From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755122Ab2DNDCA (ORCPT ); Fri, 13 Apr 2012 23:02:00 -0400 Received: from mail-pz0-f52.google.com ([209.85.210.52]:40485 "EHLO mail-pz0-f52.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753989Ab2DNDB6 (ORCPT ); Fri, 13 Apr 2012 23:01:58 -0400 Date: Sat, 14 Apr 2012 12:01:53 +0900 From: Takuya Yoshikawa To: Xiao Guangrong Cc: Avi Kivity , Marcelo Tosatti , LKML , KVM Subject: Re: [PATCH v2 10/16] KVM: MMU: fask check whether page is writable Message-Id: <20120414120153.76c3afca3726c14d10581a6c@gmail.com> In-Reply-To: <4F87FC82.2050302@linux.vnet.ibm.com> References: <4F87FA69.5060106@linux.vnet.ibm.com> <4F87FC82.2050302@linux.vnet.ibm.com> X-Mailer: Sylpheed 3.2.0beta3 (GTK+ 2.24.6; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 13 Apr 2012 18:14:26 +0800 Xiao Guangrong wrote: > Using bit 1 (PTE_LIST_WP_BIT) in rmap store the write-protect status > to avoid unnecessary shadow page walking > > Signed-off-by: Xiao Guangrong > --- > arch/x86/kvm/mmu.c | 40 ++++++++++++++++++++++++++++++++++------ > 1 files changed, 34 insertions(+), 6 deletions(-) > > diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c > index 0c6e92d..8b71908 100644 > --- a/arch/x86/kvm/mmu.c > +++ b/arch/x86/kvm/mmu.c > @@ -796,7 +796,9 @@ static int mapping_level(struct kvm_vcpu *vcpu, gfn_t large_gfn) > return level - 1; > } > > -#define PTE_LIST_DESC (0x1ull) > +#define PTE_LIST_DESC_BIT 0 > +#define PTE_LIST_WP_BIT 1 _BIT ? > +#define PTE_LIST_DESC (1 << PTE_LIST_DESC_BIT) > #define PTE_LIST_FLAG_MASK (0x3ull) > Well, I think that rmap is losing its original meaning: Before, it held just the information needed to link spteps. Now it has more roles, and getting kind of descriptor? ... > @@ -2291,9 +2310,15 @@ static int mmu_need_write_protect(struct kvm_vcpu *vcpu, gfn_t gfn, > { > struct kvm_mmu_page *s; > struct hlist_node *node; > + unsigned long *rmap; > bool need_unsync = false; > > + rmap = gfn_to_rmap(vcpu->kvm, gfn, PT_PAGE_TABLE_LEVEL); Please use consistent variable names. In other parts of this patch, you are using rmapp for this. Takuya