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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4364CC43217 for ; Tue, 4 Oct 2022 00:40:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229588AbiJDAkl (ORCPT ); Mon, 3 Oct 2022 20:40:41 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51880 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229531AbiJDAki (ORCPT ); Mon, 3 Oct 2022 20:40:38 -0400 Received: from mail-pj1-x102d.google.com (mail-pj1-x102d.google.com [IPv6:2607:f8b0:4864:20::102d]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5B6FA2AC73; Mon, 3 Oct 2022 17:40:37 -0700 (PDT) Received: by mail-pj1-x102d.google.com with SMTP id x1-20020a17090ab00100b001fda21bbc90so16907710pjq.3; Mon, 03 Oct 2022 17:40:37 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=to:references:message-id:content-transfer-encoding:cc:date :in-reply-to:from:subject:mime-version:from:to:cc:subject:date; bh=+/Mka7TP1STCGf7CSP8aOzP/j3ypJV5FS9jSff6Kndw=; b=pqGdfqbWYJvqI2Of+PeOx1WBv1PrdAmEktEt7KtFjMrkdmsQC2jJJ4M8vwN1VzfOC/ cJJbBHE6qti1z5u6bdoOqHQoT3YaUiozafzRvBx+uOVs+FEl3qJcdMnNCeeoLV8gIgff GJjNkTGx9eG2X0YsJzb+B5nmJIHSHB7MYnI3XMTIVBzMFilMBSCTBGYSP0GirTgQ72Bl sh++kqoZKYfpQepDCFQHl6FJ8WLD49clt5FXCIwPVk4bMiDiYsCfPPFDISO6Sq8xBxtS peDXEHcnp0mmAzaIfMx9s1sh1KTB27TXbSIun9uHTiFK9aDcdWIkJtybIe5iYgve+/6F RclA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=to:references:message-id:content-transfer-encoding:cc:date :in-reply-to:from:subject:mime-version:x-gm-message-state:from:to:cc :subject:date; bh=+/Mka7TP1STCGf7CSP8aOzP/j3ypJV5FS9jSff6Kndw=; b=4QkSS2rNbphzkNJhy2m8HWQOowZJnc6mLWzw3dMCxm5UQQljBpBoAD1hBIq2So/Ff+ uDkX+L8O4jo6Wrldm98S9VCWoQgRNiBwXg0odgV7cfoa46LoAIfBRMS7ysPTk7e1Hds3 lFl4OC+/8J9MGRmADrBXm8DL9Br2eXBb+e2d0czBMA+HabaambDXwE9Yp1nw+RUmGSrl Ysd2ff9AZHyp1lUTY8mnmD8nZhm30aKtbJBgTIQN9bhm8TVXrhKCJI1J9pTiLL4eUDHW DSQ0bigJWM3KHU7LSlT+ag/TQaea5dPADlkJLy+ZDpbPp/L0t2Ob1v5QQ+115O/Touel tbhQ== X-Gm-Message-State: ACrzQf1G6mNSey5OptafjdzFUoY8m7SodF90yZt0KLlEjki+YK6xu2km Tv6kZWSJ1kpIGzJZCqDfeGI= X-Google-Smtp-Source: AMsMyM4oB1eZrAcM5PukmrfyczOXgACQAqwlz9k+nfojTYnOGZfABmctQC9QWv7CCvUhblpu0GSnfA== X-Received: by 2002:a17:902:d48d:b0:178:306d:f75c with SMTP id c13-20020a170902d48d00b00178306df75cmr24637584plg.73.1664844036518; Mon, 03 Oct 2022 17:40:36 -0700 (PDT) Received: from smtpclient.apple ([66.170.99.2]) by smtp.gmail.com with ESMTPSA id c202-20020a624ed3000000b005616fd75a22sm2855137pfb.112.2022.10.03.17.40.34 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Mon, 03 Oct 2022 17:40:36 -0700 (PDT) Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 16.0 \(3696.120.41.1.1\)) Subject: Re: [PATCH v2 12/39] x86/mm: Update ptep_set_wrprotect() and pmdp_set_wrprotect() for transition from _PAGE_DIRTY to _PAGE_COW From: Nadav Amit In-Reply-To: <547f2a8a87c255c58dbf2350013f72649dfcdc10.camel@intel.com> Date: Mon, 3 Oct 2022 17:40:33 -0700 Cc: "bsingharora@gmail.com" , "hpa@zytor.com" , "Syromiatnikov, Eugene" , "peterz@infradead.org" , "rdunlap@infradead.org" , "keescook@chromium.org" , "Yu, Yu-cheng" , "Eranian, Stephane" , "kirill.shutemov@linux.intel.com" , "dave.hansen@linux.intel.com" , "linux-mm@kvack.org" , "fweimer@redhat.com" , "jannh@google.com" , "dethoma@microsoft.com" , "kcc@google.com" , "linux-arch@vger.kernel.org" , "pavel@ucw.cz" , "oleg@redhat.com" , "hjl.tools@gmail.com" , "Yang, Weijiang" , Andy Lutomirski , "jamorris@linux.microsoft.com" , "arnd@arndb.de" , "Moreira, Joao" , Thomas Gleixner , "bp@alien8.de" , "mike.kravetz@oracle.com" , "x86@kernel.org" , "linux-doc@vger.kernel.org" , "rppt@kernel.org" , "john.allen@amd.com" , "mingo@redhat.com" , "Shankar, Ravi V" , "corbet@lwn.net" , "linux-kernel@vger.kernel.org" , "linux-api@vger.kernel.org" , "gorcunov@gmail.com" Content-Transfer-Encoding: quoted-printable Message-Id: References: <20220929222936.14584-1-rick.p.edgecombe@intel.com> <20220929222936.14584-13-rick.p.edgecombe@intel.com> <64313344833c3b1701002a347d539e69276b66fb.camel@intel.com> <35EEB9F0-D99A-4664-9628-27029B52CFD1@gmail.com> <65CF3B29-BF53-4BA3-89D9-5398CEB7F813@gmail.com> <547f2a8a87c255c58dbf2350013f72649dfcdc10.camel@intel.com> To: "Edgecombe, Rick P" X-Mailer: Apple Mail (2.3696.120.41.1.1) Precedence: bulk List-ID: X-Mailing-List: linux-api@vger.kernel.org On Oct 3, 2022, at 4:38 PM, Edgecombe, Rick P = wrote: > I think the HW dirty bit will not be set here. How it works is, > pte_mkdirty() will not actually set the HW dirty bit, but instead the > software COW bit. Here is the relevant snippet: >=20 > static inline pte_t pte_mkdirty(pte_t pte) > { > pteval_t dirty =3D _PAGE_DIRTY; >=20 > /* Avoid creating Dirty=3D1,Write=3D0 PTEs */ > if (cpu_feature_enabled(X86_FEATURE_SHSTK) && !pte_write(pte)) > dirty =3D _PAGE_COW; >=20 > return pte_set_flags(pte, dirty | _PAGE_SOFT_DIRTY); > } >=20 > So for a !VM_WRITE vma, you end up with Write=3D0,Cow=3D1 PTE passed > into ptep_set_access_flags(). Does it make sense? Thanks for your patience with me. I should have read the series in = order.