From 54e9818f3903902a4ea3046035739b8770880092 Mon Sep 17 00:00:00 2001 From: Gleb Natapov Date: Sun, 5 Aug 2012 15:58:32 +0300 Subject: [PATCH] KVM: use jump label to optimize checking for in kernel local apic presence Usually all vcpus have local apic pointer initialized, so the check may be completely skipped. Signed-off-by: Gleb Natapov Signed-off-by: Avi Kivity --- arch/x86/kvm/lapic.c | 62 ++++++++++++++++++++++++++++------------------------ arch/x86/kvm/x86.c | 7 +++++- arch/x86/kvm/x86.h | 1 + 3 files changed, 41 insertions(+), 29 deletions(-) diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c index 7f77e96..650379b 100644 --- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -152,6 +152,13 @@ static inline int apic_enabled(struct kvm_lapic *apic) return apic_sw_enabled(apic) && apic_hw_enabled(apic); } +static inline bool vcpu_has_lapic(struct kvm_vcpu *vcpu) +{ + if (static_key_false(&kvm_no_apic_vcpu)) + return vcpu->arch.apic; + return true; +} + #define LVT_MASK \ (APIC_LVT_MASKED | APIC_SEND_PENDING | APIC_VECTOR_MASK) @@ -204,7 +211,7 @@ void kvm_apic_set_version(struct kvm_vcpu *vcpu) struct kvm_cpuid_entry2 *feat; u32 v = APIC_VERSION; - if (!irqchip_in_kernel(vcpu->kvm)) + if (!vcpu_has_lapic(vcpu)) return; feat = kvm_find_cpuid_entry(apic->vcpu, 0x1, 0); @@ -305,7 +312,6 @@ static inline void apic_clear_isr(int vec, struct kvm_lapic *apic) int kvm_lapic_find_highest_irr(struct kvm_vcpu *vcpu) { - struct kvm_lapic *apic = vcpu->arch.apic; int highest_irr; /* This may race with setting of irr in __apic_accept_irq() and @@ -313,9 +319,9 @@ int kvm_lapic_find_highest_irr(struct kvm_vcpu *vcpu) * will cause vmexit immediately and the value will be recalculated * on the next vmentry. */ - if (!apic) + if (!vcpu_has_lapic(vcpu)) return 0; - highest_irr = apic_find_highest_irr(apic); + highest_irr = apic_find_highest_irr(vcpu->arch.apic); return highest_irr; } @@ -1061,9 +1067,7 @@ static int apic_mmio_write(struct kvm_io_device *this, void kvm_lapic_set_eoi(struct kvm_vcpu *vcpu) { - struct kvm_lapic *apic = vcpu->arch.apic; - - if (apic) + if (vcpu_has_lapic(vcpu)) apic_reg_write(vcpu->arch.apic, APIC_EOI, 0); } EXPORT_SYMBOL_GPL(kvm_lapic_set_eoi); @@ -1098,10 +1102,9 @@ void kvm_free_lapic(struct kvm_vcpu *vcpu) u64 kvm_get_lapic_tscdeadline_msr(struct kvm_vcpu *vcpu) { struct kvm_lapic *apic = vcpu->arch.apic; - if (!apic) - return 0; - if (apic_lvtt_oneshot(apic) || apic_lvtt_period(apic)) + if (!vcpu_has_lapic(vcpu) || apic_lvtt_oneshot(apic) || + apic_lvtt_period(apic)) return 0; return apic->lapic_timer.tscdeadline; @@ -1110,10 +1113,9 @@ u64 kvm_get_lapic_tscdeadline_msr(struct kvm_vcpu *vcpu) void kvm_set_lapic_tscdeadline_msr(struct kvm_vcpu *vcpu, u64 data) { struct kvm_lapic *apic = vcpu->arch.apic; - if (!apic) - return; - if (apic_lvtt_oneshot(apic) || apic_lvtt_period(apic)) + if (!vcpu_has_lapic(vcpu) || apic_lvtt_oneshot(apic) || + apic_lvtt_period(apic)) return; hrtimer_cancel(&apic->lapic_timer.timer); @@ -1125,20 +1127,21 @@ void kvm_lapic_set_tpr(struct kvm_vcpu *vcpu, unsigned long cr8) { struct kvm_lapic *apic = vcpu->arch.apic; - if (!apic) + if (!vcpu_has_lapic(vcpu)) return; + apic_set_tpr(apic, ((cr8 & 0x0f) << 4) | (apic_get_reg(apic, APIC_TASKPRI) & 4)); } u64 kvm_lapic_get_cr8(struct kvm_vcpu *vcpu) { - struct kvm_lapic *apic = vcpu->arch.apic; u64 tpr; - if (!apic) + if (!vcpu_has_lapic(vcpu)) return 0; - tpr = (u64) apic_get_reg(apic, APIC_TASKPRI); + + tpr = (u64) apic_get_reg(vcpu->arch.apic, APIC_TASKPRI); return (tpr & 0xf0) >> 4; } @@ -1237,7 +1240,7 @@ void