drm/i915: Flush WC GGTT only on required platforms

stable inclusion
from stable-v6.6.3
commit 4a6bb69835864a8c9003feb2a4ef48acdd321436
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I8LBQP

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=4a6bb69835864a8c9003feb2a4ef48acdd321436



--------------------------------

commit 7d7a328d0e8d6edefb7b0d665185d468667588d0 upstream.

gen8_ggtt_invalidate() is only needed for limited set of platforms
where GGTT is mapped as WC. This was added as way to fix WC based GGTT in
commit 0f9b91c7 ("drm/i915: flush system agent TLBs on SNB") and
there are no reference in HW docs that forces us to use this on non-WC
backed GGTT.

This can also cause unwanted side-effects on XE_HP platforms where
GFX_FLSH_CNTL_GEN6 is not valid anymore.

v2: Add a func to detect wc ggtt detection (Ville)
v3: Improve commit log and add reference commit (Daniel)

Fixes: d2eae8e9 ("drm/i915/dg2: Drop force_probe requirement")
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Jonathan Cavitt <jonathan.cavitt@intel.com>
Cc: John Harrison <john.c.harrison@intel.com>
Cc: Andi Shyti <andi.shyti@linux.intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: <stable@vger.kernel.org> # v6.2+
Suggested-by: Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: Nirmoy Das <nirmoy.das@intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231018093815.1349-1-nirmoy.das@intel.com


(cherry picked from commit 81de3e296b10a13e5c9f13172825b0d8d9495c68)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>