drm/i915: Use ttm mmap handling for ttm bo's.

Use the ttm handlers for servicing page faults, and vm_access.

We do our own validation of read-only access, otherwise use the
ttm handlers as much as possible.

Because the ttm handlers expect the vma_node at vma->base, we slightly
need to massage the mmap handlers to look at vma_node->driver_private
to fetch the bo, if it's NULL, we assume i915's normal mmap_offset uapi
is used.

This is the easiest way to achieve compatibility without changing ttm's
semantics.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210610070152.572423-5-thomas.hellstrom@linux.intel.com

drivers/gpu/drm/i915/gem/i915_gem_mman.c

@@ -19,6 +19,7 @@
 #include "i915_gem_mman.h"
 #include "i915_trace.h"
 #include "i915_user_extensions.h"
+#include "i915_gem_ttm.h"
 #include "i915_vma.h"
 
 static inline bool
@@ -623,6 +624,8 @@ mmap_offset_attach(struct drm_i915_gem_object *obj,
 	struct i915_mmap_offset *mmo;
 	int err;
 
+	GEM_BUG_ON(obj->ops->mmap_offset || obj->ops->mmap_ops);
+
 	mmo = lookup_mmo(obj, mmap_type);
 	if (mmo)
 		goto out;
@@ -665,40 +668,47 @@ mmap_offset_attach(struct drm_i915_gem_object *obj,
 }
 
 static int
-__assign_mmap_offset(struct drm_file *file,
-		     u32 handle,
+__assign_mmap_offset(struct drm_i915_gem_object *obj,
 		     enum i915_mmap_type mmap_type,
-		     u64 *offset)
+		     u64 *offset, struct drm_file *file)
 {
-	struct drm_i915_gem_object *obj;
 	struct i915_mmap_offset *mmo;
-	int err;
 
-	obj = i915_gem_object_lookup(file, handle);
-	if (!obj)
-		return -ENOENT;
+	if (i915_gem_object_never_mmap(obj))
+		return -ENODEV;
 
-	if (i915_gem_object_never_mmap(obj)) {
-		err = -ENODEV;
-		goto out;
+	if (obj->ops->mmap_offset)  {
+		*offset = obj->ops->mmap_offset(obj);
+		return 0;
 	}
 
 	if (mmap_type != I915_MMAP_TYPE_GTT &&
 	    !i915_gem_object_has_struct_page(obj) &&
-	    !i915_gem_object_type_has(obj, I915_GEM_OBJECT_HAS_IOMEM)) {
-		err = -ENODEV;
-		goto out;
-	}
+	    !i915_gem_object_type_has(obj, I915_GEM_OBJECT_HAS_IOMEM))
+		return -ENODEV;
 
 	mmo = mmap_offset_attach(obj, mmap_type, file);
-	if (IS_ERR(mmo)) {
-		err = PTR_ERR(mmo);
-		goto out;
-	}
+	if (IS_ERR(mmo))
+		return PTR_ERR(mmo);
 
 	*offset = drm_vma_node_offset_addr(&mmo->vma_node);
-	err = 0;
-out:
+	return 0;
+}
+
+static int
+__assign_mmap_offset_handle(struct drm_file *file,
+			    u32 handle,
+			    enum i915_mmap_type mmap_type,
+			    u64 *offset)
+{
+	struct drm_i915_gem_object *obj;
+	int err;
+
+	obj = i915_gem_object_lookup(file, handle);
+	if (!obj)
+		return -ENOENT;
+
+	err = __assign_mmap_offset(obj, mmap_type, offset, file);
 	i915_gem_object_put(obj);
 	return err;
 }
@@ -718,7 +728,7 @@ i915_gem_dumb_mmap_offset(struct drm_file *file,
 	else
 		mmap_type = I915_MMAP_TYPE_GTT;
 
-	return __assign_mmap_offset(file, handle, mmap_type, offset);
+	return __assign_mmap_offset_handle(file, handle, mmap_type, offset);
 }
 
 /**
@@ -786,7 +796,7 @@ i915_gem_mmap_offset_ioctl(struct drm_device *dev, void *data,
 		return -EINVAL;
 	}
 
