From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756803Ab3GKWE0 (ORCPT ); Thu, 11 Jul 2013 18:04:26 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:43104 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756629Ab3GKWBw (ORCPT ); Thu, 11 Jul 2013 18:01:52 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Stefan Pietsch , Gleb Natapov , Paolo Bonzini Subject: [ 16/19] KVM: VMX: mark unusable segment as nonpresent Date: Thu, 11 Jul 2013 15:01:33 -0700 Message-Id: <20130711214832.452194271@linuxfoundation.org> X-Mailer: git-send-email 1.8.3.rc0.20.gb99dd2e In-Reply-To: <20130711214830.611455274@linuxfoundation.org> References: <20130711214830.611455274@linuxfoundation.org> User-Agent: quilt/0.60-5.1.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Gleb Natapov commit 03617c188f41eeeb4223c919ee7e66e5a114f2c6 upstream. Some userspaces do not preserve unusable property. Since usable segment has to be present according to VMX spec we can use present property to amend userspace bug by making unusable segment always nonpresent. vmx_segment_access_rights() already marks nonpresent segment as unusable. Reported-by: Stefan Pietsch Tested-by: Stefan Pietsch Signed-off-by: Gleb Natapov Signed-off-by: Paolo Bonzini Signed-off-by: Greg Kroah-Hartman --- arch/x86/kvm/vmx.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -3399,15 +3399,22 @@ static void vmx_get_segment(struct kvm_v var->limit = vmx_read_guest_seg_limit(vmx, seg); var->selector = vmx_read_guest_seg_selector(vmx, seg); ar = vmx_read_guest_seg_ar(vmx, seg); + var->unusable = (ar >> 16) & 1; var->type = ar & 15; var->s = (ar >> 4) & 1; var->dpl = (ar >> 5) & 3; - var->present = (ar >> 7) & 1; + /* + * Some userspaces do not preserve unusable property. Since usable + * segment has to be present according to VMX spec we can use present + * property to amend userspace bug by making unusable segment always + * nonpresent. vmx_segment_access_rights() already marks nonpresent + * segment as unusable. + */ + var->present = !var->unusable; var->avl = (ar >> 12) & 1; var->l = (ar >> 13) & 1; var->db = (ar >> 14) & 1; var->g = (ar >> 15) & 1; - var->unusable = (ar >> 16) & 1; } static u64 vmx_get_segment_base(struct kvm_vcpu *vcpu, int seg)