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: NPaolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/irq.c

@@ -57,7 +57,7 @@ static int kvm_cpu_has_extint(struct kvm_vcpu *v)
  */
 int kvm_cpu_has_injectable_intr(struct kvm_vcpu *v)
 {
-	if (!irqchip_in_kernel(v->kvm))
+	if (!lapic_in_kernel(v))
 		return v->arch.interrupt.pending;
 
 	if (kvm_cpu_has_extint(v))
@@ -75,7 +75,7 @@ int kvm_cpu_has_injectable_intr(struct kvm_vcpu *v)
  */
 int kvm_cpu_has_interrupt(struct kvm_vcpu *v)
 {
-	if (!irqchip_in_kernel(v->kvm))
+	if (!lapic_in_kernel(v))
 		return v->arch.interrupt.pending;
 
 	if (kvm_cpu_has_extint(v))
@@ -103,7 +103,7 @@ int kvm_cpu_get_interrupt(struct kvm_vcpu *v)
 {
 	int vector;
 
-	if (!irqchip_in_kernel(v->kvm))
+	if (!lapic_in_kernel(v))
 		return v->arch.interrupt.nr;
 
 	vector = kvm_cpu_get_extint(v);

arch/x86/kvm/irq.h

@@ -92,6 +92,14 @@ static inline int irqchip_in_kernel(struct kvm *kvm)
 	return vpic != NULL;
 }
 
+static inline int lapic_in_kernel(struct kvm_vcpu *vcpu)
+{
+	/* Same as irqchip_in_kernel(vcpu->kvm), but with less
+	 * pointer chasing and no unnecessary memory barriers.
+	 */
+	return vcpu->arch.apic != NULL;
+}
+
 void kvm_pic_reset(struct kvm_kpic_state *s);
 
 void kvm_inject_pending_timer_irqs(struct kvm_vcpu *vcpu);

arch/x86/kvm/lapic.c

@@ -1985,7 +1985,7 @@ int kvm_x2apic_msr_write(struct kvm_vcpu *vcpu, u32 msr, u64 data)
 	struct kvm_lapic *apic = vcpu->arch.apic;
 	u32 reg = (msr - APIC_BASE_MSR) << 4;
 
-	if (!irqchip_in_kernel(vcpu->kvm) || !apic_x2apic_mode(apic))
+	if (!lapic_in_kernel(vcpu) || !apic_x2apic_mode(apic))
 		return 1;
 
 	if (reg == APIC_ICR2)
@@ -2002,7 +2002,7 @@ int kvm_x2apic_msr_read(struct kvm_vcpu *vcpu, u32 msr, u64 *data)
 	struct kvm_lapic *apic = vcpu->arch.apic;
 	u32 reg = (msr - APIC_BASE_MSR) << 4, low, high = 0;
 
-	if (!irqchip_in_kernel(vcpu->kvm) || !apic_x2apic_mode(apic))
+	if (!lapic_in_kernel(vcpu) || !apic_x2apic_mode(apic))
 		return 1;
 
 	if (reg == APIC_DFR || reg == APIC_ICR2) {

arch/x86/kvm/mmu.c

@@ -3427,7 +3427,7 @@ static int kvm_arch_setup_async_pf(struct kvm_vcpu *vcpu, gva_t gva, gfn_t gfn)
 
 static bool can_do_async_pf(struct kvm_vcpu *vcpu)
 {
-	if (unlikely(!irqchip_in_kernel(vcpu->kvm) ||
+	if (unlikely(!lapic_in_kernel(vcpu) ||
 		     kvm_event_needs_reinjection(vcpu)))
 		return false;
 

