On 03/31/2011 11:24 AM, Gleb Natapov wrote:
On Thu, Mar 31, 2011 at 11:23:28AM +0200, Avi Kivity wrote: > On 03/30/2011 08:47 PM, Gleb Natapov wrote: > >On Wed, Mar 30, 2011 at 07:16:34PM +0200, Avi Kivity wrote: > >> On 03/30/2011 06:30 PM, Marcelo Tosatti wrote: > >> >Based on Gleb's idea, fix race between nmi injection and enabling > >> >nmi window in a simpler way. > >> > > >> >Signed-off-by: Marcelo Tosatti<mtosa...@redhat.com> > >> > > >> >diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > >> >index a6a129f..9a7cc1be 100644 > >> >--- a/arch/x86/kvm/x86.c > >> >+++ b/arch/x86/kvm/x86.c > >> >@@ -5152,6 +5152,7 @@ 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; > >> > > >> >@@ -5195,11 +5196,13 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu) > >> > if (unlikely(r)) > >> > goto out; > >> > > >> >+ nmi_pending = ACCESS_ONCE(vcpu->arch.nmi_pending); > >> >+ > >> > if (kvm_check_request(KVM_REQ_EVENT, vcpu) || req_int_win) { > >> > inject_pending_event(vcpu); > >> > > >> > /* 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); > >> > > >> > >> What about the check in inject_pending_events()? > >> > >Didn't we decide that this check is not a problem? Worst that can happen > >is NMI injection will be delayed till next exit. > > Could be very far in the future. > Next host interrupt. But with tickles host and guest yeah.
esp. important with NMI, which may be used in a situation where your tick (and everything else) are dead.
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