It appears now that we have the ring TLB invalidation in place, we need
only update the page directory cachelines that we have altered. A great
reduction from rewriting the whole 2MiB ppgtt on every update.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Acked-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191205234059.1010030-1-chris@chris-wilson.co.uk