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=-8.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,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 92E55C433DF for ; Mon, 18 May 2020 11:26:04 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 57B5F206D4 for ; Mon, 18 May 2020 11:26:04 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 57B5F206D4 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 E29FC900003; Mon, 18 May 2020 07:26:03 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id DDB59900002; Mon, 18 May 2020 07:26:03 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id CF0CC900003; Mon, 18 May 2020 07:26:03 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0028.hostedemail.com [216.40.44.28]) by kanga.kvack.org (Postfix) with ESMTP id B6E45900002 for ; Mon, 18 May 2020 07:26:03 -0400 (EDT) Received: from smtpin05.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 7BD09824805A for ; Mon, 18 May 2020 11:26:03 +0000 (UTC) X-FDA: 76829610606.05.grain01_17bd7dcd7d92a X-HE-Tag: grain01_17bd7dcd7d92a X-Filterd-Recvd-Size: 2971 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf49.hostedemail.com (Postfix) with ESMTP for ; Mon, 18 May 2020 11:26:03 +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 06174106F; Mon, 18 May 2020 04:26:02 -0700 (PDT) Received: from [10.57.27.185] (unknown [10.57.27.185]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 194B13F52E; Mon, 18 May 2020 04:25:59 -0700 (PDT) Subject: Re: [PATCH v4 24/26] arm64: mte: Introduce early param to disable MTE support To: Catalin Marinas , linux-arm-kernel@lists.infradead.org Cc: linux-arch@vger.kernel.org, Szabolcs Nagy , Andrey Konovalov , Kevin Brodsky , Peter Collingbourne , linux-mm@kvack.org, Vincenzo Frascino , Will Deacon , Dave P Martin References: <20200515171612.1020-1-catalin.marinas@arm.com> <20200515171612.1020-25-catalin.marinas@arm.com> From: Vladimir Murzin Message-ID: Date: Mon, 18 May 2020 12:26:30 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20200515171612.1020-25-catalin.marinas@arm.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit 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 5/15/20 6:16 PM, Catalin Marinas wrote: > For performance analysis it may be desirable to disable MTE altogether > via an early param. Introduce arm64.mte_disable and, if true, filter out > the sanitised ID_AA64PFR1_EL1.MTE field to avoid exposing the HWCAP to > user. > > Signed-off-by: Catalin Marinas > Cc: Will Deacon > --- > > Notes: > New in v4. > > Documentation/admin-guide/kernel-parameters.txt | 4 ++++ > arch/arm64/kernel/cpufeature.c | 11 +++++++++++ > 2 files changed, 15 insertions(+) > > diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt > index f2a93c8679e8..7436e7462b85 100644 > --- a/Documentation/admin-guide/kernel-parameters.txt > +++ b/Documentation/admin-guide/kernel-parameters.txt > @@ -373,6 +373,10 @@ > arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards > Format: ,, > > + arm64.mte_disable= > + [ARM64] Disable Linux support for the Memory > + Tagging Extension (both user and in-kernel). > + Should it really to take parameter (on/off/true/false)? It may lead to expectation that arm64.mte_disable=false should enable MT and, yes, double negatives make it look ugly, so if we do need parameter, can it be arm64.mte=on/off/true/false? Cheers Vladimir