drm/i915: Replace 4096 with PAGE_SIZE or I915_GTT_PAGE_SIZE

Start converting over from the byte count to its semantic macro, either
we want to allocate the size of a physical page in main memory or we
want the size of a virtual page in the GTT. 4096 could mean either, but
PAGE_SIZE and I915_GTT_PAGE_SIZE are explicit and should help improve
code comprehension and future changes. In the future, we may want to use
variable GTT page sizes and so have the challenge of knowing which
hardcoded values were used to represent a physical page vs the virtual
page.

v2: Look for a few more 4096s to convert, discover IS_ALIGNED().
v3: 4096ul paranoia, make fence alignment a distinct value of 4096, keep
bdw stolen w/a as 4096 until we know better.
v4: Add asserts that i915_vma_insert() start/end are aligned to GTT page
sizes.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/20170110144734.26052-1-chris@chris-wilson.co.uk
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>

1 files changed, 14 insertions, 7 deletions

diff --git a/drivers/gpu/drm/i915/i915_vma.c b/drivers/gpu/drm/i915/i915_vma.c
index f137475fab51..490914f89663 100644
--- a/drivers/gpu/drm/i915/i915_vma.c
+++ b/drivers/gpu/drm/i915/i915_vma.c
@@ -91,7 +91,7 @@ __i915_vma_create(struct drm_i915_gem_object *obj,
 	vma->vm = vm;
 	vma->obj = obj;
 	vma->size = obj->base.size;
-	vma->display_alignment = 4096;
+	vma->display_alignment = I915_GTT_MIN_ALIGNMENT;
 
 	if (view) {
 		vma->ggtt_view = *view;
@@ -115,7 +115,7 @@ __i915_vma_create(struct drm_i915_gem_object *obj,
 		vma->fence_size = i915_gem_fence_size(vm->i915, vma->size,
 						      i915_gem_object_get_tiling(obj),
 						      i915_gem_object_get_stride(obj));
-		GEM_BUG_ON(vma->fence_size & 4095);
+		GEM_BUG_ON(!IS_ALIGNED(vma->fence_size, I915_GTT_MIN_ALIGNMENT));
 
 		vma->fence_alignment = i915_gem_fence_alignment(vm->i915, vma->size,
 								i915_gem_object_get_tiling(obj),
@@ -270,7 +270,8 @@ i915_vma_misplaced(struct i915_vma *vma, u64 size, u64 alignment, u64 flags)
 	if (vma->node.size < size)
 		return true;
 
-	if (alignment && vma->node.start & (alignment - 1))
+	GEM_BUG_ON(alignment && !is_power_of_2(alignment));
+	if (alignment && !IS_ALIGNED(vma->node.start, alignment))
 		return true;
 
 	if (flags & PIN_MAPPABLE && !i915_vma_is_map_and_fenceable(vma))
@@ -302,7 +303,7 @@ void __i915_vma_set_map_and_fenceable(struct i915_vma *vma)
 		return;
 
 	fenceable = (vma->node.size >= vma->fence_size &&
-		     (vma->node.start & (vma->fence_alignment - 1)) == 0);
+		     IS_ALIGNED(vma->node.start, vma->fence_alignment));
 
 	mappable = vma->node.start + vma->fence_size <= i915_vm_to_ggtt(vma->vm)->mappable_end;
 
@@ -380,13 +381,19 @@ i915_vma_insert(struct i915_vma *vma, u64 size, u64 alignment, u64 flags)
 				  alignment, vma->fence_alignment);
 	}
 
+	GEM_BUG_ON(!IS_ALIGNED(size, I915_GTT_PAGE_SIZE));
+	GEM_BUG_ON(!IS_ALIGNED(alignment, I915_GTT_MIN_ALIGNMENT));
+	GEM_BUG_ON(!is_power_of_2(alignment));
+
 	start = flags & PIN_OFFSET_BIAS ? flags & PIN_OFFSET_MASK : 0;
+	GEM_BUG_ON(!IS_ALIGNED(start, I915_GTT_PAGE_SIZE));
 
 	end = vma->vm->total;
 	if (flags & PIN_MAPPABLE)
 		end = min_t(u64, end, dev_priv->ggtt.mappable_end);
 	if (flags & PIN_ZONE_4G)
-		end = min_t(u64, end, (1ULL << 32) - PAGE_SIZE);
+		end = min_t(u64, end, (1ULL << 32) - I915_GTT_PAGE_SIZE);
+	GEM_BUG_ON(!IS_ALIGNED(end, I915_GTT_PAGE_SIZE));
 
 	/* If binding the object/GGTT view requires more space than the entire
 	 * aperture has, reject it early before evicting everything in a vain
@@ -406,7 +413,7 @@ i915_vma_insert(struct i915_vma *vma, u64 size, u64 alignment, u64 flags)
 
 	if (flags & PIN_OFFSET_FIXED) {
 		u64 offset = flags & PIN_OFFSET_MASK;
-		if (offset & (alignment - 1) ||
+		if (!IS_ALIGNED(offset, alignment) ||
 		    range_overflows(offset, size, end)) {
 			ret = -EINVAL;
 			goto err_unpin;
@@ -440,7 +447,7 @@ i915_vma_insert(struct i915_vma *vma, u64 size, u64 alignment, u64 flags)
 		 * with zero alignment, so where possible use the optimal
 		 * path.
 		 */
-		if (alignment <= 4096)
+		if (alignment <= I915_GTT_MIN_ALIGNMENT)
 			alignment = 0;
 
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