kvm_lapic_reset(struct kvm_vcpu *vcpu) bool kvm_apic_present(struct kvm_vcpu *vcpu) { - return vcpu->arch.apic && apic_hw_enabled(vcpu->arch.apic); + return vcpu_has_lapic(vcpu) && apic_hw_enabled(vcpu->arch.apic); } int kvm_lapic_enabled(struct kvm_vcpu *vcpu) @@ -1258,10 +1261,11 @@ static bool lapic_is_periodic(struct kvm_lapic *apic) int apic_has_pending_timer(struct kvm_vcpu *vcpu) { - struct kvm_lapic *lapic = vcpu->arch.apic; + struct kvm_lapic *apic = vcpu->arch.apic; - if (lapic && apic_enabled(lapic) && apic_lvt_enabled(lapic, APIC_LVTT)) - return atomic_read(&lapic->lapic_timer.pending); + if (vcpu_has_lapic(vcpu) && apic_enabled(apic) && + apic_lvt_enabled(apic, APIC_LVTT)) + return atomic_read(&apic->lapic_timer.pending); return 0; } @@ -1371,7 +1375,7 @@ int kvm_apic_has_interrupt(struct kvm_vcpu *vcpu) struct kvm_lapic *apic = vcpu->arch.apic; int highest_irr; - if (!apic || !apic_enabled(apic)) + if (!vcpu_has_lapic(vcpu) || !apic_enabled(apic)) return -1; apic_update_ppr(apic); @@ -1399,7 +1403,10 @@ void kvm_inject_apic_timer_irqs(struct kvm_vcpu *vcpu) { struct kvm_lapic *apic = vcpu->arch.apic; - if (apic && atomic_read(&apic->lapic_timer.pending) > 0) { + if (!vcpu_has_lapic(vcpu)) + return; + + if (atomic_read(&apic->lapic_timer.pending) > 0) { if (kvm_apic_local_deliver(apic, APIC_LVTT)) atomic_dec(&apic->lapic_timer.pending); } @@ -1439,13 +1446,12 @@ void kvm_apic_post_state_restore(struct kvm_vcpu *vcpu) void __kvm_migrate_apic_timer(struct kvm_vcpu *vcpu) { - struct kvm_lapic *apic = vcpu->arch.apic; struct hrtimer *timer; - if (!apic) + if (!vcpu_has_lapic(vcpu)) return; - timer = &apic->lapic_timer.timer; + timer = &vcpu->arch.apic->lapic_timer.timer; if (hrtimer_cancel(timer)) hrtimer_start_expires(timer, HRTIMER_MODE_ABS); } @@ -1602,7 +1608,7 @@ int kvm_hv_vapic_msr_write(struct kvm_vcpu *vcpu, u32 reg, u64 data) { struct kvm_lapic *apic = vcpu->arch.apic; - if (!irqchip_in_kernel(vcpu->kvm)) + if (!vcpu_has_lapic(vcpu)) return 1; /* if this is ICR write vector before command */ @@ -1616,7 +1622,7 @@ int kvm_hv_vapic_msr_read(struct kvm_vcpu *vcpu, u32 reg, u64 *data) struct kvm_lapic *apic = vcpu->arch.apic; u32 low, high = 0; - if (!irqchip_in_kernel(vcpu->kvm)) + if (!vcpu_has_lapic(vcpu)) return 1; if (apic_reg_read(apic, reg, 4, &low)) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 29fa18d..8ebf65c 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -6152,6 +6152,8 @@ bool kvm_vcpu_compatible(struct kvm_vcpu *vcpu) return irqchip_in_kernel(vcpu->kvm) == (vcpu->arch.apic != NULL); } +struct static_key kvm_no_apic_vcpu __read_mostly; + int kvm_arch_vcpu_init(struct kvm_vcpu *vcpu) { struct page *page; @@ -6184,7 +6186,8 @@ int kvm_arch_vcpu_init(struct kvm_vcpu *vcpu) r = kvm_create_lapic(vcpu); if (r < 0) goto fail_mmu_destroy; - } + } else + static_key_slow_inc(&kvm_no_apic_vcpu); vcpu->arch.mce_banks = kzalloc(KVM_MAX_MCE_BANKS * sizeof(u64) * 4, GFP_KERNEL); @@ -6224,6 +6227,8 @@ void kvm_arch_vcpu_uninit(struct kvm_vcpu *vcpu) kvm_mmu_destroy(vcpu); srcu_read_unlock(&vcpu->kvm->srcu, idx); free_page((unsigned long)vcpu->arch.pio_data); + if (!irqchip_in_kernel(vcpu->kvm)) + static_key_slow_dec(&kvm_no_apic_vcpu); } int kvm_arch_init_vm(struct kvm *kvm, unsigned long type) diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h index 3d1134d..2b5219c 100644 --- a/arch/x86/kvm/x86.h +++ b/arch/x86/kvm/x86.h @@ -124,4 +124,5 @@ int kvm_write_guest_virt_system(struct x86_emulate_ctxt *ctxt, extern u64 host_xcr0; +extern struct static_key kvm_no_apic_vcpu; #endif -- 2.7.4