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=-5.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 C1C13C433DF for ; Wed, 29 Jul 2020 23:28:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A8C642075D for ; Wed, 29 Jul 2020 23:28:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728062AbgG2X2L (ORCPT ); Wed, 29 Jul 2020 19:28:11 -0400 Received: from mga05.intel.com ([192.55.52.43]:31754 "EHLO mga05.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726718AbgG2X2K (ORCPT ); Wed, 29 Jul 2020 19:28:10 -0400 IronPort-SDR: INjKOM/+yw7RBJgVKmxjxv1O/yz16A7RkrwIeODznbGGkaXlIxJ+BKnhTy43/np2N9N83E+Qzp 3MvaYLM4kgIQ== X-IronPort-AV: E=McAfee;i="6000,8403,9697"; a="236379224" X-IronPort-AV: E=Sophos;i="5.75,412,1589266800"; d="scan'208";a="236379224" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by fmsmga105.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 29 Jul 2020 16:28:09 -0700 IronPort-SDR: 6IXRQWPsYnycLnkAm/UyYMMR5UZE3qBPgzTNyH6mvZ9S59ktFDmD4Pala+4/KnlmVTTrjlYyVL CX3Jm5sa3jMg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.75,412,1589266800"; d="scan'208";a="394804237" Received: from sjchrist-coffee.jf.intel.com (HELO linux.intel.com) ([10.54.74.152]) by fmsmga001.fm.intel.com with ESMTP; 29 Jul 2020 16:28:08 -0700 Date: Wed, 29 Jul 2020 16:28:08 -0700 From: Sean Christopherson To: Fenghua Yu Cc: Thomas Gleixner , Borislav Petkov , Ingo Molnar , Peter Zijlstra , "Shanbhogue, Vedvyas" , "Luck, Tony" , H Peter Anvin , Andy Lutomirski , "Shankar, Ravi V" , "Li, Xiaoyao" , x86 , linux-kernel Subject: Re: [PATCH RFC] x86/bus_lock: Enable bus lock detection Message-ID: <20200729232808.GP27751@linux.intel.com> References: <1595021700-68460-1-git-send-email-fenghua.yu@intel.com> <20200729030232.GE5583@linux.intel.com> <20200729184614.GI27751@linux.intel.com> <20200729194259.GA318576@otcwcpicx6.sc.intel.com> <20200729200033.GJ27751@linux.intel.com> <20200729203557.GA318595@otcwcpicx6.sc.intel.com> <20200729203905.GN27751@linux.intel.com> <20200729220714.GA318659@otcwcpicx6.sc.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200729220714.GA318659@otcwcpicx6.sc.intel.com> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jul 29, 2020 at 10:07:14PM +0000, Fenghua Yu wrote: > Hi, Sean, > > On Wed, Jul 29, 2020 at 01:39:05PM -0700, Sean Christopherson wrote: > > On Wed, Jul 29, 2020 at 08:35:57PM +0000, Fenghua Yu wrote: > > > If sld=fatal and bld=ratelimit (both sld and bld are enabled in hw), > > > a split lock always generates #AC and kills the app and bld will never have > > > a chance to trigger #DB for split lock. So effectively the combination makes > > > the kernel to take two different actions after detecting a bus lock: if the > > > bus lock comes from a split lock, fatal (sld); if the bus lock comes from > > > lock to non-WB memory, ratelimit (bld). Seems this is not a useful combination > > > and is not what the user really wants to do because the user wants ratelimit > > > for BLD, right? > > > > I understood all off that. And as I user I want to run sld=fatal and > > bld=ratelimit to provide maximum protection, i.e. disallow split locks at > > all times, and ratelimit the crud SLD #AC can't catch. > > Then this will expand the current usages and do need two options. Let me work > on adding a new "bus_lock_detect=" option as you suggested. I'd wait for feedback from others before spending too much effort rewriting everything, I'm just one person with an opinion.