vikas.shivappa@...ux.intel.com>,
        linux-kernel <linux-kernel@...r.kernel.org>, x86 <x86@...nel.org>
Subject: Re: [PATCH v3 07/18] x86/intel_rdt: Add Haswell feature discovery

On Sun, Oct 09, 2016 at 10:09:37AM -0700, Fenghua Yu wrote:
> The MSR is not guaranteed on every stepping of the family and model machine
> because some parts may have the MSR fused off. And some bits in the MSR
> may not be implemented on some parts. And in KVM or guest, the MSR may not
> implemented. Those are reasons why we use wrmsr_safe/rdmsr_safe in Haswell
> probe.

Please add that info in a comment somewhere there as we'll all forget
about it otherwise.

Thanks.

-- 
Regards/Gruss,
    Boris.

SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg)
--