arch/x86/kvm/svm.c

@@ -3060,7 +3060,7 @@ static int cr8_write_interception(struct vcpu_svm *svm)
 	u8 cr8_prev = kvm_get_cr8(&svm->vcpu);
 	/* instruction emulation calls kvm_set_cr8() */
 	r = cr_interception(svm);
-	if (irqchip_in_kernel(svm->vcpu.kvm))
+	if (lapic_in_kernel(&svm->vcpu))
 		return r;
 	if (cr8_prev <= kvm_get_cr8(&svm->vcpu))
 		return r;
@@ -3305,7 +3305,7 @@ static int interrupt_window_interception(struct vcpu_svm *svm)
 	 * If the user space waits to inject interrupts, exit as soon as
 	 * possible
 	 */
-	if (!irqchip_in_kernel(svm->vcpu.kvm) &&
+	if (!lapic_in_kernel(&svm->vcpu) &&
 	    kvm_run->request_interrupt_window &&
 	    !kvm_cpu_has_interrupt(&svm->vcpu)) {
 		kvm_run->exit_reason = KVM_EXIT_IRQ_WINDOW_OPEN;

arch/x86/kvm/vmx.c

@@ -809,7 +809,6 @@ static void kvm_cpu_vmxon(u64 addr);
 static void kvm_cpu_vmxoff(void);
 static bool vmx_mpx_supported(void);
 static bool vmx_xsaves_supported(void);
-static int vmx_vm_has_apicv(struct kvm *kvm);
 static int vmx_cpu_uses_apicv(struct kvm_vcpu *vcpu);
 static int vmx_set_tss_addr(struct kvm *kvm, unsigned int addr);
 static void vmx_set_segment(struct kvm_vcpu *vcpu,
@@ -947,9 +946,9 @@ static inline bool cpu_has_vmx_tpr_shadow(void)
 	return vmcs_config.cpu_based_exec_ctrl & CPU_BASED_TPR_SHADOW;
 }
 
-static inline bool vm_need_tpr_shadow(struct kvm *kvm)
+static inline bool cpu_need_tpr_shadow(struct kvm_vcpu *vcpu)
 {
-	return (cpu_has_vmx_tpr_shadow()) && (irqchip_in_kernel(kvm));
+	return cpu_has_vmx_tpr_shadow() && lapic_in_kernel(vcpu);
 }
 
 static inline bool cpu_has_secondary_exec_ctrls(void)
@@ -1063,9 +1062,9 @@ static inline bool cpu_has_vmx_ple(void)
 		SECONDARY_EXEC_PAUSE_LOOP_EXITING;
 }
 
-static inline bool vm_need_virtualize_apic_accesses(struct kvm *kvm)
+static inline bool cpu_need_virtualize_apic_accesses(struct kvm_vcpu *vcpu)
 {
-	return flexpriority_enabled && irqchip_in_kernel(kvm);
+	return flexpriority_enabled && lapic_in_kernel(vcpu);
 }
 
 static inline bool cpu_has_vmx_vpid(void)
@@ -2378,7 +2377,7 @@ static void nested_vmx_setup_ctls_msrs(struct vcpu_vmx *vmx)
 	vmx->nested.nested_vmx_pinbased_ctls_high |=
 		PIN_BASED_ALWAYSON_WITHOUT_TRUE_MSR |
 		PIN_BASED_VMX_PREEMPTION_TIMER;
-	if (vmx_vm_has_apicv(vmx->vcpu.kvm))
+	if (vmx_cpu_uses_apicv(&vmx->vcpu))
 		vmx->nested.nested_vmx_pinbased_ctls_high |=
 			PIN_BASED_POSTED_INTR;
 
@@ -4333,14 +4332,9 @@ static void vmx_disable_intercept_msr_write_x2apic(u32 msr)
 			msr, MSR_TYPE_W);
 }
 
-static int vmx_vm_has_apicv(struct kvm *kvm)
-{
-	return enable_apicv && irqchip_in_kernel(kvm);
-}
-
 static int vmx_cpu_uses_apicv(struct kvm_vcpu *vcpu)
 {
-	return vmx_vm_has_apicv(vcpu->kvm);
+	return enable_apicv && lapic_in_kernel(vcpu);
 }
 
 static int vmx_complete_nested_posted_interrupt(struct kvm_vcpu *vcpu)
@@ -4520,7 +4514,7 @@ static u32 vmx_pin_based_exec_ctrl(struct vcpu_vmx *vmx)
 {
 	u32 pin_based_exec_ctrl = vmcs_config.pin_based_exec_ctrl;
 
