KVM: x86: Optimize NMI watchdog delivery

As suggested by Avi, this patch introduces a counter of VCPUs that have
LVT0 set to NMI mode. Only if the counter > 0, we push the PIT ticks via
all LAPIC LVT0 lines to enable NMI watchdog support.

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, 1 insertions, 0 deletions

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 59c3ae10de6c..09e6c56572cb 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -361,6 +361,7 @@ struct kvm_arch{
         struct kvm_ioapic *vioapic;
         struct kvm_pit *vpit;
         struct hlist_head irq_ack_notifier_list;
+        int vapics_in_nmi_mode;
 
         int round_robin_prev_vcpu;
         unsigned int tss_addr;