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=-11.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 9346BC55189 for ; Wed, 22 Apr 2020 21:20:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7C0A421582 for ; Wed, 22 Apr 2020 21:20:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726519AbgDVVU4 (ORCPT ); Wed, 22 Apr 2020 17:20:56 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53214 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726066AbgDVVUz (ORCPT ); Wed, 22 Apr 2020 17:20:55 -0400 Received: from Galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8128DC03C1A9; Wed, 22 Apr 2020 14:20:55 -0700 (PDT) Received: from [5.158.153.53] (helo=tip-bot2.lab.linutronix.de) by Galois.linutronix.de with esmtpsa (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1jRMnZ-0000Ol-VY; Wed, 22 Apr 2020 23:20:50 +0200 Received: from [127.0.1.1] (localhost [IPv6:::1]) by tip-bot2.lab.linutronix.de (Postfix) with ESMTP id 7A1641C0450; Wed, 22 Apr 2020 23:20:49 +0200 (CEST) Date: Wed, 22 Apr 2020 21:20:49 -0000 From: "tip-bot2 for Giovanni Gherdovich" Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: sched/urgent] x86, sched: Bail out of frequency invariance if base frequency is unknown Cc: Giovanni Gherdovich , "Peter Zijlstra (Intel)" , "Rafael J. Wysocki" , x86 , LKML In-Reply-To: <20200416054745.740-2-ggherdovich@suse.cz> References: <20200416054745.740-2-ggherdovich@suse.cz> MIME-Version: 1.0 Message-ID: <158759044911.28353.2414263048020355766.tip-bot2@tip-bot2> X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The following commit has been merged into the sched/urgent branch of tip: Commit-ID: 9a6c2c3c7a73ce315c57c1b002caad6fcc858d0f Gitweb: https://git.kernel.org/tip/9a6c2c3c7a73ce315c57c1b002caad6fcc858d0f Author: Giovanni Gherdovich AuthorDate: Thu, 16 Apr 2020 07:47:42 +02:00 Committer: Peter Zijlstra CommitterDate: Wed, 22 Apr 2020 23:10:13 +02:00 x86, sched: Bail out of frequency invariance if base frequency is unknown Some hypervisors such as VMWare ESXi 5.5 advertise support for X86_FEATURE_APERFMPERF but then fill all MSR's with zeroes. In particular, MSR_PLATFORM_INFO set to zero tricks the code that wants to know the base clock frequency of the CPU (highest non-turbo frequency), producing a division by zero when computing the ratio turbo_freq/base_freq necessary for frequency invariant accounting. It is to be noted that even if MSR_PLATFORM_INFO contained the appropriate data, APERF and MPERF are constantly zero on ESXi 5.5, thus freq-invariance couldn't be done in principle (not that it would make a lot of sense in a VM anyway). The real problem is advertising X86_FEATURE_APERFMPERF. This appears to be fixed in more recent versions: ESXi 6.7 doesn't advertise that feature. Fixes: 1567c3e3467c ("x86, sched: Add support for frequency invariance") Signed-off-by: Giovanni Gherdovich Signed-off-by: Peter Zijlstra (Intel) Acked-by: Rafael J. Wysocki Link: https://lkml.kernel.org/r/20200416054745.740-2-ggherdovich@suse.cz --- arch/x86/kernel/smpboot.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c index fe3ab96..3a318ec 100644 --- a/arch/x86/kernel/smpboot.c +++ b/arch/x86/kernel/smpboot.c @@ -1985,6 +1985,15 @@ static bool intel_set_max_freq_ratio(void) return false; out: + /* + * Some hypervisors advertise X86_FEATURE_APERFMPERF + * but then fill all MSR's with zeroes. + */ + if (!base_freq) { + pr_debug("Couldn't determine cpu base frequency, necessary for scale-invariant accounting.\n"); + return false; + } + arch_turbo_freq_ratio = div_u64(turbo_freq * SCHED_CAPACITY_SCALE, base_freq); arch_set_max_freq_ratio(turbo_disabled());