From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dirk Brandewie 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> References: <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> <52C7345D.30603@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mail-pd0-f175.google.com ([209.85.192.175]:61968 "EHLO mail-pd0-f175.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755259AbaAFRSl (ORCPT ); Mon, 6 Jan 2014 12:18:41 -0500 In-Reply-To: <52C7345D.30603@redhat.com> Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: Paolo Bonzini Cc: Gleb Natapov , "Rafael J. Wysocki" , Kashyap Chamarthy , Josh Boyer , One Thousand Gnomes , Viresh Kumar , "cpufreq@vger.kernel.org" , Linux PM list , "Linux-Kernel@Vger. Kernel. Org" , "Richard W.M. Jones" 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