Messages in this thread | | | Subject | Re: [patch 01/10] x86/fpu/signal: Clarify exception handling in restore_fpregs_from_user() | From | Jarkko Sakkinen <> | Date | Fri, 03 Sep 2021 09:00:16 +0300 |
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On Thu, 2021-09-02 at 16:08 +0200, Thomas Gleixner wrote: > On Thu, Sep 02 2021 at 16:08, Jarkko Sakkinen wrote: > > On Wed, 2021-09-01 at 16:47 +0000, Sean Christopherson wrote: > > > As for SGX consuming the trap number in general, it's correct. For non-KVM usage, > > > it's nice to have but not strictly necessary. Any fault except #PF on ENCLS is > > > guaranteed to be a kernel or hardware bug; SGX uses the trap number to WARN on a > > > !#PF exception, e.g. on #GP or #UD. Not having the trap number would mean losing > > > those sanity checks, which have been useful in the past. > > > > AFAIK, we do not consider #UD as a bug. Agree with the conclusion that SGX > > should never #MC, I just did not get this part. #UD is something that is > > useful for SGX run-time. > > I understood that storing the trap number is useful. I was just > questioning the #MC angle. I.e. pretending that the #MC caused by ENCLS > is recoverable.
Absolutely not.
I mixed up #UD caused by CPU executing inside enclave and ENCLS causing #UD. Sorry about that.
Because of KVM we have to catch #PF's, given that a new power cycle in the host resets the state of SGX protected memory in the guest.
> > Thanks, > > tglx
/Jarkko
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