drm/gpuvm: add an abstraction for a VM / BO combination

Add an abstraction layer between the drm_gpuva mappings of a particular
drm_gem_object and this GEM object itself. The abstraction represents a
combination of a drm_gem_object and drm_gpuvm. The drm_gem_object holds
a list of drm_gpuvm_bo structures (the structure representing this
abstraction), while each drm_gpuvm_bo contains list of mappings of this
GEM object.

This has multiple advantages:

1) We can use the drm_gpuvm_bo structure to attach it to various lists
   of the drm_gpuvm. This is useful for tracking external and evicted
   objects per VM, which is introduced in subsequent patches.

2) Finding mappings of a certain drm_gem_object mapped in a certain
   drm_gpuvm becomes much cheaper.

3) Drivers can derive and extend the structure to easily represent
   driver specific states of a BO for a certain GPUVM.

The idea of this abstraction was taken from amdgpu, hence the credit for
this idea goes to the developers of amdgpu.

Cc: Christian König <christian.koenig@amd.com>
Acked-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Signed-off-by: Danilo Krummrich <dakr@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231108001259.15123-11-dakr@redhat.com

1 files changed, 180 insertions, 5 deletions

diff --git a/include/drm/drm_gpuvm.h b/include/drm/drm_gpuvm.h
index 4e6e1fd3485a..b12fb22b0e22 100644
--- a/include/drm/drm_gpuvm.h
+++ b/include/drm/drm_gpuvm.h
@@ -25,6 +25,7 @@
  * OTHER DEALINGS IN THE SOFTWARE.
  */
 
+#include <linux/dma-resv.h>
 #include <linux/list.h>
 #include <linux/rbtree.h>
 #include <linux/types.h>
@@ -33,6 +34,7 @@
 #include <drm/drm_gem.h>
 
 struct drm_gpuvm;
+struct drm_gpuvm_bo;
 struct drm_gpuvm_ops;
 
 /**
@@ -74,6 +76,12 @@ struct drm_gpuva {
 	struct drm_gpuvm *vm;
 
 	/**
+	 * @vm_bo: the &drm_gpuvm_bo abstraction for the mapped
+	 * &drm_gem_object
+	 */
+	struct drm_gpuvm_bo *vm_bo;
+
+	/**
 	 * @flags: the &drm_gpuva_flags for this mapping
 	 */
 	enum drm_gpuva_flags flags;
@@ -108,7 +116,7 @@ struct drm_gpuva {
 		struct drm_gem_object *obj;
 
 		/**
-		 * @entry: the &list_head to attach this object to a &drm_gem_object
+		 * @entry: the &list_head to attach this object to a &drm_gpuvm_bo
 		 */
 		struct list_head entry;
 	} gem;
@@ -141,7 +149,7 @@ struct drm_gpuva {
 int drm_gpuva_insert(struct drm_gpuvm *gpuvm, struct drm_gpuva *va);
 void drm_gpuva_remove(struct drm_gpuva *va);
 
-void drm_gpuva_link(struct drm_gpuva *va);
+void drm_gpuva_link(struct drm_gpuva *va, struct drm_gpuvm_bo *vm_bo);
 void drm_gpuva_unlink(struct drm_gpuva *va);
 
 struct drm_gpuva *drm_gpuva_find(struct drm_gpuvm *gpuvm,
@@ -189,9 +197,15 @@ static inline bool drm_gpuva_invalidated(struct drm_gpuva *va)
  */
 enum drm_gpuvm_flags {
 	/**
+	 * @DRM_GPUVM_RESV_PROTECTED: GPUVM is protected externally by the
+	 * GPUVM's &dma_resv lock
+	 */
+	DRM_GPUVM_RESV_PROTECTED = BIT(0),
+
+	/**
 	 * @DRM_GPUVM_USERBITS: user defined bits
 	 */
-	DRM_GPUVM_USERBITS = BIT(0),
+	DRM_GPUVM_USERBITS = BIT(1),
 };
 
 /**
@@ -303,6 +317,19 @@ struct drm_gem_object *
 drm_gpuvm_resv_object_alloc(struct drm_device *drm);
 
