s390x/tcg: implement STOP and RESET interrupts for TCG

s390x/tcg: implement STOP and RESET interrupts for TCG

Implement them like KVM implements/handles them. Both can only be
triggered via SIGP instructions. RESET has (almost) the lowest priority if
the CPU is running, and the highest if the CPU is STOPPED. This is handled
in SIGP code already. On delivery, we only have to care about the
"CPU running" scenario.

STOP is defined to be delivered after all other interrupts have been
delivered. Therefore it has the actual lowest priority.

As both can wake up a CPU if sleeping, indicate them correctly to
external code (e.g. cpu_has_work()).

Signed-off-by: David Hildenbrand <[email protected]>
Message-Id: <20170928203708[email protected]>
Reviewed-by: Richard Henderson <[email protected]>
Signed-off-by: Cornelia Huck <[email protected]>