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=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=ham 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 939CFC2BA19 for ; Wed, 15 Apr 2020 17:00:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7339020784 for ; Wed, 15 Apr 2020 17:00:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1586970041; bh=MgOckoa6oaXylsn5YDxRnw+SO2S8/uU9ZQM4CMMYhm0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=ErWIsGdNwTA8yOq8rNW7wncpqeHR2p4/aN3j/ZcMt3Co43rCB8vJ9N+uNQUKifnDC MeLG35tMEiGAPyFwwgeDA1yFO9H1/G9D6YKB9l6VTsBRyCp921e1+RRnTFtfoXu44g W8DuUd+cW/L6zuiVPPou27dtF4UkFyolLXolyWBk= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2410589AbgDORAk (ORCPT ); Wed, 15 Apr 2020 13:00:40 -0400 Received: from mail.kernel.org ([198.145.29.99]:57224 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728755AbgDORAf (ORCPT ); Wed, 15 Apr 2020 13:00:35 -0400 Received: from willie-the-truck (236.31.169.217.in-addr.arpa [217.169.31.236]) (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 0AE31206F9; Wed, 15 Apr 2020 17:00:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1586970034; bh=MgOckoa6oaXylsn5YDxRnw+SO2S8/uU9ZQM4CMMYhm0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=cp7XRASHgNQMYStqM9ccE+H4cbmpnvWsouW1/UcDJzRy7Tj4nwWnYlg5nCtAE246T bvnQx6CzbbqsPvaDF8ASoMzrXi3scNKrNh/PmIe+hw+3dcNqI/VHdWiAfYOEXE8JtC JaG0B9RXKq7wg2MukI0p2o4VLkjDuFNms4+4269M= Date: Wed, 15 Apr 2020 18:00:29 +0100 From: Will Deacon To: Marc Zyngier Cc: linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, linux-kernel@vger.kernel.org, Suzuki K Poulose , Mark Rutland , Anshuman Khandual , Catalin Marinas , Sai Prakash Ranjan , Doug Anderson , kernel-team@android.com Subject: Re: [PATCH 3/8] arm64: cpufeature: Add CPU capability for AArch32 EL1 support Message-ID: <20200415170029.GA19615@willie-the-truck> References: <20200414213114.2378-1-will@kernel.org> <20200414213114.2378-4-will@kernel.org> <1b76993491176577567a0960a435dac0@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1b76993491176577567a0960a435dac0@kernel.org> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Marc, On Wed, Apr 15, 2020 at 09:55:57AM +0100, Marc Zyngier wrote: > On 2020-04-14 22:31, Will Deacon wrote: > > Although we emit a "SANITY CHECK" warning and taint the kernel if we > > detect a CPU mismatch for AArch32 support at EL1, we still online the > > CPU with disastrous consequences for any running 32-bit VMs. > > > > Introduce a capability for AArch32 support at EL1 so that late onlining > > of incompatible CPUs is forbidden. > > > > Signed-off-by: Will Deacon > > Definitely an improvement over the current situation, as the direct read > of ID_AA64PFR0 was always a bit dodgy. Given that I'm pretty sure these new > braindead SoCs are going to run an older version of the kernel, should we > Cc stable for this? I don't think there's a real need for -stable given that we do at least taint the kernel. That's likely to annoy vendors enough to backport this themselves ;) Will