drm/ttm: Fix up io_mem_reserve / io_mem_free calling

This patch attempts to fix up shortcomings with the current calling
sequences.

1) There's a fastpath where no locking occurs and only io_mem_reserved is
   called to obtain needed info for mapping. The fastpath is set per
   memory type manager.
2) If the fastpath is disabled, io_mem_reserve and io_mem_free will be exactly
   balanced and not called recursively for the same struct ttm_mem_reg.
3) Optionally the driver can choose to enable a per memory type manager LRU
   eviction mechanism that, when io_mem_reserve returns -EAGAIN will attempt
   to kill user-space mappings of memory in that manager to free up needed
   resources

Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Ben Skeggs <bskeggs@redhat.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

2 files changed, 60 insertions, 50 deletions

diff --git a/include/drm/ttm/ttm_bo_api.h b/include/drm/ttm/ttm_bo_api.h
index edacd483c59c..50852aad260a 100644
--- a/include/drm/ttm/ttm_bo_api.h
+++ b/include/drm/ttm/ttm_bo_api.h
@@ -74,6 +74,8 @@ struct ttm_placement {
  * @is_iomem:           is this io memory ?
  * @size:               size in byte
  * @offset:             offset from the base address
+ * @io_reserved_vm:     The VM system has a refcount in @io_reserved_count
+ * @io_reserved_count:  Refcounting the numbers of callers to ttm_mem_io_reserve
  *
  * Structure indicating the bus placement of an object.
  */
@@ -83,7 +85,8 @@ struct ttm_bus_placement {
         unsigned long   size;
         unsigned long   offset;
         bool            is_iomem;
-        bool            io_reserved;
+        bool            io_reserved_vm;
+        uint64_t        io_reserved_count;
 };
 
 
@@ -235,6 +238,7 @@ struct ttm_buffer_object {
         struct list_head lru;
         struct list_head ddestroy;
         struct list_head swap;
+        struct list_head io_reserve_lru;
         uint32_t val_seq;
         bool seq_valid;
 
diff --git a/include/drm/ttm/ttm_bo_driver.h b/include/drm/ttm/ttm_bo_driver.h
index e3b2e245db1b..1da8af6ac884 100644
--- a/include/drm/ttm/ttm_bo_driver.h
+++ b/include/drm/ttm/ttm_bo_driver.h
@@ -179,30 +179,6 @@ struct ttm_tt {
 #define TTM_MEMTYPE_FLAG_MAPPABLE      (1 << 1) /* Memory mappable */
 #define TTM_MEMTYPE_FLAG_CMA           (1 << 3) /* Can't map aperture */
 
-/**
- * struct ttm_mem_type_manager
- *
- * @has_type: The memory type has been initialized.
- * @use_type: The memory type is enabled.
- * @flags: TTM_MEMTYPE_XX flags identifying the traits of the memory
- * managed by this memory type.
- * @gpu_offset: If used, the GPU offset of the first managed page of
- * fixed memory or the first managed location in an aperture.
- * @size: Size of the managed region.
- * @available_caching: A mask of available caching types, TTM_PL_FLAG_XX,
- * as defined in ttm_placement_common.h
- * @default_caching: The default caching policy used for a buffer object
- * placed in this memory type if the user doesn't provide one.
- * @manager: The range manager used for this memory type. FIXME: If the aperture
- * has a page size different from the underlying system, the granularity
- * of this manager should take care of this. But the range allocating code
- * in ttm_bo.c needs to be modified for this.
- * @lru: The lru list for this memory type.
- *
- * This structure is used to identify and manage memory types for a device.
- * It's set up by the ttm_bo_driver::init_mem_type method.
- */
-
 struct ttm_mem_type_manager;
 
 struct ttm_mem_type_manager_func {
@@ -287,6 +263,36 @@ struct ttm_mem_type_manager_func {
         void (*debug)(struct ttm_mem_type_manager *man, const char *prefix);
 };
 
