Re: proposal to add "virtual instruction exception" to the hypervisor extension


John Hauser
 

Jonathan Behrens wrote:
I like this plan. The one comment I have is that it seems unnecessarily
opinionated about which operations trigger virtual instruction traps vs
illegal instruction traps when run in VU mode. I think we should error more
on having things trigger virtual instruction traps everywhere that it is
unlikely to require M-mode emulation. To give one example of where the
current design might go wrong: analogously to HLV and friends, HFENCE from
U-mode might be allowed via a CSR in the future, in which case it would now
require hypervisor emulation when a nested VM tried to run it in VU-mode.
Point taken. Would you like to take a stab at listing every case you
think should be included, besides HFENCE?

- John Hauser

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