[Intel-gfx] [PATCH v2 0/5] i915 pvmmio to improve GVTg performance

[Xiaolin Zhang]

To improve GVTg performance, it could reduce the mmio access trap
numbers within guest driver in some certain scenarios since mmio
access trap will introuduce vm exit/vm enter cost.

the solution in this patch set is to setup a shared memory region
which accessed both by guest and GVTg without trap cost. the shared
memory region is allocated by guest driver and guest driver will
pass the region's memory guest physical address to GVTg through
PVINFO register and later GVTg can access this region directly without
trap cost to achieve data exchange purpose between guest and GVTg.

in this patch set, 3 kind of pvmmio optimization implemented which is
controlled by enable_pvmmio PVINO register with different level flag.
1. workload submission (context submission): reduce 4 traps to 1 trap.
2. master irq: reduce 2 traps to 1 trap. 
3. ppgtt update: eliminate the cost of ppgtt write protection. 

based on the experiment, the performance was gained 4 percent (average)
improvment with regard to both media and 3D workload benchmarks.

based on the pvmmio framework, it could achive more sceneario optimization
such as globle GTT update, display plane and water mark update with guest.

v0: RFC patch set
v1: addressed RFC review comments
v2: addressed v1 review comments, added pv callbacks for pv operations

Xiaolin Zhang (5):
  drm/i915: introduced pv capability for vgpu
  drm/i915: get ready of memory for pvmmio
  drm/i915: context submission pvmmio optimization
  drm/i915: master irq pvmmio optimization
  drm/i915: ppgtt update pvmmio optimization

 drivers/gpu/drm/i915/i915_drv.c         |  2 +
 drivers/gpu/drm/i915/i915_drv.h         | 15 +++++-
 drivers/gpu/drm/i915/i915_gem_gtt.c     | 67 +++++++++++++++++++++++++
 drivers/gpu/drm/i915/i915_irq.c         | 82 ++++++++++++++++++++++++++++--
 drivers/gpu/drm/i915/i915_pvinfo.h      | 43 +++++++++++++++-
 drivers/gpu/drm/i915/i915_vgpu.c        | 44 ++++++++++++++++-
 drivers/gpu/drm/i915/intel_lrc.c        | 88 +++++++++++++++++++++++++++++++--
 drivers/gpu/drm/i915/intel_ringbuffer.h |  3 ++
 8 files changed, 333 insertions(+), 11 deletions(-)

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2.7.4