From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753860Ab2GINXN (ORCPT ); Mon, 9 Jul 2012 09:23:13 -0400 Received: from e28smtp04.in.ibm.com ([122.248.162.4]:50848 "EHLO e28smtp04.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753528Ab2GINXM (ORCPT ); Mon, 9 Jul 2012 09:23:12 -0400 Message-ID: <4FFADB37.4090705@linux.vnet.ibm.com> Date: Mon, 09 Jul 2012 21:23:03 +0800 From: Xiao Guangrong User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:13.0) Gecko/20120605 Thunderbird/13.0 MIME-Version: 1.0 To: Avi Kivity CC: Gleb Natapov , Marcelo Tosatti , LKML , KVM Subject: Re: [PATCH 1/2] KVM: X86: remove read buffer for mmio read References: <4FFA9E16.10001@linux.vnet.ibm.com> <4FFABD59.2070108@redhat.com> <20120709112346.GA23898@redhat.com> <4FFAD341.3080508@redhat.com> In-Reply-To: <4FFAD341.3080508@redhat.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit x-cbid: 12070913-5564-0000-0000-000003878328 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 07/09/2012 08:49 PM, Avi Kivity wrote: > On 07/09/2012 02:23 PM, Gleb Natapov wrote: >> >>> kvm-unit-tests.git has a test for xchg to mmio. Does it still work? >>> >>> I agree this code has to go, but it needs to be replaced by something. >>> Maybe a .valid flag in struct operand. >>> >> Valid will not enough for that. > > If we make everything go through operands, any reason why not? > I noticed some instructions need to read ESP for many times (e.g, iret_real), maybe .valid flag is not enough for this case if the stack is in MMIO, yes? IIUC, I also noticed ESP is not reset back if it is emulated fail (mmio is needed). If the stack located in mmio region, this kind of instruct will be broken, i know no guest will use mmio as stack but SDM does not limit it, is it valid?