Messages in this thread | | | Subject | Re: [PATCH] KVM: x86: emulate reserved nops from 0f/18 to 0f/1f | From | Paolo Bonzini <> | Date | Tue, 19 May 2020 10:06:25 +0200 |
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On 19/05/20 09:55, Sean Christopherson wrote: >> Running arbitrary code under the emulator is problematic anyway with >> CET, since you won't be checking ENDBR markers or updating the state >> machine. So perhaps in addition to what you say we should have a mode >> where, unless unrestricted guest is disabled, the emulator only accepts >> I/O, MOV and ALU instructions. > > Doh, I forgot all about those pesky ENDBR markers. I think a slimmed down > emulator makes sense?
Or just slimmed down opcode tables.
> Tangentially related, isn't the whole fastop thing doomed once CET kernel > support lands?
Why? You do need to add endbr markers and some of the fastop handlers won't fit in 8 bytes, but that should be it.
Paolo
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