drm/i915: Use vma resources for async unbinding

Implement async (non-blocking) unbinding by not syncing the vma before
calling unbind on the vma_resource.
Add the resulting unbind fence to the object's dma_resv from where it is
picked up by the ttm migration code.
Ideally these unbind fences should be coalesced with the migration blit
fence to avoid stalling the migration blit waiting for unbind, as they
can certainly go on in parallel, but since we don't yet have a
reasonable data structure to use to coalesce fences and attach the
resulting fence to a timeline, we defer that for now.

Note that with async unbinding, even while the unbind waits for the
preceding bind to complete before unbinding, the vma itself might have been
destroyed in the process, clearing the vma pages. Therefore we can
only allow async unbinding if we have a refcounted sg-list and keep a
refcount on that for the vma resource pages to stay intact until
binding occurs. If this condition is not met, a request for an async
unbind is diverted to a sync unbind.

v2:
- Use a separate kmem_cache for vma resources for now to isolate their
  memory allocation and aid debugging.
- Move the check for vm closed to the actual unbinding thread. Regardless
  of whether the vm is closed, we need the unbind fence to properly wait
  for capture.
- Clear vma_res::vm on unbind and update its documentation.
v4:
- Take cache coloring into account when searching for vma resources
  pending unbind. (Matthew Auld)
v5:
- Fix timeout and error check in i915_vma_resource_bind_dep_await().
- Avoid taking a reference on the object for async binding if
  async unbind capable.
- Fix braces around a single-line if statement.
v6:
- Fix up the cache coloring adjustment. (Kernel test robot <lkp@intel.com>)
- Don't allow async unbinding if the vma_res pages are not the same as
  the object pages. (Matthew Auld)
v7:
- s/unsigned long/u64/ in a number of places (Matthew Auld)

Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220110172219.107131-5-thomas.hellstrom@linux.intel.com

1 files changed, 48 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/i915_vma_resource.h b/drivers/gpu/drm/i915/i915_vma_resource.h
index 8071b40f4f9c..cb3f4e1e8457 100644
--- a/drivers/gpu/drm/i915/i915_vma_resource.h
+++ b/drivers/gpu/drm/i915/i915_vma_resource.h
@@ -10,6 +10,8 @@
 #include <linux/refcount.h>
 
 #include "i915_gem.h"
+#include "i915_sw_fence.h"
+#include "intel_runtime_pm.h"
 
 struct i915_page_sizes {
 	/**
@@ -38,6 +40,13 @@ struct i915_page_sizes {
  * @hold_count: Number of holders blocking the fence from finishing.
  * The vma itself is keeping a hold, which is released when unbind
  * is scheduled.
+ * @work: Work struct for deferred unbind work.
+ * @chain: Pointer to struct i915_sw_fence used to await dependencies.
+ * @rb: Rb node for the vm's pending unbind interval tree.
+ * @__subtree_last: Interval tree private member.
+ * @vm: non-refcounted pointer to the vm. This is for internal use only and
+ * this member is cleared after vm_resource unbind.
+ * @ops: Pointer to the backend i915_vma_ops.
  * @private: Bind backend private info.
  * @start: Offset into the address space of bind range start.
  * @node_size: Size of the allocated range manager node.
@@ -45,6 +54,8 @@ struct i915_page_sizes {
  * @page_sizes_gtt: Resulting page sizes from the bind operation.
  * @bound_flags: Flags indicating binding status.
  * @allocated: Backend private data. TODO: Should move into @private.
+ * @immediate_unbind: Unbind can be done immediately and don't need to be
+ * deferred to a work item awaiting unsignaled fences.
  *
  * The lifetime of a struct i915_vma_resource is from a binding request to
  * the actual possible asynchronous unbind has completed.
@@ -54,6 +65,12 @@ struct i915_vma_resource {
 	/* See above for description of the lock. */
 	spinlock_t lock;
 	refcount_t hold_count;
+	struct work_struct work;
+	struct i915_sw_fence chain;
+	struct rb_node rb;
+	u64 __subtree_last;
+	struct i915_address_space *vm;
+	intel_wakeref_t wakeref;
 
