drm/amdkfd: fix svm_migrate_fini warning

Device manager releases device-specific resources when a driver
disconnects from a device, devm_memunmap_pages and
devm_release_mem_region calls in svm_migrate_fini are redundant.

It causes below warning trace after patch "drm/amdgpu: Split
amdgpu_device_fini into early and late", so remove function
svm_migrate_fini.

BUG: https://gitlab.freedesktop.org/drm/amd/-/issues/1718

WARNING: CPU: 1 PID: 3646 at drivers/base/devres.c:795
devm_release_action+0x51/0x60
Call Trace:
    ? memunmap_pages+0x360/0x360
    svm_migrate_fini+0x2d/0x60 [amdgpu]
    kgd2kfd_device_exit+0x23/0xa0 [amdgpu]
    amdgpu_amdkfd_device_fini_sw+0x1d/0x30 [amdgpu]
    amdgpu_device_fini_sw+0x45/0x290 [amdgpu]
    amdgpu_driver_release_kms+0x12/0x30 [amdgpu]
    drm_dev_release+0x20/0x40 [drm]
    release_nodes+0x196/0x1e0
    device_release_driver_internal+0x104/0x1d0
    driver_detach+0x47/0x90
    bus_remove_driver+0x7a/0xd0
    pci_unregister_driver+0x3d/0x90
    amdgpu_exit+0x11/0x20 [amdgpu]
Signed-off-by: Philip Yang <Philip.Yang@amd.com>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -971,7 +971,6 @@ bool kgd2kfd_device_init(struct kfd_dev *kfd,
 void kgd2kfd_device_exit(struct kfd_dev *kfd)
 {
 	if (kfd->init_complete) {
-		svm_migrate_fini((struct amdgpu_device *)kfd->kgd);
 		device_queue_manager_uninit(kfd->dqm);
 		kfd_interrupt_exit(kfd);
 		kfd_topology_remove_device(kfd);

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

@@ -891,6 +891,10 @@ int svm_migrate_init(struct amdgpu_device *adev)
 	pgmap->ops = &svm_migrate_pgmap_ops;
 	pgmap->owner = SVM_ADEV_PGMAP_OWNER(adev);
 	pgmap->flags = MIGRATE_VMA_SELECT_DEVICE_PRIVATE;
+
+	/* Device manager releases device-specific resources, memory region and
+	 * pgmap when driver disconnects from device.
+	 */
 	r = devm_memremap_pages(adev->dev, pgmap);
 	if (IS_ERR(r)) {
 		pr_err("failed to register HMM device memory\n");
@@ -911,12 +915,3 @@ int svm_migrate_init(struct amdgpu_device *adev)
 
 	return 0;
 }
-
-void svm_migrate_fini(struct amdgpu_device *adev)
-{
-	struct dev_pagemap *pgmap = &adev->kfd.dev->pgmap;
-
-	devm_memunmap_pages(adev->dev, pgmap);
-	devm_release_mem_region(adev->dev, pgmap->range.start,
-				pgmap->range.end - pgmap->range.start + 1);
-}

drivers/gpu/drm/amd/amdkfd/kfd_migrate.h

@@ -47,7 +47,6 @@ unsigned long
 svm_migrate_addr_to_pfn(struct amdgpu_device *adev, unsigned long addr);
 
 int svm_migrate_init(struct amdgpu_device *adev);
-void svm_migrate_fini(struct amdgpu_device *adev);
 
 #else
 
@@ -55,10 +54,6 @@ static inline int svm_migrate_init(struct amdgpu_device *adev)
 {
 	return 0;
 }
-static inline void svm_migrate_fini(struct amdgpu_device *adev)
-{
-	/* empty */
-}
 
 #endif /* IS_ENABLED(CONFIG_HSA_AMD_SVM) */