From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755550Ab2DOPQg (ORCPT ); Sun, 15 Apr 2012 11:16:36 -0400 Received: from mx1.redhat.com ([209.132.183.28]:2324 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754993Ab2DOPQf (ORCPT ); Sun, 15 Apr 2012 11:16:35 -0400 Message-ID: <4F8AE64F.7080909@redhat.com> Date: Sun, 15 Apr 2012 18:16:31 +0300 From: Avi Kivity User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:11.0) Gecko/20120316 Thunderbird/11.0 MIME-Version: 1.0 To: Xiao Guangrong CC: Marcelo Tosatti , LKML , KVM Subject: Re: [PATCH v2 10/16] KVM: MMU: fask check whether page is writable References: <4F87FA69.5060106@linux.vnet.ibm.com> <4F87FC82.2050302@linux.vnet.ibm.com> In-Reply-To: <4F87FC82.2050302@linux.vnet.ibm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 04/13/2012 01:14 PM, 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 > +#define PTE_LIST_DESC (1 << PTE_LIST_DESC_BIT) > #define PTE_LIST_FLAG_MASK (0x3ull) > > static void > @@ -1067,6 +1069,12 @@ static bool rmap_can_add(struct kvm_vcpu *vcpu) > return mmu_memory_cache_free_objects(cache); > } > > +static void host_page_write_protect(u64 *spte, unsigned long *rmapp) > +{ > + if (!(*spte & SPTE_HOST_WRITEABLE)) > + __test_and_set_bit(PTE_LIST_WP_BIT, rmapp); > +} > Why is this needed, in addition to spte.SPTE_WRITE_PROTECT? -- error compiling committee.c: too many arguments to function