drm/vma: provide drm_vma_node_unmap() helper

Instead of unmapping the nodes in TTM and GEM users manually, we provide
a generic wrapper which does the correct thing for all vma-nodes.

v2: remove bdev->dev_mapping test in ttm_bo_unmap_virtual_unlocked() as
ttm_mem_io_free_vm() does nothing in that case (io_reserved_vm is 0).
v4: Fix docbook comments
v5: use drm_vma_node_size()

Cc: Dave Airlie <airlied@redhat.com>
Cc: Maarten Lankhorst <maarten.lankhorst@canonical.com>
Cc: Thomas Hellstrom <thellstrom@vmware.com>
Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Dave Airlie <airlied@gmail.com>

drivers/gpu/drm/i915/i915_gem.c

@@ -1427,11 +1427,7 @@ i915_gem_release_mmap(struct drm_i915_gem_object *obj)
 	if (!obj->fault_mappable)
 		return;
 
-	if (obj->base.dev->dev_mapping)
-		unmap_mapping_range(obj->base.dev->dev_mapping,
-				    (loff_t)drm_vma_node_offset_addr(&obj->base.vma_node),
-				    obj->base.size, 1);
-
+	drm_vma_node_unmap(&obj->base.vma_node, obj->base.dev->dev_mapping);
 	obj->fault_mappable = false;
 }
 

drivers/gpu/drm/ttm/ttm_bo.c

@@ -1488,17 +1488,8 @@ bool ttm_mem_reg_is_pci(struct ttm_bo_device *bdev, struct ttm_mem_reg *mem)
 void ttm_bo_unmap_virtual_locked(struct ttm_buffer_object *bo)
 {
 	struct ttm_bo_device *bdev = bo->bdev;
-	loff_t offset, holelen;
 
-	if (!bdev->dev_mapping)
-		return;
-
-	if (drm_vma_node_has_offset(&bo->vma_node)) {
-		offset = (loff_t) drm_vma_node_offset_addr(&bo->vma_node);
-		holelen = ((loff_t) bo->mem.num_pages) << PAGE_SHIFT;
-
-		unmap_mapping_range(bdev->dev_mapping, offset, holelen, 1);
-	}
+	drm_vma_node_unmap(&bo->vma_node, bdev->dev_mapping);
 	ttm_mem_io_free_vm(bo);
 }
 

include/drm/drm_vma_manager.h

@@ -24,6 +24,7 @@
  */
 
 #include <drm/drm_mm.h>
+#include <linux/mm.h>
 #include <linux/module.h>
 #include <linux/rbtree.h>
 #include <linux/spinlock.h>
@@ -199,4 +200,25 @@ static inline __u64 drm_vma_node_offset_addr(struct drm_vma_offset_node *node)
 	return ((__u64)node->vm_node.start) << PAGE_SHIFT;
 }
 
+/**
+ * drm_vma_node_unmap() - Unmap offset node
+ * @node: Offset node
+ * @file_mapping: Address space to unmap @node from
+ *
+ * Unmap all userspace mappings for a given offset node. The mappings must be
+ * associated with the @file_mapping address-space. If no offset exists or
+ * the address-space is invalid, nothing is done.
+ *
+ * This call is unlocked. The caller must guarantee that drm_vma_offset_remove()
+ * is not called on this node concurrently.
+ */
+static inline void drm_vma_node_unmap(struct drm_vma_offset_node *node,
+				      struct address_space *file_mapping)
+{
+	if (file_mapping && drm_vma_node_has_offset(node))
+		unmap_mapping_range(file_mapping,
+				    drm_vma_node_offset_addr(node),
+				    drm_vma_node_size(node) << PAGE_SHIFT, 1);
+}
+
 #endif /* __DRM_VMA_MANAGER_H__ */