Re: [PATCH v1 2/4] KVM: nSVM: Delay stuffing L2's current RIP into NextRIP until vCPU run

[Yosry Ahmed]

> > Doing this in svm_prepare_switch_to_guest() is wrong, or at least
> > after the svm->guest_state_loaded check. It's possible to emulate the
> > nested VMRUN without doing a vcpu_put(), which means
> > svm->guest_state_loaded will remain true and this code will be
> > skipped.
> >
> > In fact, this breaks the svm_nested_soft_inject_test test. Funny
> > enough, I was only running it with my repro changes, which papered
> > over the bug because it forced an exit to userspace after VMRUN due to
> > single-stepping, so svm->guest_state_loaded got cleared and the code
> > was executed on the next KVM_RUN, before L2 runs.
> >
> > I can move it above the svm->guest_state_loaded check, but I think I
> > will just put it in pre_svm_run() instead.
>
> I would rather not expand pre_svm_run(), and instead just open code it in
> svm_vcpu_run().  pre_svm_run() probably should never have been added, because
> it's far from a generic "pre run" API.  E.g. if we want to keep the helper around,
> it should probably be named something something ASID.

I sent a new version before I saw your response.. sorry.

How strongly do you feel about this? :P