kvm: arm64: vgic: Introduce vgic_check_iorange

Add the new vgic_check_iorange helper that checks that an iorange is
sane: the start address and size have valid alignments, the range is
within the addressable PA range, start+size doesn't overflow, and the
start wasn't already defined.

No functional change.
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Ricardo Koller <ricarkol@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20211005011921.437353-2-ricarkol@google.com

arch/arm64/kvm/vgic/vgic-kvm-device.c

@@ -29,6 +29,28 @@ int vgic_check_ioaddr(struct kvm *kvm, phys_addr_t *ioaddr,
 	return 0;
 }
 
+int vgic_check_iorange(struct kvm *kvm, phys_addr_t ioaddr,
+		       phys_addr_t addr, phys_addr_t alignment,
+		       phys_addr_t size)
+{
+	int ret;
+
+	ret = vgic_check_ioaddr(kvm, &ioaddr, addr, alignment);
+	if (ret)
+		return ret;
+
+	if (!IS_ALIGNED(size, alignment))
+		return -EINVAL;
+
+	if (addr + size < addr)
+		return -EINVAL;
+
+	if (addr + size > kvm_phys_size(kvm))
+		return -E2BIG;
+
+	return 0;
+}
+
 static int vgic_check_type(struct kvm *kvm, int type_needed)
 {
 	if (kvm->arch.vgic.vgic_model != type_needed)

arch/arm64/kvm/vgic/vgic.h

@@ -175,6 +175,10 @@ void vgic_irq_handle_resampling(struct vgic_irq *irq,
 int vgic_check_ioaddr(struct kvm *kvm, phys_addr_t *ioaddr,
 		      phys_addr_t addr, phys_addr_t alignment);
 
+int vgic_check_iorange(struct kvm *kvm, phys_addr_t ioaddr,
+		       phys_addr_t addr, phys_addr_t alignment,
+		       phys_addr_t size);
+
 void vgic_v2_fold_lr_state(struct kvm_vcpu *vcpu);
 void vgic_v2_populate_lr(struct kvm_vcpu *vcpu, struct vgic_irq *irq, int lr);
 void vgic_v2_clear_lr(struct kvm_vcpu *vcpu, int lr);