From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752468Ab1HVOcw (ORCPT ); Mon, 22 Aug 2011 10:32:52 -0400 Received: from mx1.redhat.com ([209.132.183.28]:32149 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750818Ab1HVOct (ORCPT ); Mon, 22 Aug 2011 10:32:49 -0400 Date: Mon, 22 Aug 2011 11:32:35 -0300 From: Marcelo Tosatti To: Xiao Guangrong Cc: Avi Kivity , LKML , KVM Subject: Re: [PATCH 02/11] KVM: x86: tag the instructions which are used to write page table Message-ID: <20110822143235.GA4797@amt.cnet> References: <4E4A10E8.5090705@cn.fujitsu.com> <4E4A1117.1030608@cn.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4E4A1117.1030608@cn.fujitsu.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Aug 16, 2011 at 02:41:27PM +0800, Xiao Guangrong wrote: > The idea is from Avi: > | tag instructions that are typically used to modify the page tables, and > | drop shadow if any other instruction is used. > | The list would include, I'd guess, and, or, bts, btc, mov, xchg, cmpxchg, > | and cmpxchg8b. > > This patch is used to tag the instructions and in the later path, shadow page > is dropped if it is written by other instructions What is the advantage of doing this again? What is the point of dropping shadow if the instruction is emulated?