From patchwork Mon May 11 14:55:22 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Xiao Guangrong X-Patchwork-Id: 6378351 Return-Path: X-Original-To: patchwork-kvm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork2.web.kernel.org (Postfix) with ESMTP id A770DBEEE1 for ; Mon, 11 May 2015 15:03:41 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id BC182206F9 for ; Mon, 11 May 2015 15:03:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 74DF7206FB for ; Mon, 11 May 2015 15:03:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752255AbbEKPDS (ORCPT ); Mon, 11 May 2015 11:03:18 -0400 Received: from mga02.intel.com ([134.134.136.20]:13294 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751053AbbEKO7H (ORCPT ); Mon, 11 May 2015 10:59:07 -0400 Received: from orsmga003.jf.intel.com ([10.7.209.27]) by orsmga101.jf.intel.com with ESMTP; 11 May 2015 07:59:06 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.13,407,1427785200"; d="scan'208";a="569526198" Received: from xiao.sh.intel.com ([10.239.159.86]) by orsmga003.jf.intel.com with ESMTP; 11 May 2015 07:59:05 -0700 From: Xiao Guangrong To: pbonzini@redhat.com Cc: gleb@kernel.org, mtosatti@redhat.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Xiao Guangrong Subject: [PATCH 2/2] KVM: MMU: document smap_andnot_wp Date: Mon, 11 May 2015 22:55:22 +0800 Message-Id: <1431356122-8500-2-git-send-email-guangrong.xiao@linux.intel.com> X-Mailer: git-send-email 2.1.0 In-Reply-To: <1431356122-8500-1-git-send-email-guangrong.xiao@linux.intel.com> References: <1431356122-8500-1-git-send-email-guangrong.xiao@linux.intel.com> Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org X-Spam-Status: No, score=-6.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, T_RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Document this new role field Signed-off-by: Xiao Guangrong --- Documentation/virtual/kvm/mmu.txt | 18 ++++++++++++++---- 1 file changed, 14 insertions(+), 4 deletions(-) diff --git a/Documentation/virtual/kvm/mmu.txt b/Documentation/virtual/kvm/mmu.txt index 53838d9..c59bd9b 100644 --- a/Documentation/virtual/kvm/mmu.txt +++ b/Documentation/virtual/kvm/mmu.txt @@ -169,6 +169,10 @@ Shadow pages contain the following information: Contains the value of cr4.smep && !cr0.wp for which the page is valid (pages for which this is true are different from other pages; see the treatment of cr0.wp=0 below). + role.smap_andnot_wp: + Contains the value of cr4.smap && !cr0.wp for which the page is valid + (pages for which this is true are different from other pages; see the + treatment of cr0.wp=0 below). gfn: Either the guest page table containing the translations shadowed by this page, or the base page frame for linear translations. See role.direct. @@ -344,10 +348,16 @@ on fault type: (user write faults generate a #PF) -In the first case there is an additional complication if CR4.SMEP is -enabled: since we've turned the page into a kernel page, the kernel may now -execute it. We handle this by also setting spte.nx. If we get a user -fetch or read fault, we'll change spte.u=1 and spte.nx=gpte.nx back. +In the first case there are two additional complications: +- if CR4.SMEP is enabled: since we've turned the page into a kernel page, + the kernel may now execute it. We handle this by also setting spte.nx. + If we get a user fetch or read fault, we'll change spte.u=1 and + spte.nx=gpte.nx back. +- if CR4.SMAP is disabled: since the page has been changed to a kernel + page, it can not be reused when CR4.SMAP is enabled. We set + CR4.SMAP && !CR0.WP into shadow page's role to avoid this case. Note, + here we do not care the case that CR4.SMAP is enabled since KVM will + directly inject #PF to guest due to failed permission check. To prevent an spte that was converted into a kernel page with cr0.wp=0 from being written by the kernel after cr0.wp has changed to 1, we make