drm/i915/gtt: Fix the boundary check for vm area

The check for start + length >= total_vm_size is
wrong since start + length can be exactly the size of
the vm.

Fix the check to allow allocation to boundary.

Fixes a regression in commit 4dd738e9cd79
("drm/i915: Fix 32b overflow check in gen8_ppgtt_alloc_page_directories")

Testcase: igt/gem_evict_everything/swapping-interruptible
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=90399
Tested-by: Lu Hua <huax.lu@intel.com>
Cc: Chris Wilson <chris@chris.wilson.co.uk>
Cc: Dave Gordon <david.s.gordon@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Michel Thierry <michel.thierry@intel.com>
Signed-off-by: Mika Kuoppala <mika.kuoppala@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
index e3bcc3ba7e405f28dd764752ba72d941222ccb20..17b7df0b561f1bdc2476060b8eabbd34095c377a 100644 (file)
--- a/drivers/gpu/drm/i915/i915_gem_gtt.c
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
@@ -757,7 +757,7 @@ static int gen8_ppgtt_alloc_page_directories(struct i915_hw_ppgtt *ppgtt,
        WARN_ON(!bitmap_empty(new_pds, GEN8_LEGACY_PDPES));
 
        /* FIXME: upper bound must not overflow 32 bits  */
-       WARN_ON((start + length) >= (1ULL << 32));
+       WARN_ON((start + length) > (1ULL << 32));
 
        gen8_for_each_pdpe(pd, pdp, start, length, temp, pdpe) {
                if (pd)