KVM: nVMX: Enable nested posted interrupt processing

If vcpu has a interrupt in vmx non-root mode, injecting that interrupt
requires a vmexit.  With posted interrupt processing, the vmexit
is not needed, and interrupts are fully taken care of by hardware.
In nested vmx, this feature avoids much more vmexits than non-nested vmx.

When L1 asks L0 to deliver L1's posted interrupt vector, and the target
VCPU is in non-root mode, we use a physical ipi to deliver POSTED_INTR_NV
to the target vCPU.  Using POSTED_INTR_NV avoids unexpected interrupts
if a concurrent vmexit happens and L1's vector is different with L0's.
The IPI triggers posted interrupt processing in the target physical CPU.

In case the target vCPU was not in guest mode, complete the posted
interrupt delivery on the next entry to L2.
Signed-off-by: NWincy Van <fanwenyi0529@gmail.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/lapic.c

@@ -325,17 +325,24 @@ static u8 count_vectors(void *bitmap)
 	return count;
 }
 
-void kvm_apic_update_irr(struct kvm_vcpu *vcpu, u32 *pir)
+void __kvm_apic_update_irr(u32 *pir, void *regs)
 {
 	u32 i, pir_val;
-	struct kvm_lapic *apic = vcpu->arch.apic;
 
 	for (i = 0; i <= 7; i++) {
 		pir_val = xchg(&pir[i], 0);
 		if (pir_val)
-			*((u32 *)(apic->regs + APIC_IRR + i * 0x10)) |= pir_val;
+			*((u32 *)(regs + APIC_IRR + i * 0x10)) |= pir_val;
 	}
 }
+EXPORT_SYMBOL_GPL(__kvm_apic_update_irr);
+
+void kvm_apic_update_irr(struct kvm_vcpu *vcpu, u32 *pir)
+{
+	struct kvm_lapic *apic = vcpu->arch.apic;
+
+	__kvm_apic_update_irr(pir, apic->regs);
+}
 EXPORT_SYMBOL_GPL(kvm_apic_update_irr);
 
 static inline void apic_set_irr(int vec, struct kvm_lapic *apic)

arch/x86/kvm/lapic.h

@@ -57,6 +57,7 @@ u64 kvm_lapic_get_base(struct kvm_vcpu *vcpu);
 void kvm_apic_set_version(struct kvm_vcpu *vcpu);
 
 void kvm_apic_update_tmr(struct kvm_vcpu *vcpu, u32 *tmr);
+void __kvm_apic_update_irr(u32 *pir, void *regs);
 void kvm_apic_update_irr(struct kvm_vcpu *vcpu, u32 *pir);
 int kvm_apic_set_irq(struct kvm_vcpu *vcpu, struct kvm_lapic_irq *irq,
 		unsigned long *dest_map);

arch/x86/kvm/vmx.c

@@ -218,6 +218,7 @@ struct __packed vmcs12 {
 	u64 tsc_offset;
 	u64 virtual_apic_page_addr;
 	u64 apic_access_addr;
+	u64 posted_intr_desc_addr;
 	u64 ept_pointer;
 	u64 eoi_exit_bitmap0;
 	u64 eoi_exit_bitmap1;
@@ -337,6 +338,7 @@ struct __packed vmcs12 {
 	u32 vmx_preemption_timer_value;
 	u32 padding32[7]; /* room for future expansion */
 	u16 virtual_processor_id;
+	u16 posted_intr_nv;
 	u16 guest_es_selector;
 	u16 guest_cs_selector;
 	u16 guest_ss_selector;
@@ -409,6 +411,10 @@ struct nested_vmx {
 	 */
 	struct page *apic_access_page;
 	struct page *virtual_apic_page;
+	struct page *pi_desc_page;
+	struct pi_desc *pi_desc;
+	bool pi_pending;
+	u16 posted_intr_nv;
 	u64 msr_ia32_feature_control;
 
 	struct hrtimer preemption_timer;
@@ -623,6 +629,7 @@ static int max_shadow_read_write_fields =
 
