drm/i915/gt: Fix reservation address in ggtt_reserve_guc_top

There is an assertion in ggtt_reserve_guc_top that the global GTT
is of size at least GUC_GGTT_TOP, which is not the case on a 32-bit
platform; see commit 562d55d991b39ce376c492df2f7890fd6a541ffc
("drm/i915/bdw: Only use 2g GGTT for 32b platforms"). If GEM_BUG_ON
is enabled, this triggers a BUG(); if GEM_BUG_ON is disabled, the
subsequent reservation fails and the driver fails to initialise
the device:

i915 0000:00:02.0: [drm:i915_init_ggtt [i915]] Failed to reserve top of GGTT for GuC
i915 0000:00:02.0: Device initialization failed (-28)
i915 0000:00:02.0: Please file a bug on drm/i915; see https://gitlab.freedesktop.org/drm/intel/-/wikis/How-to-file-i915-bugs for details.
i915: probe of 0000:00:02.0 failed with error -28

Make the reservation at the top of the available space, whatever
that is, instead of assuming that the top will be GUC_GGTT_TOP.

Fixes: 911800765ef6 ("drm/i915/uc: Reserve upper range of GGTT")
Link: https://gitlab.freedesktop.org/drm/intel/-/issues/9080
Signed-off-by: Javier Pello <[email protected]>
Reviewed-by: Daniele Ceraolo Spurio <[email protected]>
Cc: Fernando Pacheco <[email protected]>
Cc: Chris Wilson <[email protected]>
Cc: Jani Nikula <[email protected]>
Cc: Joonas Lahtinen <[email protected]>
Cc: Rodrigo Vivi <[email protected]>
Cc: Tvrtko Ursulin <[email protected]>
Cc: [email protected]
Cc: [email protected] # v5.3+
Signed-off-by: John Harrison <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]
(cherry picked from commit 0f3fa942d91165c2702577e9274d2ee1c7212afc)
Signed-off-by: Rodrigo Vivi <[email protected]>

0 files changed, 0 insertions, 0 deletions