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_PASS,URIBL_BLOCKED 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 067C7ECDFD0 for ; Fri, 14 Sep 2018 13:21:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BF449204EC for ; Fri, 14 Sep 2018 13:21:49 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org BF449204EC Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linutronix.de Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728320AbeINSgK (ORCPT ); Fri, 14 Sep 2018 14:36:10 -0400 Received: from Galois.linutronix.de ([146.0.238.70]:50012 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728164AbeINSfb (ORCPT ); Fri, 14 Sep 2018 14:35:31 -0400 Received: from localhost ([127.0.0.1] helo=nanos.tec.linutronix.de) by Galois.linutronix.de with esmtp (Exim 4.80) (envelope-from ) id 1g0o1t-0006p4-NB; Fri, 14 Sep 2018 15:21:01 +0200 Message-Id: <20180914131302.110697717@linutronix.de> User-Agent: quilt/0.65 Date: Fri, 14 Sep 2018 15:09:23 +0200 From: Thomas Gleixner To: LKML Cc: x86@kernel.org, Peter Zijlstra , Bin Yang , Dave Hansen , Mark Gross Subject: [patch V2 06/10] x86/mm/cpa: Avoid static protection checks on unmap References: <20180914130917.155416208@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline; filename=x86-mm-cpa--Avoid-static-protection-checks-on-unmap.patch Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org If the new pgprot has the PRESENT bit cleared, then conflicts vs. RW/NX are completely irrelevant. Before: 1G pages checked: 2 1G pages sameprot: 0 1G pages preserved: 0 2M pages checked: 540 2M pages sameprot: 466 2M pages preserved: 47 4K pages checked: 800770 4K pages set-checked: 7668 After: 1G pages checked: 2 1G pages sameprot: 0 1G pages preserved: 0 2M pages checked: 540 2M pages sameprot: 466 2M pages preserved: 47 4K pages checked: 800709 4K pages set-checked: 7668 Signed-off-by: Thomas Gleixner --- arch/x86/mm/pageattr.c | 7 +++++++ 1 file changed, 7 insertions(+) --- a/arch/x86/mm/pageattr.c +++ b/arch/x86/mm/pageattr.c @@ -522,6 +522,13 @@ static inline pgprot_t static_protection pgprotval_t forbidden, res; unsigned long end; + /* + * There is no point in checking RW/NX conflicts when the requested + * mapping is setting the page !PRESENT. + */ + if (!(pgprot_val(prot) & _PAGE_PRESENT)) + return prot; + /* Operate on the virtual address */ end = start + npg * PAGE_SIZE - 1;