-	if (!vmx_vm_has_apicv(vmx->vcpu.kvm))
+	if (!vmx_cpu_uses_apicv(&vmx->vcpu))
 		pin_based_exec_ctrl &= ~PIN_BASED_POSTED_INTR;
 	return pin_based_exec_ctrl;
 }
@@ -4532,7 +4526,7 @@ static u32 vmx_exec_control(struct vcpu_vmx *vmx)
 	if (vmx->vcpu.arch.switch_db_regs & KVM_DEBUGREG_WONT_EXIT)
 		exec_control &= ~CPU_BASED_MOV_DR_EXITING;
 
-	if (!vm_need_tpr_shadow(vmx->vcpu.kvm)) {
+	if (!cpu_need_tpr_shadow(&vmx->vcpu)) {
 		exec_control &= ~CPU_BASED_TPR_SHADOW;
 #ifdef CONFIG_X86_64
 		exec_control |= CPU_BASED_CR8_STORE_EXITING |
@@ -4549,7 +4543,7 @@ static u32 vmx_exec_control(struct vcpu_vmx *vmx)
 static u32 vmx_secondary_exec_control(struct vcpu_vmx *vmx)
 {
 	u32 exec_control = vmcs_config.cpu_based_2nd_exec_ctrl;
-	if (!vm_need_virtualize_apic_accesses(vmx->vcpu.kvm))
+	if (!cpu_need_virtualize_apic_accesses(&vmx->vcpu))
 		exec_control &= ~SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES;
 	if (vmx->vpid == 0)
 		exec_control &= ~SECONDARY_EXEC_ENABLE_VPID;
@@ -4563,7 +4557,7 @@ static u32 vmx_secondary_exec_control(struct vcpu_vmx *vmx)
 		exec_control &= ~SECONDARY_EXEC_UNRESTRICTED_GUEST;
 	if (!ple_gap)
 		exec_control &= ~SECONDARY_EXEC_PAUSE_LOOP_EXITING;
-	if (!vmx_vm_has_apicv(vmx->vcpu.kvm))
+	if (!vmx_cpu_uses_apicv(&vmx->vcpu))
 		exec_control &= ~(SECONDARY_EXEC_APIC_REGISTER_VIRT |
 				  SECONDARY_EXEC_VIRTUAL_INTR_DELIVERY);
 	exec_control &= ~SECONDARY_EXEC_VIRTUALIZE_X2APIC_MODE;
@@ -4624,7 +4618,7 @@ static int vmx_vcpu_setup(struct vcpu_vmx *vmx)
 				vmx_secondary_exec_control(vmx));
 	}
 
-	if (vmx_vm_has_apicv(vmx->vcpu.kvm)) {
+	if (vmx_cpu_uses_apicv(&vmx->vcpu)) {
 		vmcs_write64(EOI_EXIT_BITMAP0, 0);
 		vmcs_write64(EOI_EXIT_BITMAP1, 0);
 		vmcs_write64(EOI_EXIT_BITMAP2, 0);
@@ -4768,7 +4762,7 @@ static void vmx_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
 
 	if (cpu_has_vmx_tpr_shadow() && !init_event) {
 		vmcs_write64(VIRTUAL_APIC_PAGE_ADDR, 0);
-		if (vm_need_tpr_shadow(vcpu->kvm))
+		if (cpu_need_tpr_shadow(vcpu))
 			vmcs_write64(VIRTUAL_APIC_PAGE_ADDR,
 				     __pa(vcpu->arch.apic->regs));
 		vmcs_write32(TPR_THRESHOLD, 0);
@@ -4776,7 +4770,7 @@ static void vmx_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
 
 	kvm_make_request(KVM_REQ_APIC_PAGE_RELOAD, vcpu);
 
