From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757490AbbKSMCs (ORCPT ); Thu, 19 Nov 2015 07:02:48 -0500 Received: from mx1.redhat.com ([209.132.183.28]:51792 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755422AbbKSMCr (ORCPT ); Thu, 19 Nov 2015 07:02:47 -0500 Subject: Re: [PATCH] KVM: x86: don't expose syscall/sysret to intel 32-bit guest To: Wanpeng Li References: <564DACF5.9090908@redhat.com> Cc: Wanpeng li , kvm , "linux-kernel@vger.kernel.org" From: Paolo Bonzini Message-ID: <564DBA60.2010707@redhat.com> Date: Thu, 19 Nov 2015 13:02:40 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.3.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 19/11/2015 13:01, Wanpeng Li wrote: > > This is not correct. As far as I know, the SYSCALL bit is always > > present in CPUID, even if the machine is running in 32-bit mode; CPUID > > documentation (SDM Volume 2) explicitly documents bit 11 as "Bit 11: > > SYSCALL/SYSRET available in 64-bit mode". > > No, I try a 32-bit linux host kernel, cpuid tool shows that SYSCALL > bit is not set. Ok, let me try... Paolo