1. A method, comprising: allocating, to a first device coupled to a bus that operates in accordance with a bus address space, multiple bus addresses of the bus address space; providing direct access over the bus to a local address space of the first device by defining a mapping between at least some of the addresses of the local address space and the allocated bus addresses of the bus address space; in response to detecting that a second device requires to access a given local address in the local address space of the first device that is not currently mapped by the defined mapping to any of the allocated bus addresses, modifying the defined mapping to also map the given local address of the first device to a respective bus address among the allocated bus addresses; and accessing the given local address of the first device directly, by the second device, using the modified mapping of the defined mapping.