drm/amdkfd: Document and fix GTT BO kmap API

Removed an unused parameter from two functions and added kernel-doc
comments.
Signed-off-by: Felix Kuehling <Felix.Kuehling@amd.com>
Reviewed-by: Philip Yang <Philip.Yang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -280,10 +280,9 @@ int amdgpu_amdkfd_gpuvm_unmap_memory_from_gpu(
 		struct amdgpu_device *adev, struct kgd_mem *mem, void *drm_priv);
 int amdgpu_amdkfd_gpuvm_sync_memory(
 		struct amdgpu_device *adev, struct kgd_mem *mem, bool intr);
-int amdgpu_amdkfd_gpuvm_map_gtt_bo_to_kernel(struct amdgpu_device *adev,
-		struct kgd_mem *mem, void **kptr, uint64_t *size);
-void amdgpu_amdkfd_gpuvm_unmap_gtt_bo_from_kernel(struct amdgpu_device *adev,
-		struct kgd_mem *mem);
+int amdgpu_amdkfd_gpuvm_map_gtt_bo_to_kernel(struct kgd_mem *mem,
+					     void **kptr, uint64_t *size);
+void amdgpu_amdkfd_gpuvm_unmap_gtt_bo_from_kernel(struct kgd_mem *mem);
 
 int amdgpu_amdkfd_gpuvm_restore_process_bos(void *process_info,
 					    struct dma_fence **ef);

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

@@ -2083,8 +2083,21 @@ int amdgpu_amdkfd_gpuvm_sync_memory(
 	return ret;
 }
 
-int amdgpu_amdkfd_gpuvm_map_gtt_bo_to_kernel(struct amdgpu_device *adev,
-		struct kgd_mem *mem, void **kptr, uint64_t *size)
+/** amdgpu_amdkfd_gpuvm_map_gtt_bo_to_kernel() - Map a GTT BO for kernel CPU access
+ *
+ * @mem: Buffer object to be mapped for CPU access
+ * @kptr[out]: pointer in kernel CPU address space
+ * @size[out]: size of the buffer
+ *
+ * Pins the BO and maps it for kernel CPU access. The eviction fence is removed
+ * from the BO, since pinned BOs cannot be evicted. The bo must remain on the
+ * validate_list, so the GPU mapping can be restored after a page table was
+ * evicted.
+ *
+ * Return: 0 on success, error code on failure
+ */
+int amdgpu_amdkfd_gpuvm_map_gtt_bo_to_kernel(struct kgd_mem *mem,
+					     void **kptr, uint64_t *size)
 {
 	int ret;
 	struct amdgpu_bo *bo = mem->bo;
@@ -2135,8 +2148,15 @@ int amdgpu_amdkfd_gpuvm_map_gtt_bo_to_kernel(struct amdgpu_device *adev,
 	return ret;
 }
 
-void amdgpu_amdkfd_gpuvm_unmap_gtt_bo_from_kernel(struct amdgpu_device *adev,
-						  struct kgd_mem *mem)
+/** amdgpu_amdkfd_gpuvm_map_gtt_bo_to_kernel() - Unmap a GTT BO for kernel CPU access
+ *
+ * @mem: Buffer object to be unmapped for CPU access
+ *
+ * Removes the kernel CPU mapping and unpins the BO. It does not restore the
+ * eviction fence, so this function should only be used for cleanup before the
+ * BO is destroyed.
+ */
+void amdgpu_amdkfd_gpuvm_unmap_gtt_bo_from_kernel(struct kgd_mem *mem)
 {
 	struct amdgpu_bo *bo = mem->bo;
 

drivers/gpu/drm/amd/amdkfd/kfd_events.c

@@ -377,8 +377,7 @@ int kfd_kmap_event_page(struct kfd_process *p, uint64_t event_page_offset)
 		return -EINVAL;
 	}
 
-	err = amdgpu_amdkfd_gpuvm_map_gtt_bo_to_kernel(kfd->adev,
-					mem, &kern_addr, &size);
+	err = amdgpu_amdkfd_gpuvm_map_gtt_bo_to_kernel(mem, &kern_addr, &size);
 	if (err) {
 		pr_err("Failed to map event page to kernel\n");
 		return err;
@@ -387,7 +386,7 @@ int kfd_kmap_event_page(struct kfd_process *p, uint64_t event_page_offset)
 	err = kfd_event_page_set(p, kern_addr, size, event_page_offset);
 	if (err) {
 		pr_err("Failed to set event page\n");
-		amdgpu_amdkfd_gpuvm_unmap_gtt_bo_from_kernel(kfd->adev, mem);
+		amdgpu_amdkfd_gpuvm_unmap_gtt_bo_from_kernel(mem);
 		return err;
 	}
 	return err;

drivers/gpu/drm/amd/amdkfd/kfd_process.c

@@ -693,7 +693,7 @@ static void kfd_process_free_gpuvm(struct kgd_mem *mem,
 	struct kfd_dev *dev = pdd->dev;
 
 	if (kptr) {
-		amdgpu_amdkfd_gpuvm_unmap_gtt_bo_from_kernel(dev->adev, mem);
+		amdgpu_amdkfd_gpuvm_unmap_gtt_bo_from_kernel(mem);
 		kptr = NULL;
 	}
 
@@ -733,7 +733,7 @@ static int kfd_process_alloc_gpuvm(struct kfd_process_device *pdd,
 	}
 
 	if (kptr) {
-		err = amdgpu_amdkfd_gpuvm_map_gtt_bo_to_kernel(kdev->adev,
+		err = amdgpu_amdkfd_gpuvm_map_gtt_bo_to_kernel(
 				(struct kgd_mem *)*mem, kptr, NULL);
 		if (err) {
 			pr_debug("Map GTT BO to kernel failed\n");
@@ -999,7 +999,7 @@ static void kfd_process_kunmap_signal_bo(struct kfd_process *p)
 	if (!mem)
 		goto out;
 
-	amdgpu_amdkfd_gpuvm_unmap_gtt_bo_from_kernel(kdev->adev, mem);
+	amdgpu_amdkfd_gpuvm_unmap_gtt_bo_from_kernel(mem);
 
 out:
 	mutex_unlock(&p->mutex);