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=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,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 73348C2B9F7 for ; Mon, 24 May 2021 13:46:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 47497613B0 for ; Mon, 24 May 2021 13:46:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232907AbhEXNrh (ORCPT ); Mon, 24 May 2021 09:47:37 -0400 Received: from mail.kernel.org ([198.145.29.99]:41158 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232409AbhEXNrf (ORCPT ); Mon, 24 May 2021 09:47:35 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id CBE1861090; Mon, 24 May 2021 13:46:04 +0000 (UTC) Date: Mon, 24 May 2021 14:46:02 +0100 From: Catalin Marinas To: Will Deacon 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: <20210524134602.GA14645@arm.com> References: <20210518094725.7701-1-will@kernel.org> <20210518094725.7701-3-will@kernel.org> <20210521104155.GC6675@arm.com> <20210524120959.GB14913@willie-the-truck> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210524120959.GB14913@willie-the-truck> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, May 24, 2021 at 01:09:59PM +0100, Will Deacon wrote: > 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). Ah, you are right, no need for an additional check. -- Catalin 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=-5.6 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,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 16918C2B9F7 for ; Mon, 24 May 2021 23:08:53 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id D02A96140F for ; Mon, 24 May 2021 23:08:52 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D02A96140F Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=EdZ2QRhoIaVFYFTuifl7GaoQuM3OFxetEwUK2bZmVt8=; b=jh6zf/QcWBk3LM XidVA7jGkDJdCkB1i41BqyepQFX8FCtF9mzqW/sI1+3hDkjkL9TtIvWj7s7M51kuLaHueuL92gF84 PYUZITEQUvMrPzqsbpxbOnbe4XGz2EtcbjzZzxjJtg6FM9luFTT28/DNv542iZNnLB8h82EmvX9/9 bm60SFFH06SbkFkejjfLJIFeSvOP1dB+ZsGVrBMbCfZQyCnKp8pPoXhVon5tDVuErtr2VUEfZp8vu 3hdKFRABYWaLg2dZksBy1QafFyuqXeMyYCgrRn/bwRvg3II/4DfDig/3QbzF/z22gpr80QrgMrbtA w1d0EcjDJBFXxL8o2OFQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94 #2 (Red Hat Linux)) id 1llJf8-002H2d-Kr; Mon, 24 May 2021 23:07:07 +0000 Received: from mail.kernel.org ([198.145.29.99]) by bombadil.infradead.org with esmtps (Exim 4.94 #2 (Red Hat Linux)) id 1llAuG-000y0r-Kg for linux-arm-kernel@lists.infradead.org; Mon, 24 May 2021 13:46:10 +0000 Received: by mail.kernel.org (Postfix) with ESMTPSA id CBE1861090; Mon, 24 May 2021 13:46:04 +0000 (UTC) Date: Mon, 24 May 2021 14:46:02 +0100 From: Catalin Marinas To: Will Deacon 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: <20210524134602.GA14645@arm.com> References: <20210518094725.7701-1-will@kernel.org> <20210518094725.7701-3-will@kernel.org> <20210521104155.GC6675@arm.com> <20210524120959.GB14913@willie-the-truck> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20210524120959.GB14913@willie-the-truck> User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210524_064608_717753_B50D7D2C X-CRM114-Status: GOOD ( 15.96 ) 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: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Mon, May 24, 2021 at 01:09:59PM +0100, Will Deacon wrote: > 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). Ah, you are right, no need for an additional check. -- Catalin _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel