Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752854Ab2FMCB0 (ORCPT ); Tue, 12 Jun 2012 22:01:26 -0400 Received: from mx1.redhat.com ([209.132.183.28]:52799 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751988Ab2FMCBZ (ORCPT ); Tue, 12 Jun 2012 22:01:25 -0400 Date: Tue, 12 Jun 2012 23:01:03 -0300 From: Marcelo Tosatti To: Xiao Guangrong Cc: Avi Kivity , LKML , KVM Subject: Re: [PATCH v6 5/9] KVM: MMU: introduce SPTE_MMU_WRITEABLE bit Message-ID: <20120613020103.GB3119@amt.cnet> References: <4FC470C7.5040700@linux.vnet.ibm.com> <4FC4716A.8030304@linux.vnet.ibm.com> <20120611233212.GA29573@amt.cnet> <4FD6A833.6060206@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4FD6A833.6060206@linux.vnet.ibm.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 Content-Length: 1011 Lines: 27 On Tue, Jun 12, 2012 at 10:23:47AM +0800, Xiao Guangrong wrote: > On 06/12/2012 07:32 AM, Marcelo Tosatti wrote: > > > On Tue, May 29, 2012 at 02:49:14PM +0800, Xiao Guangrong wrote: > >> This bit indicates whether the spte can be writable on MMU, that means > >> the corresponding gpte is writable and the corresponding gfn is not > >> protected by shadow page protection > > > > Why is this still necessary, now that only sptes of direct shadow pages > > are updated locklessly? > > > > > Yes, but it is still needed, for nested npt/ept, we need protect > the nested page tables. Sure, but shadowed L1 nested pagetables are not direct shadow pages. They are shadows of L1 nested pagetables. Checking sp->direct should be enough (instead of the flags). -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/