From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760144Ab3LFXrw (ORCPT ); Fri, 6 Dec 2013 18:47:52 -0500 Received: from youngberry.canonical.com ([91.189.89.112]:48439 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1161383Ab3LFXMi (ORCPT ); Fri, 6 Dec 2013 18:12:38 -0500 From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Gleb Natapov , Paolo Bonzini , Kamal Mostafa Subject: [PATCH 3.8 045/152] KVM: x86: fix emulation of "movzbl %bpl, %eax" Date: Fri, 6 Dec 2013 15:09:29 -0800 Message-Id: <1386371476-2477-46-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 1.8.3.2 In-Reply-To: <1386371476-2477-1-git-send-email-kamal@canonical.com> References: <1386371476-2477-1-git-send-email-kamal@canonical.com> X-Extended-Stable: 3.8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.8.13.14 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Paolo Bonzini commit daf727225b8abfdfe424716abac3d15a3ac5626a upstream. When I was looking at RHEL5.9's failure to start with unrestricted_guest=0/emulate_invalid_guest_state=1, I got it working with a slightly older tree than kvm.git. I now debugged the remaining failure, which was introduced by commit 660696d1 (KVM: X86 emulator: fix source operand decoding for 8bit mov[zs]x instructions, 2013-04-24) introduced a similar mis-emulation to the one in commit 8acb4207 (KVM: fix sil/dil/bpl/spl in the mod/rm fields, 2013-05-30). The incorrect decoding occurs in 8-bit movzx/movsx instructions whose 8-bit operand is sil/dil/bpl/spl. Needless to say, "movzbl %bpl, %eax" does occur in RHEL5.9's decompression prolog, just a handful of instructions before finally giving control to the decompressed vmlinux and getting out of the invalid guest state. Because OpMem8 bypasses decode_modrm, the same handling of the REX prefix must be applied to OpMem8. Reported-by: Michele Baldessari Cc: Gleb Natapov Signed-off-by: Paolo Bonzini Signed-off-by: Gleb Natapov Signed-off-by: Kamal Mostafa --- arch/x86/kvm/emulate.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c index d330b3c..c047b35 100644 --- a/arch/x86/kvm/emulate.c +++ b/arch/x86/kvm/emulate.c @@ -4031,7 +4031,10 @@ static int decode_operand(struct x86_emulate_ctxt *ctxt, struct operand *op, case OpMem8: ctxt->memop.bytes = 1; if (ctxt->memop.type == OP_REG) { - ctxt->memop.addr.reg = decode_register(ctxt, ctxt->modrm_rm, 1); + int highbyte_regs = ctxt->rex_prefix == 0; + + ctxt->memop.addr.reg = decode_register(ctxt, ctxt->modrm_rm, + highbyte_regs); fetch_register_operand(&ctxt->memop); } goto mem_common; -- 1.8.3.2