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=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,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 1A834C54FD0 for ; Fri, 24 Apr 2020 13:57:51 +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 D9A2B2087E for ; Fri, 24 Apr 2020 13:57:50 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="d21lv0GP" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D9A2B2087E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-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.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject: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=uiMiYheJ0IjuDJQhmS/MhjKdRVMmKX1tLiLhVE+EvEc=; b=d21lv0GPlPZz29 BthDSMl0E0GlCFvm0re0UDxtln1BWdANvCwKt3jcb5q6+qIOSFvCDqeSDNrpj8S+FBORH8mJhZXKn rZV+jNQlqHi4c3e9v4pOYjUmzO1hcgnsS3k3yt+T746dfebKnUjSBCylalkybtjP1xzYikstMI6er WFsSy6pX8Ycp5Pt+p3/4vRWGbq/wRLEPaMaZArQtiCKRKHAEoOnbZ/zahKgKxq1jBWvoSJ9Kz6G1E DQTGKBIuwcWqmUVGkPj63M4fQRVTdr8E3Zb+LJUoa+ivcEYmxL4yitCNT4VkNp4tvu0k60yOasODl HM1CyFvTJyeKK5Wqx4gw==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jRypy-0006XO-2l; Fri, 24 Apr 2020 13:57:50 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jRypu-0006WM-LC for linux-arm-kernel@lists.infradead.org; Fri, 24 Apr 2020 13:57:47 +0000 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 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-Disposition: inline In-Reply-To: <20200421142603.3894-22-catalin.marinas@arm.com> 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-20200424_065746_744455_064EAAB8 X-CRM114-Status: GOOD ( 15.94 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-arch@vger.kernel.org, Richard Earnshaw , Suzuki K Poulose , Szabolcs Nagy , Andrey Konovalov , Kevin Brodsky , Rob Herring , Peter Collingbourne , linux-mm@kvack.org, Mark Rutland , Vincenzo Frascino , Will Deacon Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org 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 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel