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=-10.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable 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 BB176C43331 for ; Mon, 8 Mar 2021 16:52:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 77CD365227 for ; Mon, 8 Mar 2021 16:52:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231143AbhCHQwI (ORCPT ); Mon, 8 Mar 2021 11:52:08 -0500 Received: from mga06.intel.com ([134.134.136.31]:18037 "EHLO mga06.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229818AbhCHQv6 (ORCPT ); Mon, 8 Mar 2021 11:51:58 -0500 IronPort-SDR: RWbEuP4Jjbm1SJ/0pYMC8GqkKQB2hEImRPRu7UHuXYV57wiEDu/mKH0XmdtnV5Sf9HpL19TIhD EcBN+EeyLsEw== X-IronPort-AV: E=McAfee;i="6000,8403,9917"; a="249443244" X-IronPort-AV: E=Sophos;i="5.81,232,1610438400"; d="scan'208";a="249443244" Received: from orsmga002.jf.intel.com ([10.7.209.21]) by orsmga104.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 08 Mar 2021 08:51:58 -0800 IronPort-SDR: Ra6tLTStpq8dq36RZhKli0M2oVxfITFaaO3HQz+7ILvFtrtpvijqoqpCk6bbPegkcGxyt+LxRG 15Q2Lh7fpluQ== X-IronPort-AV: E=Sophos;i="5.81,232,1610438400"; d="scan'208";a="385909914" Received: from yyu32-mobl1.amr.corp.intel.com (HELO [10.209.186.31]) ([10.209.186.31]) by orsmga002-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 08 Mar 2021 08:51:56 -0800 Subject: Re: [PATCH v21 10/26] x86/mm: Update pte_modify for _PAGE_COW To: Borislav Petkov Cc: x86@kernel.org, "H. Peter Anvin" , Thomas Gleixner , Ingo Molnar , linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-api@vger.kernel.org, Arnd Bergmann , Andy Lutomirski , Balbir Singh , Cyrill Gorcunov , Dave Hansen , Eugene Syromiatnikov , Florian Weimer , "H.J. Lu" , Jann Horn , Jonathan Corbet , Kees Cook , Mike Kravetz , Nadav Amit , Oleg Nesterov , Pavel Machek , Peter Zijlstra , Randy Dunlap , "Ravi V. Shankar" , Vedvyas Shanbhogue , Dave Martin , Weijiang Yang , Pengfei Xu , Haitao Huang References: <20210217222730.15819-1-yu-cheng.yu@intel.com> <20210217222730.15819-11-yu-cheng.yu@intel.com> <20210305142940.GC2685@zn.tnic> From: "Yu, Yu-cheng" Message-ID: Date: Mon, 8 Mar 2021 08:51:55 -0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.8.0 MIME-Version: 1.0 In-Reply-To: <20210305142940.GC2685@zn.tnic> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 3/5/2021 6:29 AM, Borislav Petkov wrote: > On Wed, Feb 17, 2021 at 02:27:14PM -0800, Yu-cheng Yu wrote: >> @@ -787,16 +802,34 @@ static inline pte_t pte_modify(pte_t pte, pgprot_t newprot) >> */ >> val &= _PAGE_CHG_MASK; >> val |= check_pgprot(newprot) & ~_PAGE_CHG_MASK; >> + val = fixup_dirty_pte(val); > > Do I see it correctly that you can do here and below: > > /* > * Fix up potential shadow stack page flags because the RO, Dirty PTE is > * special. > */ > if (pte_dirty()) { > pte_mkclean(); > pte_mkdirty(); > } > > ? Yes, this looks better. Thanks! > > That fixup thing looks grafted and not like a normal flow to me. >