KVM: use jump label to optimize checking for SW enabled apic in spurious interrupt register
Usually all APICs are SW enabled so the check can be optimized out.
Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 5b46cab..7f77e96 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -127,9 +127,24 @@
return MSR_IA32_APICBASE_ENABLE;
}
-static inline int apic_sw_enabled(struct kvm_lapic *apic)
+struct static_key_deferred apic_sw_disabled __read_mostly;
+
+static inline void apic_set_spiv(struct kvm_lapic *apic, u32 val)
{
- return apic_get_reg(apic, APIC_SPIV) & APIC_SPIV_APIC_ENABLED;
+ if ((apic_get_reg(apic, APIC_SPIV) ^ val) & APIC_SPIV_APIC_ENABLED) {
+ if (val & APIC_SPIV_APIC_ENABLED)
+ static_key_slow_dec_deferred(&apic_sw_disabled);
+ else
+ static_key_slow_inc(&apic_sw_disabled.key);
+ }
+ apic_set_reg(apic, APIC_SPIV, val);
+}
+
+static inline int apic_sw_enabled(struct kvm_lapic *apic)
+{
+ if (static_key_false(&apic_sw_disabled.key))
+ return apic_get_reg(apic, APIC_SPIV) & APIC_SPIV_APIC_ENABLED;
+ return APIC_SPIV_APIC_ENABLED;
}
static inline int apic_enabled(struct kvm_lapic *apic)
@@ -918,7 +933,7 @@
u32 mask = 0x3ff;
if (apic_get_reg(apic, APIC_LVR) & APIC_LVR_DIRECTED_EOI)
mask |= APIC_SPIV_DIRECTED_EOI;
- apic_set_reg(apic, APIC_SPIV, val & mask);
+ apic_set_spiv(apic, val & mask);
if (!(val & APIC_SPIV_APIC_ENABLED)) {
int i;
u32 lvt_val;
@@ -1055,18 +1070,23 @@
void kvm_free_lapic(struct kvm_vcpu *vcpu)
{
+ struct kvm_lapic *apic = vcpu->arch.apic;
+
if (!vcpu->arch.apic)
return;
- hrtimer_cancel(&vcpu->arch.apic->lapic_timer.timer);
+ hrtimer_cancel(&apic->lapic_timer.timer);
if (!(vcpu->arch.apic_base & MSR_IA32_APICBASE_ENABLE))
static_key_slow_dec_deferred(&apic_hw_disabled);
- if (vcpu->arch.apic->regs)
- free_page((unsigned long)vcpu->arch.apic->regs);
+ if (!(apic_get_reg(apic, APIC_SPIV) & APIC_SPIV_APIC_ENABLED))
+ static_key_slow_dec_deferred(&apic_sw_disabled);
- kfree(vcpu->arch.apic);
+ if (apic->regs)
+ free_page((unsigned long)apic->regs);
+
+ kfree(apic);
}
/*
@@ -1182,7 +1202,7 @@
SET_APIC_DELIVERY_MODE(0, APIC_MODE_EXTINT));
apic_set_reg(apic, APIC_DFR, 0xffffffffU);
- apic_set_reg(apic, APIC_SPIV, 0xff);
+ apic_set_spiv(apic, 0xff);
apic_set_reg(apic, APIC_TASKPRI, 0);
apic_set_reg(apic, APIC_LDR, 0);
apic_set_reg(apic, APIC_ESR, 0);
@@ -1335,6 +1355,7 @@
kvm_lapic_set_base(vcpu,
APIC_DEFAULT_PHYS_BASE | MSR_IA32_APICBASE_ENABLE);
+ static_key_slow_inc(&apic_sw_disabled.key); /* sw disabled at reset */
kvm_lapic_reset(vcpu);
kvm_iodevice_init(&apic->dev, &apic_mmio_ops);
@@ -1404,6 +1425,7 @@
kvm_lapic_set_base(vcpu, vcpu->arch.apic_base);
kvm_apic_set_version(vcpu);
+ apic_set_spiv(apic, apic_get_reg(apic, APIC_SPIV));
apic_update_ppr(apic);
hrtimer_cancel(&apic->lapic_timer.timer);
@@ -1624,4 +1646,5 @@
{
/* do not patch jump label more than once per second */
jump_label_rate_limit(&apic_hw_disabled, HZ);
+ jump_label_rate_limit(&apic_sw_disabled, HZ);
}