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=-3.9 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 77FCEC2D0E2 for ; Tue, 22 Sep 2020 08:13:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D35A323A1B for ; Tue, 22 Sep 2020 08:13:23 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=alien8.de header.i=@alien8.de header.b="gZxU80Do" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726645AbgIVINW (ORCPT ); Tue, 22 Sep 2020 04:13:22 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35830 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726483AbgIVINU (ORCPT ); Tue, 22 Sep 2020 04:13:20 -0400 Received: from mail.skyhub.de (mail.skyhub.de [IPv6:2a01:4f8:190:11c2::b:1457]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5E6BEC061755 for ; Tue, 22 Sep 2020 01:13:20 -0700 (PDT) Received: from zn.tnic (p200300ec2f0bfb00524dde00a85e5113.dip0.t-ipconnect.de [IPv6:2003:ec:2f0b:fb00:524d:de00:a85e:5113]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.skyhub.de (SuperMail on ZX Spectrum 128k) with ESMTPSA id BF7931EC047E; Tue, 22 Sep 2020 10:13:18 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alien8.de; s=dkim; t=1600762398; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:in-reply-to:in-reply-to: references:references; bh=RO2mwEZQvbGv43zRsrwkkh5Y8NPYbXfILlq13bVVM58=; b=gZxU80DorfVEsOkK9g6HQnW2kx2knAGdhVgQlPkPicf4AUv6bkMi19vJY9tLqUYoiIw0mB g6nn02f4nb0CpTDrccAbHc0xZMSPv5fG5vdAyKjFMThnGmZu1L7PQ2zxNzHM44/TZXJQB5 CVoDdHFlrP1PyElsxBadC9l1G5anqoM= Date: Tue, 22 Sep 2020 10:13:12 +0200 From: Borislav Petkov To: Thomas Gleixner , Dave Hansen Cc: x86-ml , lkml Subject: Re: [RFC PATCH] Use feature bit names in clearcpuid= Message-ID: <20200922081312.GA22660@zn.tnic> References: <20200920154228.GB7473@zn.tnic> <87mu1ib5mw.fsf@nanos.tec.linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <87mu1ib5mw.fsf@nanos.tec.linutronix.de> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Sep 22, 2020 at 10:03:03AM +0200, Thomas Gleixner wrote: > On Sun, Sep 20 2020 at 17:42, Borislav Petkov wrote: > > Hi, > > > > so tglx hates this clearcpuid= interface where you have to give the > > X86_FEATURE array indices in order to disable a feature bit for testing. > > Below is a first attempt (lightly tested in a VM only) to accept the bit > > names from /proc/cpuinfo too. > > > > I say "too" because not all feature bits have names and we would still > > have to support the numbers. Yeah, yuck. > > > > An exemplary cmdline would then be something like: > > > > clearcpuid=de,440,smca,succory,bmi1,3dnow ("succory" is wrong on > > purpose). > > > > and it says: > > > > [ 0.000000] Clearing CPUID bits: de 13:24 smca bmi1 3dnow > > > > Also, I'm thinking we should taint the kernel when this option is used. > > > > Thoughts? > > Yes, instead of making it differently horrible, can we finally remove that > nonsense which should have never been there in the first place? Fine with me - I don't need it. I believe dhansen has a use-case or two, CCed. -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette