From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [PATCH v2 1/6] KVM: MMU: fix forgot flush vcpu tlbs Date: Wed, 17 Nov 2010 18:26:51 +0200 Message-ID: <4CE4024B.4090600@redhat.com> References: <4CE355A0.6020907@cn.fujitsu.com> <20101117152943.GA18959@amt.cnet> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Xiao Guangrong , LKML , KVM To: Marcelo Tosatti Return-path: Received: from mx1.redhat.com ([209.132.183.28]:37052 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933790Ab0KQQ06 (ORCPT ); Wed, 17 Nov 2010 11:26:58 -0500 In-Reply-To: <20101117152943.GA18959@amt.cnet> Sender: kvm-owner@vger.kernel.org List-ID: On 11/17/2010 05:29 PM, Marcelo Tosatti wrote: > > diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h > > index ba00eef..58b4d9a 100644 > > --- a/arch/x86/kvm/paging_tmpl.h > > +++ b/arch/x86/kvm/paging_tmpl.h > > @@ -781,6 +781,7 @@ static int FNAME(sync_page)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp, > > else > > nonpresent = shadow_notrap_nonpresent_pte; > > drop_spte(vcpu->kvm,&sp->spt[i], nonpresent); > > + kvm_flush_remote_tlbs(vcpu->kvm); > > continue; > > } > > This is not needed. Guest is responsible for flushing on > present->nonpresent change. sync_page drop_spte kvm_mmu_notifier_invalidate_page kvm_unmap_rmapp spte doesn't exist -> no flush page is freed guest can write into freed page? I don't think we need to flush immediately; set a "tlb dirty" bit somewhere that is cleareded when we flush the tlb. kvm_mmu_notifier_invalidate_page() can consult the bit and force a flush if set. -- error compiling committee.c: too many arguments to function