 static const unsigned short vmcs_field_to_offset_table[] = {
 	FIELD(VIRTUAL_PROCESSOR_ID, virtual_processor_id),
+	FIELD(POSTED_INTR_NV, posted_intr_nv),
 	FIELD(GUEST_ES_SELECTOR, guest_es_selector),
 	FIELD(GUEST_CS_SELECTOR, guest_cs_selector),
 	FIELD(GUEST_SS_SELECTOR, guest_ss_selector),
@@ -648,6 +655,7 @@ static const unsigned short vmcs_field_to_offset_table[] = {
 	FIELD64(TSC_OFFSET, tsc_offset),
 	FIELD64(VIRTUAL_APIC_PAGE_ADDR, virtual_apic_page_addr),
 	FIELD64(APIC_ACCESS_ADDR, apic_access_addr),
+	FIELD64(POSTED_INTR_DESC_ADDR, posted_intr_desc_addr),
 	FIELD64(EPT_POINTER, ept_pointer),
 	FIELD64(EOI_EXIT_BITMAP0, eoi_exit_bitmap0),
 	FIELD64(EOI_EXIT_BITMAP1, eoi_exit_bitmap1),
@@ -800,6 +808,7 @@ 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_set_tss_addr(struct kvm *kvm, unsigned int addr);
 static void vmx_set_segment(struct kvm_vcpu *vcpu,
 			    struct kvm_segment *var, int seg);
@@ -1157,6 +1166,11 @@ static inline bool nested_cpu_has_vid(struct vmcs12 *vmcs12)
 	return nested_cpu_has2(vmcs12, SECONDARY_EXEC_VIRTUAL_INTR_DELIVERY);
 }
 
+static inline bool nested_cpu_has_posted_intr(struct vmcs12 *vmcs12)
+{
+	return vmcs12->pin_based_vm_exec_control & PIN_BASED_POSTED_INTR;
+}
+
 static inline bool is_exception(u32 intr_info)
 {
 	return (intr_info & (INTR_INFO_INTR_TYPE_MASK | INTR_INFO_VALID_MASK))
@@ -2360,6 +2374,9 @@ 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))
+		vmx->nested.nested_vmx_pinbased_ctls_high |=
+			PIN_BASED_POSTED_INTR;
 
 	/* exit controls */
 	rdmsr(MSR_IA32_VMX_EXIT_CTLS,
@@ -4312,6 +4329,64 @@ static int vmx_vm_has_apicv(struct kvm *kvm)
 	return enable_apicv && irqchip_in_kernel(kvm);
 }
 
+static int vmx_complete_nested_posted_interrupt(struct kvm_vcpu *vcpu)
+{
+	struct vcpu_vmx *vmx = to_vmx(vcpu);
+	int max_irr;
+	void *vapic_page;
+	u16 status;
+
+	if (vmx->nested.pi_desc &&
+	    vmx->nested.pi_pending) {
+		vmx->nested.pi_pending = false;
+		if (!pi_test_and_clear_on(vmx->nested.pi_desc))
+			return 0;
+
+		max_irr = find_last_bit(
+			(unsigned long *)vmx->nested.pi_desc->pir, 256);
+
+		if (max_irr == 256)
+			return 0;
+
+		vapic_page = kmap(vmx->nested.virtual_apic_page);
+		if (!vapic_page) {
+			WARN_ON(1);
+			return -ENOMEM;
+		}
+		__kvm_apic_update_irr(vmx->nested.pi_desc->pir, vapic_page);
+		kunmap(vmx->nested.virtual_apic_page);
+
+		status = vmcs_read16(GUEST_INTR_STATUS);
+		if ((u8)max_irr > ((u8)status & 0xff)) {
+			status &= ~0xff;
+			status |= (u8)max_irr;
+			vmcs_write16(GUEST_INTR_STATUS, status);
+		}
+	}
+	return 0;
+}
+
+static int vmx_deliver_nested_posted_interrupt(struct kvm_vcpu *vcpu,
+						int vector)
+{
+	struct vcpu_vmx *vmx = to_vmx(vcpu);
+
+	if (is_guest_mode(vcpu) &&
+	    vector == vmx->nested.posted_intr_nv) {
+		/* the PIR and ON have been set by L1. */
+		if (vcpu->mode == IN_GUEST_MODE)
+			apic->send_IPI_mask(get_cpu_mask(vcpu->cpu),
+				POSTED_INTR_VECTOR);
+		/*
+		 * If a posted intr is not recognized by hardware,
+		 * we will accomplish it in the next vmentry.
+		 */
+		vmx->nested.pi_pending = true;
+		kvm_make_request(KVM_REQ_EVENT, vcpu);
+		return 0;
+	}
+	return -1;
+}
 /*
  * Send interrupt to vcpu via posted interrupt way.
  * 1. If target vcpu is running(non-root mode), send posted interrupt
@@ -4324,6 +4399,10 @@ static void vmx_deliver_posted_interrupt(struct kvm_vcpu *vcpu, int vector)
 	struct vcpu_vmx *vmx = to_vmx(vcpu);
 	int r;
 
