1 files changed, 19 insertions, 0 deletions

diff --git a/arch/x86/kvm/i8254.c b/arch/x86/kvm/i8254.c
index 59ebd37ad79e..e665d1c623ca 100644
--- a/arch/x86/kvm/i8254.c
+++ b/arch/x86/kvm/i8254.c
@@ -603,10 +603,29 @@ void kvm_free_pit(struct kvm *kvm)
 
 static void __inject_pit_timer_intr(struct kvm *kvm)
 {
+        struct kvm_vcpu *vcpu;
+        int i;
+
         mutex_lock(&kvm->lock);
         kvm_set_irq(kvm, kvm->arch.vpit->irq_source_id, 0, 1);
         kvm_set_irq(kvm, kvm->arch.vpit->irq_source_id, 0, 0);
         mutex_unlock(&kvm->lock);
+
+        /*
+         * Provides NMI watchdog support via Virtual Wire mode.
+         * The route is: PIT -> PIC -> LVT0 in NMI mode.
+         *
+         * Note: Our Virtual Wire implementation is simplified, only
+         * propagating PIT interrupts to all VCPUs when they have set
+         * LVT0 to NMI delivery. Other PIC interrupts are just sent to
+         * VCPU0, and only if its LVT0 is in EXTINT mode.
+         */
+        if (kvm->arch.vapics_in_nmi_mode > 0)
+                for (i = 0; i < KVM_MAX_VCPUS; ++i) {
+                        vcpu = kvm->vcpus[i];
+                        if (vcpu)
+                                kvm_apic_nmi_wd_deliver(vcpu);
+                }
 }
 
 void kvm_inject_pit_timer_irqs(struct kvm_vcpu *vcpu)