From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lai Jiangshan Subject: Re: [PATCH v2 2/4] KVM: MMU: Move accessed/dirty bit checks from rmap_remove() to drop_spte() Date: Mon, 07 Jun 2010 16:16:49 +0800 Message-ID: <4C0CAAF1.2040202@cn.fujitsu.com> References: <1275894659-17656-1-git-send-email-avi@redhat.com> <1275894659-17656-3-git-send-email-avi@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Cc: Marcelo Tosatti , kvm@vger.kernel.org To: Avi Kivity Return-path: Received: from cn.fujitsu.com ([222.73.24.84]:64224 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1756508Ab0FGIQa (ORCPT ); Mon, 7 Jun 2010 04:16:30 -0400 In-Reply-To: <1275894659-17656-3-git-send-email-avi@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: Avi Kivity wrote: > Since we need to make the check atomic, move it to the place that will > set the new spte. > > Signed-off-by: Avi Kivity > --- > arch/x86/kvm/mmu.c | 17 +++++++++-------- > 1 files changed, 9 insertions(+), 8 deletions(-) > > diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c > index 16cedc9..b5a2d3d 100644 > --- a/arch/x86/kvm/mmu.c > +++ b/arch/x86/kvm/mmu.c > @@ -620,19 +620,11 @@ static void rmap_remove(struct kvm *kvm, u64 *spte) > struct kvm_rmap_desc *desc; > struct kvm_rmap_desc *prev_desc; > struct kvm_mmu_page *sp; > - pfn_t pfn; > gfn_t gfn; > unsigned long *rmapp; > int i; > > - if (!is_rmap_spte(*spte)) > - return; > sp = page_header(__pa(spte)); > - pfn = spte_to_pfn(*spte); > - if (*spte & shadow_accessed_mask) > - kvm_set_pfn_accessed(pfn); > - if (is_writable_pte(*spte)) > - kvm_set_pfn_dirty(pfn); > gfn = kvm_mmu_page_get_gfn(sp, spte - sp->spt); > rmapp = gfn_to_rmap(kvm, gfn, sp->role.level); > if (!*rmapp) { > @@ -668,6 +660,15 @@ static void rmap_remove(struct kvm *kvm, u64 *spte) > > static void drop_spte(struct kvm *kvm, u64 *sptep, u64 new_spte) > { > + pfn_t pfn; > + > + if (!is_rmap_spte(*sptep)) > + return; Missing __set_spte(sptep, new_spte); ? > + pfn = spte_to_pfn(*sptep); > + if (*sptep & shadow_accessed_mask) > + kvm_set_pfn_accessed(pfn); > + if (is_writable_pte(*sptep)) > + kvm_set_pfn_dirty(pfn); > rmap_remove(kvm, sptep); > __set_spte(sptep, new_spte); > }