KVM: x86: keep track of LVT0 changes under APICv

Memory-mapped LVT0 register already contains the new value when APICv
traps so we can't directly detect a change.
Memorize a bit we are interested in to enable legacy NMI watchdog.

Suggested-by: Yoshida Nobuo <yoshida.nb@ncos.nec.co.jp>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index e0f721bfabcb42fd6b73545c382501100c8c851e..954e98a8c2e38bf9861d4d6349eb721264e8cb18 100644 (file)
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -1257,16 +1257,17 @@ static void start_apic_timer(struct kvm_lapic *apic)
 
 static void apic_manage_nmi_watchdog(struct kvm_lapic *apic, u32 lvt0_val)
 {
-       int nmi_wd_enabled = apic_lvt_nmi_mode(kvm_apic_get_reg(apic, APIC_LVT0));
+       bool lvt0_in_nmi_mode = apic_lvt_nmi_mode(lvt0_val);
 
-       if (apic_lvt_nmi_mode(lvt0_val)) {
-               if (!nmi_wd_enabled) {
+       if (apic->lvt0_in_nmi_mode != lvt0_in_nmi_mode) {
+               apic->lvt0_in_nmi_mode = lvt0_in_nmi_mode;
+               if (lvt0_in_nmi_mode) {
                        apic_debug("Receive NMI setting on APIC_LVT0 "
                                   "for cpu %d\n", apic->vcpu->vcpu_id);
                        atomic_inc(&apic->vcpu->kvm->arch.vapics_in_nmi_mode);
-               }
-       } else if (nmi_wd_enabled)
-               atomic_dec(&apic->vcpu->kvm->arch.vapics_in_nmi_mode);
+               } else
+                       atomic_dec(&apic->vcpu->kvm->arch.vapics_in_nmi_mode);
+       }
 }
 
 static int apic_reg_write(struct kvm_lapic *apic, u32 reg, u32 val)
@@ -1597,6 +1598,7 @@ void kvm_lapic_reset(struct kvm_vcpu *vcpu, bool init_event)
        if (!(vcpu->kvm->arch.disabled_quirks & KVM_QUIRK_LINT0_REENABLED))
                apic_set_reg(apic, APIC_LVT0,
                             SET_APIC_DELIVERY_MODE(0, APIC_MODE_EXTINT));
+       apic_manage_nmi_watchdog(apic, kvm_apic_get_reg(apic, APIC_LVT0));
 
        apic_set_reg(apic, APIC_DFR, 0xffffffffU);
        apic_set_spiv(apic, 0xff);

diff --git a/arch/x86/kvm/lapic.h b/arch/x86/kvm/lapic.h
index f2f4e10ab7724640fb02ea3b6ea31ec08cfe95a4..71952748222a4a08597711acc21a599c9c499990 100644 (file)
--- a/arch/x86/kvm/lapic.h
+++ b/arch/x86/kvm/lapic.h
@@ -26,6 +26,7 @@ struct kvm_lapic {
        struct kvm_vcpu *vcpu;
        bool sw_enabled;
        bool irr_pending;
+       bool lvt0_in_nmi_mode;
        /* Number of bits set in ISR. */
        s16 isr_count;
        /* The highest vector set in ISR; if -1 - invalid, must scan ISR. */