-	return __assign_mmap_offset(file, args->handle, type, &args->offset);
+	return __assign_mmap_offset_handle(file, args->handle, type, &args->offset);
 }
 
 static void vm_open(struct vm_area_struct *vma)
@@ -890,8 +900,18 @@ int i915_gem_mmap(struct file *filp, struct vm_area_struct *vma)
 		 * destroyed and will be invalid when the vma manager lock
 		 * is released.
 		 */
-		mmo = container_of(node, struct i915_mmap_offset, vma_node);
-		obj = i915_gem_object_get_rcu(mmo->obj);
+		if (!node->driver_private) {
+			mmo = container_of(node, struct i915_mmap_offset, vma_node);
+			obj = i915_gem_object_get_rcu(mmo->obj);
+
+			GEM_BUG_ON(obj && obj->ops->mmap_ops);
+		} else {
+			obj = i915_gem_object_get_rcu
+				(container_of(node, struct drm_i915_gem_object,
+					      base.vma_node));
+
+			GEM_BUG_ON(obj && !obj->ops->mmap_ops);
+		}
 	}
 	drm_vma_offset_unlock_lookup(dev->vma_offset_manager);
 	rcu_read_unlock();
@@ -913,7 +933,9 @@ int i915_gem_mmap(struct file *filp, struct vm_area_struct *vma)
 	}
 
 	vma->vm_flags |= VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP;
-	vma->vm_private_data = mmo;
+
+	if (i915_gem_object_has_iomem(obj))
+		vma->vm_flags |= VM_IO;
 
 	/*
 	 * We keep the ref on mmo->obj, not vm_file, but we require
@@ -927,6 +949,15 @@ int i915_gem_mmap(struct file *filp, struct vm_area_struct *vma)
 	/* Drop the initial creation reference, the vma is now holding one. */
 	fput(anon);
 
+	if (obj->ops->mmap_ops) {
+		vma->vm_page_prot = pgprot_decrypted(vm_get_page_prot(vma->vm_flags));
+		vma->vm_ops = obj->ops->mmap_ops;
+		vma->vm_private_data = node->driver_private;
+		return 0;
+	}
+
+	vma->vm_private_data = mmo;
+
 	switch (mmo->mmap_type) {
 	case I915_MMAP_TYPE_WC:
 		vma->vm_page_prot =

drivers/gpu/drm/i915/gem/i915_gem_object.h

@@ -342,22 +342,22 @@ struct scatterlist *
 __i915_gem_object_get_sg(struct drm_i915_gem_object *obj,
 			 struct i915_gem_object_page_iter *iter,
 			 unsigned int n,
-			 unsigned int *offset, bool allow_alloc);
+			 unsigned int *offset, bool allow_alloc, bool dma);
 
 static inline struct scatterlist *
 i915_gem_object_get_sg(struct drm_i915_gem_object *obj,
 		       unsigned int n,
 		       unsigned int *offset, bool allow_alloc)
 {
-	return __i915_gem_object_get_sg(obj, &obj->mm.get_page, n, offset, allow_alloc);
+	return __i915_gem_object_get_sg(obj, &obj->mm.get_page, n, offset, allow_alloc, false);
 }
 
 static inline struct scatterlist *
 i915_gem_object_get_sg_dma(struct drm_i915_gem_object *obj,
 			   unsigned int n,
 			   unsigned int *offset, bool allow_alloc)
 {
-	return __i915_gem_object_get_sg(obj, &obj->mm.get_dma_page, n, offset, allow_alloc);
+	return __i915_gem_object_get_sg(obj, &obj->mm.get_dma_page, n, offset, allow_alloc, true);
 }
 
 struct page *

drivers/gpu/drm/i915/gem/i915_gem_object_types.h

@@ -61,6 +61,7 @@ struct drm_i915_gem_object_ops {
 		     const struct drm_i915_gem_pread *arg);
 	int (*pwrite)(struct drm_i915_gem_object *obj,
 		      const struct drm_i915_gem_pwrite *arg);
+	u64 (*mmap_offset)(struct drm_i915_gem_object *obj);
 
 	int (*dmabuf_export)(struct drm_i915_gem_object *obj);
 
@@ -79,6 +80,7 @@ struct drm_i915_gem_object_ops {
 	void (*delayed_free)(struct drm_i915_gem_object *obj);
 	void (*release)(struct drm_i915_gem_object *obj);
 
+	const struct vm_operations_struct *mmap_ops;
 	const char *name; /* friendly name for debug, e.g. lockdep classes */
 };
 
@@ -328,6 +330,7 @@ struct drm_i915_gem_object {
 
 	struct {
 		struct sg_table *cached_io_st;
+		struct i915_gem_object_page_iter get_io_page;
 		bool created:1;
 	} ttm;
 

drivers/gpu/drm/i915/gem/i915_gem_pages.c

@@ -467,9 +467,8 @@ __i915_gem_object_get_sg(struct drm_i915_gem_object *obj,
 			 struct i915_gem_object_page_iter *iter,
 			 unsigned int n,
 			 unsigned int *offset,
-			 bool allow_alloc)
+			 bool allow_alloc, bool dma)
 {
-	const bool dma = iter == &obj->mm.get_dma_page;
 	struct scatterlist *sg;
 	unsigned int idx, count;