[PATCH] drm/amdkfd: Fix partial migrate issue

[Deng, Emily]

[AMD Official Use Only - AMD Internal Distribution Only]

>-----Original Message-----
>From: Kuehling, Felix <Felix.Kuehling at amd.com>
>Sent: Saturday, January 4, 2025 7:10 AM
>To: Deng, Emily <Emily.Deng at amd.com>; amd-gfx at lists.freedesktop.org
>Subject: Re: [PATCH] drm/amdkfd: Fix partial migrate issue
>
>
>On 2025-01-02 19:06, Emily Deng wrote:
>> For partial migrate from ram to vram, the migrate->cpages is not equal
>> to migrate->npages, should use migrate->npages to check all needed
>> migrate pages which could be copied or not.
>>
>> And only need to set those pages could be migrated to migrate->dst[i],
>> or the migrate_vma_pages will migrate the wrong pages based on the migrate-
>>dst[i].
>>
>> Signed-off-by: Emily Deng <Emily.Deng at amd.com>
>
>Good catch. But I think it's still not quite right. See inline.
>
>
>> ---
>>   drivers/gpu/drm/amd/amdkfd/kfd_migrate.c | 8 ++++----
>>   1 file changed, 4 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_migrate.c
>> b/drivers/gpu/drm/amd/amdkfd/kfd_migrate.c
>> index 4b275937d05e..5c96c2d425e3 100644
>> --- a/drivers/gpu/drm/amd/amdkfd/kfd_migrate.c
>> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_migrate.c
>> @@ -278,7 +278,7 @@ svm_migrate_copy_to_vram(struct kfd_node *node, struct
>svm_range *prange,
>>                       struct migrate_vma *migrate, struct dma_fence **mfence,
>>                       dma_addr_t *scratch, uint64_t ttm_res_offset)
>>   {
>> -    uint64_t npages = migrate->cpages;
>> +    uint64_t npages = migrate->npages;
>>      struct amdgpu_device *adev = node->adev;
>>      struct device *dev = adev->dev;
>>      struct amdgpu_res_cursor cursor;
>> @@ -299,9 +299,6 @@ svm_migrate_copy_to_vram(struct kfd_node *node, struct
>svm_range *prange,
>>              struct page *spage;
>>
>>              dst[i] = cursor.start + (j << PAGE_SHIFT);
>> -            migrate->dst[i] = svm_migrate_addr_to_pfn(adev, dst[i]);
>> -            svm_migrate_get_vram_page(prange, migrate->dst[i]);
>> -            migrate->dst[i] = migrate_pfn(migrate->dst[i]);
>>
>>              spage = migrate_pfn_to_page(migrate->src[i]);
>>              if (spage && !is_zone_device_page(spage)) {
>
>We should also check (migrate->src[i] & MIGRATE_PFN_MIGRATE) to catch only the
>pages that are ready to migrate (i.e. not already in device memory and not pinned by
>someone else).
>
>Regards,
>   Felix
>The code " if (spage && !is_zone_device_page(spage)) {" is already checked whether the page could be migrated or not. Because after called migrate_vma_setup, for those pages couldn't be migrated it will be set to NULL.

Emily Deng
Best Wishes


>
>> @@ -345,6 +342,9 @@ svm_migrate_copy_to_vram(struct kfd_node *node, struct
>svm_range *prange,
>>              } else {
>>                      j++;
>>              }
>> +            migrate->dst[i] = svm_migrate_addr_to_pfn(adev, dst[i]);
>> +            svm_migrate_get_vram_page(prange, migrate->dst[i]);
>> +            migrate->dst[i] = migrate_pfn(migrate->dst[i]);
>>      }
>>
>>      r = svm_migrate_copy_memory_gart(adev, src + i - j, dst + i - j, j,