static int vgic_v3_alloc_redist_region()

in kvm/vgic/vgic-mmio-v3.c [796:862]

• 47 lines of code
• 15 McCabe index (conditional complexity)

static int vgic_v3_alloc_redist_region(struct kvm *kvm, uint32_t index,
				       gpa_t base, uint32_t count)
{
	struct vgic_dist *d = &kvm->arch.vgic;
	struct vgic_redist_region *rdreg;
	struct list_head *rd_regions = &d->rd_regions;
	int nr_vcpus = atomic_read(&kvm->online_vcpus);
	size_t size = count ? count * KVM_VGIC_V3_REDIST_SIZE
			    : nr_vcpus * KVM_VGIC_V3_REDIST_SIZE;
	int ret;

	/* cross the end of memory ? */
	if (base + size < base)
		return -EINVAL;

	if (list_empty(rd_regions)) {
		if (index != 0)
			return -EINVAL;
	} else {
		rdreg = list_last_entry(rd_regions,
					struct vgic_redist_region, list);

		/* Don't mix single region and discrete redist regions */
		if (!count && rdreg->count)
			return -EINVAL;

		if (!count)
			return -EEXIST;

		if (index != rdreg->index + 1)
			return -EINVAL;
	}

	/*
	 * For legacy single-region redistributor regions (!count),
	 * check that the redistributor region does not overlap with the
	 * distributor's address space.
	 */
	if (!count && !IS_VGIC_ADDR_UNDEF(d->vgic_dist_base) &&
		vgic_dist_overlap(kvm, base, size))
		return -EINVAL;

	/* collision with any other rdist region? */
	if (vgic_v3_rdist_overlap(kvm, base, size))
		return -EINVAL;

	rdreg = kzalloc(sizeof(*rdreg), GFP_KERNEL_ACCOUNT);
	if (!rdreg)
		return -ENOMEM;

	rdreg->base = VGIC_ADDR_UNDEF;

	ret = vgic_check_iorange(kvm, rdreg->base, base, SZ_64K, size);
	if (ret)
		goto free;

	rdreg->base = base;
	rdreg->count = count;
	rdreg->free_index = 0;
	rdreg->index = index;

	list_add_tail(&rdreg->list, rd_regions);
	return 0;
free:
	kfree(rdreg);
	return ret;
}