Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755929Ab0KBG4Z (ORCPT ); Tue, 2 Nov 2010 02:56:25 -0400 Received: from mx1.redhat.com ([209.132.183.28]:30429 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753059Ab0KBG4T (ORCPT ); Tue, 2 Nov 2010 02:56:19 -0400 Date: Tue, 2 Nov 2010 08:56:13 +0200 From: Gleb Natapov To: Xiao Guangrong Cc: Avi Kivity , Marcelo Tosatti , LKML , KVM Subject: Re: [RFC PATCH v2 7/7] KVM: KVM: don't break vcpu 'halt' state due to apfs Message-ID: <20101102065613.GA7881@redhat.com> References: <4CCE8143.3090105@cn.fujitsu.com> <4CCE82BC.3090000@cn.fujitsu.com> <20101101125551.GD31722@redhat.com> <4CCF77B2.9080604@cn.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4CCF77B2.9080604@cn.fujitsu.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2173 Lines: 52 On Tue, Nov 02, 2010 at 10:30:10AM +0800, Xiao Guangrong wrote: > On 11/01/2010 08:55 PM, Gleb Natapov wrote: > > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > > index 2cfdf2d..f7aed95 100644 > > --- a/arch/x86/kvm/x86.c > > +++ b/arch/x86/kvm/x86.c > > @@ -5295,8 +5295,9 @@ static int __vcpu_run(struct kvm_vcpu *vcpu) > > { > > switch(vcpu->arch.mp_state) { > > case KVM_MP_STATE_HALTED: > > - vcpu->arch.mp_state = > > - KVM_MP_STATE_RUNNABLE; > > + if (list_empty_careful(&vcpu->async_pf.done)) > > + vcpu->arch.mp_state = > > + KVM_MP_STATE_RUNNABLE; > > if nmi/interrupt and apfs completed event occur at the same time, we will miss to > exit halt sate. Maybe we can check the pending event here, see below patch please. > No, we will not. If nmi/interrupt and apfs completed event occur at the same time kvm_vcpu_block() will exit with KVM_REQ_UNHALT set, but cpu will not be unhalted because of list_empty_careful(&vcpu->async_pf.done) check. Vcpu then will process pending apf completion and enter kvm_vcpu_block() again which will immediately exit because kvm_arch_vcpu_runnable() will return true since there is pending nmi/interrupt. This time vcpu will be unhalted. > > case KVM_MP_STATE_RUNNABLE: > > vcpu->arch.apf.halted = false; > > break; > > @@ -6279,6 +6280,7 @@ void kvm_arch_async_page_present(struct kvm_vcpu *vcpu, > > vcpu->arch.fault.error_code = 0; > > vcpu->arch.fault.address = work->arch.token; > > kvm_inject_page_fault(vcpu); > > + vcpu->arch.mp_state = KVM_MP_STATE_RUNNABLE; > > } > > } > > Have a stupid question, why we make the vcpu runnable here? Sorry i don't know > kvm pv guest to much. :-( Because kvm_arch_vcpu_runnable() does not check for pending exceptions. Since now we do not unhalt vcpu when apf completion happens we need to unhalt it here. But, as I said, the patch is untested. -- Gleb. -- 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/