Re: Help with Understanding vcpu xstate restore error during vm migration

[Fonyuy-Asheri Caleb <fonyuy-asheri.caleb@xxxxxxxx>]

> 
> None of these require extra state (i.e. registers), hence ...
> 
>> Per my current understanding, I would expect more xstates on the VM than
>> supported on the target
>> server and hence a failure with xstate verification when restoring CPU state.
> 
> ... no extra "xstates" (as you name it).

I see. Makes more sense now. So if i understand correctly, not all these 
features
have states and hence are not all taken into account during xstate 
verification. 

> 
>> However migrating a guest from Source to target works.
>> 
>> Note that these extra avx512 features are all visible to the guest I migrate.
> 
> Ah yes. While that's a bug, it's a known one I think, awaiting further work
> that Andrew has been meaning to do for quite some time, yet always getting
> preempted by security stuff and other emergencies. For guests to migrate
> safely, I think right now it is required that you limit features visible to
> them on the source host.

Noted. Will take that into account when evaluating the impact of unnecessary 
features. 

> 
> Jan

Thanks again Jan

Caleb