KVM: arm64: vgic-its: Add pointer to corresponding kvm_device

Going from the ITS structure to the corresponding KVM structure
would be quite handy at times. The kvm_device pointer that is
passed at create time is quite convenient for this, so let's
keep a copy of it in the vgic_its structure.

This will be put to a good use in subsequent patches.
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

include/kvm/arm_vgic.h

@@ -138,6 +138,7 @@ struct vgic_its {
 	bool			enabled;
 	bool			initialized;
 	struct vgic_io_device	iodev;
+	struct kvm_device	*dev;
 
 	/* These registers correspond to GITS_BASER{0,1} */
 	u64			baser_device_table;

virt/kvm/arm/vgic/vgic-its.c

@@ -1368,6 +1368,7 @@ static int vgic_its_create(struct kvm_device *dev, u32 type)
 	dev->kvm->arch.vgic.has_its = true;
 	its->initialized = false;
 	its->enabled = false;
+	its->dev = dev;
 
 	its->baser_device_table = INITIAL_BASER_VALUE			|
 		((u64)GITS_BASER_TYPE_DEVICE << GITS_BASER_TYPE_SHIFT);