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Commit 1499e54a authored by Gleb Natapov's avatar Gleb Natapov Committed by Avi Kivity
Browse files

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: default avatarMarcelo Tosatti <mtosatti@redhat.com>
parent c761e586

arch/x86/kvm/x86.c

+10 −1
Original line number Original line Diff line number Diff line
@@ -5171,6 +5171,7 @@ static void kvm_put_guest_xcr0(struct kvm_vcpu *vcpu) 
static int vcpu_enter_guest(struct kvm_vcpu *vcpu)

static int vcpu_enter_guest(struct kvm_vcpu *vcpu)

{

{

	int r;

	int r;

	bool nmi_pending;

	bool req_int_win = !irqchip_in_kernel(vcpu->kvm) &&

	bool req_int_win = !irqchip_in_kernel(vcpu->kvm) &&

		vcpu->run->request_interrupt_window;

		vcpu->run->request_interrupt_window;
@@ -5214,11 +5215,19 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu) 
	if (unlikely(r))

	if (unlikely(r))

		goto out;

		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) {

	if (kvm_check_request(KVM_REQ_EVENT, vcpu) || req_int_win) {

		inject_pending_event(vcpu);

		inject_pending_event(vcpu);





		/* enable NMI/IRQ window open exits if needed */

		/* enable NMI/IRQ window open exits if needed */

		if (vcpu->arch.nmi_pending)

		if (nmi_pending)

			kvm_x86_ops->enable_nmi_window(vcpu);

			kvm_x86_ops->enable_nmi_window(vcpu);

		else if (kvm_cpu_has_interrupt(vcpu) || req_int_win)

		else if (kvm_cpu_has_interrupt(vcpu) || req_int_win)

			kvm_x86_ops->enable_irq_window(vcpu);

			kvm_x86_ops->enable_irq_window(vcpu);