spapr: Implement H_CONFER

This does not do directed yielding and is not quite as strict as PAPR
specifies in terms of precise dispatch behaviour. This generally will
mean suboptimal performance, rather than guest misbehaviour. Linux
does not rely on exact dispatch behaviour.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Message-Id: <20190718034214.14948-4-npiggin@gmail.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
1 file changed