From mboxrd@z Thu Jan  1 00:00:00 1970
From: Paolo Bonzini <pbonzini@redhat.com>
Subject: Re: intel_pstate divide error with v3.13-rc4-256-gb7000ad
Date: Fri, 03 Jan 2014 23:06:21 +0100
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References: <CA+5PVA6YpKc6kYK5UiTnGLZpB8uts=-QPtyhotAyZ2kuoG8PPQ@mail.gmail.com> <4794554.Hmd2RUNYDT@vostro.rjw.lan> <52C18A23.10703@redhat.com> <3710588.K8glfx1cYs@vostro.rjw.lan> <52C6F3B4.3050904@gmail.com> <20140103180435.GK10961@minantech.com> <52C716C1.6070704@gmail.com>
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To: Dirk Brandewie <dirk.brandewie@gmail.com>
Cc: Gleb Natapov <gleb@kernel.org>, "Rafael J. Wysocki" <rjw@rjwysocki.net>, Kashyap Chamarthy <kchamart@redhat.com>, Josh Boyer <jwboyer@fedoraproject.org>, One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk>, Viresh Kumar <viresh.kumar@linaro.org>, "cpufreq@vger.kernel.org" <cpufreq@vger.kernel.org>, Linux PM list <linux-pm@vger.kernel.org>, "Linux-Kernel@Vger. Kernel. Org" <linux-kernel@vger.kernel.org>, "Richard W.M. Jones" <rjones@redhat.com>
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Il 03/01/2014 21:00, Dirk Brandewie ha scritto:
> +    case MSR_IA32_MPERF:
> +    case MSR_IA32_APERF:

These should never be accessed.  A KVM VM will always have
CPUID[06H].ECX = 0, and the Intel manual says that the MSRs are only
present if CPUID returns that value with bit 0 set.

I think the actual bug is that intel_pstate_init does not check the
feature bits in CPUID (either manually or via x86_match_cpu).

Paolo