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=-11.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable 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 7AD47C43460 for ; Mon, 17 May 2021 19:17:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5B4F36108D for ; Mon, 17 May 2021 19:17:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232328AbhEQTSf (ORCPT ); Mon, 17 May 2021 15:18:35 -0400 Received: from mail.kernel.org ([198.145.29.99]:55948 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232147AbhEQTSe (ORCPT ); Mon, 17 May 2021 15:18:34 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 32E64610CD; Mon, 17 May 2021 19:17:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1621279038; bh=bclKj3T5OzMHwLMDNU1qKI1Dt6RViH88PuPQbMHGRr4=; h=References:In-Reply-To:From:Date:Subject:To:Cc:From; b=KyL2dYeDr8a1Y7Nyx672Enhc8n14G0dS9jL60PBUVlds1wh0Kdck4guWmafFfhg3J V/ekBJ1Ql309JKIuC1rjKGqWTk69+8rbZC3OXkgujcOA1IwG+WanN1rZzn8DFNq58P /4Ge3UjjnbW/X2xIj/v3ah6CBy+bqbmzwaeUf2DnCjnnyQh71YCuAu60u1LC/sRfdX A6sthgM1T6iZHrLWLnp8kj4P0Zaksio3dAh/JeYsqNwFSoJb6sigvVkmFUsiWMpdSa 1iPEgKN+HfvtijCxyo4Gyzw5hjVgmCocJjrLVI/Sc8TKaf81WO2pcQnEypbxJ/7TF8 RkyiDl/acaF8g== Received: by mail-ed1-f43.google.com with SMTP id f1so8221677edt.4; Mon, 17 May 2021 12:17:18 -0700 (PDT) X-Gm-Message-State: AOAM532i4vG8E7/FdVOGp00Zfb4EVe5XRevYp5PWWTyzjt6mBHKVILlt wldue9jApE5nsrm2DrfyI96UjX9mXOWmjQig+Q== X-Google-Smtp-Source: ABdhPJxwWUTWR46pVeUhN6Po3a3w6B9MWb0twgV12pS8uxUBoS8TpJ9ffrEiu87zRYE9GCN0FD+HyoyXgJTdXkElYnA= X-Received: by 2002:a05:6402:54e:: with SMTP id i14mr1895380edx.289.1621279036856; Mon, 17 May 2021 12:17:16 -0700 (PDT) MIME-Version: 1.0 References: <20210517155458.1016707-1-sudeep.holla@arm.com> In-Reply-To: <20210517155458.1016707-1-sudeep.holla@arm.com> From: Rob Herring Date: Mon, 17 May 2021 14:17:05 -0500 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v4] dt-bindings: dvfs: Add support for generic performance domains To: Sudeep Holla Cc: "linux-kernel@vger.kernel.org" , devicetree@vger.kernel.org, Manivannan Sadhasivam , Hector Yuan , Viresh Kumar , Bjorn Andersson Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, May 17, 2021 at 10:55 AM Sudeep Holla wrote: > > The CLKSCREW attack [0] exposed security vulnerabilities in energy management > implementations where untrusted software had direct access to clock and > voltage hardware controls. In this attack, the malicious software was able to > place the platform into unsafe overclocked or undervolted configurations. Such > configurations then enabled the injection of predictable faults to reveal > secrets. > > Many Arm-based systems used to or still use voltage regulator and clock > frameworks in the kernel. These frameworks allow callers to independently > manipulate frequency and voltage settings. Such implementations can render > systems susceptible to this form of attack. > > Attacks such as CLKSCREW are now being mitigated by not having direct and > independent control of clock and voltage in the kernel and moving that > control to a trusted entity, such as the SCP firmware or secure world > firmware/software which are to perform sanity checking on the requested > performance levels, thereby preventing any attempted malicious programming. > > With the advent of such an abstraction, there is a need to replace the > generic clock and regulator bindings used by such devices with a generic > performance domains bindings. > > [0] https://www.usenix.org/conference/usenixsecurity17/technical-sessions/presentation/tang > > Link: https://lore.kernel.org/r/20201116181356.804590-1-sudeep.holla@arm.com > Cc: Rob Herring > Acked-by: Viresh Kumar > Signed-off-by: Sudeep Holla Reviewed-by: Rob Herring