KVM: x86: Fix and refactor NMI watchdog emulation

This patch refactors the NMI watchdog delivery patch, consolidating
tests and providing a proper API for delivering watchdog events.

An included micro-optimization is to check only for apic_hw_enabled in
kvm_apic_local_deliver (the test for LVT mask is covering the
soft-disabled case already).

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Acked-by: Sheng Yang <sheng@linux.intel.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

1 files changed, 9 insertions, 6 deletions

diff --git a/arch/x86/kvm/i8254.c b/arch/x86/kvm/i8254.c
index 580cc1d01c7d..b6fcf5a9e502 100644
--- a/arch/x86/kvm/i8254.c
+++ b/arch/x86/kvm/i8254.c
@@ -612,15 +612,18 @@ static void __inject_pit_timer_intr(struct kvm *kvm)
         mutex_unlock(&kvm->lock);
 
         /*
-         * Provides NMI watchdog support in IOAPIC mode.
-         * The route is: PIT -> PIC -> LVT0 in NMI mode,
-         * timer IRQs will continue to flow through the IOAPIC.
+         * 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.
          */
         for (i = 0; i < KVM_MAX_VCPUS; ++i) {
                 vcpu = kvm->vcpus[i];
-                if (!vcpu)
-                        continue;
-                kvm_apic_local_deliver(vcpu, APIC_LVT0);
+                if (vcpu)
+                        kvm_apic_nmi_wd_deliver(vcpu);
         }
 }