... I guess this is the misunderstanding. I'm not proposing to delegate the WFI trap to the guest, but rather *the WFI instruction*: HS-mode could optionally let WFI run in VS-mode, even if it wouldn't complete within a bounded time. This is because, if you don't overcommit CPUs, there's no advantage in getting out of VS-mode and doing the wait for interrupts in HS-mode.
Okay, I get it now. You're proposing we bring back hstatus.VTW, the HS-mode analog to mstatus.TW. (We had the VTW bit originally in hstatus, but dropped it long ago.)
