drm/amdgpu: Use mmu_interval_insert instead of hmm_mirror

Remove the interval tree in the driver and rely on the tree maintained by
the mmu_notifier for delivering mmu_notifier invalidation callbacks.

For some reason amdgpu has a very complicated arrangement where it tries
to prevent duplicate entries in the interval_tree, this is not necessary,
each amdgpu_bo can be its own stand alone entry. interval_tree already
allows duplicates and overlaps in the tree.

Also, there is no need to remove entries upon a release callback, the
mmu_interval API safely allows objects to remain registered beyond the
lifetime of the mm. The driver only has to stop touching the pages during
release.

Link: https://lore.kernel.org/r/20191112202231.3856-12-jgg@ziepe.caReviewed-by: Philip Yang <Philip.Yang@amd.com>
Tested-by: Philip Yang <Philip.Yang@amd.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

drivers/gpu/drm/amd/amdgpu/amdgpu.h

@@ -1006,6 +1006,8 @@ struct amdgpu_device {
 	struct mutex  lock_reset;
 	struct amdgpu_doorbell_index doorbell_index;
 
+	struct mutex			notifier_lock;
+
 	int asic_reset_res;
 	struct work_struct		xgmi_reset_work;
 

drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c

@@ -481,8 +481,7 @@ static void remove_kgd_mem_from_kfd_bo_list(struct kgd_mem *mem,
  *
  * Returns 0 for success, negative errno for errors.
  */
-static int init_user_pages(struct kgd_mem *mem, struct mm_struct *mm,
-			   uint64_t user_addr)
+static int init_user_pages(struct kgd_mem *mem, uint64_t user_addr)
 {
 	struct amdkfd_process_info *process_info = mem->process_info;
 	struct amdgpu_bo *bo = mem->bo;
@@ -1195,7 +1194,7 @@ int amdgpu_amdkfd_gpuvm_alloc_memory_of_gpu(
 	add_kgd_mem_to_kfd_bo_list(*mem, avm->process_info, user_addr);
 
 	if (user_addr) {
-		ret = init_user_pages(*mem, current->mm, user_addr);
+		ret = init_user_pages(*mem, user_addr);
 		if (ret)
 			goto allocate_init_user_pages_failed;
 	}

drivers/gpu/drm/amd/amdgpu/amdgpu_device.c

@@ -2633,6 +2633,7 @@ int amdgpu_device_init(struct amdgpu_device *adev,
 	mutex_init(&adev->virt.vf_errors.lock);
 	hash_init(adev->mn_hash);
 	mutex_init(&adev->lock_reset);
+	mutex_init(&adev->notifier_lock);
 	mutex_init(&adev->virt.dpm_mutex);
 	mutex_init(&adev->psp.mutex);
 

drivers/gpu/drm/amd/amdgpu/amdgpu_mn.h

@@ -39,12 +39,10 @@ enum amdgpu_mn_type {
  * struct amdgpu_mn
  *
  * @adev: amdgpu device pointer
- * @mm: process address space
  * @type: type of MMU notifier
  * @work: destruction work item
  * @node: hash table node to find structure by adev and mn
  * @lock: rw semaphore protecting the notifier nodes
- * @objects: interval tree containing amdgpu_mn_nodes
  * @mirror: HMM mirror function support
  *
  * Data for each amdgpu device and process address space.
@@ -52,7 +50,6 @@ enum amdgpu_mn_type {
 struct amdgpu_mn {
 	/* constant after initialisation */
 	struct amdgpu_device	*adev;
-	struct mm_struct	*mm;
 	enum amdgpu_mn_type	type;
 
 	/* only used on destruction */
@@ -63,7 +60,6 @@ struct amdgpu_mn {
 
 	/* objects protected by lock */
 	struct rw_semaphore	lock;
-	struct rb_root_cached	objects;
 
 #ifdef CONFIG_HMM_MIRROR
 	/* HMM mirror */

drivers/gpu/drm/amd/amdgpu/amdgpu_object.h

@@ -30,6 +30,9 @@
 
 #include <drm/amdgpu_drm.h>
 #include "amdgpu.h"
+#ifdef CONFIG_MMU_NOTIFIER
+#include <linux/mmu_notifier.h>
+#endif
 
 #define AMDGPU_BO_INVALID_OFFSET	LONG_MAX
 #define AMDGPU_BO_MAX_PLACEMENTS	3
@@ -100,10 +103,12 @@ struct amdgpu_bo {
 	struct ttm_bo_kmap_obj		dma_buf_vmap;
 	struct amdgpu_mn		*mn;
 
-	union {
-		struct list_head	mn_list;
+
+#ifdef CONFIG_MMU_NOTIFIER
+	struct mmu_interval_notifier	notifier;
+#endif
+
 	struct list_head		shadow_list;
-	};
 
 	struct kgd_mem                  *kfd_bo;
 };