[Intel-gfx] [PATCH v5] drm/i915: Enable WaProgramMgsrForCorrectSliceSpecificMmioReads for Gen9

[Chiou, Cooper]

I've tested on GLK, KBL, CFL Intel NUC devices and got the following performance results, there is no performance regression per my testing.
and CI build test has passed as well.

Patch: [v5] drm/i915: Enable WaProgramMgsrForCorrectSliceSpecificMmioReads for Gen9
Test suite: phoronix-test-suite.supertuxkart.1024x768.Fullscreen.Ultimate.1.GranParadisoIsland.frames_per_second
Kernel version: 5.12.0-rc1 (drm-tip)

a. Device: Intel NUC kit NUC7JY Gemini Lake Celeron J4005 @2.7GHz (2 Cores)
    Without patch, fps=57.45
    With patch, fps=57.49
b. Device: Intel NUC kit NUC8BEH Coffee Lake Core i3-8109U @3.6GHz(4 Cores)
    Without patch, fps=117.23
    With patch, fps=117.27
c. Device: Intel NUC kit NUC7i3BNH Kaby Lake Core i3-7100U @2.4GHz(4 Cores)
    Without patch, fps=114.05
    With patch, fps=114.34

Meanwhile, Intel lkp team has validated performance test on lkp-kbl-nuc1 and no regression as the following.
f69d02e37a85645a  d912096c40cdc3bc9364966971 testcase/testparams/testbox
----------------  -------------------------- ---------------------------
          %stddev      change         %stddev
              \          |                \
      29.79                       29.67
phoronix-test-suite/performance-true-Fullscreen-Ultimate-1-Gran_Paradiso_Island__Approxima-supertuxkart-1.5.2-ucode=0xde/lkp-kbl-nuc1
      29.79                       29.67        GEO-MEAN phoronix-test-suite.supertuxkart.1280x1024.Fullscreen.Ultimate.1.GranParadisoIsland.frames_per_second

Hi Tvrtko,
Please help to review this patch since this is urgent for Google Chrome KBL/CML/GLK projects.

Best Regards,
Cooper