KVM: arm/arm64: Check if irq lines to the GIC are already used

We check if other in-kernel devices have already been connected to the
GIC for a particular interrupt line when possible.

For the PMU, we can do this whenever setting the PMU interrupt number
from userspace.

For the timers, we have to wait until we try to enable the timer,
because we have a concept of default IRQ numbers that userspace
shouldn't have to work around in the initialization phase.
Signed-off-by: Christoffer Dall <cdall@linaro.org>
Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>

virt/kvm/arm/arch_timer.c

@@ -618,20 +618,22 @@ void kvm_timer_vcpu_terminate(struct kvm_vcpu *vcpu)
 	kvm_vgic_unmap_phys_irq(vcpu, vtimer->irq.irq);
 }
 
-static bool timer_irqs_are_valid(struct kvm *kvm)
+static bool timer_irqs_are_valid(struct kvm_vcpu *vcpu)
 {
-	struct kvm_vcpu *vcpu;
 	int vtimer_irq, ptimer_irq;
-	int i;
+	int i, ret;
 
-	vcpu = kvm_get_vcpu(kvm, 0);
 	vtimer_irq = vcpu_vtimer(vcpu)->irq.irq;
-	ptimer_irq = vcpu_ptimer(vcpu)->irq.irq;
+	ret = kvm_vgic_set_owner(vcpu, vtimer_irq, vcpu_vtimer(vcpu));
+	if (ret)
+		return false;
 
-	if (vtimer_irq == ptimer_irq)
+	ptimer_irq = vcpu_ptimer(vcpu)->irq.irq;
+	ret = kvm_vgic_set_owner(vcpu, ptimer_irq, vcpu_ptimer(vcpu));
+	if (ret)
 		return false;
 
-	kvm_for_each_vcpu(i, vcpu, kvm) {
+	kvm_for_each_vcpu(i, vcpu, vcpu->kvm) {
 		if (vcpu_vtimer(vcpu)->irq.irq != vtimer_irq ||
 		    vcpu_ptimer(vcpu)->irq.irq != ptimer_irq)
 			return false;
@@ -659,7 +661,7 @@ int kvm_timer_enable(struct kvm_vcpu *vcpu)
 	if (!vgic_initialized(vcpu->kvm))
 		return -ENODEV;
 
-	if (!timer_irqs_are_valid(vcpu->kvm)) {
+	if (!timer_irqs_are_valid(vcpu)) {
 		kvm_debug("incorrectly configured timer irqs\n");
 		return -EINVAL;
 	}

virt/kvm/arm/pmu.c

@@ -480,6 +480,8 @@ static int kvm_arm_pmu_v3_init(struct kvm_vcpu *vcpu)
 		return -EBUSY;
 
 	if (irqchip_in_kernel(vcpu->kvm)) {
+		int ret;
+
 		/*
 		 * If using the PMU with an in-kernel virtual GIC
 		 * implementation, we require the GIC to be already
@@ -490,6 +492,11 @@ static int kvm_arm_pmu_v3_init(struct kvm_vcpu *vcpu)
 
 		if (!kvm_arm_pmu_irq_initialized(vcpu))
 			return -ENXIO;
+
+		ret = kvm_vgic_set_owner(vcpu, vcpu->arch.pmu.irq_num,
+					 &vcpu->arch.pmu);
+		if (ret)
+			return ret;
 	}
 
 	vcpu->arch.pmu.created = true;