From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934120AbaFSRw6 (ORCPT ); Thu, 19 Jun 2014 13:52:58 -0400 Received: from mga01.intel.com ([192.55.52.88]:20029 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932295AbaFSRw4 (ORCPT ); Thu, 19 Jun 2014 13:52:56 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.01,508,1400050800"; d="scan'208";a="558105555" From: Andi Kleen To: Peter Zijlstra 5A Cc: "Liang\, Kan" , "linux-kernel\@vger.kernel.org" , "kvm\@vger.kernel.org" , "Kleen\, Andi" Subject: Re: [PATCH 1/2] perf: ignore LBR and offcore_rsp. References: <37D7C6CF3E00A74B8858931C1DB2F0770148F513@SHSMSX103.ccr.corp.intel.com> <20140618155916.GZ6758@twins.programming.kicks-ass.net> <87lhsu8arx.fsf@tassilo.jf.intel.com> Date: Thu, 19 Jun 2014 10:52:52 -0700 In-Reply-To: <87lhsu8arx.fsf@tassilo.jf.intel.com> (Andi Kleen's message of "Wed, 18 Jun 2014 09:04:02 -0700") Message-ID: <87ha3g947f.fsf@tassilo.jf.intel.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.3 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Andi Kleen writes: >> >>> Signed-off-by: Kan Liang >> >> And here I thought that Andi was of the opinion that if you set CPUID to >> indicate a particular CPU you had better also handle all its MSRs. > > Yes, philosophically that would be the right way, > but we needed a short term fix to stop things from crashing, and that > was the simplest. I should add there is another reason for this patch now, and doing it in perf instead of somewhere else (this should probably go into the description). With PT on enabling LBR can #GP. So perf needs to handle this case without crashing. This can happen independently of any hypervisors. -Andi -- ak@linux.intel.com -- Speaking for myself only