From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754934Ab1ABHcJ (ORCPT ); Sun, 2 Jan 2011 02:32:09 -0500 Received: from mail.windriver.com ([147.11.1.11]:37138 "EHLO mail.windriver.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754895Ab1ABHZn (ORCPT ); Sun, 2 Jan 2011 02:25:43 -0500 From: Paul Gortmaker To: stable@kernel.org, linux-kernel@vger.kernel.org Cc: stable-review@kernel.org, Xiao Guangrong , Marcelo Tosatti , Paul Gortmaker Subject: [34-longterm 233/260] KVM: MMU: fix direct sp's access corrupted Date: Sun, 2 Jan 2011 02:18:49 -0500 Message-Id: <1293952756-15010-234-git-send-email-paul.gortmaker@windriver.com> X-Mailer: git-send-email 1.7.3.3 In-Reply-To: <1293952756-15010-1-git-send-email-paul.gortmaker@windriver.com> References: <1293952756-15010-1-git-send-email-paul.gortmaker@windriver.com> X-OriginalArrivalTime: 02 Jan 2011 07:24:25.0011 (UTC) FILETIME=[15344830:01CBAA4E] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Xiao Guangrong commit 9e7b0e7fba45ca3c6357aeb7091ebc281f1de365 upstream. If the mapping is writable but the dirty flag is not set, we will find the read-only direct sp and setup the mapping, then if the write #PF occur, we will mark this mapping writable in the read-only direct sp, now, other real read-only mapping will happily write it without #PF. It may hurt guest's COW Fixed by re-install the mapping when write #PF occur. Signed-off-by: Xiao Guangrong Signed-off-by: Marcelo Tosatti Signed-off-by: Paul Gortmaker --- arch/x86/kvm/paging_tmpl.h | 28 ++++++++++++++++++++++++++-- 1 files changed, 26 insertions(+), 2 deletions(-) diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h index 81eab9a..a535c87 100644 --- a/arch/x86/kvm/paging_tmpl.h +++ b/arch/x86/kvm/paging_tmpl.h @@ -318,8 +318,32 @@ static u64 *FNAME(fetch)(struct kvm_vcpu *vcpu, gva_t addr, break; } - if (is_shadow_present_pte(*sptep) && !is_large_pte(*sptep)) - continue; + if (is_shadow_present_pte(*sptep) && !is_large_pte(*sptep)) { + struct kvm_mmu_page *child; + unsigned direct_access; + + if (level != gw->level) + continue; + + /* + * For the direct sp, if the guest pte's dirty bit + * changed form clean to dirty, it will corrupt the + * sp's access: allow writable in the read-only sp, + * so we should update the spte at this point to get + * a new sp with the correct access. + */ + direct_access = gw->pt_access & gw->pte_access; + if (!is_dirty_gpte(gw->ptes[gw->level - 1])) + direct_access &= ~ACC_WRITE_MASK; + + child = page_header(*sptep & PT64_BASE_ADDR_MASK); + if (child->role.access == direct_access) + continue; + + mmu_page_remove_parent_pte(child, sptep); + __set_spte(sptep, shadow_trap_nonpresent_pte); + kvm_flush_remote_tlbs(vcpu->kvm); + } if (is_large_pte(*sptep)) { rmap_remove(vcpu->kvm, sptep); -- 1.7.3.3