Doing so means that we don't have to save the flags anywhere and gets
rid of the last reference to to_book3s(vcpu) in arch/powerpc/kvm/book3s.c.

Doing so is OK because a program interrupt won't be generated at the
same time as any other synchronous interrupt.  If a program interrupt
and an asynchronous interrupt (external or decrementer) are generated
at the same time, the program interrupt will be delivered, which is
correct because it has a higher priority, and then the asynchronous
interrupt will be masked.

We don't ever generate system reset or machine check interrupts to the
guest, but if we did, then we would need to make sure they got delivered
rather than the program interrupt.  The current code would be wrong in
this situation anyway since it would deliver the program interrupt as
well as the reset/machine check interrupt.
Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Alexander Graf <agraf@suse.de>