 /**
+ * drm_gpuvm_resv_protected() - indicates whether &DRM_GPUVM_RESV_PROTECTED is
+ * set
+ * @gpuvm: the &drm_gpuvm
+ *
+ * Returns: true if &DRM_GPUVM_RESV_PROTECTED is set, false otherwise.
+ */
+static inline bool
+drm_gpuvm_resv_protected(struct drm_gpuvm *gpuvm)
+{
+	return gpuvm->flags & DRM_GPUVM_RESV_PROTECTED;
+}
+
+/**
  * drm_gpuvm_resv() - returns the &drm_gpuvm's &dma_resv
  * @gpuvm__: the &drm_gpuvm
  *
@@ -326,6 +353,12 @@ drm_gpuvm_resv_object_alloc(struct drm_device *drm);
 #define drm_gpuvm_resv_assert_held(gpuvm__) \
 	dma_resv_assert_held(drm_gpuvm_resv(gpuvm__))
 
+#define drm_gpuvm_resv_held(gpuvm__) \
+	dma_resv_held(drm_gpuvm_resv(gpuvm__))
+
+#define drm_gpuvm_resv_assert_held(gpuvm__) \
+	dma_resv_assert_held(drm_gpuvm_resv(gpuvm__))
+
 static inline struct drm_gpuva *
 __drm_gpuva_next(struct drm_gpuva *va)
 {
@@ -405,6 +438,125 @@ __drm_gpuva_next(struct drm_gpuva *va)
 	list_for_each_entry_safe(va__, next__, &(gpuvm__)->rb.list, rb.entry)
 
 /**
+ * struct drm_gpuvm_bo - structure representing a &drm_gpuvm and
+ * &drm_gem_object combination
+ *
+ * This structure is an abstraction representing a &drm_gpuvm and
+ * &drm_gem_object combination. It serves as an indirection to accelerate
+ * iterating all &drm_gpuvas within a &drm_gpuvm backed by the same
+ * &drm_gem_object.
+ *
+ * Furthermore it is used cache evicted GEM objects for a certain GPU-VM to
+ * accelerate validation.
+ *
+ * Typically, drivers want to create an instance of a struct drm_gpuvm_bo once
+ * a GEM object is mapped first in a GPU-VM and release the instance once the
+ * last mapping of the GEM object in this GPU-VM is unmapped.
+ */
+struct drm_gpuvm_bo {
+	/**
+	 * @vm: The &drm_gpuvm the @obj is mapped in. This is a reference
+	 * counted pointer.
+	 */
+	struct drm_gpuvm *vm;
+
+	/**
+	 * @obj: The &drm_gem_object being mapped in @vm. This is a reference
+	 * counted pointer.
+	 */
+	struct drm_gem_object *obj;
+
+	/**
+	 * @kref: The reference count for this &drm_gpuvm_bo.
+	 */
+	struct kref kref;
+
+	/**
+	 * @list: Structure containing all &list_heads.
+	 */
+	struct {
+		/**
+		 * @gpuva: The list of linked &drm_gpuvas.
+		 *
+		 * It is safe to access entries from this list as long as the
+		 * GEM's gpuva lock is held. See also struct drm_gem_object.
+		 */
+		struct list_head gpuva;
+
+		/**
+		 * @entry: Structure containing all &list_heads serving as
+		 * entry.
+		 */
+		struct {
+			/**
+			 * @gem: List entry to attach to the &drm_gem_objects
+			 * gpuva list.
+			 */
+			struct list_head gem;
+		} entry;
+	} list;
+};
+
+struct drm_gpuvm_bo *
+drm_gpuvm_bo_create(struct drm_gpuvm *gpuvm,
+		    struct drm_gem_object *obj);
+
+struct drm_gpuvm_bo *
+drm_gpuvm_bo_obtain(struct drm_gpuvm *gpuvm,
+		    struct drm_gem_object *obj);
+struct drm_gpuvm_bo *
+drm_gpuvm_bo_obtain_prealloc(struct drm_gpuvm_bo *vm_bo);
+
+/**
+ * drm_gpuvm_bo_get() - acquire a struct drm_gpuvm_bo reference
+ * @vm_bo: the &drm_gpuvm_bo to acquire the reference of
+ *
+ * This function acquires an additional reference to @vm_bo. It is illegal to
+ * call this without already holding a reference. No locks required.
+ */
+static inline struct drm_gpuvm_bo *
+drm_gpuvm_bo_get(struct drm_gpuvm_bo *vm_bo)
+{
+	kref_get(&vm_bo->kref);
+	return vm_bo;
+}
+
+void drm_gpuvm_bo_put(struct drm_gpuvm_bo *vm_bo);
+
+struct drm_gpuvm_bo *
+drm_gpuvm_bo_find(struct drm_gpuvm *gpuvm,
+		  struct drm_gem_object *obj);
+
+/**
+ * drm_gpuvm_bo_for_each_va() - iterator to walk over a list of &drm_gpuva
+ * @va__: &drm_gpuva structure to assign to in each iteration step
+ * @vm_bo__: the &drm_gpuvm_bo the &drm_gpuva to walk are associated with
+ *
+ * This iterator walks over all &drm_gpuva structures associated with the
+ * &drm_gpuvm_bo.
+ *
+ * The caller must hold the GEM's gpuva lock.
+ */
+#define drm_gpuvm_bo_for_each_va(va__, vm_bo__) \
+	list_for_each_entry(va__, &(vm_bo)->list.gpuva, gem.entry)
+
+/**
+ * drm_gpuvm_bo_for_each_va_safe() - iterator to safely walk over a list of
+ * &drm_gpuva
+ * @va__: &drm_gpuva structure to assign to in each iteration step
+ * @next__: &next &drm_gpuva to store the next step
+ * @vm_bo__: the &drm_gpuvm_bo the &drm_gpuva to walk are associated with
+ *
+ * This iterator walks over all &drm_gpuva structures associated with the
+ * &drm_gpuvm_bo. It is implemented with list_for_each_entry_safe(), hence
+ * it is save against removal of elements.
+ *
+ * The caller must hold the GEM's gpuva lock.
+ */
+#define drm_gpuvm_bo_for_each_va_safe(va__, next__, vm_bo__) \
+	list_for_each_entry_safe(va__, next__, &(vm_bo)->list.gpuva, gem.entry)
+
+/**
  * enum drm_gpuva_op_type - GPU VA operation type
  *
  * Operations to alter the GPU VA mappings tracked by the &drm_gpuvm.
@@ -673,8 +825,7 @@ drm_gpuvm_prefetch_ops_create(struct drm_gpuvm *gpuvm,
 				 u64 addr, u64 range);
 
