In accordance with disclosed embodiments, there are provided systems, methods, and apparatuses for implementing high speed serial controller testing. For instance, in accordance with one embodiment, there is a functional semiconductor device, comprising: a serial Input/Output interface (serial IO interface); a device fabric to carry transactions between a plurality of components of the functional semiconductor device; virtualized device logic embedded within the serial IO interface; a transaction originator to originate a transaction and issue the transaction onto the device fabric directed toward the serial IO interface; in which the virtualized device logic is to receive the transaction at the serial IO interface via the device fabric; in which the virtualized device logic is to modify the transaction received to form a modified transaction; in which the virtualized device logic is to issue the modified transaction onto the device fabric; and in which the modified transaction is returned to the transaction originator. Other related embodiments are disclosed.