a method , system and computer program product are provided for implementing coherent accelerator function isolation for virtualization in an input / output adapter in a computer system . a coherent accelerator provides accelerator function units , each afu is adapted to operate independently of the other afus to perform a computing task that can be implemented within application software on a processor . the afu has access to system memory bound to the application software and is adapted to make copies of that memory within afu memory - cache in the afu . as part of this memory coherency domain , each of the afu memory - cache and processor memory - cache is adapted to be aware of changes to data commonly in either cache as well as data changed in memory of which the respective cache contains a copy .