A first processor that has a trusted relationship with a trusted memory region (TMR) that includes a first region for storing microcode used to execute a microcontroller on a second processor and a second region for storing data associated with the microcontroller. The microcontroller supports a virtual function that is executed on the second processor. An access controller is configured by the first processor to selectively provide the microcontroller with access to the TMR based on whether the request is to write in the first region. The access controller grants read requests from the microcontroller to read from the first region and denies write requests from the microcontroller to write to the first region. The access controller grants requests from the microcontroller to read from the second region or write to the second region.