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=-4.0 required=3.0 tests=BAYES_00,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no 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 53110C433E0 for ; Mon, 22 Feb 2021 09:48:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1225564E44 for ; Mon, 22 Feb 2021 09:48:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230214AbhBVJsF (ORCPT ); Mon, 22 Feb 2021 04:48:05 -0500 Received: from mail.kernel.org ([198.145.29.99]:51106 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230169AbhBVJrt (ORCPT ); Mon, 22 Feb 2021 04:47:49 -0500 Received: from disco-boy.misterjones.org (disco-boy.misterjones.org [51.254.78.96]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 910C564E2F; Mon, 22 Feb 2021 09:47:08 +0000 (UTC) Received: from disco-boy.misterjones.org ([51.254.78.96] helo=www.loen.fr) by disco-boy.misterjones.org with esmtpsa (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 (Exim 4.94) (envelope-from ) id 1lE7o2-00FI1i-EN; Mon, 22 Feb 2021 09:47:06 +0000 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Date: Mon, 22 Feb 2021 09:47:06 +0000 From: Marc Zyngier To: =?UTF-8?Q?Jonathan_Neusch=C3=A4fer?= Cc: linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, linux-kernel@vger.kernel.org, Prasad Sodagudi , Srinivas Ramana , Catalin Marinas , Hector Martin , Ajay Patil , kernel-team@android.com, Will Deacon , Ard Biesheuvel Subject: Re: [PATCH v7 23/23] [DO NOT MERGE] arm64: Cope with CPUs stuck in VHE mode In-Reply-To: References: <20210208095732.3267263-1-maz@kernel.org> <20210208095732.3267263-24-maz@kernel.org> User-Agent: Roundcube Webmail/1.4.11 Message-ID: <4d4e9a5cff65dbd8861f829089f570e5@kernel.org> X-Sender: maz@kernel.org X-SA-Exim-Connect-IP: 51.254.78.96 X-SA-Exim-Rcpt-To: j.ne@posteo.net, linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, linux-kernel@vger.kernel.org, psodagud@codeaurora.org, sramana@codeaurora.org, catalin.marinas@arm.com, marcan@marcan.st, pajay@qti.qualcomm.com, kernel-team@android.com, will@kernel.org, ardb@kernel.org X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Jonathan, On 2021-02-22 09:35, Jonathan Neuschäfer wrote: > Hi, > > On Mon, Feb 08, 2021 at 09:57:32AM +0000, Marc Zyngier wrote: >> It seems that the CPU known as Apple M1 has the terrible habit >> of being stuck with HCR_EL2.E2H==1, in violation of the architecture. > > Minor nitpick from the sideline: The M1 SoC has two kinds of CPU in it > (Icestorm and Firestorm), which makes "CPU known as Apple M1" a bit > imprecise. Fair enough. How about something along the lines of: "At least some of the CPUs integrated in the Apple M1 SoC have the terrible habit..." > In practicality it seems unlikely though, that Icestorm and Firestorm > act differently with regards to the code in this patch. This is my hunch as well. And if they did, it shouldn't be a big deal: the "architecture compliant" CPUs would simply transition via EL1 as expected, and join their buggy friends running at EL2 slightly later. Thanks, M. -- Jazz is not dead. It just smells funny...