From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: KVM: x86: vcpu state writeback should be aware of REQ_NMI Date: Thu, 24 Mar 2011 15:33:35 +0200 Message-ID: <4D8B482F.9070408@redhat.com> References: <20110324124700.GA26882@amt.cnet> <20110324132716.GA13195@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Marcelo Tosatti , kvm To: Gleb Natapov Return-path: Received: from mx1.redhat.com ([209.132.183.28]:42004 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753009Ab1CXNdj (ORCPT ); Thu, 24 Mar 2011 09:33:39 -0400 Received: from int-mx01.intmail.prod.int.phx2.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id p2ODXc1p006736 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Thu, 24 Mar 2011 09:33:38 -0400 In-Reply-To: <20110324132716.GA13195@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On 03/24/2011 03:27 PM, Gleb Natapov wrote: > On Thu, Mar 24, 2011 at 09:47:00AM -0300, Marcelo Tosatti wrote: > > > > Since "Fix race between nmi injection and enabling nmi window", pending NMI > > can be represented in KVM_REQ_NMI vcpu->requests bit. > > > > When setting vcpu state via SET_VCPU_EVENTS, for example during reset, > > the REQ_NMI bit should be cleared otherwise pending NMI is transferred > > to nmi_pending upon vcpu entry. > > > > Also should consider requests bit on runnable conditional. > > > > BZ: http://bugzilla.redhat.com/show_bug.cgi?id=684719 > > > Looks like we need to clear request bit on cpu reset too. KVM_REQ_NMI > start to become more complicated that it was initially. May be replaced > it with something like this: > > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index 1b8b16a..6a66d19 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -5151,6 +5151,7 @@ static void kvm_put_guest_xcr0(struct kvm_vcpu *vcpu) > static int vcpu_enter_guest(struct kvm_vcpu *vcpu) > { > int r; > + int nmi_pending; > bool req_int_win = !irqchip_in_kernel(vcpu->kvm)&& > vcpu->run->request_interrupt_window; > > @@ -5188,19 +5189,19 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu) > r = 1; > goto out; > } > - if (kvm_check_request(KVM_REQ_NMI, vcpu)) > - vcpu->arch.nmi_pending = true; > } > > r = kvm_mmu_reload(vcpu); > if (unlikely(r)) > goto out; > > + nmi_pending = vcpu->arch.nmi_pending; > + ACCESS_ONCE() to prevent compiler cleverness > if (kvm_check_request(KVM_REQ_EVENT, vcpu) || req_int_win) { > inject_pending_event(vcpu); This can use a newer vcpu->arch.nmi_pending. > > /* enable NMI/IRQ window open exits if needed */ > - if (vcpu->arch.nmi_pending) > + if (nmi_pending) > kvm_x86_ops->enable_nmi_window(vcpu); > else if (kvm_cpu_has_interrupt(vcpu) || req_int_win) > kvm_x86_ops->enable_irq_window(vcpu); -- error compiling committee.c: too many arguments to function