From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752783Ab1HCIJQ (ORCPT ); Wed, 3 Aug 2011 04:09:16 -0400 Received: from mx1.redhat.com ([209.132.183.28]:47978 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752063Ab1HCIJL (ORCPT ); Wed, 3 Aug 2011 04:09:11 -0400 Message-ID: <4E39021F.8070508@redhat.com> Date: Wed, 03 Aug 2011 11:09:03 +0300 From: Avi Kivity User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.18) Gecko/20110621 Fedora/3.1.11-1.fc15 Thunderbird/3.1.11 MIME-Version: 1.0 To: Xiao Guangrong CC: Marcelo Tosatti , LKML , KVM Subject: Re: [PATCH v2 02/12] KVM: x86: tag the instructions which are used to write page table References: <4E37DA49.1040000@cn.fujitsu.com> <4E37DA73.7010908@cn.fujitsu.com> <4E37EB8E.6080207@redhat.com> <4E38E477.2000208@cn.fujitsu.com> In-Reply-To: <4E38E477.2000208@cn.fujitsu.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 08/03/2011 09:02 AM, Xiao Guangrong wrote: > > Note we don't need to actually emulate, just decode, since page_fault can tell us whether a write failed due to page tables or mmio. > > > > This is a interesting feature. If it happens, i will just drop the shadow pages > and retry these instructions directly. Note it's a little dangerous. If the guest uses a non-page-table modifying instruction on the PDE that points to the instruction, then we will unmap the instruction and go to an infinite loop. Maybe it's better to emulate if we can't find a fix for that. One way would be to emulate every 20 instructions; this breaks us out of the loop but reduces costly emulations to 5%. -- error compiling committee.c: too many arguments to function