x86, apicv: add virtual interrupt delivery support

Virtual interrupt delivery avoids KVM to inject vAPIC interrupts
manually, which is fully taken care of by the hardware. This needs
some special awareness into existing interrupr injection path:

- for pending interrupt, instead of direct injection, we may need
  update architecture specific indicators before resuming to guest.

- A pending interrupt, which is masked by ISR, should be also
  considered in above update action, since hardware will decide
  when to inject it at right time. Current has_interrupt and
  get_interrupt only returns a valid vector from injection p.o.v.

Reviewed-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Yang Zhang <yang.z.zhang@Intel.com>
Signed-off-by: Gleb Natapov <gleb@redhat.com>

1 files changed, 21 insertions, 2 deletions

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index b9f55299ed7e..cf512e70c797 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -5565,7 +5565,7 @@ static void inject_pending_event(struct kvm_vcpu *vcpu)
 			vcpu->arch.nmi_injected = true;
 			kvm_x86_ops->set_nmi(vcpu);
 		}
-	} else if (kvm_cpu_has_interrupt(vcpu)) {
+	} else if (kvm_cpu_has_injectable_intr(vcpu)) {
 		if (kvm_x86_ops->interrupt_allowed(vcpu)) {
 			kvm_queue_interrupt(vcpu, kvm_cpu_get_interrupt(vcpu),
 					    false);
@@ -5633,6 +5633,16 @@ static void kvm_gen_update_masterclock(struct kvm *kvm)
 #endif
 }
 
+static void update_eoi_exitmap(struct kvm_vcpu *vcpu)
+{
+	u64 eoi_exit_bitmap[4];
+
+	memset(eoi_exit_bitmap, 0, 32);
+
+	kvm_ioapic_calculate_eoi_exitmap(vcpu, eoi_exit_bitmap);
+	kvm_x86_ops->load_eoi_exitmap(vcpu, eoi_exit_bitmap);
+}
+
 static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
 {
 	int r;
@@ -5686,6 +5696,8 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
 			kvm_handle_pmu_event(vcpu);
 		if (kvm_check_request(KVM_REQ_PMI, vcpu))
 			kvm_deliver_pmi(vcpu);
+		if (kvm_check_request(KVM_REQ_EOIBITMAP, vcpu))
+			update_eoi_exitmap(vcpu);
 	}
 
 	if (kvm_check_request(KVM_REQ_EVENT, vcpu) || req_int_win) {
@@ -5694,10 +5706,17 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
 		/* enable NMI/IRQ window open exits if needed */
 		if (vcpu->arch.nmi_pending)
 			kvm_x86_ops->enable_nmi_window(vcpu);
-		else if (kvm_cpu_has_interrupt(vcpu) || req_int_win)
+		else if (kvm_cpu_has_injectable_intr(vcpu) || req_int_win)
 			kvm_x86_ops->enable_irq_window(vcpu);
 
 		if (kvm_lapic_enabled(vcpu)) {
+			/*
+			 * Update architecture specific hints for APIC
+			 * virtual interrupt delivery.
+			 */
+			if (kvm_x86_ops->hwapic_irr_update)
+				kvm_x86_ops->hwapic_irr_update(vcpu,
+					kvm_lapic_find_highest_irr(vcpu));
 			update_cr8_intercept(vcpu);
 			kvm_lapic_sync_to_vapic(vcpu);
 		}