KVM: arm/arm64: implement kvm_io_bus MMIO handling for the VGIC

Currently we use a lot of VGIC specific code to do the MMIO
dispatching.
Use the previous reworks to add kvm_io_bus style MMIO handlers.

Those are not yet called by the MMIO abort handler, also the actual
VGIC emulator function do not make use of it yet, but will be enabled
with the following patches.

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>
diff --git a/include/kvm/arm_vgic.h b/include/kvm/arm_vgic.h
index 9092fad..f90140c 100644
--- a/include/kvm/arm_vgic.h
+++ b/include/kvm/arm_vgic.h
@@ -24,6 +24,7 @@
 #include <linux/irqreturn.h>
 #include <linux/spinlock.h>
 #include <linux/types.h>
+#include <kvm/iodev.h>
 
 #define VGIC_NR_IRQS_LEGACY	256
 #define VGIC_NR_SGIS		16
@@ -147,6 +148,14 @@
 	int	(*map_resources)(struct kvm *, const struct vgic_params *);
 };
 
+struct vgic_io_device {
+	gpa_t addr;
+	int len;
+	const struct vgic_io_range *reg_ranges;
+	struct kvm_vcpu *redist_vcpu;
+	struct kvm_io_device dev;
+};
+
 struct vgic_dist {
 	spinlock_t		lock;
 	bool			in_kernel;