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=-5.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 E8D42C83000 for ; Wed, 29 Apr 2020 18:42:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CE2932072A for ; Wed, 29 Apr 2020 18:42:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727032AbgD2SmG (ORCPT ); Wed, 29 Apr 2020 14:42:06 -0400 Received: from mga07.intel.com ([134.134.136.100]:19663 "EHLO mga07.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726481AbgD2SmF (ORCPT ); Wed, 29 Apr 2020 14:42:05 -0400 IronPort-SDR: 3A0ySfikSO6rqK6P190+42619h6h73IbUuc186G2miZ/8gFjd6+qAFsWQsNBAixdI5PPaZUkOK 0+CG/WUGX22w== X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga005.jf.intel.com ([10.7.209.41]) by orsmga105.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 29 Apr 2020 11:42:04 -0700 IronPort-SDR: Zyukxp0GZrKgrYBy2Q4V3lJkWfXkgn0LdHF9H7i4bh8DKSAOKpNLMjRZbQKit/XJdmqPFHgC1w sAaF0CAN+6/A== X-IronPort-AV: E=Sophos;i="5.73,332,1583222400"; d="scan'208";a="432657402" Received: from rchatre-mobl.amr.corp.intel.com (HELO [10.255.229.38]) ([10.255.229.38]) by orsmga005-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 29 Apr 2020 11:42:04 -0700 Subject: Re: [PATCH 2/2] x86/resctrl: Support CPUID enumeration of MBM counter width To: Borislav Petkov Cc: tglx@linutronix.de, fenghua.yu@intel.com, tony.luck@intel.com, kuo-lang.tseng@intel.com, mingo@redhat.com, babu.moger@amd.com, hpa@zytor.com, x86@kernel.org, linux-kernel@vger.kernel.org References: <76dc65631c373e0c1c9f3e8aaa768f022a2c989c.1585763047.git.reinette.chatre@intel.com> <20200429181149.GE16407@zn.tnic> From: Reinette Chatre Message-ID: <6fb58472-88f2-925b-3a4e-4692957a9582@intel.com> Date: Wed, 29 Apr 2020 11:42:03 -0700 User-Agent: Mozilla/5.0 (Windows NT 6.3; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: <20200429181149.GE16407@zn.tnic> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Borislav, On 4/29/2020 11:11 AM, Borislav Petkov wrote: > On Wed, Apr 01, 2020 at 10:51:02AM -0700, Reinette Chatre wrote: >> diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c >> index 4cdb123ff66a..8552d2fadc15 100644 >> --- a/arch/x86/kernel/cpu/common.c >> +++ b/arch/x86/kernel/cpu/common.c >> @@ -856,6 +856,8 @@ static void init_speculation_control(struct cpuinfo_x86 *c) >> >> static void init_cqm(struct cpuinfo_x86 *c) >> { >> + c->x86_cache_mbm_width_offset = -1; >> + >> if (!cpu_has(c, X86_FEATURE_CQM_LLC)) { >> c->x86_cache_max_rmid = -1; >> c->x86_cache_occ_scale = -1; >> @@ -875,6 +877,9 @@ static void init_cqm(struct cpuinfo_x86 *c) >> >> c->x86_cache_max_rmid = ecx; >> c->x86_cache_occ_scale = ebx; >> + /* EAX contents is only defined for Intel CPUs */ >> + if (c->x86_vendor == X86_VENDOR_INTEL) >> + c->x86_cache_mbm_width_offset = eax & 0xff; > > Remind me again pls why is all this RDT stuff replicated per CPU instead > of it being properly detected somewhere down in resctrl_late_init()? > > Looking at get_rdt_resources(), it kinda wants to have that in there > too? > > IOW, how about moving all that gunk in init_cqm() to resctrl/ where it > truly belongs? Doesn't have to be this patchset but this patchset can > start moving it... I am not familiar with the history to clarify to you why the RDT feature enumeration is not consistent. Even so, there was an effort to consolidate this in [1] but it was found to go against the goal of centralizing the CPUID information [2] and was not pursued further. I would be happy to revisit this if this is the direction that you prefer. This would essentially be resubmitting [1] though. Do you expect that this change would receive a different reception at this time? Thank you Reinette [1] https://lore.kernel.org/lkml/1560705250-211820-2-git-send-email-fenghua.yu@intel.com/ [2] https://lore.kernel.org/lkml/alpine.DEB.2.21.1906162141301.1760@nanos.tec.linutronix.de/