Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752304AbaFONNV (ORCPT ); Sun, 15 Jun 2014 09:13:21 -0400 Received: from mailgw12.technion.ac.il ([132.68.225.12]:22664 "EHLO mailgw12.technion.ac.il" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752047AbaFONNM (ORCPT ); Sun, 15 Jun 2014 09:13:12 -0400 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: AgECAPuanVOERCABjGdsb2JhbABariIBAQaZJAGBABYPAQEBJzyEBAEFJ1IQUVcZiELJWIUmF4VjiRMHFoQtBIo5pyU X-IPAS-Result: AgECAPuanVOERCABjGdsb2JhbABariIBAQaZJAGBABYPAQEBJzyEBAEFJ1IQUVcZiELJWIUmF4VjiRMHFoQtBIo5pyU X-IronPort-AV: E=Sophos;i="5.01,481,1400014800"; d="scan'208";a="111523993" From: Nadav Amit To: pbonzini@redhat.com Cc: gleb@kernel.org, tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com, x86@kernel.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Nadav Amit Subject: [PATCH 5/6] KVM: x86: NOP emulation clears (incorrectly) the high 32-bits of RAX Date: Sun, 15 Jun 2014 16:13:01 +0300 Message-Id: <1402837982-24959-6-git-send-email-namit@cs.technion.ac.il> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1402837982-24959-1-git-send-email-namit@cs.technion.ac.il> References: <1402837982-24959-1-git-send-email-namit@cs.technion.ac.il> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On long-mode the current NOP (0x90) emulation still writes back to RAX. As a result, EAX is zero-extended and the high 32-bits of RAX are cleared. Signed-off-by: Nadav Amit --- arch/x86/kvm/emulate.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c index b354531..eb93eb4 100644 --- a/arch/x86/kvm/emulate.c +++ b/arch/x86/kvm/emulate.c @@ -4663,8 +4663,9 @@ special_insn: break; case 0x90 ... 0x97: /* nop / xchg reg, rax */ if (ctxt->dst.addr.reg == reg_rmw(ctxt, VCPU_REGS_RAX)) - break; - rc = em_xchg(ctxt); + ctxt->dst.type = OP_NONE; + else + rc = em_xchg(ctxt); break; case 0x98: /* cbw/cwde/cdqe */ switch (ctxt->op_bytes) { -- 1.9.1 -- 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/