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KVM: x86: better fix for race between nmi injection and enabling nmi window 

Fix race between nmi injection and enabling nmi window in a simpler way.

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
This commit is contained in:
Gleb Natapov 2011-04-01 11:26:29 -03:00 committed by Avi Kivity
parent c761e5868e
commit 1499e54af0
1 changed files with 10 additions and 1 deletions
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11
arch/x86/kvm/x86.c
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@ -5171,6 +5171,7 @@ static void kvm_put_guest_xcr0(struct kvm_vcpu *vcpu)
static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
{
int r;
bool nmi_pending;
bool req_int_win = !irqchip_in_kernel(vcpu->kvm) &&
vcpu->run->request_interrupt_window;
@ -5214,11 +5215,19 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
if (unlikely(r))
goto out;
/*
* An NMI can be injected between local nmi_pending read and
* vcpu->arch.nmi_pending read inside inject_pending_event().
* But in that case, KVM_REQ_EVENT will be set, which makes
* the race described above benign.
*/
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);