Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757116Ab0DVTbs (ORCPT ); Thu, 22 Apr 2010 15:31:48 -0400 Received: from mx1.redhat.com ([209.132.183.28]:30426 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756974Ab0DVTaD (ORCPT ); Thu, 22 Apr 2010 15:30:03 -0400 Date: Thu, 22 Apr 2010 16:29:47 -0300 From: Marcelo Tosatti To: Xiao Guangrong Cc: Avi Kivity , KVM list , LKML Subject: Re: [PATCH 6/10] KVM MMU: don't write-protect if have new mapping to unsync page Message-ID: <20100422192947.GA2280@amt.cnet> References: <4BCFE581.8050305@cn.fujitsu.com> <4BCFE8F0.7010509@cn.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4BCFE8F0.7010509@cn.fujitsu.com> User-Agent: Mutt/1.5.20 (2009-08-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3623 Lines: 106 On Thu, Apr 22, 2010 at 02:13:04PM +0800, Xiao Guangrong wrote: > If have new mapping to the unsync page(i.e, add a new parent), just > update the page from sp->gfn but not write-protect gfn, and if need > create new shadow page form sp->gfn, we should sync it > > Signed-off-by: Xiao Guangrong > --- > arch/x86/kvm/mmu.c | 27 +++++++++++++++++++-------- > 1 files changed, 19 insertions(+), 8 deletions(-) > > diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c > index fd027a6..8607a64 100644 > --- a/arch/x86/kvm/mmu.c > +++ b/arch/x86/kvm/mmu.c > @@ -1196,16 +1196,20 @@ static void kvm_unlink_unsync_page(struct kvm *kvm, struct kvm_mmu_page *sp) > > static int kvm_mmu_zap_page(struct kvm *kvm, struct kvm_mmu_page *sp); > > -static int kvm_sync_page(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp) > +static int kvm_sync_page(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp, > + bool clear_unsync) > { > if (sp->role.cr4_pae != !!is_pae(vcpu)) { > kvm_mmu_zap_page(vcpu->kvm, sp); > return 1; > } > > - if (rmap_write_protect(vcpu->kvm, sp->gfn)) > - kvm_flush_remote_tlbs(vcpu->kvm); > - kvm_unlink_unsync_page(vcpu->kvm, sp); > + if (clear_unsync) { > + if (rmap_write_protect(vcpu->kvm, sp->gfn)) > + kvm_flush_remote_tlbs(vcpu->kvm); > + kvm_unlink_unsync_page(vcpu->kvm, sp); > + } > + > if (vcpu->arch.mmu.sync_page(vcpu, sp)) { > kvm_mmu_zap_page(vcpu->kvm, sp); > return 1; > @@ -1293,7 +1297,7 @@ static void mmu_sync_children(struct kvm_vcpu *vcpu, > kvm_flush_remote_tlbs(vcpu->kvm); > > for_each_sp(pages, sp, parents, i) { > - kvm_sync_page(vcpu, sp); > + kvm_sync_page(vcpu, sp, true); > mmu_pages_clear_parents(&parents); > } > cond_resched_lock(&vcpu->kvm->mmu_lock); > @@ -1313,7 +1317,7 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu, > unsigned index; > unsigned quadrant; > struct hlist_head *bucket; > - struct kvm_mmu_page *sp; > + struct kvm_mmu_page *sp, *unsync_sp = NULL; > struct hlist_node *node, *tmp; > > role = vcpu->arch.mmu.base_role; > @@ -1332,12 +1336,16 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu, > hlist_for_each_entry_safe(sp, node, tmp, bucket, hash_link) > if (sp->gfn == gfn) { > if (sp->unsync) > - if (kvm_sync_page(vcpu, sp)) > - continue; > + unsync_sp = sp; Xiao, I don't see a reason why you can't create a new mapping to an unsync page. The code already creates shadow pte entries using unsync pagetables. So all you need would be to kvm_sync_pages before write protecting. Also make sure kvm_sync_pages is in place here before enabling multiple unsync shadows, in the patch series. > > if (sp->role.word != role.word) > continue; > > + if (unsync_sp && kvm_sync_page(vcpu, unsync_sp, false)) { > + unsync_sp = NULL; > + continue; > + } > + > mmu_page_add_parent_pte(vcpu, sp, parent_pte); > if (sp->unsync_children) { > set_bit(KVM_REQ_MMU_SYNC, &vcpu->requests); > @@ -1346,6 +1354,9 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu, > trace_kvm_mmu_get_page(sp, false); > return sp; > } > + if (unsync_sp) > + kvm_sync_page(vcpu, unsync_sp, true); > + > ++vcpu->kvm->stat.mmu_cache_miss; > sp = kvm_mmu_alloc_page(vcpu, parent_pte); > if (!sp) > -- > 1.6.1.2 > -- 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/