+	r = vmx_deliver_nested_posted_interrupt(vcpu, vector);
+	if (!r)
+		return;
+
 	if (pi_test_and_set_pir(vector, &vmx->pi_desc))
 		return;
 
@@ -6585,6 +6664,7 @@ static inline void nested_release_vmcs12(struct vcpu_vmx *vmx)
 		vmcs_write32(SECONDARY_VM_EXEC_CONTROL, exec_control);
 		vmcs_write64(VMCS_LINK_POINTER, -1ull);
 	}
+	vmx->nested.posted_intr_nv = -1;
 	kunmap(vmx->nested.current_vmcs12_page);
 	nested_release_page(vmx->nested.current_vmcs12_page);
 	vmx->nested.current_vmptr = -1ull;
@@ -6613,6 +6693,12 @@ static void free_nested(struct vcpu_vmx *vmx)
 		nested_release_page(vmx->nested.virtual_apic_page);
 		vmx->nested.virtual_apic_page = NULL;
 	}
+	if (vmx->nested.pi_desc_page) {
+		kunmap(vmx->nested.pi_desc_page);
+		nested_release_page(vmx->nested.pi_desc_page);
+		vmx->nested.pi_desc_page = NULL;
+		vmx->nested.pi_desc = NULL;
+	}
 
 	nested_free_all_saved_vmcss(vmx);
 }
@@ -8320,6 +8406,7 @@ static struct kvm_vcpu *vmx_create_vcpu(struct kvm *kvm, unsigned int id)
 	if (nested)
 		nested_vmx_setup_ctls_msrs(vmx);
 
+	vmx->nested.posted_intr_nv = -1;
 	vmx->nested.current_vmptr = -1ull;
 	vmx->nested.current_vmcs12 = NULL;
 
@@ -8565,6 +8652,31 @@ static bool nested_get_vmcs12_pages(struct kvm_vcpu *vcpu,
 			return false;
 	}
 
+	if (nested_cpu_has_posted_intr(vmcs12)) {
+		if (!IS_ALIGNED(vmcs12->posted_intr_desc_addr, 64))
+			return false;
+
+		if (vmx->nested.pi_desc_page) { /* shouldn't happen */
+			kunmap(vmx->nested.pi_desc_page);
+			nested_release_page(vmx->nested.pi_desc_page);
+		}
+		vmx->nested.pi_desc_page =
+			nested_get_page(vcpu, vmcs12->posted_intr_desc_addr);
+		if (!vmx->nested.pi_desc_page)
+			return false;
+
+		vmx->nested.pi_desc =
+			(struct pi_desc *)kmap(vmx->nested.pi_desc_page);
+		if (!vmx->nested.pi_desc) {
+			nested_release_page_clean(vmx->nested.pi_desc_page);
+			return false;
+		}
+		vmx->nested.pi_desc =
+			(struct pi_desc *)((void *)vmx->nested.pi_desc +
+			(unsigned long)(vmcs12->posted_intr_desc_addr &
+			(PAGE_SIZE - 1)));
+	}
+
 	return true;
 }
 
