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=-7.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 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 BA334C04FF3 for ; Mon, 24 May 2021 12:10:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9C9A7613B6 for ; Mon, 24 May 2021 12:10:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232110AbhEXMLe (ORCPT ); Mon, 24 May 2021 08:11:34 -0400 Received: from mail.kernel.org ([198.145.29.99]:52254 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232662AbhEXMLe (ORCPT ); Mon, 24 May 2021 08:11:34 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 03CD9610A6; Mon, 24 May 2021 12:10:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1621858206; bh=FKrYa9wRIMDhYZ616MV0mGehueLTvFDWOr+340TGuqA=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Vesc9sRDCdI2+F9Nqo5LUge6k+kq8/zXd6yY2lML3vjNbzJqm5aFpnJmgKEJey4L7 oE58PDkTRRImcuawBLkvaCkK7YTyHhSWVSPkqxzlF6/XT7bPnxt7hwnCDhojSpT2G5 yDHYlBpl+Aktln9aiELBHf+khHFC5lrBXUuvSwaTI0FPYBMUnmv4/okfVaRnnLOAI2 GtI44mWwa4nA8YhrYOO+NYjPRZ9ocj8kBYAXfI0WSXsxSb5j+ezYKJgEvt1ECybPAC MBhHlBDHbpukX5ulb7lIawVxd8sNrM49Un9AZfxoKGeFMO1T2mvTyOfRzBwKIjvsc0 r/8mzil5vgiSg== Date: Mon, 24 May 2021 13:09:59 +0100 From: Will Deacon To: Catalin Marinas Cc: linux-arm-kernel@lists.infradead.org, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, Marc Zyngier , Greg Kroah-Hartman , Peter Zijlstra , Morten Rasmussen , Qais Yousef , Suren Baghdasaryan , Quentin Perret , Tejun Heo , Li Zefan , Johannes Weiner , Ingo Molnar , Juri Lelli , Vincent Guittot , "Rafael J. Wysocki" , kernel-team@android.com Subject: Re: [PATCH v6 02/21] arm64: Allow mismatched 32-bit EL0 support Message-ID: <20210524120959.GB14913@willie-the-truck> References: <20210518094725.7701-1-will@kernel.org> <20210518094725.7701-3-will@kernel.org> <20210521104155.GC6675@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210521104155.GC6675@arm.com> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-arch@vger.kernel.org On Fri, May 21, 2021 at 11:41:56AM +0100, Catalin Marinas wrote: > On Tue, May 18, 2021 at 10:47:06AM +0100, Will Deacon wrote: > > +static int enable_mismatched_32bit_el0(unsigned int cpu) > > +{ > > + struct cpuinfo_arm64 *info = &per_cpu(cpu_data, cpu); > > + bool cpu_32bit = id_aa64pfr0_32bit_el0(info->reg_id_aa64pfr0); > > + > > + if (cpu_32bit) { > > + cpumask_set_cpu(cpu, cpu_32bit_el0_mask); > > + static_branch_enable_cpuslocked(&arm64_mismatched_32bit_el0); > > It may be worth only calling static_branch_enable_cpuslocked() if not > already set, in case you try this on a system with lots of CPUs. static_key_enable_cpuslocked() already checks this early on, so I don't think we need another check here (note that we're not calling stop_machine() here _anyway_; the '_cpuslocked' suffix just says that we're already holding cpu_hotplug_lock via the notifier). Will