From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9248A221545; Tue, 15 Apr 2025 18:38:32 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744742312; cv=none; b=P31R4+H1I3ysevBs4libIa/ZK7kCZpiAfaxftDHArRTl4PtvplxbSdaVxrKzYSjOmSkbdSnl3hPFJAcLGZ73uZ1cZganJe3wO0VDFwsTE6sKh23ssbJ1gH/1REYibDGW2gTmKfPCmKknUq1VDNY6c/3qMwG0Md71cMHntiQMsqk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744742312; c=relaxed/simple; bh=8sTrdGHxgk2UV7lZ8rQBn3TJV8+tH9FZocMeuFQMZWQ=; h=Date:Message-ID:From:To:Cc:Subject:In-Reply-To:References: MIME-Version:Content-Type; b=aHyuFmKoyr8dBDBUxscQWkqtT1Qfb3WbH0oSlVdyyWOXA5Fu8/+Nu/VqtC2lpRNBKqhA2y2R6gELrDpmvYGbNKEZb31JUDdIZAz4q2iyEdNEei1wW6SR0I5h5xIds3IkTpqt+LNnW0EFiSIM2mjIJm8YcMs/9WeexYjOb4uqgNM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=dsu+EDUA; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="dsu+EDUA" Received: by smtp.kernel.org (Postfix) with ESMTPSA id EE9D9C4CEE9; Tue, 15 Apr 2025 18:38:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1744742312; bh=8sTrdGHxgk2UV7lZ8rQBn3TJV8+tH9FZocMeuFQMZWQ=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=dsu+EDUACmCA6zhAGLRHs3P1BUByWRnTU2Xouqnty5lyNEObmL7qY5kcphNN4kdrP oLsXHFpN4JD4OXuIeUVWz+9uU/TipEdVKfH5alE+5Qes8xNB2EabSm/qrtYMHTlXNp uv9WjbYaSUC/7roI7sgz8yAuGC9y38BaoCinjI/YPp5IFSyMeF9BVus34x4JBSGXba ESHAPtgk8vni8PmUKfwHFPdGPiZpLbnOyygWoiQF5rSUu5pkivHXmqJHSb5mS5dVQW vtDxmS7zln4sK7k4Ujv1Ztt+wtW8xtHc/xuaPjVTsvNvsP5gGx9d/ZrAfF72YC13cO 0W7UhzCInAQXA== Received: from sofa.misterjones.org ([185.219.108.64] helo=goblin-girl.misterjones.org) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.95) (envelope-from ) id 1u4lAz-005mSe-Vh; 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) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: 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 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.