From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932832Ab0IXQdy (ORCPT ); Fri, 24 Sep 2010 12:33:54 -0400 Received: from kroah.org ([198.145.64.141]:38465 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932762Ab0IXQ2n (ORCPT ); Fri, 24 Sep 2010 12:28:43 -0400 X-Mailbox-Line: From gregkh@clark.site Fri Sep 24 09:26:19 2010 Message-Id: <20100924162619.748639015@clark.site> User-Agent: quilt/0.48-11.2 Date: Fri, 24 Sep 2010 09:24:44 -0700 From: Greg KH To: linux-kernel@vger.kernel.org, stable@kernel.org, greg@kroah.com Cc: stable-review@kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, avi@redhat.com, mtosatti@redhat.com, Xiao Guangrong Subject: [56/80] KVM: MMU: fix direct sps access corrupted In-Reply-To: <20100924162706.GA7381@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2.6.35-stable review patch. If anyone has any objections, please let us know. ------------------ 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: Greg Kroah-Hartman --- arch/x86/kvm/paging_tmpl.h | 28 ++++++++++++++++++++++++++-- 1 file changed, 26 insertions(+), 2 deletions(-) --- a/arch/x86/kvm/paging_tmpl.h +++ b/arch/x86/kvm/paging_tmpl.h @@ -324,8 +324,32 @@ static u64 *FNAME(fetch)(struct kvm_vcpu 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);