From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756792Ab2GKJt4 (ORCPT ); Wed, 11 Jul 2012 05:49:56 -0400 Received: from casper.infradead.org ([85.118.1.10]:56273 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752790Ab2GKJty convert rfc822-to-8bit (ORCPT ); Wed, 11 Jul 2012 05:49:54 -0400 Message-ID: <1342000187.3462.134.camel@twins> Subject: Re: perf with precise attribute kills all KVM based VMs From: Peter Zijlstra To: Gleb Natapov Cc: David Ahern , Avi Kivity , LKML Date: Wed, 11 Jul 2012 11:49:47 +0200 In-Reply-To: <20120711071006.GF23898@redhat.com> References: <4FFAE6D8.5050609@gmail.com> <20120709141904.GC7298@redhat.com> <1341843844.3462.75.camel@twins> <4FFAED16.7050204@redhat.com> <4FFAEF13.7010108@gmail.com> <1341845396.3462.81.camel@twins> <4FFAEFF1.9000706@redhat.com> <1341845999.3462.86.camel@twins> <4FFCBD00.1030109@gmail.com> <20120711071006.GF23898@redhat.com> Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT X-Mailer: Evolution 3.2.2- Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2012-07-11 at 10:10 +0300, Gleb Natapov wrote: > Looks like Avi is right about the overshoot. Can you test something like this? > > diff --git a/arch/x86/kernel/cpu/perf_event_intel.c b/arch/x86/kernel/cpu/perf_event_intel.c > index 166546e..5fb371a 100644 > --- a/arch/x86/kernel/cpu/perf_event_intel.c > +++ b/arch/x86/kernel/cpu/perf_event_intel.c > @@ -1374,8 +1374,11 @@ static struct perf_guest_switch_msr *intel_guest_get_msrs(int *nr) > arr[0].msr = MSR_CORE_PERF_GLOBAL_CTRL; > arr[0].host = x86_pmu.intel_ctrl & ~cpuc->intel_ctrl_guest_mask; > arr[0].guest = x86_pmu.intel_ctrl & ~cpuc->intel_ctrl_host_mask; > + arr[1].msr = MSR_IA32_PEBS_ENABLE; > + arr[1].host = cpuc->pebs_enabled; > + arr[1].guest = 0; > + *nr = 2; > > - *nr = 1; > return arr; > } You also need to clear TR, BTS, BTINT from MSR_IA32_DEBUGCTLMSR and ideally you'd also clear MSR_IA32_DS_AREA so that any write will be a proper NULL deref or such.