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=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 B2E45C433DB for ; Mon, 1 Mar 2021 19:01:23 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 2AE1660241 for ; Mon, 1 Mar 2021 19:01:23 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2AE1660241 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 7138B8D0095; Mon, 1 Mar 2021 14:01:22 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 6C35D8D0063; Mon, 1 Mar 2021 14:01:22 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 58CB18D0095; Mon, 1 Mar 2021 14:01:22 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0061.hostedemail.com [216.40.44.61]) by kanga.kvack.org (Postfix) with ESMTP id 429DE8D0063 for ; Mon, 1 Mar 2021 14:01:22 -0500 (EST) Received: from smtpin16.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id EF728180ACF75 for ; Mon, 1 Mar 2021 19:01:21 +0000 (UTC) X-FDA: 77872223562.16.73EBFB5 Received: from mga04.intel.com (mga04.intel.com [192.55.52.120]) by imf08.hostedemail.com (Postfix) with ESMTP id C7EB8801AE4D for ; Mon, 1 Mar 2021 19:00:58 +0000 (UTC) IronPort-SDR: AHeERZZZelpvWSzW21UOtJlbU0YeJirQAhXmptCw0ssgywzSUZDei5lELE97ltJcFJUr+IDke0 RjQ11Cq7O8hw== X-IronPort-AV: E=McAfee;i="6000,8403,9910"; a="184127969" X-IronPort-AV: E=Sophos;i="5.81,215,1610438400"; d="scan'208";a="184127969" Received: from orsmga001.jf.intel.com ([10.7.209.18]) by fmsmga104.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 01 Mar 2021 10:59:58 -0800 IronPort-SDR: 9AtqZ+/g/XE8E5dnue//mblk5Mu7epGgq4velIrovp2wXLot6ybGW9lDf86j8bdDia0L/yp4JC sAgAshYwQz/w== X-IronPort-AV: E=Sophos;i="5.81,215,1610438400"; d="scan'208";a="444403546" Received: from yyu32-mobl1.amr.corp.intel.com (HELO [10.212.116.218]) ([10.212.116.218]) by orsmga001-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 01 Mar 2021 10:59:56 -0800 Subject: Re: [PATCH v21 08/26] x86/mm: Introduce _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> <20210217222730.15819-9-yu-cheng.yu@intel.com> <20210301155234.GF6699@zn.tnic> From: "Yu, Yu-cheng" Message-ID: <5d98a4f7-5882-2e6e-7b76-295b73c17152@intel.com> Date: Mon, 1 Mar 2021 10:59:44 -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: <20210301155234.GF6699@zn.tnic> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Stat-Signature: nzmzicrk8x5zww8yduzktwkcsggiw4f3 X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: C7EB8801AE4D Received-SPF: none (intel.com>: No applicable sender policy available) receiver=imf08; identity=mailfrom; envelope-from=""; helo=mga04.intel.com; client-ip=192.55.52.120 X-HE-DKIM-Result: none/none X-HE-Tag: 1614625258-644500 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 3/1/2021 7:52 AM, Borislav Petkov wrote: > On Wed, Feb 17, 2021 at 02:27:12PM -0800, Yu-cheng Yu wrote: >> @@ -182,7 +206,7 @@ static inline int pud_young(pud_t pud) >> >> static inline int pte_write(pte_t pte) >> { >> - return pte_flags(pte) & _PAGE_RW; > > Put here a comment along the lines of: > > /* > * Shadow stack pages are always writable - but not by normal > * instructions but only by shadow stack operations. Therefore, the > * W=0, D=1 test. > */ > > to make it clear what this means. > >> + return (pte_flags(pte) & _PAGE_RW) || pte_shstk(pte); >> } >> >> static inline int pte_huge(pte_t pte) >> @@ -314,6 +338,24 @@ static inline pte_t pte_clear_flags(pte_t pte, pteval_t clear) >> return native_make_pte(v & ~clear); >> } >> >> +static inline pte_t pte_make_cow(pte_t pte) > > pte_mkcow like the rest of the "pte_mkX" functions. > > And below too, for the other newly added pXd_make_* helpers. > > >> static inline pmd_t pmd_mkdirty(pmd_t pmd) >> { >> - return pmd_set_flags(pmd, _PAGE_DIRTY | _PAGE_SOFT_DIRTY); >> + pmdval_t dirty = _PAGE_DIRTY; >> + >> + /* Avoid creating (HW)Dirty=1, Write=0 PMDs */ >> + if (cpu_feature_enabled(X86_FEATURE_SHSTK) && !(pmd_flags(pmd) & _PAGE_RW)) > > !(pmd_write(pmd)) > >> + dirty = _PAGE_COW; >> + >> + return pmd_set_flags(pmd, dirty | _PAGE_SOFT_DIRTY); >> +} > > ... > >> static inline pud_t pud_mkdirty(pud_t pud) >> { >> - return pud_set_flags(pud, _PAGE_DIRTY | _PAGE_SOFT_DIRTY); >> + pudval_t dirty = _PAGE_DIRTY; >> + >> + /* Avoid creating (HW)Dirty=1, Write=0 PUDs */ >> + if (cpu_feature_enabled(X86_FEATURE_SHSTK) && !(pud_flags(pud) & _PAGE_RW)) > > !(pud_write(pud)) > > I will update. Thanks! -- Yu-cheng