-	if (vmx_vm_has_apicv(vcpu->kvm))
+	if (vmx_cpu_uses_apicv(vcpu))
 		memset(&vmx->pi_desc, 0, sizeof(struct pi_desc));
 
 	if (vmx->vpid != 0)
@@ -5316,7 +5310,7 @@ static int handle_cr(struct kvm_vcpu *vcpu)
 				u8 cr8 = (u8)val;
 				err = kvm_set_cr8(vcpu, cr8);
 				kvm_complete_insn_gp(vcpu, err);
-				if (irqchip_in_kernel(vcpu->kvm))
+				if (lapic_in_kernel(vcpu))
 					return 1;
 				if (cr8_prev <= cr8)
 					return 1;
@@ -5535,7 +5529,7 @@ static int handle_interrupt_window(struct kvm_vcpu *vcpu)
 	 * If the user space waits to inject interrupts, exit as soon as
 	 * possible
 	 */
-	if (!irqchip_in_kernel(vcpu->kvm) &&
+	if (!lapic_in_kernel(vcpu) &&
 	    vcpu->run->request_interrupt_window &&
 	    !kvm_cpu_has_interrupt(vcpu)) {
 		vcpu->run->exit_reason = KVM_EXIT_IRQ_WINDOW_OPEN;
@@ -7944,10 +7938,10 @@ static void vmx_set_virtual_x2apic_mode(struct kvm_vcpu *vcpu, bool set)
 	 * apicv
 	 */
 	if (!cpu_has_vmx_virtualize_x2apic_mode() ||
-				!vmx_vm_has_apicv(vcpu->kvm))
+				!vmx_cpu_uses_apicv(vcpu))
 		return;
 
-	if (!vm_need_tpr_shadow(vcpu->kvm))
+	if (!cpu_need_tpr_shadow(vcpu))
 		return;
 
 	sec_exec_control = vmcs_read32(SECONDARY_VM_EXEC_CONTROL);
@@ -8052,7 +8046,7 @@ static void vmx_hwapic_irr_update(struct kvm_vcpu *vcpu, int max_irr)
 static void vmx_load_eoi_exitmap(struct kvm_vcpu *vcpu)
 {
 	u64 *eoi_exit_bitmap = vcpu->arch.eoi_exit_bitmap;
-	if (!vmx_vm_has_apicv(vcpu->kvm))
+	if (!vmx_cpu_uses_apicv(vcpu))
 		return;
 
 	vmcs_write64(EOI_EXIT_BITMAP0, eoi_exit_bitmap[0]);
@@ -8551,7 +8545,7 @@ static struct kvm_vcpu *vmx_create_vcpu(struct kvm *kvm, unsigned int id)
 	put_cpu();
 	if (err)
 		goto free_vmcs;
-	if (vm_need_virtualize_apic_accesses(kvm)) {
+	if (cpu_need_virtualize_apic_accesses(&vmx->vcpu)) {
 		err = alloc_apic_access_page(kvm);
 		if (err)
 			goto free_vmcs;
@@ -9344,7 +9338,7 @@ static void prepare_vmcs02(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12)
 				vmcs_write64(APIC_ACCESS_ADDR,
 				  page_to_phys(vmx->nested.apic_access_page));
 		} else if (!(nested_cpu_has_virt_x2apic_mode(vmcs12)) &&
-			    (vm_need_virtualize_apic_accesses(vmx->vcpu.kvm))) {
+			    cpu_need_virtualize_apic_accesses(&vmx->vcpu)) {
 			exec_control |=
 				SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES;
 			kvm_vcpu_reload_apic_access_page(vcpu);

arch/x86/kvm/x86.c

@@ -788,7 +788,7 @@ int kvm_set_cr8(struct kvm_vcpu *vcpu, unsigned long cr8)
 {
 	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 @@ EXPORT_SYMBOL_GPL(kvm_set_cr8);
 
 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 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
 		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 @@ void kvm_arch_exit(void)
 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 @@ void kvm_vcpu_reload_apic_access_page(struct kvm_vcpu *vcpu)
 {
 	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 @@ void kvm_arch_mmu_notifier_invalidate_page(struct kvm *kvm,
 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 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
 	}
 
 	/* 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_is_bsp(struct kvm_vcpu *vcpu)
 
 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 @@ 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))
+	if (!lapic_in_kernel(vcpu))
 		static_key_slow_dec(&kvm_no_apic_vcpu);
 }