Re: [RFC PATCH 04/10 v2 ] x86/fpu: eager switch PKRU state

[Sebastian Andrzej Siewior]

On 2018-09-19 07:55:51 [+0200], Paolo Bonzini wrote:
> A kthread can do use_mm/unuse_mm.

indeed. The FPU struct for the kernel thread isn't valid / does not
contain the expected PKRU value. So loading the pkru value from the
struct FPU does not work as expected. We could set it to 0 for a kernel
thread so we don't end up with a random value.
If we want to get this usecase working then we would have to move pkru
value from FPU to mm_struct and consider it in use_mm(). Do we want
this?

> Paolo

Sebastian