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=-13.2 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_IN_DEF_DKIM_WL autolearn=no 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 46E43C2D0E4 for ; Tue, 17 Nov 2020 21:22:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D2CA724181 for ; Tue, 17 Nov 2020 21:22:23 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="OIte6M7w" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727184AbgKQVWD (ORCPT ); Tue, 17 Nov 2020 16:22:03 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49624 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726802AbgKQVWC (ORCPT ); Tue, 17 Nov 2020 16:22:02 -0500 Received: from mail-il1-x130.google.com (mail-il1-x130.google.com [IPv6:2607:f8b0:4864:20::130]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0D9DBC0613CF for ; Tue, 17 Nov 2020 13:22:01 -0800 (PST) Received: by mail-il1-x130.google.com with SMTP id y9so18933ilb.0 for ; Tue, 17 Nov 2020 13:22:01 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to; bh=katWkOXeT9cKSkuNJDqg8k4n6KRzCgL5P/0+AH0wLfM=; b=OIte6M7wsOrmtWwknxeObOn8TCXuM0vl3WAjff4DmRbczKi4M8UaTl51zQ2FW7gJaC d/zEWf4Mu2SE5K2yCrMLK/NQsU9FtlhqIyA2sk6oqxiUWaoqh8q9Rvzos36JxoLSG9y3 eKqArLFp4ESRwR/4stCGSzWFcb/BLNvqZzunIFQrfvHjoS1PXAzKl7u29oxfqFm6mojb 3vJJFewJ3GYkdUG2FGhWIIPU10LpqipW1urXgZLfi+mIUeIAXWP7q8nDR79/hrviKIG1 KEsdLsTSimbhSj+SW25moXW+UABKy0TbdFT7ktcsa+er7dPGw9wfK8ylaFS+dDAi/wxL 0Csw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to; bh=katWkOXeT9cKSkuNJDqg8k4n6KRzCgL5P/0+AH0wLfM=; b=jfVchzk/4Y9g2jfRgu9GllamLyIn6rFiXPI+VFZzUfIeshCOovCBdNoy/Epni+Cfsa 1q29E8SgEUoyt6i1E/RFty5s7SZqYd3lwNNXNH/LhPKR4VeteRbkx7KgiDTdOGUZVXWR 82+iIlZB3GlqIZ8tdeyLqAs6FXqI0CgCxJcQDWYCftix0eHuX5kXXGIiYevEsDWpydt0 OVzWtKEY/wTr+6QOPrycwPtViH6lp2H4bpL3p2zU0da8TxOIoDhxhVksHjr4pEWr7E+D 9igtxja9VNfkjwRPNig+YqTdtFebjFbW2jMoiqoENM0NVajE4G9FrmTwg3r2TlGU1h1z VaQw== X-Gm-Message-State: AOAM530zc2tVcOobRpSZ79GezoUCffVIdiCe9YvB45Gz1A+6qNomu2Fg 32fdWgIMYuFo1wkCswMpbDeo8aUrZdAnTZedGsA7xQ== X-Google-Smtp-Source: ABdhPJwTvUsHon0yqAwCAQ/HKINxkyrmpzvT0T7DloiMnk9xVSN6K66nTVynT8fA5GiB/fWU1ceb353MfwQodERr9Lo= X-Received: by 2002:a92:1f19:: with SMTP id i25mr14165325ile.198.1605648119997; Tue, 17 Nov 2020 13:21:59 -0800 (PST) MIME-Version: 1.0 References: <20200615063837.GA14668@zn.tnic> <20200714121955.GA2080@chrisdown.name> <20200714154728.GA3101@nazgul.tnic> <20200714160448.GC2080@chrisdown.name> <20201117210018.GA4247@weirdfishes> In-Reply-To: <20201117210018.GA4247@weirdfishes> From: Matthew Garrett Date: Tue, 17 Nov 2020 13:21:48 -0800 Message-ID: Subject: Re: [PATCH -v2.1] x86/msr: Filter MSR writes To: Mathieu Chouquet-Stringer , Matthew Garrett , Chris Down , Borislav Petkov , Linux Kernel Mailing List , sean.j.christopherson@intel.com, tony.luck@intel.com, Linus Torvalds , "the arch/x86 maintainers" , kernel-team@fb.com, Len Brown Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Nov 17, 2020 at 1:00 PM Mathieu Chouquet-Stringer wrote: > I'm late to the party but it seems allowing MSR_IA32_ENERGY_PERF_BIAS > has the downside of flagging the kernel as tainted without telling you > why if you use something like x86_energy_perf_policy (from > tools/power/x86/x86_energy_perf_policy) which itself is used by tuned. I initially pushed back against a kernel interface for MSR_IA32_ENERGY_PERF_BIAS (cc: Len Brown, who tried mightily to convince me I was wrong here) on the grounds that it was exporting an implementation detail rather than providing a generic interface, and that it was something that could be done via userland instead. I thought we'd end up with more examples of similar functionality and could tie it into something more reasonable - history has proven me wrong on that. I think it's probably reasonable to dust off the driver that Len submitted however many years ago and push that into the kernel now.