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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 10A10C6FA82 for ; Mon, 12 Sep 2022 14:41:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230245AbiILOl2 (ORCPT ); Mon, 12 Sep 2022 10:41:28 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50842 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230210AbiILOlX (ORCPT ); Mon, 12 Sep 2022 10:41:23 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 73FEF1FCF7; Mon, 12 Sep 2022 07:41:22 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id F0B9261224; Mon, 12 Sep 2022 14:41:21 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 15DFAC433C1; Mon, 12 Sep 2022 14:41:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1662993681; bh=LIlb3/sVDRiailHPluUwQ0BEaWEPEWV2j5OvEnX4BQU=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Z20p49e/gOyYdaaXvpTh9ebRDz8SRpomkbTdwpuTeoWcY4Lh29F9pV38PlR5cqRSO DUzd+p80O5DoQCbthS5VXjG2YJADK0OSPf4+cSH121d1mBq1FixCRa8gdugzKk0DuA SpxXG4RJj08HbLRaFz32mZ8AHg0CVJJUJIZTeUwE= Date: Mon, 12 Sep 2022 16:41:45 +0200 From: Greg Kroah-Hartman To: Ionela Voinescu Cc: Catalin Marinas , Will Deacon , James Morse , stable@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH stable-5.10] arm64: errata: add detection for AMEVCNTR01 incrementing incorrectly Message-ID: References: <20220912135226.31027-1-ionela.voinescu@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220912135226.31027-1-ionela.voinescu@arm.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Sep 12, 2022 at 02:52:26PM +0100, Ionela Voinescu wrote: > commit e89d120c4b720e232cc6a94f0fcbd59c15d41489 upstream. > > The AMU counter AMEVCNTR01 (constant counter) should increment at the same > rate as the system counter. On affected Cortex-A510 cores, AMEVCNTR01 > increments incorrectly giving a significantly higher output value. This > results in inaccurate task scheduler utilization tracking. > > Work around this problem by keeping the reference values of affected > counters to 0. This results in disabling the single user of this > counter: Frequency Invariance Engine (FIE). > This effect is the same to firmware disabling affected counters, in > which case 0 will be returned when reading the disabled counters. > > Therefore, AMU counters will not be used for frequency invariance for > affected CPUs and CPUs in the same cpufreq policy. AMUs can still be used > for frequency invariance for unaffected CPUs in the system. > > The above is achieved through adding a new erratum: ARM64_ERRATUM_2457168. > > Signed-off-by: Ionela Voinescu > Cc: Catalin Marinas > Cc: Will Deacon > Cc: James Morse > Link: https://lore.kernel.org/r/20220819103050.24211-1-ionela.voinescu@arm.com > --- > > Hi, > > This is a backport to stable 5.10.142 of the upstream commit > e89d120c4b72 arm64: errata: add detection for AMEVCNTR01 incrementing incorrectly > > This is sent separately as there were conflicts that needed resolving > when applying the mainline patch. Compared to the upstream version this > no longer handles the FFH usecase, as FFH support is not present in 5.10. > Therefore the commit message and Kconfig description are modified to > only describe the effect on FIE caused by this erratum. Both backports now queued up, thanks. greg k-h