 struct drm_gpuva_ops *
-drm_gpuvm_gem_unmap_ops_create(struct drm_gpuvm *gpuvm,
-			       struct drm_gem_object *obj);
+drm_gpuvm_bo_unmap_ops_create(struct drm_gpuvm_bo *vm_bo);
 
 void drm_gpuva_ops_free(struct drm_gpuvm *gpuvm,
 			struct drm_gpuva_ops *ops);
@@ -727,6 +878,30 @@ struct drm_gpuvm_ops {
 	void (*op_free)(struct drm_gpuva_op *op);
 
 	/**
+	 * @vm_bo_alloc: called when the &drm_gpuvm allocates
+	 * a struct drm_gpuvm_bo
+	 *
+	 * Some drivers may want to embed struct drm_gpuvm_bo into driver
+	 * specific structures. By implementing this callback drivers can
+	 * allocate memory accordingly.
+	 *
+	 * This callback is optional.
+	 */
+	struct drm_gpuvm_bo *(*vm_bo_alloc)(void);
+
+	/**
+	 * @vm_bo_free: called when the &drm_gpuvm frees a
+	 * struct drm_gpuvm_bo
+	 *
+	 * Some drivers may want to embed struct drm_gpuvm_bo into driver
+	 * specific structures. By implementing this callback drivers can
+	 * free the previously allocated memory accordingly.
+	 *
+	 * This callback is optional.
+	 */
+	void (*vm_bo_free)(struct drm_gpuvm_bo *vm_bo);
+
+	/**
 	 * @sm_step_map: called from &drm_gpuvm_sm_map to finally insert the
 	 * mapping once all previous steps were completed
 	 *