+/**
+ * struct ttm_mem_type_manager
+ *
+ * @has_type: The memory type has been initialized.
+ * @use_type: The memory type is enabled.
+ * @flags: TTM_MEMTYPE_XX flags identifying the traits of the memory
+ * managed by this memory type.
+ * @gpu_offset: If used, the GPU offset of the first managed page of
+ * fixed memory or the first managed location in an aperture.
+ * @size: Size of the managed region.
+ * @available_caching: A mask of available caching types, TTM_PL_FLAG_XX,
+ * as defined in ttm_placement_common.h
+ * @default_caching: The default caching policy used for a buffer object
+ * placed in this memory type if the user doesn't provide one.
+ * @func: structure pointer implementing the range manager. See above
+ * @priv: Driver private closure for @func.
+ * @io_reserve_mutex: Mutex optionally protecting shared io_reserve structures
+ * @use_io_reserve_lru: Use an lru list to try to unreserve io_mem_regions
+ * reserved by the TTM vm system.
+ * @io_reserve_lru: Optional lru list for unreserving io mem regions.
+ * @io_reserve_fastpath: Only use bdev::driver::io_mem_reserve to obtain
+ * static information. bdev::driver::io_mem_free is never used.
+ * @lru: The lru list for this memory type.
+ *
+ * This structure is used to identify and manage memory types for a device.
+ * It's set up by the ttm_bo_driver::init_mem_type method.
+ */
+
+
+
 struct ttm_mem_type_manager {
         struct ttm_bo_device *bdev;
 
@@ -303,6 +309,15 @@ struct ttm_mem_type_manager {
         uint32_t default_caching;
         const struct ttm_mem_type_manager_func *func;
         void *priv;
+        struct mutex io_reserve_mutex;
+        bool use_io_reserve_lru;
+        bool io_reserve_fastpath;
+
+        /*
+         * Protected by @io_reserve_mutex:
+         */
+
+        struct list_head io_reserve_lru;
 
         /*
          * Protected by the global->lru_lock.
@@ -758,31 +773,6 @@ extern void ttm_bo_mem_put_locked(struct ttm_buffer_object *bo,
 
 extern int ttm_bo_wait_cpu(struct ttm_buffer_object *bo, bool no_wait);
 
-/**
- * ttm_bo_pci_offset - Get the PCI offset for the buffer object memory.
- *
- * @bo Pointer to a struct ttm_buffer_object.
- * @bus_base On return the base of the PCI region
- * @bus_offset On return the byte offset into the PCI region
- * @bus_size On return the byte size of the buffer object or zero if
- * the buffer object memory is not accessible through a PCI region.
- *
- * Returns:
- * -EINVAL if the buffer object is currently not mappable.
- * 0 otherwise.
- */
-
-extern int ttm_bo_pci_offset(struct ttm_bo_device *bdev,
-                             struct ttm_mem_reg *mem,
-                             unsigned long *bus_base,
-                             unsigned long *bus_offset,
-                             unsigned long *bus_size);
-
-extern int ttm_mem_io_reserve(struct ttm_bo_device *bdev,
-                                struct ttm_mem_reg *mem);
-extern void ttm_mem_io_free(struct ttm_bo_device *bdev,
-                                struct ttm_mem_reg *mem);
-
 extern void ttm_bo_global_release(struct drm_global_reference *ref);
 extern int ttm_bo_global_init(struct drm_global_reference *ref);
 
@@ -815,6 +805,22 @@ extern int ttm_bo_device_init(struct ttm_bo_device *bdev,
 extern void ttm_bo_unmap_virtual(struct ttm_buffer_object *bo);
 
 /**
+ * ttm_bo_unmap_virtual
+ *
+ * @bo: tear down the virtual mappings for this BO
+ *
+ * The caller must take ttm_mem_io_lock before calling this function.
+ */
+extern void ttm_bo_unmap_virtual_locked(struct ttm_buffer_object *bo);
+
+extern int ttm_mem_io_reserve_vm(struct ttm_buffer_object *bo);
+extern void ttm_mem_io_free_vm(struct ttm_buffer_object *bo);
+extern int ttm_mem_io_lock(struct ttm_mem_type_manager *man,
+                           bool interruptible);
+extern void ttm_mem_io_unlock(struct ttm_mem_type_manager *man);
+
+
+/**
  * ttm_bo_reserve:
  *
  * @bo: A pointer to a struct ttm_buffer_object.