From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754662AbaFWJT5 (ORCPT ); Mon, 23 Jun 2014 05:19:57 -0400 Received: from casper.infradead.org ([85.118.1.10]:46532 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752862AbaFWJTz (ORCPT ); Mon, 23 Jun 2014 05:19:55 -0400 Date: Mon, 23 Jun 2014 11:19:52 +0200 From: Peter Zijlstra To: Andi Kleen 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. Message-ID: <20140623091952.GP19860@laptop.programming.kicks-ass.net> References: <37D7C6CF3E00A74B8858931C1DB2F0770148F513@SHSMSX103.ccr.corp.intel.com> <20140618155916.GZ6758@twins.programming.kicks-ass.net> <87lhsu8arx.fsf@tassilo.jf.intel.com> <87ha3g947f.fsf@tassilo.jf.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87ha3g947f.fsf@tassilo.jf.intel.com> User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jun 19, 2014 at 10:52:52AM -0700, Andi Kleen wrote: > 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. WTH is a PT?