From c5cc421ba3219b90f11d151bc55f1608c12830fa Mon Sep 17 00:00:00 2001 From: Gleb Natapov Date: Sun, 5 Aug 2012 15:58:30 +0300 Subject: [PATCH] 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 Signed-off-by: Avi Kivity --- arch/x86/kvm/lapic.c | 29 ++++++++++++++++++++++++++++- arch/x86/kvm/lapic.h | 1 + arch/x86/kvm/x86.c | 1 + 3 files changed, 30 insertions(+), 1 deletion(-) diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c index c3f14fe..5b46cab 100644 --- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -34,6 +34,7 @@ #include #include #include +#include #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); +} diff --git a/arch/x86/kvm/lapic.h b/arch/x86/kvm/lapic.h index 166766f..73fa299 100644 --- a/arch/x86/kvm/lapic.h +++ b/arch/x86/kvm/lapic.h @@ -78,4 +78,5 @@ static inline bool kvm_hv_vapic_assist_page_enabled(struct kvm_vcpu *vcpu) } int kvm_lapic_enable_pv_eoi(struct kvm_vcpu *vcpu, u64 data); +void kvm_lapic_init(void); #endif diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 3cafbb1..29fa18d 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -4903,6 +4903,7 @@ int kvm_arch_init(void *opaque) if (cpu_has_xsave) host_xcr0 = xgetbv(XCR_XFEATURE_ENABLED_MASK); + kvm_lapic_init(); return 0; out: -- 2.7.4