Re: [PATCH v4] drm/amdkfd: Use huge page size to check split svm range alignment

[Philip Yang <yangp@amd.com>]

On 2025-11-24 09:55, Chen, Xiaogang wrote:
> [AMD Official Use Only - AMD Internal Distribution Only]
>
> ping
>
> -----Original Message-----
> From: Xiaogang.Chen <xiaogang.chen@amd.com>
> Sent: Thursday, November 20, 2025 9:51 AM
> To: amd-gfx@lists.freedesktop.org
> Cc: Chen, Xiaogang <Xiaogang.Chen@amd.com>
> Subject: [PATCH v4] drm/amdkfd: Use huge page size to check split svm range alignment
>
> From: Xiaogang Chen <xiaogang.chen@amd.com>
>
> Fixes: 7ef6b2d4b7e5 (drm/amdkfd: remap unaligned svm ranges that have split)
>
> When split svm ranges that have been mapped using huge page should use huge page size(2MB) to check split range alignment, not prange->granularity that means migration granularity.
>
> Signed-off-by: Xiaogang Chen <xiaogang.chen@amd.com>
> ---
>   drivers/gpu/drm/amd/amdkfd/kfd_svm.c | 46 +++++++++++++++++++---------
>   1 file changed, 32 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_svm.c b/drivers/gpu/drm/amd/amdkfd/kfd_svm.c
> index 521c14c7a789..7fe9d569d416 100644
> --- a/drivers/gpu/drm/amd/amdkfd/kfd_svm.c
> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_svm.c
> @@ -1144,30 +1144,48 @@ static int
>   svm_range_split_tail(struct svm_range *prange, uint64_t new_last,
>                       struct list_head *insert_list, struct list_head *remap_list)  {
> +       unsigned long last_align_down = ALIGN_DOWN(prange->last, 512);
> +       unsigned long start_align = ALIGN(prange->start, 512);
> +       bool huge_page_mapping = last_align_down > start_align;
>          struct svm_range *tail = NULL;
> -       int r = svm_range_split(prange, prange->start, new_last, &tail);
> +       int r;
>
> -       if (!r) {
> -               list_add(&tail->list, insert_list);
> -               if (!IS_ALIGNED(new_last + 1, 1UL << prange->granularity))
> -                       list_add(&tail->update_list, remap_list);
> -       }
> -       return r;
> +       r = svm_range_split(prange, prange->start, new_last, &tail);
> +
> +       if (r)
> +               return r;
> +
> +       list_add(&tail->list, insert_list);
> +
> +       if (huge_page_mapping && tail->start > start_align &&
> +           tail->start < last_align_down && (!IS_ALIGNED(tail->start, 512)))
> +               list_add(&tail->update_list, remap_list);
> +
> +       return 0;
>   }
>
>   static int
>   svm_range_split_head(struct svm_range *prange, uint64_t new_start,
>                       struct list_head *insert_list, struct list_head *remap_list)  {
> +       unsigned long last_align_down = ALIGN_DOWN(prange->last, 512);
> +       unsigned long start_align = ALIGN(prange->start, 512);
> +       bool huge_page_mapping = last_align_down > start_align;
>          struct svm_range *head = NULL;
> -       int r = svm_range_split(prange, new_start, prange->last, &head);
> +       int r;
>
> -       if (!r) {
> -               list_add(&head->list, insert_list);
> -               if (!IS_ALIGNED(new_start, 1UL << prange->granularity))
> -                       list_add(&head->update_list, remap_list);
> -       }
> -       return r;
> +       r = svm_range_split(prange, new_start, prange->last, &head);
> +
> +       if (r)
> +               return r;
> +
> +       list_add(&head->list, insert_list);
> +
> +       if (huge_page_mapping && head->last > start_align &&
> +           head->last < last_align_down && (!IS_ALIGNED(head->last, 512)))
replace all head->last with head->last + 1 in the if condition, or use 
new_start instead.

With this fixed, this patch is
Reviewed-by: Philip Yang <Philip.Yang@amd.com>
> +               list_add(&head->update_list, remap_list);
> +
> +       return 0;
>   }
>
>   static void
> --
> 2.34.1
>