drm/i915: Wa32bitGeneralStateOffset & Wa32bitInstructionBaseOffset

There are some allocations that must be only referenced by 32-bit
offsets. To limit the chances of having the first 4GB already full,
objects not requiring this workaround use DRM_MM_SEARCH_BELOW/
DRM_MM_CREATE_TOP flags

In specific, any resource used with flat/heapless (0x00000000-0xfffff000)
General State Heap (GSH) or Instruction State Heap (ISH) must be in a
32-bit range, because the General State Offset and Instruction State
Offset are limited to 32-bits.

Objects must have EXEC_OBJECT_SUPPORTS_48B_ADDRESS flag to indicate if
they can be allocated above the 32-bit address range. To limit the
chances of having the first 4GB already full, objects will use
DRM_MM_SEARCH_BELOW + DRM_MM_CREATE_TOP flags when possible.

The libdrm user of the EXEC_OBJECT_SUPPORTS_48B_ADDRESS flag is here:
http://lists.freedesktop.org/archives/intel-gfx/2015-September/075836.html

v2: Changed flag logic from neeeds_32b, to supports_48b.
v3: Moved 48-bit support flag back to exec_object. (Chris, Daniel)
v4: Split pin flags into PIN_ZONE_4G and PIN_HIGH; update PIN_OFFSET_MASK
to use last PIN_ defined instead of hard-coded value; use correct limit
check in eb_vma_misplaced. (Chris)
v5: Don't touch PIN_OFFSET_MASK and update workaround comment (Chris)
v6: Apply pin-high for ggtt too (Chris)
v7: Handle simultaneous pin-high and pin-mappable end correctly (Akash)
    Fix check for entries currently using +4GB addresses, use min_t and
    other polish in object_bind_to_vm (Chris)
v8: Commit message updated to point to libdrm patch.
v9: vmas are allocated in the correct ozone, so only check flag when the
    vma has not been allocated. (Chris)

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> (v4)
Signed-off-by: Michel Thierry <michel.thierry@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_drv.h

@@ -2819,6 +2819,8 @@ void i915_gem_vma_destroy(struct i915_vma *vma);
 #define PIN_OFFSET_BIAS	(1<<3)
 #define PIN_USER	(1<<4)
 #define PIN_UPDATE	(1<<5)
+#define PIN_ZONE_4G	(1<<6)
+#define PIN_HIGH	(1<<7)
 #define PIN_OFFSET_MASK (~4095)
 int __must_check
 i915_gem_object_pin(struct drm_i915_gem_object *obj,

drivers/gpu/drm/i915/i915_gem.c

@@ -3354,11 +3354,9 @@ i915_gem_object_bind_to_vm(struct drm_i915_gem_object *obj,
 	struct drm_device *dev = obj->base.dev;
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	u32 fence_alignment, unfenced_alignment;
+	u32 search_flag, alloc_flag;
+	u64 start, end;
 	u64 size, fence_size;
-	u64 start =
-		flags & PIN_OFFSET_BIAS ? flags & PIN_OFFSET_MASK : 0;
-	u64 end =
-		flags & PIN_MAPPABLE ? dev_priv->gtt.mappable_end : vm->total;
 	struct i915_vma *vma;
 	int ret;
 
@@ -3398,6 +3396,13 @@ i915_gem_object_bind_to_vm(struct drm_i915_gem_object *obj,
 		size = flags & PIN_MAPPABLE ? fence_size : obj->base.size;
 	}
 
+	start = flags & PIN_OFFSET_BIAS ? flags & PIN_OFFSET_MASK : 0;
+	end = vm->total;
+	if (flags & PIN_MAPPABLE)
+		end = min_t(u64, end, dev_priv->gtt.mappable_end);
+	if (flags & PIN_ZONE_4G)
+		end = min_t(u64, end, (1ULL << 32));
+
 	if (alignment == 0)
 		alignment = flags & PIN_MAPPABLE ? fence_alignment :
 						unfenced_alignment;
@@ -3433,13 +3438,21 @@ i915_gem_object_bind_to_vm(struct drm_i915_gem_object *obj,
 	if (IS_ERR(vma))
 		goto err_unpin;
 
+	if (flags & PIN_HIGH) {
+		search_flag = DRM_MM_SEARCH_BELOW;
+		alloc_flag = DRM_MM_CREATE_TOP;
+	} else {
+		search_flag = DRM_MM_SEARCH_DEFAULT;
+		alloc_flag = DRM_MM_CREATE_DEFAULT;
+	}
+
 search_free:
 	ret = drm_mm_insert_node_in_range_generic(&vm->mm, &vma->node,
 						  size, alignment,
 						  obj->cache_level,
 						  start, end,
-						  DRM_MM_SEARCH_DEFAULT,
-						  DRM_MM_CREATE_DEFAULT);
+						  search_flag,
+						  alloc_flag);
 	if (ret) {
 		ret = i915_gem_evict_something(dev, vm, size, alignment,
 					       obj->cache_level,

drivers/gpu/drm/i915/i915_gem_execbuffer.c

@@ -590,10 +590,17 @@ i915_gem_execbuffer_reserve_vma(struct i915_vma *vma,
 		flags |= PIN_GLOBAL;
 
 	if (!drm_mm_node_allocated(&vma->node)) {
+		/* Wa32bitGeneralStateOffset & Wa32bitInstructionBaseOffset,
+		 * limit address to the first 4GBs for unflagged objects.
+		 */
+		if ((entry->flags & EXEC_OBJECT_SUPPORTS_48B_ADDRESS) == 0)
+			flags |= PIN_ZONE_4G;
 		if (entry->flags & __EXEC_OBJECT_NEEDS_MAP)
 			flags |= PIN_GLOBAL | PIN_MAPPABLE;
 		if (entry->flags & __EXEC_OBJECT_NEEDS_BIAS)
 			flags |= BATCH_OFFSET_BIAS | PIN_OFFSET_BIAS;
+		if ((flags & PIN_MAPPABLE) == 0)
+			flags |= PIN_HIGH;
 	}
 
 	ret = i915_gem_object_pin(obj, vma->vm, entry->alignment, flags);
@@ -671,6 +678,10 @@ eb_vma_misplaced(struct i915_vma *vma)
 	if (entry->flags & __EXEC_OBJECT_NEEDS_MAP && !obj->map_and_fenceable)
 		return !only_mappable_for_reloc(entry->flags);
 
+	if ((entry->flags & EXEC_OBJECT_SUPPORTS_48B_ADDRESS) == 0 &&
+	    (vma->node.start + vma->node.size - 1) >> 32)
+		return true;
+
 	return false;
 }
 

include/uapi/drm/i915_drm.h

@@ -690,7 +690,8 @@ struct drm_i915_gem_exec_object2 {
 #define EXEC_OBJECT_NEEDS_FENCE (1<<0)
 #define EXEC_OBJECT_NEEDS_GTT	(1<<1)
 #define EXEC_OBJECT_WRITE	(1<<2)
-#define __EXEC_OBJECT_UNKNOWN_FLAGS -(EXEC_OBJECT_WRITE<<1)
+#define EXEC_OBJECT_SUPPORTS_48B_ADDRESS (1<<3)
+#define __EXEC_OBJECT_UNKNOWN_FLAGS -(EXEC_OBJECT_SUPPORTS_48B_ADDRESS<<1)
 	__u64 flags;
 
 	__u64 rsvd1;