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=-5.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, 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 A649AC54FCB for ; Fri, 24 Apr 2020 13:57:46 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 6C34F20776 for ; Fri, 24 Apr 2020 13:57:46 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6C34F20776 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 16A638E0005; Fri, 24 Apr 2020 09:57:46 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 0F26E8E0003; Fri, 24 Apr 2020 09:57:46 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id EFB088E0005; Fri, 24 Apr 2020 09:57:45 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0202.hostedemail.com [216.40.44.202]) by kanga.kvack.org (Postfix) with ESMTP id D36FC8E0003 for ; Fri, 24 Apr 2020 09:57:45 -0400 (EDT) Received: from smtpin29.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 819E2180AD822 for ; Fri, 24 Apr 2020 13:57:45 +0000 (UTC) X-FDA: 76742901690.29.bath38_60c908a587b61 X-HE-Tag: bath38_60c908a587b61 X-Filterd-Recvd-Size: 3054 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf05.hostedemail.com (Postfix) with ESMTP for ; Fri, 24 Apr 2020 13:57:44 +0000 (UTC) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 2EA7931B; Fri, 24 Apr 2020 06:57:44 -0700 (PDT) Received: from gaia (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 67B803F68F; Fri, 24 Apr 2020 06:57:42 -0700 (PDT) Date: Fri, 24 Apr 2020 14:57:36 +0100 From: Catalin Marinas To: linux-arm-kernel@lists.infradead.org Cc: Will Deacon , Vincenzo Frascino , Szabolcs Nagy , Richard Earnshaw , Kevin Brodsky , Andrey Konovalov , Peter Collingbourne , linux-mm@kvack.org, linux-arch@vger.kernel.org, Rob Herring , Mark Rutland , Suzuki K Poulose Subject: Re: [PATCH v3 21/23] arm64: mte: Check the DT memory nodes for MTE support Message-ID: <20200424135735.GB5551@gaia> References: <20200421142603.3894-1-catalin.marinas@arm.com> <20200421142603.3894-22-catalin.marinas@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200421142603.3894-22-catalin.marinas@arm.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue, Apr 21, 2020 at 03:26:01PM +0100, Catalin Marinas wrote: > Even if the ID_AA64PFR1_EL1 register advertises the presence of MTE, it > is not guaranteed that the memory system on the SoC supports the > feature. In the absence of system-wide MTE support, the behaviour is > undefined and the kernel should not enable the MTE memory type in > MAIR_EL1. > > For FDT, add an 'arm,armv8.5-memtag' property to the /memory nodes and > check for its presence during MTE probing. For example: > > memory@80000000 { > device_type = "memory"; > arm,armv8.5-memtag; > reg = <0x00000000 0x80000000 0 0x80000000>, > <0x00000008 0x80000000 0 0x80000000>; > }; > > If the /memory nodes are not present in DT or if at least one node does > not support MTE, the feature will be disabled. On EFI systems, it is > assumed that the memory description matches the EFI memory map (if not, > it is considered a firmware bug). > > MTE is not currently supported on ACPI systems. > > Signed-off-by: Catalin Marinas > Cc: Rob Herring > Cc: Mark Rutland > Cc: Will Deacon > Cc: Suzuki K Poulose This patch turns out to be incomplete. While it does not expose the HWCAP2_MTE to user when the above DT property is not present, it still allows user access to the ID_AA64PFR1_EL1.MTE field (via MRS emulations) since it is marked as visible. -- Catalin