drm/i915/gtt: Fix rounding for 36b

The top-level page directory for 36b is a single entry, not multiple
like 32b. Fix up the rounding on the calculation of the size of the top
level so that we populate the 4th level correctly for 36b.
Reported-by: Jose Souza <jose.souza@intel.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Fixes: 1eda701e ("drm/i915/gtt: Recursive cleanup for gen8")
Cc: Abdiel Janulgue <abdiel.janulgue@linux.intel.com>
Cc: Jose Souza <jose.souza@intel.com>
Tested-by: José Roberto de Souza <jose.souza@intel.com>
Reviewed-by: Abdiel Janulgue <abdiel.janulgue@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190719130737.5835-1-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/i915_gem_gtt.c

@@ -905,6 +905,12 @@ static inline unsigned int gen8_pt_count(u64 start, u64 end)
 		return end - start;
 }
 
+static inline unsigned int gen8_pd_top_count(const struct i915_address_space *vm)
+{
+	unsigned int shift = __gen8_pte_shift(vm->top);
+	return (vm->total + (1ull << shift) - 1) >> shift;
+}
+
 static void __gen8_ppgtt_cleanup(struct i915_address_space *vm,
 				 struct i915_page_directory *pd,
 				 int count, int lvl)
@@ -930,9 +936,7 @@ static void gen8_ppgtt_cleanup(struct i915_address_space *vm)
 	if (intel_vgpu_active(vm->i915))
 		gen8_ppgtt_notify_vgt(ppgtt, false);
 
-	__gen8_ppgtt_cleanup(vm, ppgtt->pd,
-			     vm->total >> __gen8_pte_shift(vm->top),
-			     vm->top);
+	__gen8_ppgtt_cleanup(vm, ppgtt->pd, gen8_pd_top_count(vm), vm->top);
 	free_scratch(vm);
 }
 
@@ -1392,7 +1396,7 @@ static int gen8_preallocate_top_level_pdp(struct i915_ppgtt *ppgtt)
 	unsigned int idx;
 
 	GEM_BUG_ON(vm->top != 2);
-	GEM_BUG_ON((vm->total >> __gen8_pte_shift(2)) != GEN8_3LVL_PDPES);
+	GEM_BUG_ON(gen8_pd_top_count(vm) != GEN8_3LVL_PDPES);
 
 	for (idx = 0; idx < GEN8_3LVL_PDPES; idx++) {
 		struct i915_page_directory *pde;
@@ -1429,7 +1433,7 @@ static void ppgtt_init(struct i915_ppgtt *ppgtt, struct intel_gt *gt)
 static struct i915_page_directory *
 gen8_alloc_top_pd(struct i915_address_space *vm)
 {
-	const unsigned int count = vm->total >> __gen8_pte_shift(vm->top);
+	const unsigned int count = gen8_pd_top_count(vm);
 	struct i915_page_directory *pd;
 
 	GEM_BUG_ON(count > ARRAY_SIZE(pd->entry));
@@ -1515,8 +1519,7 @@ static struct i915_ppgtt *gen8_ppgtt_create(struct drm_i915_private *i915)
 
 err_free_pd:
 	__gen8_ppgtt_cleanup(&ppgtt->vm, ppgtt->pd,
-			     ppgtt->vm.total >> __gen8_pte_shift(ppgtt->vm.top),
-			     ppgtt->vm.top);
+			     gen8_pd_top_count(&ppgtt->vm), ppgtt->vm.top);
 err_free_scratch:
 	free_scratch(&ppgtt->vm);
 err_free: