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From: Dirk Brandewie <dirk.brandewie@gmail.com>
To: Paolo Bonzini <pbonzini@redhat.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>
Subject: Re: intel_pstate divide error with v3.13-rc4-256-gb7000ad
Date: Mon, 06 Jan 2014 09:18:44 -0800
Message-ID: <52CAE574.3010304@gmail.com> (raw)
In-Reply-To: <52C7345D.30603@redhat.com>

On 01/03/2014 02:06 PM, Paolo Bonzini wrote:
> Il 03/01/2014 21:00, Dirk Brandewie ha scritto:
>> +    case MSR_IA32_MPERF:
>> +    case MSR_IA32_APERF:
>
OK I will spin the patch to only add MSR_PLATFORM_INFO.

> 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).

I will add the feature check.

What are the differences between the first and the nested KVM's?
At load time intel_pstate checks that APERF and MPERF are incrementing
and that PLATFORM_INFO has some value.  Somehow these checks pass
in the nested environment and we fall over when the CPU is being added
by cpufreq.

--Dirk


  reply index

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-12-24 14:36 Josh Boyer
2013-12-24 16:06 ` Viresh Kumar
2013-12-27 12:24   ` One Thousand Gnomes
2013-12-27 12:47     ` Gleb Natapov
2013-12-27 13:46       ` Josh Boyer
2013-12-27 14:15         ` Kashyap Chamarthy
2013-12-27 14:34           ` Richard W.M. Jones
2013-12-27 16:52           ` Gleb Natapov
2013-12-27 17:01             ` Gleb Natapov
2013-12-27 17:17               ` Richard W.M. Jones
2013-12-27 17:17               ` Kashyap Chamarthy
2013-12-27 21:51                 ` Rafael J. Wysocki
2013-12-29 12:12                   ` Kashyap Chamarthy
2013-12-29 15:04                     ` Rafael J. Wysocki
2013-12-30 14:58                       ` Kashyap Chamarthy
2013-12-31  2:07                         ` Rafael J. Wysocki
2014-01-03 17:30                           ` Dirk Brandewie
2014-01-03 18:04                             ` Gleb Natapov
2014-01-03 20:00                               ` Dirk Brandewie
2014-01-03 22:06                                 ` Paolo Bonzini
2014-01-06 17:18                                   ` Dirk Brandewie [this message]
2014-01-07 16:11                                     ` Gleb Natapov
2014-01-03 22:46                               ` Rafael J. Wysocki
2014-01-04  8:35                                 ` Paolo Bonzini
2014-01-04 14:38                                   ` Rafael J. Wysocki
2014-01-04 17:38                                     ` Paolo Bonzini
2014-01-04 17:48                                       ` Gleb Natapov
2014-01-04 21:38                                         ` Rafael J. Wysocki
2014-01-06 11:20                                           ` Paolo Bonzini
2014-01-06 11:37                                             ` Rafael J. Wysocki
2014-01-06 18:40                                               ` Dirk Brandewie
2013-12-27 14:35   ` Rafael J. Wysocki

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