[PATCH v2] drm/i915: limit PPGTT size to 2GB in 32-bit platforms

[Michel Thierry <michel.thierry@intel.com>]

And prevent overflow warning during compilation. We already set this limit
for the GGTT.

This is a temporary patch until a full replacement of size_t variables
(inadequate in 32-bit kernel) is in place.

Regression from:
	commit a4e0bedca678c81eea4cd79a4bd502335639f73a
	Author: Michel Thierry <michel.thierry@intel.com>
	Date:   Wed Apr 8 12:13:35 2015 +0100

		drm/i915: Use complete address space in true PPGTT

v2: Prettify code and explain why this is needed. (Chris)

Suggested-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Michel Thierry <michel.thierry@intel.com>
---
 drivers/gpu/drm/i915/i915_gem_gtt.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
index 17b7df0..0653c28 100644
--- a/drivers/gpu/drm/i915/i915_gem_gtt.c
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
@@ -951,7 +951,16 @@ static int gen8_ppgtt_init(struct i915_hw_ppgtt *ppgtt)
 	gen8_initialize_pd(&ppgtt->base, ppgtt->scratch_pd);
 
 	ppgtt->base.start = 0;
-	ppgtt->base.total = 1ULL << 32;
+#ifdef CONFIG_X86_32
+		/* While we have a proliferation of size_t variables
+		 * we cannot represent the full ppgtt size on 32bit,
+		 * so limit it to the same size as the GGTT (currently
+		 * 2GiB).
+		 */
+		ppgtt->base.total = to_i915(ppgtt->base.dev)->gtt.base.total;
+#else
+		ppgtt->base.total = 1ULL << 32;
+#endif
 	ppgtt->base.cleanup = gen8_ppgtt_cleanup;
 	ppgtt->base.allocate_va_range = gen8_alloc_va_range;
 	ppgtt->base.insert_entries = gen8_ppgtt_insert_entries;
-- 
2.4.0

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