An apparatus and method are described for mediate pass through and shared memory page merging. For example, one embodiment of a method comprises: generating a page identifier (PI) for each of a set ofguest memory pages, wherein equivalent PIs indicate that the corresponding memory pages are the same; upon detecting that a first guest memory page and a second guest memory page have PIs that are equal, merging the first and second guest memory pages into a single memory page; detecting that the first guest memory page is to be used for a direct memory access (DMA) operation; and responsively unmerging the first and second guest memory pages.