 	/**
 	 * struct i915_vma_bindinfo - Information needed for async bind
@@ -73,13 +90,17 @@ struct i915_vma_resource {
 		bool lmem:1;
 	} bi;
 
+	const struct i915_vma_ops *ops;
 	void *private;
 	u64 start;
 	u64 node_size;
 	u64 vma_size;
 	u32 page_sizes_gtt;
+
 	u32 bound_flags;
 	bool allocated:1;
+	bool immediate_unbind:1;
+	bool needs_wakeref:1;
 };
 
 bool i915_vma_resource_hold(struct i915_vma_resource *vma_res,
@@ -90,6 +111,8 @@ void i915_vma_resource_unhold(struct i915_vma_resource *vma_res,
 
 struct i915_vma_resource *i915_vma_resource_alloc(void);
 
+void i915_vma_resource_free(struct i915_vma_resource *vma_res);
+
 struct dma_fence *i915_vma_resource_unbind(struct i915_vma_resource *vma_res);
 
 void __i915_vma_resource_init(struct i915_vma_resource *vma_res);
@@ -119,10 +142,12 @@ static inline void i915_vma_resource_put(struct i915_vma_resource *vma_res)
 /**
  * i915_vma_resource_init - Initialize a vma resource.
  * @vma_res: The vma resource to initialize
+ * @vm: Pointer to the vm.
  * @pages: The pages sg-table.
  * @page_sizes: Page sizes of the pages.
  * @readonly: Whether the vma should be bound read-only.
  * @lmem: Whether the vma points to lmem.
+ * @ops: The backend ops.
  * @private: Bind backend private info.
  * @start: Offset into the address space of bind range start.
  * @node_size: Size of the allocated range manager node.
@@ -134,20 +159,24 @@ static inline void i915_vma_resource_put(struct i915_vma_resource *vma_res)
  * allocation is not allowed.
  */
 static inline void i915_vma_resource_init(struct i915_vma_resource *vma_res,
+					  struct i915_address_space *vm,
 					  struct sg_table *pages,
 					  const struct i915_page_sizes *page_sizes,
 					  bool readonly,
 					  bool lmem,
+					  const struct i915_vma_ops *ops,
 					  void *private,
 					  u64 start,
 					  u64 node_size,
 					  u64 size)
 {
 	__i915_vma_resource_init(vma_res);
+	vma_res->vm = vm;
 	vma_res->bi.pages = pages;
 	vma_res->bi.page_sizes = *page_sizes;
 	vma_res->bi.readonly = readonly;
 	vma_res->bi.lmem = lmem;
+	vma_res->ops = ops;
 	vma_res->private = private;
 	vma_res->start = start;
 	vma_res->node_size = node_size;
@@ -157,6 +186,25 @@ static inline void i915_vma_resource_init(struct i915_vma_resource *vma_res,
 static inline void i915_vma_resource_fini(struct i915_vma_resource *vma_res)
 {
 	GEM_BUG_ON(refcount_read(&vma_res->hold_count) != 1);
+	i915_sw_fence_fini(&vma_res->chain);
 }
 
+int i915_vma_resource_bind_dep_sync(struct i915_address_space *vm,
+				    u64 first,
+				    u64 last,
+				    bool intr);
+
+int i915_vma_resource_bind_dep_await(struct i915_address_space *vm,
+				     struct i915_sw_fence *sw_fence,
+				     u64 first,
+				     u64 last,
+				     bool intr,
+				     gfp_t gfp);
+
+void i915_vma_resource_bind_dep_sync_all(struct i915_address_space *vm);
+
+void i915_vma_resource_module_exit(void);
+
+int i915_vma_resource_module_init(void);
+
 #endif