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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED 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 25C7AC43142 for ; Tue, 26 Jun 2018 11:02:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D519426993 for ; Tue, 26 Jun 2018 11:02:56 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D519426993 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lxorguk.ukuu.org.uk Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934448AbeFZLCz (ORCPT ); Tue, 26 Jun 2018 07:02:55 -0400 Received: from www.llwyncelyn.cymru ([82.70.14.225]:50114 "EHLO fuzix.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933444AbeFZLCx (ORCPT ); Tue, 26 Jun 2018 07:02:53 -0400 Received: from alans-desktop (82-70-14-226.dsl.in-addr.zen.co.uk [82.70.14.226]) by fuzix.org (8.15.2/8.15.2) with ESMTP id w5QB2M5O029834; Tue, 26 Jun 2018 12:02:22 +0100 Date: Tue, 26 Jun 2018 12:02:21 +0100 From: Alan Cox To: Peter Zijlstra Cc: Alan Cox , Fenghua Yu , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Ashok Raj , Dave Hansen , Rafael Wysocki , Tony Luck , Ravi V Shankar , Arjan van de Ven , linux-kernel , x86 Subject: Re: [RFC PATCH 06/16] x86/split_lock: Save #AC setting for split lock in firmware in boot time and restore the setting in reboot Message-ID: <20180626120221.7fbd0eff@alans-desktop> In-Reply-To: <20180626090521.GF2494@hirez.programming.kicks-ass.net> References: <1527435965-202085-1-git-send-email-fenghua.yu@intel.com> <1527435965-202085-7-git-send-email-fenghua.yu@intel.com> <20180621195823.GD13636@worktop.programming.kicks-ass.net> <1529680267.4364.50.camel@linux.intel.com> <20180626090521.GF2494@hirez.programming.kicks-ass.net> Organization: Intel Corporation X-Mailer: Claws Mail 3.16.0 (GTK+ 2.24.32; x86_64-redhat-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 26 Jun 2018 11:05:21 +0200 Peter Zijlstra wrote: > On Fri, Jun 22, 2018 at 04:11:07PM +0100, Alan Cox wrote: > > On Thu, 2018-06-21 at 21:58 +0200, Peter Zijlstra wrote: > > > On Sun, May 27, 2018 at 08:45:55AM -0700, Fenghua Yu wrote: > > > > Firmware may contain split locked instructions. > > > > > > I think that's the wrong attitude. You should mandate in your BIOS > > > development guide that Firmware _MUST_NOT_ contain unaligned LOCK > > > prefixed instructions. > > > > > > > In the longer term I would agree entirely with that sentiment. > > But then how do we deal with SMIs ? On a system doing that level of real time you don't do SMIs. I think Thomas comment that this shouldn't be in a production kernel because the firmware people need to have their house in order before that is a fair one. (and I've already been poking people to make sure this is documented properly as a requirement) Alan