For QEMU, the majority of the work in enabling instruction interpretation is handled via new VFIO ioctls to SET the appropriate interpretation and interrupt forwarding modes, and to GET the function handle to use for interpretive execution. This series implements these new ioctls, as well as adding a new, optional 'interpret' parameter to zpci which can be used to disable interpretation support (interpret=off) as well as an 'forwarding_assist' parameter to determine whether or not the firmware assist will be used for interrupt delivery (default when interpretation is in use) or whether the host will be responsible for delivering all interrupts (forwarding_assist=off). The ZPCI_INTERP CPU feature is added beginning with the z14 model to enable this support. As a consequence of implementing zPCI interpretation, ISM devices now become eligible for passthrough (but only when zPCI interpretation is available).
