Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754605AbbHFPab (ORCPT ); Thu, 6 Aug 2015 11:30:31 -0400 Received: from mail-lb0-f172.google.com ([209.85.217.172]:36256 "EHLO mail-lb0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754271AbbHFPaa (ORCPT ); Thu, 6 Aug 2015 11:30:30 -0400 MIME-Version: 1.0 In-Reply-To: <20150806152151.GG25159@twins.programming.kicks-ass.net> References: <1437407346-31186-1-git-send-email-kan.liang@intel.com> <37D7C6CF3E00A74B8858931C1DB2F077018D16F1@SHSMSX103.ccr.corp.intel.com> <37D7C6CF3E00A74B8858931C1DB2F077018D206A@SHSMSX103.ccr.corp.intel.com> <37D7C6CF3E00A74B8858931C1DB2F077018D2103@SHSMSX103.ccr.corp.intel.com> <20150806152151.GG25159@twins.programming.kicks-ass.net> From: Andy Lutomirski Date: Thu, 6 Aug 2015 08:30:08 -0700 Message-ID: Subject: Re: [tip:perf/core] perf/x86: Add an MSR PMU driver To: Peter Zijlstra Cc: "Liang, Kan" , Thomas Gleixner , "linux-kernel@vger.kernel.org" , "H. Peter Anvin" , Andrew Lutomirski , Linus Torvalds , Ingo Molnar , "linux-tip-commits@vger.kernel.org" Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 808 Lines: 18 On Thu, Aug 6, 2015 at 8:21 AM, Peter Zijlstra wrote: > On Tue, Aug 04, 2015 at 08:39:27PM +0000, Liang, Kan wrote: > - default: > - err = -ENOTSUPP; > + if (!msr[i].test() || rdmsrl_safe(msr[i].msr, &val)) > + msr[i].attr = NULL; IIRC rdmsrl_safe literally never fails under QEMU TCG, and I'm not entirely sure what happens under KVM if emulation kicks in. It might pay to keep the model check for the non-architectural stuff, or at least check for a nonzero return value. --Andy -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/