From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id ED8CFC10F0E for ; Mon, 15 Apr 2019 12:42:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C7DB5206B6 for ; Mon, 15 Apr 2019 12:42:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727458AbfDOMmG (ORCPT ); Mon, 15 Apr 2019 08:42:06 -0400 Received: from mx1.redhat.com ([209.132.183.28]:38426 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726094AbfDOMmG (ORCPT ); Mon, 15 Apr 2019 08:42:06 -0400 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 1605C89C33; Mon, 15 Apr 2019 12:42:06 +0000 (UTC) Received: from gigantic.usersys.redhat.com (helium.bos.redhat.com [10.18.17.132]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 5F9745D717; Mon, 15 Apr 2019 12:42:05 +0000 (UTC) From: Bandan Das To: Peter Zijlstra Cc: Ingo Molnar , Arnaldo Carvalho de Melo , Jiri Olsa , linux-kernel@vger.kernel.org, x86@kernel.org Subject: Re: [PATCH] perf/x86: descriptive failure messages for PMU init References: <20190415120444.GN11158@hirez.programming.kicks-ass.net> Date: Mon, 15 Apr 2019 08:42:04 -0400 In-Reply-To: <20190415120444.GN11158@hirez.programming.kicks-ass.net> (Peter Zijlstra's message of "Mon, 15 Apr 2019 14:04:44 +0200") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.27]); Mon, 15 Apr 2019 12:42:06 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Peter, Peter Zijlstra writes: > On Fri, Apr 12, 2019 at 03:09:17PM -0400, Bandan Das wrote: >> >> There's a default warning message that gets printed, however, >> there are various failure conditions: >> - a msr read can fail >> - a msr write can fail >> - a msr has an unexpected value >> - all msrs have unexpected values (disable PMU) >> >> Also, commit commit 005bd0077a79 ("perf/x86: Modify error message in >> virtualized environment") completely removed printing the msr in >> question but these messages could be helpful for debugging vPMUs as >> well. Add them back and change them to pr_debugs, this keeps the >> behavior the same for baremetal. >> >> Lastly, use %llx to silence checkpatch > > Yuck... if you're debugging a hypervisor, you can bloody well run your > own kernel with additional print slattered around. > > The whole make an exception for virt bullshit was already pushing it, > this is just insane. > The only virt specific parts are the pr_debugs which I can remove and replace with unconditional pr_err()s as suggested by Jiri. Is that ok ? Bandan >> @@ -266,12 +282,30 @@ static bool check_hw_exists(void) >> return true; >> >> msr_fail: >> - if (boot_cpu_has(X86_FEATURE_HYPERVISOR)) { >> + if (virt) >> pr_cont("PMU not available due to virtualization, using software events only.\n"); >> - } else { >> - pr_cont("Broken PMU hardware detected, using software events only.\n"); >> - pr_err("Failed to access perfctr msr (MSR %x is %Lx)\n", >> - reg, val_new); >> + switch (status) { >> + case READ_FAIL: >> + if (virt) >> + pr_debug("Failed to read perfctr msr (MSR %x)\n", reg); >> + else >> + pr_err("Failed to read perfctr msr (MSR %x)\n", reg); >> + break; >> + case WRITE_FAIL: >> + if (virt) >> + pr_debug("Failed to write perfctr msr (MSR %x, wrote: %llx, read: %llx)\n", >> + reg, val, val_new); >> + else >> + pr_err("Failed to write perfctr msr (MSR %x, wrote: %llx, read: %llx)\n", >> + reg, val, val_new); >> + break; >> + case PMU_FAIL: >> + /* fall through for default message */ >> + default: >> + if (virt) >> + pr_debug("Broken PMU hardware detected, using software events only.\n"); >> + else >> + pr_cont("Broken PMU hardware detected, using software events only.\n"); >> }