From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754031AbaGHJZY (ORCPT ); Tue, 8 Jul 2014 05:25:24 -0400 Received: from bombadil.infradead.org ([198.137.202.9]:43865 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751834AbaGHJZV (ORCPT ); Tue, 8 Jul 2014 05:25:21 -0400 Date: Tue, 8 Jul 2014 11:25:13 +0200 From: Peter Zijlstra To: kan.liang@intel.com Cc: andi@firstfloor.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org Subject: Re: [PATCH V3 1/2] perf ignore LBR and offcore_rsp. Message-ID: <20140708092513.GB6758@twins.programming.kicks-ass.net> References: <1404740066-4374-1-git-send-email-kan.liang@intel.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="9uH70MWbZgudpa7t" Content-Disposition: inline In-Reply-To: <1404740066-4374-1-git-send-email-kan.liang@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 --9uH70MWbZgudpa7t Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Mon, Jul 07, 2014 at 06:34:25AM -0700, kan.liang@intel.com wrote: > + /* > + * Access LBR MSR may cause #GP under certain circumstances. > + * E.g. KVM doesn't support LBR MSR > + * Check all LBT MSR here. > + * Disable LBR access if any LBR MSRs can not be accessed. > + */ > + if (x86_pmu.lbr_nr) { > + x86_pmu.lbr_msr_access = check_msr(x86_pmu.lbr_tos); > + for (i = 0; i < x86_pmu.lbr_nr; i++) { > + x86_pmu.lbr_msr_access &= > + check_msr(x86_pmu.lbr_from + i); > + x86_pmu.lbr_msr_access &= > + check_msr(x86_pmu.lbr_to + i); > + } > + } So I was going to refer you to an email I send earlier telling you that this was wrong, but then found it got stuck in a mailqueue on my laptop :-( In any case its wrong; just clear lbr_nr and kill lbr_msr_access. We already check lbr_nr in all the right places and you added lbr_msr_access to far too few of them (also the fact that every place you check lbr_msr_access already had an lbr_nr test should've been a clue). --9uH70MWbZgudpa7t Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (GNU/Linux) iQIcBAEBAgAGBQJTu7j5AAoJEHZH4aRLwOS6tJIP/10OHJ0vI/W9HhrRX0yGPLUA LdDfzUYzY4nrymxYi3j6qBvnyXoF28jSRJegx4bUOn1Dyw+jPV9hkLU2XaaHbfPF tDooilqwC6BLvnKtd9I/dJjXstUSqNDdhOumiXU+Duq6E65LfuRwjeyuvyQj7WXZ i3NKY3OEenrHb6bUf42xLARdB1JYt9OBTrKzzuqSbAfIstmERFByySmIE0oQwxvX 7pN7LUOzMd0HF+eL9xZpdIAZtBaAOuhewiibtK/+FHKyJtqVXtYpXFWW6zdQ7swd 64BjJG5B26AyWumbNbNPrLgVzivBWS9oVMZ00wc9AFsafckODXMNdPN/4xVGKOl+ Z/dXXzXJU/W+xJ7R7qxX2UMgFegJKpzQTK/ymVzaI2X32Ibt8tsY+1BGFHoM50V0 HnCZMvEXGOF2sYfPZ8w8FVD/WPSkDmQoI9EJl5kCLv3JCBxaStWtzMmuW0jv2Gr7 +mnpiL2geemfRGGZej4OPqaxNWo8bzm1y4y14RZWmUv9wR1wLZle0qSa14TTN1ws mKSGeD9ijyZMgv1EfphNJLIgAgElolz3ijmWcYFIQPsIt3jYCwhAOugorxa8BNYn y3veXZvo6qDTsaYz/J5k015h63M8WRtaTFrykRmw95PKiMJQvu21+sGYxlB/1uqu oAedFwlR8xAzVk2jPiBd =ecZb -----END PGP SIGNATURE----- --9uH70MWbZgudpa7t--