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_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 93A92C32771 for ; Wed, 15 Jan 2020 22:27:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 54DBC222C3 for ; Wed, 15 Jan 2020 22:27:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729785AbgAOW16 (ORCPT ); Wed, 15 Jan 2020 17:27:58 -0500 Received: from mga05.intel.com ([192.55.52.43]:36295 "EHLO mga05.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728931AbgAOW16 (ORCPT ); Wed, 15 Jan 2020 17:27:58 -0500 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from orsmga002.jf.intel.com ([10.7.209.21]) by fmsmga105.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 15 Jan 2020 14:27:57 -0800 X-IronPort-AV: E=Sophos;i="5.70,323,1574150400"; d="scan'208";a="243057420" Received: from agluck-desk2.sc.intel.com (HELO agluck-desk2.amr.corp.intel.com) ([10.3.52.68]) by orsmga002-auth.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 15 Jan 2020 14:27:55 -0800 Date: Wed, 15 Jan 2020 14:27:54 -0800 From: "Luck, Tony" To: Sean Christopherson Cc: Peter Zijlstra , Ingo Molnar , Fenghua Yu , Thomas Gleixner , Ingo Molnar , Borislav Petkov , H Peter Anvin , Ashok Raj , Ravi V Shankar , linux-kernel , x86 Subject: Re: [PATCH v11] x86/split_lock: Enable split lock detection by kernel Message-ID: <20200115222754.GA13804@agluck-desk2.amr.corp.intel.com> References: <20191121130153.GS4097@hirez.programming.kicks-ass.net> <20191121171214.GD12042@gmail.com> <20191121173444.GA5581@agluck-desk2.amr.corp.intel.com> <20191122105141.GY4114@hirez.programming.kicks-ass.net> <20191122152715.GA1909@hirez.programming.kicks-ass.net> <20191123003056.GA28761@agluck-desk2.amr.corp.intel.com> <20191125161348.GA12178@linux.intel.com> <20191212085948.GS2827@hirez.programming.kicks-ass.net> <20200110192409.GA23315@agluck-desk2.amr.corp.intel.com> <20200114055521.GI14928@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200114055521.GI14928@linux.intel.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jan 13, 2020 at 09:55:21PM -0800, Sean Christopherson wrote: > On Fri, Jan 10, 2020 at 11:24:09AM -0800, Luck, Tony wrote: All comments accepted and code changed ... except for these three: > > +#define TIF_SLD 18 /* split_lock_detect */ > > A more informative name comment would be helpful since the flag is set when > SLD is disabled by the previous task. Something like? > > #define TIF_NEED_SLD_RESTORE 18 /* Restore split lock detection on context switch */ That name is more informative ... but it is also really, really long. Are you sure? > > +bool handle_user_split_lock(struct pt_regs *regs, long error_code) > > +{ > > + if ((regs->flags & X86_EFLAGS_AC) || sld_state == sld_fatal) > > + return false; > > Maybe add "|| WARN_ON_ONCE(sld_state != sld_off)" to try to prevent the > kernel from going fully into the weeds if a spurious #AC occurs. Can a spurious #AC occur? I don't see how. > > @@ -242,7 +243,6 @@ do_trap(int trapnr, int signr, char *str, struct pt_regs *regs, > > { > > struct task_struct *tsk = current; > > > > - > > Whitespace. > > > if (!do_trap_no_signal(tsk, trapnr, str, regs, error_code)) > > return; I'm staring at the post patch code, and I can't see what whitespace issue you see. -Tony