Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754610AbbEKPDU (ORCPT ); Mon, 11 May 2015 11:03:20 -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 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.13,407,1427785200"; d="scan'208";a="569526198" 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: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2440 Lines: 51 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 -- 2.1.0 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/