@@ -8700,7 +8812,8 @@ static int nested_vmx_check_apicv_controls(struct kvm_vcpu *vcpu,
 {
 	if (!nested_cpu_has_virt_x2apic_mode(vmcs12) &&
 	    !nested_cpu_has_apic_reg_virt(vmcs12) &&
-	    !nested_cpu_has_vid(vmcs12))
+	    !nested_cpu_has_vid(vmcs12) &&
+	    !nested_cpu_has_posted_intr(vmcs12))
 		return 0;
 
 	/*
@@ -8719,6 +8832,17 @@ static int nested_vmx_check_apicv_controls(struct kvm_vcpu *vcpu,
 	   !nested_exit_on_intr(vcpu))
 		return -EINVAL;
 
+	/*
+	 * bits 15:8 should be zero in posted_intr_nv,
+	 * the descriptor address has been already checked
+	 * in nested_get_vmcs12_pages.
+	 */
+	if (nested_cpu_has_posted_intr(vmcs12) &&
+	   (!nested_cpu_has_vid(vmcs12) ||
+	    !nested_exit_intr_ack_set(vcpu) ||
+	    vmcs12->posted_intr_nv & 0xff00))
+		return -EINVAL;
+
 	/* tpr shadow is needed by all apicv features. */
 	if (!nested_cpu_has(vmcs12, CPU_BASED_TPR_SHADOW))
 		return -EINVAL;
@@ -8961,8 +9085,23 @@ static void prepare_vmcs02(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12)
 
 	exec_control = vmcs12->pin_based_vm_exec_control;
 	exec_control |= vmcs_config.pin_based_exec_ctrl;
-	exec_control &= ~(PIN_BASED_VMX_PREEMPTION_TIMER |
-                          PIN_BASED_POSTED_INTR);
+	exec_control &= ~PIN_BASED_VMX_PREEMPTION_TIMER;
+
+	if (nested_cpu_has_posted_intr(vmcs12)) {
+		/*
+		 * Note that we use L0's vector here and in
+		 * vmx_deliver_nested_posted_interrupt.
+		 */
+		vmx->nested.posted_intr_nv = vmcs12->posted_intr_nv;
+		vmx->nested.pi_pending = false;
+		vmcs_write64(POSTED_INTR_NV, POSTED_INTR_VECTOR);
+		vmcs_write64(POSTED_INTR_DESC_ADDR,
+			page_to_phys(vmx->nested.pi_desc_page) +
+			(unsigned long)(vmcs12->posted_intr_desc_addr &
+			(PAGE_SIZE - 1)));
+	} else
+		exec_control &= ~PIN_BASED_POSTED_INTR;
+
 	vmcs_write32(PIN_BASED_VM_EXEC_CONTROL, exec_control);
 
 	vmx->nested.preemption_timer_expired = false;
@@ -9498,9 +9637,10 @@ static int vmx_check_nested_events(struct kvm_vcpu *vcpu, bool external_intr)
 		if (vmx->nested.nested_run_pending)
 			return -EBUSY;
 		nested_vmx_vmexit(vcpu, EXIT_REASON_EXTERNAL_INTERRUPT, 0, 0);
+		return 0;
 	}
 
-	return 0;
+	return vmx_complete_nested_posted_interrupt(vcpu);
 }
 
 static u32 vmx_get_preemption_timer_value(struct kvm_vcpu *vcpu)
@@ -9878,6 +10018,12 @@ static void nested_vmx_vmexit(struct kvm_vcpu *vcpu, u32 exit_reason,
 		nested_release_page(vmx->nested.virtual_apic_page);
 		vmx->nested.virtual_apic_page = NULL;
 	}
+	if (vmx->nested.pi_desc_page) {
+		kunmap(vmx->nested.pi_desc_page);
+		nested_release_page(vmx->nested.pi_desc_page);
+		vmx->nested.pi_desc_page = NULL;
+		vmx->nested.pi_desc = NULL;
+	}
 
 	/*
 	 * We are now running in L2, mmu_notifier will force to reload the