Interaction between Ssmpu and mstatus.TVM/hstatus.VTVM?

[dramforever]

It is not mentioned in the Ssmpu specification what happens if the smpu* CSRs are accessed in S-mode with mstatus.TVM = 1, or in VS-mode with hstatus.VTVM = 1. It seems reasonable to assume that doing so raises an Illegal Instruction exception or a Virtual Instruction Fault exception, respectively, but it might be a good idea to spell it out.