In XenGT, ioreq copy is used to trap mmio write and ppgtt write. Both
of them are memory write, ioreq handler couldn't distinguish them. So
ioreq handler probe the ppgtt write handler, if it is succuess, this
ioreq is ppgtt write, otherwise it is mmio write.
So ppgtt write handler should return an error at the failure of finding
page track, it is fatal to implement ioreq handler in XenGT.
Signed-off-by: Xiong Zhang <xiong.y.zhang@intel.com>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>
page_track_handler take lock at the beginning, the lock should be released
at the failure of finding page track. Otherwise deadlock will happen.
Fixes: e502a2af4c ("drm/i915/gvt: Provide generic page_track infrastructure for write-protected page")
Signed-off-by: Xiong Zhang <xiong.y.zhang@intel.com>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>
This patch provide generic page_track infrastructure for write-protected
guest page. The old page_track logic gets rewrote and now stays in a new
standalone page_track.c. This page track infrastructure can be both used
by vGUC and GTT shadowing.
The important change is that it uses radix tree instead of hash table.
We don't have a predictable number of pages that will be tracked.
Here is some performance data (duration in us) of looking up a element:
Before: (aka. intel_vgpu_find_tracked_page)
0.091 0.089 0.090 ... 0.093 0.091 0.087 ... 0.292 0.285 0.292 0.291
After: (aka. intel_vgpu_find_page_track)
0.104 0.105 0.100 0.102 0.102 0.100 ... 0.101 0.101 0.105 0.105
The hash table has good performance at beginning, but turns bad with
more pages being tracked even no 3D applications are running. As
expected, radix tree has stable duration and very quick.
The overall benchmark (tested with Heaven Benchmark) marginally improved
since this is not the bottleneck. What we benefit more from this change
is scalability.
Signed-off-by: Changbin Du <changbin.du@intel.com>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>
