KVM: x86: introduce lapic_in_kernel

Avoid pointer chasing and memory barriers, and simplify the code
when split irqchip (LAPIC in kernel, IOAPIC/PIC in userspace)
is introduced.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index c4adb88..88fb3bf 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -788,7 +788,7 @@
 {
 	if (cr8 & CR8_RESERVED_BITS)
 		return 1;
-	if (irqchip_in_kernel(vcpu->kvm))
+	if (lapic_in_kernel(vcpu))
 		kvm_lapic_set_tpr(vcpu, cr8);
 	else
 		vcpu->arch.cr8 = cr8;
@@ -798,7 +798,7 @@
 
 unsigned long kvm_get_cr8(struct kvm_vcpu *vcpu)
 {
-	if (irqchip_in_kernel(vcpu->kvm))
+	if (lapic_in_kernel(vcpu))
 		return kvm_lapic_get_cr8(vcpu);
 	else
 		return vcpu->arch.cr8;
@@ -3175,7 +3175,7 @@
 		struct kvm_vapic_addr va;
 
 		r = -EINVAL;
-		if (!irqchip_in_kernel(vcpu->kvm))
+		if (!lapic_in_kernel(vcpu))
 			goto out;
 		r = -EFAULT;
 		if (copy_from_user(&va, argp, sizeof va))
@@ -5666,7 +5666,7 @@
 int kvm_vcpu_halt(struct kvm_vcpu *vcpu)
 {
 	++vcpu->stat.halt_exits;
-	if (irqchip_in_kernel(vcpu->kvm)) {
+	if (lapic_in_kernel(vcpu)) {
 		vcpu->arch.mp_state = KVM_MP_STATE_HALTED;
 		return 1;
 	} else {
@@ -6162,7 +6162,7 @@
 {
 	struct page *page = NULL;
 
-	if (!irqchip_in_kernel(vcpu->kvm))
+	if (!lapic_in_kernel(vcpu))
 		return;
 
 	if (!kvm_x86_ops->set_apic_access_page_addr)
@@ -6200,7 +6200,7 @@
 static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
 {
 	int r;
-	bool req_int_win = !irqchip_in_kernel(vcpu->kvm) &&
+	bool req_int_win = !lapic_in_kernel(vcpu) &&
 		vcpu->run->request_interrupt_window;
 	bool req_immediate_exit = false;
 
@@ -6597,7 +6597,7 @@
 	}
 
 	/* re-sync apic's tpr */
-	if (!irqchip_in_kernel(vcpu->kvm)) {
+	if (!lapic_in_kernel(vcpu)) {
 		if (kvm_set_cr8(vcpu, kvm_run->cr8) != 0) {
 			r = -EINVAL;
 			goto out;
@@ -7297,7 +7297,7 @@
 
 bool kvm_vcpu_compatible(struct kvm_vcpu *vcpu)
 {
-	return irqchip_in_kernel(vcpu->kvm) == (vcpu->arch.apic != NULL);
+	return irqchip_in_kernel(vcpu->kvm) == lapic_in_kernel(vcpu);
 }
 
 struct static_key kvm_no_apic_vcpu __read_mostly;
@@ -7391,7 +7391,7 @@
 	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))
+	if (!lapic_in_kernel(vcpu))
 		static_key_slow_dec(&kvm_no_apic_vcpu);
 }