From patchwork Tue Apr 23 16:29:20 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Changbin Du X-Patchwork-Id: 10913555 X-Patchwork-Delegate: bhelgaas@google.com Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id EF296112C for ; Tue, 23 Apr 2019 16:40:16 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id DF13D285C9 for ; Tue, 23 Apr 2019 16:40:16 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id D2B54287E5; Tue, 23 Apr 2019 16:40:16 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.0 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FROM,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 31DEA285C9 for ; Tue, 23 Apr 2019 16:40:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729281AbfDWQiZ (ORCPT ); Tue, 23 Apr 2019 12:38:25 -0400 Received: from mail-pl1-f196.google.com ([209.85.214.196]:32848 "EHLO mail-pl1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729458AbfDWQiV (ORCPT ); Tue, 23 Apr 2019 12:38:21 -0400 Received: by mail-pl1-f196.google.com with SMTP id t16so7813088plo.0; Tue, 23 Apr 2019 09:38:20 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=BwOUj6DWdN3iA6cgbfDcU43ryEgaCKSsuoVnmmfiYvA=; b=tZM1unYFIvpmzxfXqjgBWrIpWgbO8x5mlykfx+g4MiugNXXuijOBS+GqTikW1jKISg NqobuFafddCTQ+JIalIIwlL/53URcdBC7xTCiDmpjINgapHqmNCJzE2JcD/hic8MCXjs J7lRe1dsM3gh7O9yeZ92LWe0HTlO5TB/UXku2jJCSQB0Aiftz843llCpdJMI0FHRhIau yfF0XOKkDQxNqQF8AsjcMHZhvC7sTZfCyOGsEgyMqcGF5CQA0n6LRL4NueQXTNRXaLXB iMex/UtWgt+ezQ5BcIFCg/bJRpA/3VavSiTIc41ALjvbX41Vpnr3z+6BR/x5j3xWLkpQ 0zQg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=BwOUj6DWdN3iA6cgbfDcU43ryEgaCKSsuoVnmmfiYvA=; b=AQwMkdajK4P/HBKL1htaev/OW4mueobm3uXN1dYU4s0vilNovliDmXGjCD/RogWT8n JJ0BhJa4vupLejtv/glQ1cygoI9f3MwBq5JwClx9v5bpThfAHT0vXWWu0613pXFB5Tq3 XHwBZVgWa/JoF1aCJmn4HfoVQn4x/Qg55YUEXlcbcveqgxmVqWiO8s9dvNbJoj5t/DT0 u+m5LPh33gro9LlODnxZR/ShR/dJkCpQ9cUi9dC7SLtyZf425Txmr5LxwVwhieDbvVKM CDDdUMpYdPgXBbVRGs2uCJQ+gvF+Wfc+JbHNF9Vq2y04QOJT1NJatiM+lDvE1xd0byDH sd4Q== X-Gm-Message-State: APjAAAUGyrJdnWPBhra+spRXYjOTxdYkmNKOXQA9btZOwSFI44t4SiiN LG72yqjGu2+iEdLKH9zkTWA= X-Google-Smtp-Source: APXvYqxfrRmUBhbHmsyN9wfFEdmN2iUGu9aAXAAk0gi4wFiCEZM64Aodt63M+ExKCVyPBtCEBGcXlA== X-Received: by 2002:a17:902:9686:: with SMTP id n6mr27708241plp.282.1556037500432; Tue, 23 Apr 2019 09:38:20 -0700 (PDT) Received: from localhost.localdomain ([104.238.181.70]) by smtp.gmail.com with ESMTPSA id v1sm24364801pff.81.2019.04.23.09.38.15 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 23 Apr 2019 09:38:19 -0700 (PDT) From: Changbin Du To: Jonathan Corbet Cc: Bjorn Helgaas , rjw@rjwysocki.net, linux-pci@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, tglx@linutronix.de, mingo@redhat.com, x86@kernel.org, fenghua.yu@intel.com, linuxppc-dev@lists.ozlabs.org, linux-acpi@vger.kernel.org, linux-gpio@vger.kernel.org, mchehab+samsung@kernel.org, Changbin Du Subject: [PATCH v4 51/63] Documentation: x86: convert pti.txt to reST Date: Wed, 24 Apr 2019 00:29:20 +0800 Message-Id: <20190423162932.21428-52-changbin.du@gmail.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190423162932.21428-1-changbin.du@gmail.com> References: <20190423162932.21428-1-changbin.du@gmail.com> MIME-Version: 1.0 Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP This converts the plain text documentation to reStructuredText format and add it to Sphinx TOC tree. No essential content change. Signed-off-by: Changbin Du --- Documentation/x86/index.rst | 1 + Documentation/x86/{pti.txt => pti.rst} | 19 ++++++++++++++----- 2 files changed, 15 insertions(+), 5 deletions(-) rename Documentation/x86/{pti.txt => pti.rst} (95%) diff --git a/Documentation/x86/index.rst b/Documentation/x86/index.rst index a0426ab156bd..1c675cef14d7 100644 --- a/Documentation/x86/index.rst +++ b/Documentation/x86/index.rst @@ -21,3 +21,4 @@ Linux x86 Support protection-keys intel_mpx amd-memory-encryption + pti diff --git a/Documentation/x86/pti.txt b/Documentation/x86/pti.rst similarity index 95% rename from Documentation/x86/pti.txt rename to Documentation/x86/pti.rst index 5cd58439ad2d..44b98f99ca8a 100644 --- a/Documentation/x86/pti.txt +++ b/Documentation/x86/pti.rst @@ -1,9 +1,15 @@ +.. SPDX-License-Identifier: GPL-2.0 + +========================== +Page Table Isolation (PTI) +========================== + Overview ======== -Page Table Isolation (pti, previously known as KAISER[1]) is a +Page Table Isolation (pti, previously known as KAISER [1]_) is a countermeasure against attacks on the shared user/kernel address -space such as the "Meltdown" approach[2]. +space such as the "Meltdown" approach [2]_. To mitigate this class of attacks, we create an independent set of page tables for use only when running userspace applications. When @@ -60,6 +66,7 @@ Protection against side-channel attacks is important. But, this protection comes at a cost: 1. Increased Memory Use + a. Each process now needs an order-1 PGD instead of order-0. (Consumes an additional 4k per process). b. The 'cpu_entry_area' structure must be 2MB in size and 2MB @@ -68,6 +75,7 @@ this protection comes at a cost: is decompressed, but no space in the kernel image itself. 2. Runtime Cost + a. CR3 manipulation to switch between the page table copies must be done at interrupt, syscall, and exception entry and exit (it can be skipped when the kernel is interrupted, @@ -142,8 +150,9 @@ ideally doing all of these in parallel: interrupted, including nested NMIs. Using "-c" boosts the rate of NMIs, and using two -c with separate counters encourages nested NMIs and less deterministic behavior. + :: - while true; do perf record -c 10000 -e instructions,cycles -a sleep 10; done + while true; do perf record -c 10000 -e instructions,cycles -a sleep 10; done 4. Launch a KVM virtual machine. 5. Run 32-bit binaries on systems supporting the SYSCALL instruction. @@ -182,5 +191,5 @@ that are worth noting here. tended to be TLB invalidation issues. Usually invalidating the wrong PCID, or otherwise missing an invalidation. -1. https://gruss.cc/files/kaiser.pdf -2. https://meltdownattack.com/meltdown.pdf +.. [1] https://gruss.cc/files/kaiser.pdf +.. [2] https://meltdownattack.com/meltdown.pdf