drm/amdkfd: Fix NULL pointer dereference for set_scratch_backing_va()

Currently this function pointer is missing for GFX10. Considering it is
a void function since GFX9, fix it by checking the function pointer
before dereferencing it.
Signed-off-by: Yong Zhao <Yong.Zhao@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -312,7 +312,6 @@ static const struct kfd2kgd_calls kfd2kgd = {
 			kgd_gfx_v9_get_atc_vmid_pasid_mapping_pasid,
 	.get_atc_vmid_pasid_mapping_valid =
 			kgd_gfx_v9_get_atc_vmid_pasid_mapping_valid,
-	.set_scratch_backing_va = kgd_gfx_v9_set_scratch_backing_va,
 	.get_tile_config = kgd_gfx_v9_get_tile_config,
 	.set_vm_context_page_table_base = kgd_gfx_v9_set_vm_context_page_table_base,
 	.invalidate_tlbs = kgd_gfx_v9_invalidate_tlbs,

drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gfx_v9.c

@@ -781,15 +781,6 @@ uint32_t kgd_gfx_v9_address_watch_get_offset(struct kgd_dev *kgd,
 	return 0;
 }
 
-void kgd_gfx_v9_set_scratch_backing_va(struct kgd_dev *kgd,
-					uint64_t va, uint32_t vmid)
-{
-	/* No longer needed on GFXv9. The scratch base address is
-	 * passed to the shader by the CP. It's the user mode driver's
-	 * responsibility.
-	 */
-}
-
 void kgd_gfx_v9_set_vm_context_page_table_base(struct kgd_dev *kgd, uint32_t vmid,
 		uint64_t page_table_base)
 {
@@ -835,7 +826,6 @@ static const struct kfd2kgd_calls kfd2kgd = {
 			kgd_gfx_v9_get_atc_vmid_pasid_mapping_pasid,
 	.get_atc_vmid_pasid_mapping_valid =
 			kgd_gfx_v9_get_atc_vmid_pasid_mapping_valid,
-	.set_scratch_backing_va = kgd_gfx_v9_set_scratch_backing_va,
 	.get_tile_config = kgd_gfx_v9_get_tile_config,
 	.set_vm_context_page_table_base = kgd_gfx_v9_set_vm_context_page_table_base,
 	.invalidate_tlbs = kgd_gfx_v9_invalidate_tlbs,

drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gfx_v9.h

@@ -61,8 +61,6 @@ uint16_t kgd_gfx_v9_get_atc_vmid_pasid_mapping_pasid(struct kgd_dev *kgd,
 		uint8_t vmid);
 void kgd_gfx_v9_set_vm_context_page_table_base(struct kgd_dev *kgd, uint32_t vmid,
 		uint64_t page_table_base);
-void kgd_gfx_v9_set_scratch_backing_va(struct kgd_dev *kgd,
-					uint64_t va, uint32_t vmid);
 int kgd_gfx_v9_invalidate_tlbs(struct kgd_dev *kgd, uint16_t pasid);
 int kgd_gfx_v9_invalidate_tlbs_vmid(struct kgd_dev *kgd, uint16_t vmid);
 int kgd_gfx_v9_get_tile_config(struct kgd_dev *kgd,

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

@@ -1128,7 +1128,7 @@ static int kfd_ioctl_set_scratch_backing_va(struct file *filep,
 	mutex_unlock(&p->mutex);
 
 	if (dev->dqm->sched_policy == KFD_SCHED_POLICY_NO_HWS &&
-	    pdd->qpd.vmid != 0)
+	    pdd->qpd.vmid != 0 && dev->kfd2kgd->set_scratch_backing_va)
 		dev->kfd2kgd->set_scratch_backing_va(
 			dev->kgd, args->va_addr, pdd->qpd.vmid);
 

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

@@ -220,8 +220,9 @@ static int allocate_vmid(struct device_queue_manager *dqm,
 	/* invalidate the VM context after pasid and vmid mapping is set up */
 	kfd_flush_tlb(qpd_to_pdd(qpd));
 
-	dqm->dev->kfd2kgd->set_scratch_backing_va(
-		dqm->dev->kgd, qpd->sh_hidden_private_base, qpd->vmid);
+	if (dqm->dev->kfd2kgd->set_scratch_backing_va)
+		dqm->dev->kfd2kgd->set_scratch_backing_va(dqm->dev->kgd,
+				qpd->sh_hidden_private_base, qpd->vmid);
 
 	return 0;
 }

drivers/gpu/drm/amd/include/kgd_kfd_interface.h

@@ -298,8 +298,13 @@ struct kfd2kgd_calls {
 					struct kgd_dev *kgd,
 					uint8_t vmid);
 
+	/* No longer needed from GFXv9 onward. The scratch base address is
+	 * passed to the shader by the CP. It's the user mode driver's
+	 * responsibility.
+	 */
 	void (*set_scratch_backing_va)(struct kgd_dev *kgd,
 				uint64_t va, uint32_t vmid);
+
 	int (*get_tile_config)(struct kgd_dev *kgd, struct tile_config *config);
 
 	void (*set_vm_context_page_table_base)(struct kgd_dev *kgd,