[Intel-gfx] [PATCH 0/7] GEN8 PPGTT cleanups + 4GB support

[Ben Widawsky]

The following patches rework a lot of the PPGTT cleanup and
initialization code. In the short term, this should allow us to use all
4GB address space as well as get the code ready for adding full PPGTT
support to BDW.

Aside from making the code clearer, the more discrete functions make
finer grained page table allocation much easier to manage. Previously,
we were allocating one gigantic contiguous chunk for the GEN8 page
tables. This required a 4MB contiguous allocation. On modern Linux, such
a large allocation is impossible, and so we fell back to a 2GB address
space requiring only 2MB for page tables.

The GEN8 PPGTT code was in poor shape to begin with because the effort
was on getting functionality quickly to new platforms, and this was
achieved by largely copy and pasting the GEN6 code and altering where
needed. I initially tried to do the finer grained allocation as a single
patch, and was really unsatisfied with the results.

One nice outcome (I feel) is everything gets referenced as a PDPE/PDE/PTE, or
index thereof. It becomes easy to convert these things to the graphics virtual
address, or vice-versa. The win will be when we start to map address ranges
more dynamically, specifically, allocate the page tables, PDEs, and map the
PDEs.

The last patch is totally optional. I've or its equivalent quite a few
times in various series, but it never seems to stick.

After we get this merged, I'll submit BDW full PPGTT. I also have a blog post
about this stuff in the works.

Ben Widawsky (7):
  drm/i915/bdw: Split up PPGTT cleanup
  drm/i915/bdw: Reorganize PPGTT init
  drm/i915/bdw: Split ppgtt initialization up
  drm/i915: Make clear/insert vfuncs args absolute
  drm/i915/bdw: Reorganize PT allocations
  Revert "drm/i915/bdw: Limit GTT to 2GB"
  drm/i915: Update i915_gem_gtt.c copyright

 drivers/gpu/drm/i915/i915_drv.h     |  13 +-
 drivers/gpu/drm/i915/i915_gem_gtt.c | 463 +++++++++++++++++++++++++-----------
 2 files changed, 332 insertions(+), 144 deletions(-)

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1.8.5.2