Matthew Auld noted that on more recent systems (such as the parser for
gen9) we may have objects that are larger than expected by the GEM uAPI
(i.e. greater than u32). These objects would have incorrect implicit
batch lengths, causing the parser to reject them for being incomplete,
or worse.

Based on a patch by Matthew Auld.
Reported-by: NMatthew Auld <matthew.auld@intel.com>
Fixes: 435e8fc0 ("drm/i915: Allow parsing of unsized batches")
Testcase: igt/gem_exec_params/larger-than-life-batch
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Matthew Auld <matthew.auld@intel.com>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Cc: Jon Bloomfield <jon.bloomfield@intel.com>
Reviewed-by: NMatthew Auld <matthew.auld@intel.com>
Cc: stable@vger.kernel.org
Link: https://patchwork.freedesktop.org/patch/msgid/20201015115954.871-1-chris@chris-wilson.co.uk