Received: by 2002:a05:6358:7058:b0:131:369:b2a3 with SMTP id 24csp1584560rwp; Thu, 13 Jul 2023 13:11:57 -0700 (PDT) X-Google-Smtp-Source: APBJJlGNVGTFIsruFYTXO+R0DjqjRtrFctDhjDdNwWWuVACgu3g0R+t/8/bp3mv/aC6GsKUlMrSL X-Received: by 2002:a2e:80da:0:b0:2b6:de52:34f with SMTP id r26-20020a2e80da000000b002b6de52034fmr2178673ljg.24.1689279117337; Thu, 13 Jul 2023 13:11:57 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1689279117; cv=none; d=google.com; s=arc-20160816; b=bnOSOICY1Fb6zKxVXA3ZHJZ5RcrYbDBCJc7g4CWUkEGKHTUAm3fbaup2AoJcftgfrO 2dZvKW6Bjv6BDKDpx+kwUF2q84e7WIOXn0st9zmnv5o3VzHis11rOrH4u2/UN77Q4Lio dBYCg3YEMuw+UIF4ks4deuXndMo6hLAwWAHEtCMNA9S6XfIoOlwOulARKOmE5ZQtfWsO E7DBv39mUU+Ll2qFl8cTrAAws9U6agBbvDLc72QK1YnjI90yrhaLX6K1wt0hvmL/3Hy7 Ekxah46yuzRqz/eMmtAZQAn/10qknBIvqt/IHOKL0MZc/QDpeATY41CAZ0xvhLp9EQ0b BggA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:in-reply-to:content-disposition:mime-version :references:message-id:subject:cc:to:from:date; bh=QpDQqeJhm7MgjmsRA8jJu+hrlkFGbxZLYEiDW46b5TQ=; fh=x/afr8rcjrDlW8vD40JVIV2VGsOBPUbIChD/i8AaAKI=; b=QDcqwiX7kGxMRWsrCq6D/4x1m1E7ahlSrUKNqJXM1TNT4qOW2PGDk6PgS9CpggVtD4 7kjPy01Pkw7GkRVIKHqtESncJpcs131CUA5w/De9P6blZkBcuDYDDGEq2dAZzjIY4tSc 9bn7oO5qsohz1uLomihzOUi46QhvuhDWgxFuBuowlsK+znAbKrmrYbJegMRIbhLwHl4S bQqCGyn7C7+BJmmrODlNbE61bMjQyL30hBzMSh9Bajf9wRVXXBfVJg9hkYZLfYndf/8C CzhX1ytBObouLxn0tvfuLg4ZrxANQIew8Lvj8C+fGSm/b68LCJyBQuHFvENOJhI+wWRd krtA== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=arm.com Return-Path: Received: from out1.vger.email (out1.vger.email. [2620:137:e000::1:20]) by mx.google.com with ESMTP id jz21-20020a170906bb1500b00991cbb3d4a6si1396372ejb.115.2023.07.13.13.11.33; Thu, 13 Jul 2023 13:11:57 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=arm.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232845AbjGMTI5 (ORCPT + 99 others); Thu, 13 Jul 2023 15:08:57 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55070 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229651AbjGMTI4 (ORCPT ); Thu, 13 Jul 2023 15:08:56 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 653581993; Thu, 13 Jul 2023 12:08:53 -0700 (PDT) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 716E61570; Thu, 13 Jul 2023 12:09:35 -0700 (PDT) Received: from FVFF77S0Q05N.cambridge.arm.com (unknown [10.37.36.116]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 1495E3F67D; Thu, 13 Jul 2023 12:08:50 -0700 (PDT) Date: Thu, 13 Jul 2023 20:08:48 +0100 From: Mark Rutland To: "Aiqun(Maria) Yu" Cc: Will Deacon , corbet@lwn.net, catalin.marinas@arm.com, maz@kernel.org, quic_pkondeti@quicinc.com, quic_kaushalk@quicinc.com, quic_satyap@quicinc.com, quic_shashim@quicinc.com, quic_songxue@quicinc.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH] arm64: Add the arm64.nolse_atomics command line option Message-ID: References: <20230710093751.GC32673@willie-the-truck> <5cf15f85-0397-96f7-4110-13494551b53b@quicinc.com> <20230711082226.GA1554@willie-the-truck> <84f0994a-26de-c20a-a32f-ec8fe41df3a3@quicinc.com> <20230711102510.GA1809@willie-the-truck> <67c2621f-4cad-2495-9785-7737246d3e90@quicinc.com> <604ac52d-4336-744f-2ab8-44d1c93fbaa8@quicinc.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Spam-Status: No, score=-4.2 required=5.0 tests=BAYES_00,RCVD_IN_DNSWL_MED, SPF_HELO_NONE,SPF_NONE,T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jul 13, 2023 at 10:08:34PM +0800, Aiqun(Maria) Yu wrote: > On 7/13/2023 7:20 PM, Mark Rutland wrote: > > Are you saying that LSE atomics to *cacheable* mappings do not work on your > > system? > > > > Specifically, when using a Normal Inner-Shareable Inner-Writeback > > Outer-Writeback mapping, do the LSE atomics work or not work? > *cacheable* mapping have the LSE atomic is not working if far atomic is > performed. Thanks for confirming; the fact that this doesn't work on *cacheable* memory is definitely a major issue. I think everyone is confused here because of the earlier mention of non-cachable accesses (which don't matter). I know that some CPU implementations have EL3 control bits to force LSE atomics to be performed near (e.g. in Cortex-A55, the CPUECTLR.ATOM control bits), which would avoid the issue while still allowing the LSE atomics to be used. If those can be configured in EL3 firmware, that would be a preferable workaround. Can you say which CPUs are integrated in this system? and/or can you check if such control bits exist? Thanks, Mark.