A method, system, and computer program product for enforcing logical partitioning of input/output slots within a data processing system is provided. In one embodiment, the system includes a hypervisor and at least one DMA address checking component. The hypervisor receives non-direct-memory-access requests for access to input/output slots and prohibits devices within one logical partition from accessing the input/output slots assigned to a different logical partition. The DMA address checking component receives direct-memory-access requests and prohibits requests for addresses not within the same logical partition as the requesting device from being completed. Requests with addresses corresponding to the same logical partition as the requesting device are placed on the primary PCI bus by the DMA address checking component for delivery to the system memory.