KVM: arm/arm64: prepare GICv3 emulation to use kvm_io_bus MMIO handling

Using the framework provided by the recent vgic.c changes, we
register a kvm_io_bus device on mapping the virtual GICv3 resources.
The distributor mapping is pretty straight forward, but the
redistributors need some more love, since they need to be tagged with
the respective redistributor (read: VCPU) they are connected with.
We use the kvm_io_bus framework to register one devices per VCPU.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

include/kvm/arm_vgic.h

@@ -252,6 +252,7 @@ struct vgic_dist {
 
 	struct vgic_vm_ops	vm_ops;
 	struct vgic_io_device	dist_iodev;
+	struct vgic_io_device	*redist_iodevs;
 };
 
 struct vgic_v2_cpu_if {

virt/kvm/arm/vgic-v3-emul.c

@@ -758,6 +758,9 @@ static int vgic_v3_map_resources(struct kvm *kvm,
 {
 	int ret = 0;
 	struct vgic_dist *dist = &kvm->arch.vgic;
+	gpa_t rdbase = dist->vgic_redist_base;
+	struct vgic_io_device *iodevs = NULL;
+	int i;
 
 	if (!irqchip_in_kernel(kvm))
 		return 0;
@@ -783,7 +786,41 @@ static int vgic_v3_map_resources(struct kvm *kvm,
 		goto out;
 	}
 
-	kvm->arch.vgic.ready = true;
+	ret = vgic_register_kvm_io_dev(kvm, dist->vgic_dist_base,
+				       GIC_V3_DIST_SIZE, vgic_v3_dist_ranges,
+				       -1, &dist->dist_iodev);
+	if (ret)
+		goto out;
+
+	iodevs = kcalloc(dist->nr_cpus, sizeof(iodevs[0]), GFP_KERNEL);
+	if (!iodevs) {
+		ret = -ENOMEM;
+		goto out_unregister;
+	}
+
+	for (i = 0; i < dist->nr_cpus; i++) {
+		ret = vgic_register_kvm_io_dev(kvm, rdbase,
+					       SZ_128K, vgic_redist_ranges,
+					       i, &iodevs[i]);
+		if (ret)
+			goto out_unregister;
+		rdbase += GIC_V3_REDIST_SIZE;
+	}
+
+	dist->redist_iodevs = iodevs;
+	dist->ready = true;
+	goto out;
+
+out_unregister:
+	kvm_io_bus_unregister_dev(kvm, KVM_MMIO_BUS, &dist->dist_iodev.dev);
+	if (iodevs) {
+		for (i = 0; i < dist->nr_cpus; i++) {
+			if (iodevs[i].dev.ops)
+				kvm_io_bus_unregister_dev(kvm, KVM_MMIO_BUS,
+							  &iodevs[i].dev);
+		}
+	}
+
 out:
 	if (ret)
 		kvm_vgic_destroy(kvm);