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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS 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 2D59AC43381 for ; Wed, 27 Feb 2019 23:48:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E8DC6218A4 for ; Wed, 27 Feb 2019 23:48:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730393AbfB0XsO (ORCPT ); Wed, 27 Feb 2019 18:48:14 -0500 Received: from mx1.redhat.com ([209.132.183.28]:35042 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728397AbfB0XsO (ORCPT ); Wed, 27 Feb 2019 18:48:14 -0500 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id D73364AD50; Wed, 27 Feb 2019 23:48:13 +0000 (UTC) Received: from prarit.bos.redhat.com (prarit-guest.khw1.lab.eng.bos.redhat.com [10.16.200.63]) by smtp.corp.redhat.com (Postfix) with ESMTP id 7D2245ED32; Wed, 27 Feb 2019 23:48:12 +0000 (UTC) Subject: Re: [PATCH] x86/fpu: Parse comma separated list passed in clearcpuid To: Peter Zijlstra Cc: linux-kernel@vger.kernel.org, Thomas Gleixner , Ingo Molnar , Borislav Petkov , "H. Peter Anvin" , Andi Kleen , x86@kernel.org, linux-doc@vger.kernel.org References: <20190221131225.22063-1-prarit@redhat.com> <20190221134847.GQ32494@hirez.programming.kicks-ass.net> From: Prarit Bhargava Message-ID: <388fecd4-9b99-f405-fed4-1f6c3b53bc8b@redhat.com> Date: Wed, 27 Feb 2019 18:48:11 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.4.0 MIME-Version: 1.0 In-Reply-To: <20190221134847.GQ32494@hirez.programming.kicks-ass.net> Content-Type: text/plain; charset=utf-8 Content-Language: en-GB Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.30]); Wed, 27 Feb 2019 23:48:14 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2/21/19 8:48 AM, Peter Zijlstra wrote: > On Thu, Feb 21, 2019 at 08:12:25AM -0500, Prarit Bhargava wrote: >> Users cannot disable multiple CPU features with the kernel parameter >> clearcpuid=. For example, "clearcpuid=154 clearcpuid=227" only disables >> CPUID bit 154. >> >> Previous to commit 0c2a3913d6f5 ("x86/fpu: Parse clearcpuid= as early XSAVE >> argument") it was possible to pass multiple clearcpuid options as kernel >> parameters using individual entries. With the new code it isn't easy to >> replicate exactly that behaviour but a comma separated list can be easily >> implemented, eg) "clearcpuid=154,227" >> >> Make the clearcpuid parse a comma-separated list of values instead of only >> a single value. > > Can we also please kill the value thing entirely and only accept > strings. Having to reverse engineer the numbers is madness. > > Also, wth would you want to disable XSAVE and EPB ? > It looks like Fenghua has implemented this here: https://marc.info/?l=linux-kernel&m=154908490105208&w=2 so please drop this patch. Thanks, P.