KVM: x86: use static calls to reduce kvm_x86_ops overhead

Convert kvm_x86_ops to use static calls. Note that all kvm_x86_ops are
covered here except for 'pmu_ops and 'nested ops'.

Here are some numbers running cpuid in a loop of 1 million calls averaged
over 5 runs, measured in the vm (lower is better).

Intel Xeon 3000MHz:

           |default    |mitigations=off
-------------------------------------
vanilla    |.671s      |.486s
static call|.573s(-15%)|.458s(-6%)

AMD EPYC 2500MHz:

           |default    |mitigations=off
-------------------------------------
vanilla    |.710s      |.609s
static call|.664s(-6%) |.609s(0%)

Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Sean Christopherson <seanjc@google.com>
Signed-off-by: Jason Baron <jbaron@akamai.com>
Message-Id: <e057bf1b8a7ad15652df6eeba3f907ae758d3399.1610680941.git.jbaron@akamai.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 15 insertions, 15 deletions

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 87f6b5a5a272..9e0f78c0a256 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -484,7 +484,7 @@ static inline void apic_clear_irr(int vec, struct kvm_lapic *apic)
 	if (unlikely(vcpu->arch.apicv_active)) {
 		/* need to update RVI */
 		kvm_lapic_clear_vector(vec, apic->regs + APIC_IRR);
-		kvm_x86_ops.hwapic_irr_update(vcpu,
+		static_call(kvm_x86_hwapic_irr_update)(vcpu,
 				apic_find_highest_irr(apic));
 	} else {
 		apic->irr_pending = false;
@@ -515,7 +515,7 @@ static inline void apic_set_isr(int vec, struct kvm_lapic *apic)
 	 * just set SVI.
 	 */
 	if (unlikely(vcpu->arch.apicv_active))
-		kvm_x86_ops.hwapic_isr_update(vcpu, vec);
+		static_call(kvm_x86_hwapic_isr_update)(vcpu, vec);
 	else {
 		++apic->isr_count;
 		BUG_ON(apic->isr_count > MAX_APIC_VECTOR);
@@ -563,8 +563,8 @@ static inline void apic_clear_isr(int vec, struct kvm_lapic *apic)
 	 * and must be left alone.
 	 */
 	if (unlikely(vcpu->arch.apicv_active))
-		kvm_x86_ops.hwapic_isr_update(vcpu,
-					       apic_find_highest_isr(apic));
+		static_call(kvm_x86_hwapic_isr_update)(vcpu,
+						apic_find_highest_isr(apic));
 	else {
 		--apic->isr_count;
 		BUG_ON(apic->isr_count < 0);
@@ -701,7 +701,7 @@ static int apic_has_interrupt_for_ppr(struct kvm_lapic *apic, u32 ppr)
 {
 	int highest_irr;
 	if (apic->vcpu->arch.apicv_active)
-		highest_irr = kvm_x86_ops.sync_pir_to_irr(apic->vcpu);
+		highest_irr = static_call(kvm_x86_sync_pir_to_irr)(apic->vcpu);
 	else
 		highest_irr = apic_find_highest_irr(apic);
 	if (highest_irr == -1 || (highest_irr & 0xF0) <= ppr)
@@ -1090,7 +1090,7 @@ static int __apic_accept_irq(struct kvm_lapic *apic, int delivery_mode,
 						       apic->regs + APIC_TMR);
 		}
 
-		if (kvm_x86_ops.deliver_posted_interrupt(vcpu, vector)) {
+		if (static_call(kvm_x86_deliver_posted_interrupt)(vcpu, vector)) {
 			kvm_lapic_set_irr(vector, apic);
 			kvm_make_request(KVM_REQ_EVENT, vcpu);
 			kvm_vcpu_kick(vcpu);
@@ -1814,7 +1814,7 @@ static void cancel_hv_timer(struct kvm_lapic *apic)
 {
 	WARN_ON(preemptible());
 	WARN_ON(!apic->lapic_timer.hv_timer_in_use);
-	kvm_x86_ops.cancel_hv_timer(apic->vcpu);
+	static_call(kvm_x86_cancel_hv_timer)(apic->vcpu);
 	apic->lapic_timer.hv_timer_in_use = false;
 }
 
@@ -1831,7 +1831,7 @@ static bool start_hv_timer(struct kvm_lapic *apic)
 	if (!ktimer->tscdeadline)
 		return false;
 
-	if (kvm_x86_ops.set_hv_timer(vcpu, ktimer->tscdeadline, &expired))
+	if (static_call(kvm_x86_set_hv_timer)(vcpu, ktimer->tscdeadline, &expired))
 		return false;
 
 	ktimer->hv_timer_in_use = true;
@@ -2261,7 +2261,7 @@ void kvm_lapic_set_base(struct kvm_vcpu *vcpu, u64 value)
 		kvm_apic_set_x2apic_id(apic, vcpu->vcpu_id);
 
 	if ((old_value ^ value) & (MSR_IA32_APICBASE_ENABLE | X2APIC_ENABLE))
-		kvm_x86_ops.set_virtual_apic_mode(vcpu);
+		static_call(kvm_x86_set_virtual_apic_mode)(vcpu);
 
 	apic->base_address = apic->vcpu->arch.apic_base &
 			     MSR_IA32_APICBASE_BASE;
@@ -2338,9 +2338,9 @@ void kvm_lapic_reset(struct kvm_vcpu *vcpu, bool init_event)
 	vcpu->arch.pv_eoi.msr_val = 0;
 	apic_update_ppr(apic);
 	if (vcpu->arch.apicv_active) {
-		kvm_x86_ops.apicv_post_state_restore(vcpu);
-		kvm_x86_ops.hwapic_irr_update(vcpu, -1);
-		kvm_x86_ops.hwapic_isr_update(vcpu, -1);
+		static_call(kvm_x86_apicv_post_state_restore)(vcpu);
+		static_call(kvm_x86_hwapic_irr_update)(vcpu, -1);
+		static_call(kvm_x86_hwapic_isr_update)(vcpu, -1);
 	}
 
 	vcpu->arch.apic_arb_prio = 0;
@@ -2601,10 +2601,10 @@ int kvm_apic_set_state(struct kvm_vcpu *vcpu, struct kvm_lapic_state *s)
 	kvm_apic_update_apicv(vcpu);
 	apic->highest_isr_cache = -1;
 	if (vcpu->arch.apicv_active) {
-		kvm_x86_ops.apicv_post_state_restore(vcpu);
-		kvm_x86_ops.hwapic_irr_update(vcpu,
+		static_call(kvm_x86_apicv_post_state_restore)(vcpu);
+		static_call(kvm_x86_hwapic_irr_update)(vcpu,
 				apic_find_highest_irr(apic));
-		kvm_x86_ops.hwapic_isr_update(vcpu,
+		static_call(kvm_x86_hwapic_isr_update)(vcpu,
 				apic_find_highest_isr(apic));
 	}
 	kvm_make_request(KVM_REQ_EVENT, vcpu);