From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755993AbaEGOoE (ORCPT ); Wed, 7 May 2014 10:44:04 -0400 Received: from mx1.redhat.com ([209.132.183.28]:49870 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751108AbaEGOoC (ORCPT ); Wed, 7 May 2014 10:44:02 -0400 From: Bandan Das To: Nadav Amit Cc: mtosatti@redhat.com, pbonzini@redhat.com, hpa@zytor.com, gleb@kernel.org, tglx@linutronix.de, mingo@redhat.com, x86@kernel.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 5/5] KVM: x86: Fix wrong masking on relative jump/call References: <1399465972-4026-1-git-send-email-namit@cs.technion.ac.il> <1399465972-4026-6-git-send-email-namit@cs.technion.ac.il> Date: Wed, 07 May 2014 10:43:50 -0400 In-Reply-To: <1399465972-4026-6-git-send-email-namit@cs.technion.ac.il> (Nadav Amit's message of "Wed, 7 May 2014 15:32:52 +0300") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.3 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Nadav Amit writes: > Relative jumps and calls do the masking according to the operand size, and not > according to the address size as the KVM emulator does today. In 64-bit mode, > the resulting RIP is always 64-bit. Otherwise it is masked according to the > instruction operand-size. Note that when 16-bit address size is used, bits > 63:32 are unmodified. > > Signed-off-by: Nadav Amit > --- > arch/x86/kvm/emulate.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c > index 6833b41..e406705 100644 > --- a/arch/x86/kvm/emulate.c > +++ b/arch/x86/kvm/emulate.c > @@ -506,7 +506,9 @@ static void rsp_increment(struct x86_emulate_ctxt *ctxt, int inc) > > static inline void jmp_rel(struct x86_emulate_ctxt *ctxt, int rel) > { > - register_address_increment(ctxt, &ctxt->_eip, rel); > + /* 64-bit mode relative jumps are always 64-bit; otherwise mask */ > + int op_bytes = ctxt->mode == X86EMUL_MODE_PROT64 ? 8 : ctxt->op_bytes; Just a nit, probably break this up for readability ? > + masked_increment(&ctxt->eip, op_bytes, rel); > } > > static u32 desc_limit_scaled(struct desc_struct *desc)