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Commit 54e9818f authored by Gleb Natapov's avatar Gleb Natapov Committed by Avi Kivity
Browse files

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: default avatarGleb Natapov <gleb@redhat.com>
Signed-off-by: default avatarAvi Kivity <avi@redhat.com>
parent f8c1ea10

arch/x86/kvm/lapic.c

+34 −28
Original line number Diff line number Diff line
@@ -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))

arch/x86/kvm/x86.c

+6 −1
Original line number Diff line number Diff line
@@ -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)

arch/x86/kvm/x86.h

+1 −0
Original line number Diff line number Diff line
@@ -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