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Tue, 15 Apr 2025 19:38:30 +0100 Date: Tue, 15 Apr 2025 19:38:29 +0100 Message-ID: <86zfghjmmy.wl-maz@kernel.org> From: Marc Zyngier To: D Scott Phillips Cc: Catalin Marinas , James Clark , James Morse , Joey Gouly , Kevin Brodsky , Mark Brown , Mark Rutland , Oliver Upton , "Rob Herring (Arm)" , Shameer Kolothum , Shiqi Liu , Will Deacon , Yicong Yang , kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org (open list) Subject: Re: [PATCH 2/2] arm64: errata: Work around AmpereOne's erratum AC04_CPU_23 In-Reply-To: <20250415154711.1698544-2-scott@os.amperecomputing.com> References: <20250415154711.1698544-1-scott@os.amperecomputing.com> <20250415154711.1698544-2-scott@os.amperecomputing.com> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/29.4 (aarch64-unknown-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; charset=US-ASCII X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: scott@os.amperecomputing.com, catalin.marinas@arm.com, james.clark@linaro.org, james.morse@arm.com, joey.gouly@arm.com, kevin.brodsky@arm.com, broonie@kernel.org, mark.rutland@arm.com, oliver.upton@linux.dev, robh@kernel.org, shameerali.kolothum.thodi@huawei.com, shiqiliu@hust.edu.cn, will@kernel.org, yangyicong@hisilicon.com, kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250415_113833_078265_6E7E5B02 X-CRM114-Status: GOOD ( 13.86 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Tue, 15 Apr 2025 16:47:11 +0100, D Scott Phillips wrote: > > Updates to HCR_EL2 can rarely corrupt simultaneous translations from > either earlier translations (back to the previous dsb) or later > translations (up to the next isb). Put a dsb before and isb after writes > to HCR_EL2. If the write to HCR_EL2 can corrupt translations, what guarantees that such write placed on a page boundary (therefore requiring another TLB lookup to continue in sequence) will be able to get to the ISB? M. -- Without deviation from the norm, progress is not possible.