Received: by 2002:a05:6a10:8c0a:0:0:0:0 with SMTP id go10csp1863039pxb; Sat, 23 Jan 2021 08:03:30 -0800 (PST) X-Google-Smtp-Source: ABdhPJyZ+2ZORp8I01Zbuy6bgTYK0JCBPbXkrLyKXlocIQ/Cl2H4CjJ/gB9UH77LMMEWNRqnhD2p X-Received: by 2002:aa7:c784:: with SMTP id n4mr989825eds.332.1611417810138; Sat, 23 Jan 2021 08:03:30 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1611417810; cv=none; d=google.com; s=arc-20160816; b=jQ9y/KFvt/7EX9hvA3L0Ikgf6xTHTaxhC/p2Dkff+/UMfh5GZ/vrhJO0nH4QyE9oOq boKduYhQqANOKNc0Xzsw7pUSra38X34gBTjf2xS34WU9OzrpB866Iyoymrnzr9o4h4jb acZGfPdKpjedjv0+/xq8sQsv0biu7RwexhpGuGJGYjao00l9dWVK5i9KkTGEMHhlb/68 jooatiMTc5q0IXeE+MJNxBIo/5eylXWOQXaDVvDXY6Rmhxqyrp2qz1cc9FMb9jFmqHes luBXeArFIE5h/Qfimf+JnEdXX3Bk5K3EoVVVLv/yS13sYthtdWwEy9L1fNQBUCY/SOo8 5VyA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:content-transfer-encoding:content-language :in-reply-to:mime-version:user-agent:date:message-id:from:references :cc:to:subject; bh=yJubiL2XeNCBNfh/ea3YOaSFKKih1Ut9AXWZzmA5RKI=; b=a5biTClTTuBhmJ5Bua/nhITpct67JbSpnzMiSpLrlz18L+ftwjwwoXVJGFvBkHkS/K AxE5fKNVv8QUugQCbO0bT1x6TPjdRDlFaR7lc1kaPPDUbPEuyFKPYUO/yu5XgjLK2hrY VeQYn9JlTbtzAjOoUDniZ/L0N0CiuafrWUGrxs+HnC9Su+SaSdmSmD01xvO1kJPjQ2Km bn/WhzdLYL1z4CUGY1PpOHDkRgFqgfmBjM7+SZsKpJ2nD8kYDIZV5OdzrOZC5Z5aJiC+ fDxz7ZaLlhbKoamA6WUeKvjKpde2X8fSb4ijrZEfNPmVuNmNKXH7AEML/e+Lv1Y9fjHN LAqg== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=arm.com Return-Path: Received: from vger.kernel.org (vger.kernel.org. [23.128.96.18]) by mx.google.com with ESMTP id di7si4793655edb.527.2021.01.23.08.03.05; Sat, 23 Jan 2021 08:03:30 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=arm.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725922AbhAWQBB (ORCPT + 99 others); Sat, 23 Jan 2021 11:01:01 -0500 Received: from foss.arm.com ([217.140.110.172]:47752 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725910AbhAWQA7 (ORCPT ); Sat, 23 Jan 2021 11:00:59 -0500 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 977DB11D4; Sat, 23 Jan 2021 08:00:12 -0800 (PST) Received: from [10.57.40.145] (unknown [10.57.40.145]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 605AD3F68F; Sat, 23 Jan 2021 08:00:07 -0800 (PST) Subject: Re: [PATCH v4 09/21] arm64: cpufeature: Add global feature override facility To: Marc Zyngier , linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, linux-kernel@vger.kernel.org Cc: Catalin Marinas , Will Deacon , Mark Rutland , David Brazdil , Alexandru Elisei , Ard Biesheuvel , Jing Zhang , Ajay Patil , Prasad Sodagudi , Srinivas Ramana , James Morse , Julien Thierry , kernel-team@android.com References: <20210118094533.2874082-1-maz@kernel.org> <20210118094533.2874082-10-maz@kernel.org> From: Suzuki K Poulose Message-ID: Date: Sat, 23 Jan 2021 15:59:59 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.6.1 MIME-Version: 1.0 In-Reply-To: <20210118094533.2874082-10-maz@kernel.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-GB Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 1/18/21 9:45 AM, Marc Zyngier wrote: > Add a facility to globally override a feature, no matter what > the HW says. Yes, this sounds dangerous, but we do respect the > "safe" value for a given feature. This doesn't mean the user > doesn't need to know what they are doing. > > Nothing uses this yet, so we are pretty safe. For now. > > Signed-off-by: Marc Zyngier Reviewed-by: Suzuki K Poulose