arm/arm64: KVM: dont rely on a valid GICH base address

To check whether the vGIC was already initialized, we currently check
the GICH base address for not being NULL. Since with GICv3 we may
get along without this address, lets use the irqchip_in_kernel()
function to detect an already initialized vGIC.
Signed-off-by: NAndre Przywara <andre.przywara@arm.com>
Acked-by: NChristoffer Dall <christoffer.dall@linaro.org>
Acked-by: NMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: NChristoffer Dall <christoffer.dall@linaro.org>

virt/kvm/arm/vgic.c

@@ -2094,7 +2094,7 @@ int kvm_vgic_create(struct kvm *kvm, u32 type)
 
 	mutex_lock(&kvm->lock);
 
-	if (kvm->arch.vgic.vctrl_base) {
+	if (irqchip_in_kernel(kvm)) {
 		ret = -EEXIST;
 		goto out;
 	}