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=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,USER_AGENT_MUTT 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 CC055C4360F for ; Thu, 4 Apr 2019 16:02:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 98F3C2082E for ; Thu, 4 Apr 2019 16:02:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729212AbfDDQCE (ORCPT ); Thu, 4 Apr 2019 12:02:04 -0400 Received: from mga05.intel.com ([192.55.52.43]:18965 "EHLO mga05.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728710AbfDDQCE (ORCPT ); Thu, 4 Apr 2019 12:02:04 -0400 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from orsmga005.jf.intel.com ([10.7.209.41]) by fmsmga105.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 04 Apr 2019 09:02:03 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.60,308,1549958400"; d="scan'208";a="313154179" Received: from romley-ivt3.sc.intel.com ([172.25.110.60]) by orsmga005.jf.intel.com with ESMTP; 04 Apr 2019 09:02:02 -0700 Date: Thu, 4 Apr 2019 08:54:23 -0700 From: Fenghua Yu To: Borislav Petkov Cc: Thomas Gleixner , Ingo Molnar , H Peter Anvin , Dave Hansen , Paolo Bonzini , Ashok Raj , Peter Zijlstra , Kalle Valo , Xiaoyao Li , Michael Chan , Ravi V Shankar , linux-kernel , x86 , linux-wireless@vger.kernel.org, netdev@vger.kernel.org, kvm@vger.kernel.org Subject: Re: [PATCH v6 01/20] x86/common: Align cpu_caps_cleared and cpu_caps_set to unsigned long Message-ID: <20190404155422.GA177894@romley-ivt3.sc.intel.com> References: <1554326526-172295-1-git-send-email-fenghua.yu@intel.com> <1554326526-172295-2-git-send-email-fenghua.yu@intel.com> <20190404143942.GD22539@zn.tnic> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190404143942.GD22539@zn.tnic> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Apr 04, 2019 at 04:39:43PM +0200, Borislav Petkov wrote: > On Wed, Apr 03, 2019 at 02:21:47PM -0700, Fenghua Yu wrote: > > cpu_caps_cleared and cpu_caps_set may not be aligned to unsigned long. > > Atomic operations (i.e. set_bit and clear_bit) on the bitmaps may access > > Please end function names with parentheses. Sure. > > > two cache lines (a.k.a. split lock) and lock the bus to block all memory > > not "lock the bus" but "cause the CPU to do a bus lock... " Sure. > > > accesses from other processors to ensure atomicity. > > > > To avoid the overall performance degradation from the bus locking, align > > the two variables to unsigned long. > > > > Defining the variables as unsigned long may also fix the issue because > > they are naturally aligned to unsigned long. But that needs additional > > code changes. Adding __aligned(unsigned long) is a simpler fix. > > > > Signed-off-by: Fenghua Yu > > --- > > arch/x86/kernel/cpu/common.c | 5 +++-- > > 1 file changed, 3 insertions(+), 2 deletions(-) > > With the above nitpicks addressed: > > Reviewed-by: Borislav Petkov Thank you for your review! -Fenghua