From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [PATCH 4/4] KVM: MMU: Don't touch unsync sp in kvm_mmu_pte_write() Date: Mon, 20 Sep 2010 17:24:47 +0200 Message-ID: <4C977CBF.6030702@redhat.com> References: <4C976D48.6020400@cn.fujitsu.com> <4C976DF6.1020905@cn.fujitsu.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Cc: Marcelo Tosatti , LKML , KVM To: Xiao Guangrong Return-path: In-Reply-To: <4C976DF6.1020905@cn.fujitsu.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org On 09/20/2010 04:21 PM, Xiao Guangrong wrote: > Gfn may have many shadow pages, when one sp need be synced, we write > protected sp->gfn and sync this sp but we keep other shadow pages > asynchronous > > So, while gfn happen page fault, let it not touches unsync page, the unsync > page only updated at invlpg/flush TLB time > > @@ -3157,6 +3164,9 @@ void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa, > > mask.cr0_wp = mask.cr4_pae = mask.nxe = 1; > for_each_gfn_indirect_valid_sp(vcpu->kvm, sp, gfn, node) { > + if (sp->unsync) > + continue; > + > Not sure this is a win. If a gpte is updated from having p=0 to p=1 (or permissions upgraded), we may not have an invlpg to sync the spte, since the hardware doesn't require it. With this change, we may get an extra #PF. -- error compiling committee.c: too many arguments to function