KVM: arm/arm64: vgic-new: Implement kvm_vgic_vcpu_pending_irq

Tell KVM whether a particular VCPU has an IRQ that needs handling
in the guest. This is used to decide whether a VCPU is runnable.
Signed-off-by: Eric Auger <eric.auger@linaro.org>
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>

include/kvm/vgic/vgic.h

@@ -184,6 +184,8 @@ struct vgic_cpu {
 int kvm_vgic_inject_irq(struct kvm *kvm, int cpuid, unsigned int intid,
 			bool level);
 
+int kvm_vgic_vcpu_pending_irq(struct kvm_vcpu *vcpu);
+
 #define irqchip_in_kernel(k)	(!!((k)->arch.vgic.in_kernel))
 #define vgic_initialized(k)	(false)
 #define vgic_ready(k)		((k)->arch.vgic.ready)

virt/kvm/arm/vgic/vgic.c

@@ -520,3 +520,28 @@ void kvm_vgic_flush_hwstate(struct kvm_vcpu *vcpu)
 	vgic_flush_lr_state(vcpu);
 	spin_unlock(&vcpu->arch.vgic_cpu.ap_list_lock);
 }
+
+int kvm_vgic_vcpu_pending_irq(struct kvm_vcpu *vcpu)
+{
+	struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu;
+	struct vgic_irq *irq;
+	bool pending = false;
+
+	if (!vcpu->kvm->arch.vgic.enabled)
+		return false;
+
+	spin_lock(&vgic_cpu->ap_list_lock);
+
+	list_for_each_entry(irq, &vgic_cpu->ap_list_head, ap_list) {
+		spin_lock(&irq->irq_lock);
+		pending = irq->pending && irq->enabled;
+		spin_unlock(&irq->irq_lock);
+
+		if (pending)
+			break;
+	}
+
+	spin_unlock(&vgic_cpu->ap_list_lock);
+
+	return pending;
+}