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authorGleb Natapov <gleb@redhat.com>2012-08-05 14:58:30 +0200
committerAvi Kivity <avi@redhat.com>2012-08-06 18:00:43 +0200
commitc5cc421ba3219b90f11d151bc55f1608c12830fa (patch)
treefa21392981697bbc01ed14c8aab98653622c5a33 /arch/x86/kvm/lapic.c
parentjump_label: Export jump_label_rate_limit() (diff)
downloadlinux-c5cc421ba3219b90f11d151bc55f1608c12830fa.tar.xz
linux-c5cc421ba3219b90f11d151bc55f1608c12830fa.zip
KVM: use jump label to optimize checking for HW enabled APIC in APIC_BASE MSR
Usually all APICs are HW enabled so the check can be optimized out. Signed-off-by: Gleb Natapov <gleb@redhat.com> Signed-off-by: Avi Kivity <avi@redhat.com>
Diffstat (limited to 'arch/x86/kvm/lapic.c')
-rw-r--r--arch/x86/kvm/lapic.c29
1 files changed, 28 insertions, 1 deletions
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index c3f14fe51e9b..5b46cab044a5 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -34,6 +34,7 @@
#include <asm/current.h>
#include <asm/apicdef.h>
#include <linux/atomic.h>
+#include <linux/jump_label.h>
#include "kvm_cache_regs.h"
#include "irq.h"
#include "trace.h"
@@ -117,9 +118,13 @@ static inline int __apic_test_and_clear_vector(int vec, void *bitmap)
return __test_and_clear_bit(VEC_POS(vec), (bitmap) + REG_POS(vec));
}
+struct static_key_deferred apic_hw_disabled __read_mostly;
+
static inline int apic_hw_enabled(struct kvm_lapic *apic)
{
- return (apic)->vcpu->arch.apic_base & MSR_IA32_APICBASE_ENABLE;
+ if (static_key_false(&apic_hw_disabled.key))
+ return apic->vcpu->arch.apic_base & MSR_IA32_APICBASE_ENABLE;
+ return MSR_IA32_APICBASE_ENABLE;
}
static inline int apic_sw_enabled(struct kvm_lapic *apic)
@@ -1055,6 +1060,9 @@ void kvm_free_lapic(struct kvm_vcpu *vcpu)
hrtimer_cancel(&vcpu->arch.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);
@@ -1125,6 +1133,14 @@ void kvm_lapic_set_base(struct kvm_vcpu *vcpu, u64 value)
return;
}
+ /* update jump label if enable bit changes */
+ if ((vcpu->arch.apic_base ^ value) & MSR_IA32_APICBASE_ENABLE) {
+ if (value & MSR_IA32_APICBASE_ENABLE)
+ static_key_slow_dec_deferred(&apic_hw_disabled);
+ else
+ static_key_slow_inc(&apic_hw_disabled.key);
+ }
+
if (!kvm_vcpu_is_bsp(apic->vcpu))
value &= ~MSR_IA32_APICBASE_BSP;
@@ -1311,6 +1327,11 @@ int kvm_create_lapic(struct kvm_vcpu *vcpu)
HRTIMER_MODE_ABS);
apic->lapic_timer.timer.function = apic_timer_fn;
+ /*
+ * APIC is created enabled. This will prevent kvm_lapic_set_base from
+ * thinking that APIC satet has changed.
+ */
+ vcpu->arch.apic_base = MSR_IA32_APICBASE_ENABLE;
kvm_lapic_set_base(vcpu,
APIC_DEFAULT_PHYS_BASE | MSR_IA32_APICBASE_ENABLE);
@@ -1598,3 +1619,9 @@ int kvm_lapic_enable_pv_eoi(struct kvm_vcpu *vcpu, u64 data)
return kvm_gfn_to_hva_cache_init(vcpu->kvm, &vcpu->arch.pv_eoi.data,
addr);
}
+
+void kvm_lapic_init(void)
+{
+ /* do not patch jump label more than once per second */
+ jump_label_rate_limit(&apic_hw_disabled, HZ);
+}