[PATCH] drm/amdkfd: Fix partial migrate issue

[Chen, Xiaogang]

On 1/2/2025 6:06 PM, 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>
> ---
>   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;
I agree this part.
>   	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)) {
> @@ -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]);

I think what current code misses here is that migrate->dst[i] should 
match migrate->src[i]: migrate->dst[i](vram page) got set for page that 
will be migrated from system ram, otherwise migrate->dst[i] should be 
zero. Your change makes migrates->dst[i] not set though its page has 
been migrated by svm_migrate_copy_memory_gart for the case that cpages 
!= npages, because you set migrate->dst[i] at end of loop and use 
'continue' after migration.

The page migration happens at svm_migrate_copy_memory_gart, not 
migrate_vma_pages that migrates struct page meta-data from source struct 
page to destination struct page and has mmu notification.

Regards

Xiaogang

>   	}
>   
>   	r = svm_migrate_copy_memory_gart(adev, src + i - j, dst + i - j, j,
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