Patent ID: 7444493

Claim:
An apparatus comprising: a table structure indexed by a source identifier of an input/output (I/O) transaction specifying a guest physical address and requested by an I/O device to map the I/O device to a domain assigned to the I/O device, the table structure comprising a root table to store root entries indexed by portion of the source identifier, and a context table coupled to the root table to store context entries referenced by the root entries, the context entries mapping the I/O device to the domain, each of the root entries comprising a root present indicator to indicate if the each of the root entries is present, and a context table pointer to reference the context table; and an address translation structure coupled to the table structure to translate the guest physical address to a host physical address corresponding to the I/O transaction; wherein each of the context entries comprises: a context present indicator to indicate if the each of the context entries is present; a domain identifier to identify the domain; a guest address width to define size of a physical address space of the domain; and an address space root to define base of the physical address space of the domain or a page table in the address translation structure.