drm/amdgpu: Add notifier lock for KFD userptrs

Add a per-process MMU notifier lock for processing notifiers from
userptrs. Use that lock to properly synchronize page table updates with
MMU notifiers.
Signed-off-by: Felix Kuehling <Felix.Kuehling@amd.com>
Reviewed-by: Xiaogang Chen<Xiaogang.Chen@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -29,6 +29,7 @@
 #include <linux/mm.h>
 #include <linux/kthread.h>
 #include <linux/workqueue.h>
+#include <linux/mmu_notifier.h>
 #include <kgd_kfd_interface.h>
 #include <drm/ttm/ttm_execbuf_util.h>
 #include "amdgpu_sync.h"
@@ -65,6 +66,7 @@ struct kgd_mem {
 	struct mutex lock;
 	struct amdgpu_bo *bo;
 	struct dma_buf *dmabuf;
+	struct hmm_range *range;
 	struct list_head attachments;
 	/* protected by amdkfd_process_info.lock */
 	struct ttm_validate_buffer validate_list;
@@ -75,7 +77,7 @@ struct kgd_mem {
 
 	uint32_t alloc_flags;
 
-	atomic_t invalid;
+	uint32_t invalid;
 	struct amdkfd_process_info *process_info;
 
 	struct amdgpu_sync sync;
@@ -131,7 +133,8 @@ struct amdkfd_process_info {
 	struct amdgpu_amdkfd_fence *eviction_fence;
 
 	/* MMU-notifier related fields */
-	atomic_t evicted_bos;
+	struct mutex notifier_lock;
+	uint32_t evicted_bos;
 	struct delayed_work restore_userptr_work;
 	struct pid *pid;
 	bool block_mmu_notifications;
@@ -180,7 +183,8 @@ int kfd_debugfs_kfd_mem_limits(struct seq_file *m, void *data);
 bool amdkfd_fence_check_mm(struct dma_fence *f, struct mm_struct *mm);
 struct amdgpu_amdkfd_fence *to_amdgpu_amdkfd_fence(struct dma_fence *f);
 int amdgpu_amdkfd_remove_fence_on_pt_pd_bos(struct amdgpu_bo *bo);
-int amdgpu_amdkfd_evict_userptr(struct kgd_mem *mem, struct mm_struct *mm);
+int amdgpu_amdkfd_evict_userptr(struct mmu_interval_notifier *mni,
+				unsigned long cur_seq, struct kgd_mem *mem);
 #else
 static inline
 bool amdkfd_fence_check_mm(struct dma_fence *f, struct mm_struct *mm)
@@ -201,7 +205,8 @@ int amdgpu_amdkfd_remove_fence_on_pt_pd_bos(struct amdgpu_bo *bo)
 }
 
 static inline
-int amdgpu_amdkfd_evict_userptr(struct kgd_mem *mem, struct mm_struct *mm)
+int amdgpu_amdkfd_evict_userptr(struct mmu_interval_notifier *mni,
+				unsigned long cur_seq, struct kgd_mem *mem)
 {
 	return 0;
 }

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

@@ -105,17 +105,11 @@ static bool amdgpu_hmm_invalidate_hsa(struct mmu_interval_notifier *mni,
 				      unsigned long cur_seq)
 {
 	struct amdgpu_bo *bo = container_of(mni, struct amdgpu_bo, notifier);
-	struct amdgpu_device *adev = amdgpu_ttm_adev(bo->tbo.bdev);
 
 	if (!mmu_notifier_range_blockable(range))
 		return false;
 
-	mutex_lock(&adev->notifier_lock);
-
-	mmu_interval_set_seq(mni, cur_seq);
-
-	amdgpu_amdkfd_evict_userptr(bo->kfd_bo, bo->notifier.mm);
-	mutex_unlock(&adev->notifier_lock);
+	amdgpu_amdkfd_evict_userptr(mni, cur_seq, bo->kfd_bo);
 
 	return true;
 }
@@ -244,9 +238,9 @@ int amdgpu_hmm_range_get_pages(struct mmu_interval_notifier *notifier,
 	return r;
 }
 
-int amdgpu_hmm_range_get_pages_done(struct hmm_range *hmm_range)
+bool amdgpu_hmm_range_get_pages_done(struct hmm_range *hmm_range)
 {
-	int r;
+	bool r;
 
 	r = mmu_interval_read_retry(hmm_range->notifier,
 				    hmm_range->notifier_seq);

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

@@ -29,12 +29,13 @@
 #include <linux/rwsem.h>
 #include <linux/workqueue.h>
 #include <linux/interval_tree.h>
+#include <linux/mmu_notifier.h>
 
 int amdgpu_hmm_range_get_pages(struct mmu_interval_notifier *notifier,
 			       uint64_t start, uint64_t npages, bool readonly,
 			       void *owner, struct page **pages,
 			       struct hmm_range **phmm_range);
-int amdgpu_hmm_range_get_pages_done(struct hmm_range *hmm_range);
+bool amdgpu_hmm_range_get_pages_done(struct hmm_range *hmm_range);
 
 #if defined(CONFIG_HMM_MIRROR)
 int amdgpu_hmm_register(struct amdgpu_bo *bo, unsigned long addr);

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

@@ -695,8 +695,19 @@ int amdgpu_ttm_tt_get_user_pages(struct amdgpu_bo *bo, struct page **pages,
 	return r;
 }
 
+/* amdgpu_ttm_tt_discard_user_pages - Discard range and pfn array allocations
+ */
+void amdgpu_ttm_tt_discard_user_pages(struct ttm_tt *ttm,
+				      struct hmm_range *range)
+{
+	struct amdgpu_ttm_tt *gtt = (void *)ttm;
+
+	if (gtt && gtt->userptr && range)
+		amdgpu_hmm_range_get_pages_done(range);
+}
+
 /*
- * amdgpu_ttm_tt_userptr_range_done - stop HMM track the CPU page table change
+ * amdgpu_ttm_tt_get_user_pages_done - stop HMM track the CPU page table change
  * Check if the pages backing this ttm range have been invalidated
  *
  * Returns: true if pages are still valid
@@ -714,10 +725,6 @@ bool amdgpu_ttm_tt_get_user_pages_done(struct ttm_tt *ttm,
 
 	WARN_ONCE(!range->hmm_pfns, "No user pages to check\n");
 
-	/*
-	 * FIXME: Must always hold notifier_lock for this, and must
-	 * not ignore the return code.
-	 */
 	return !amdgpu_hmm_range_get_pages_done(range);
 }
 #endif

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

@@ -159,6 +159,8 @@ uint64_t amdgpu_ttm_domain_start(struct amdgpu_device *adev, uint32_t type);
 #if IS_ENABLED(CONFIG_DRM_AMDGPU_USERPTR)
 int amdgpu_ttm_tt_get_user_pages(struct amdgpu_bo *bo, struct page **pages,
 				 struct hmm_range **range);
+void amdgpu_ttm_tt_discard_user_pages(struct ttm_tt *ttm,
+				      struct hmm_range *range);
 bool amdgpu_ttm_tt_get_user_pages_done(struct ttm_tt *ttm,
 				       struct hmm_range *range);
 #else
@@ -168,6 +170,10 @@ static inline int amdgpu_ttm_tt_get_user_pages(struct amdgpu_bo *bo,
 {
 	return -EPERM;
 }
+static inline void amdgpu_ttm_tt_discard_user_pages(struct ttm_tt *ttm,
+						    struct hmm_range *range)
+{
+}
 static inline bool amdgpu_ttm_tt_get_user_pages_done(struct ttm_tt *ttm,
 						     struct hmm_range *range)
 {