Re: [PATCH 3/3] KVM: SVM: allow to intercept all exceptions for debug

Sean Christopherson
2021-03-18T16:36:34Z

On Thu, Mar 18, 2021, Joerg Roedel wrote:
> On Thu, Mar 18, 2021 at 11:24:25AM +0200, Maxim Levitsky wrote:
> > But again this is a debug feature, and it is intended to allow the user
> > to shoot himself in the foot.
>
> And one can't debug SEV-ES guests with it, so what is the point of
> enabling it for them too?

Agreed. I can see myself enabling debug features by default, it would be nice
to not having to go out of my way to disable them for SEV-ES/SNP guests.

Skipping SEV-ES guests should not be difficult; KVM could probably even
print a message stating that the debug hook is being ignored. One thought would
be to snapshot debug_intercept_exceptions at VM creation, and simply zero it out
for incompatible guests. That would also allow changing debug_intercept_exceptions
without reloading KVM, which IMO would be very convenient.