Re: [PATCH 2/3] amd/amdkfd: Unmap range from GPUs based on granularity

["Chen, Xiaogang" <xiaogang.chen@amd.com>]

On 9/29/2023 9:11 AM, Philip Yang wrote:
> Caution: This message originated from an External Source. Use proper caution when opening attachments, clicking links, or responding.
>
>
> Align unmap range start and last address to granularity boundary.
> Skip unmap if range is already unmapped from GPUs.
>
> This also solve the rocgdb CWSR migration related issue.
>
> Signed-off-by: Philip Yang <Philip.Yang@amd.com>
> ---
>   drivers/gpu/drm/amd/amdkfd/kfd_svm.c | 35 ++++++++++++++++++++++++----
>   1 file changed, 31 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_svm.c b/drivers/gpu/drm/amd/amdkfd/kfd_svm.c
> index 626e0dd4ec79..ac65bf25c685 100644
> --- a/drivers/gpu/drm/amd/amdkfd/kfd_svm.c
> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_svm.c
> @@ -2004,6 +2004,26 @@ static void svm_range_restore_work(struct work_struct *work)
>          mmput(mm);
>   }
>
> +static unsigned long
> +svm_range_align_start(struct svm_range *prange, unsigned long start)
> +{
> +       unsigned long start_align;
> +
> +       start_align = ALIGN_DOWN(start, 1UL << prange->granularity);
> +       start_align = max_t(unsigned long, start_align, prange->start);
> +       return start_align;
> +}
> +
> +static unsigned long
> +svm_range_align_last(struct svm_range *prange, unsigned long last)
> +{
> +       unsigned long last_align;
> +
> +       last_align = ALIGN(last, 1UL << prange->granularity) - 1;

should be ALIGN(last + 1, 1UL << prange->granularity) - 1;? Here last is 
included last page number.

Regards

Xiaogang

> +       last_align = min_t(unsigned long, last_align, prange->last);
> +       return last_align;
> +}
> +
>   /**
>    * svm_range_evict - evict svm range
>    * @prange: svm range structure
> @@ -2078,6 +2098,12 @@ svm_range_evict(struct svm_range *prange, struct mm_struct *mm,
>                  unsigned long s, l;
>                  uint32_t trigger;
>
> +               if (!svm_range_partial_mapped(prange, start, last)) {
> +                       pr_debug("svms 0x%p [0x%lx 0x%lx] unmapped already\n",
> +                               prange->svms, start, last);
> +                       return 0;
> +               }
> +
>                  if (event == MMU_NOTIFY_MIGRATE)
>                          trigger = KFD_SVM_UNMAP_TRIGGER_MMU_NOTIFY_MIGRATE;
>                  else
> @@ -2085,16 +2111,17 @@ svm_range_evict(struct svm_range *prange, struct mm_struct *mm,
>
>                  pr_debug("invalidate unmap svms 0x%p [0x%lx 0x%lx] from GPUs\n",
>                           prange->svms, start, last);
> +
>                  list_for_each_entry(pchild, &prange->child_list, child_list) {
>                          mutex_lock_nested(&pchild->lock, 1);
> -                       s = max(start, pchild->start);
> -                       l = min(last, pchild->last);
> +                       s = svm_range_align_start(pchild, start);
> +                       l = svm_range_align_last(pchild, last);
>                          if (l >= s)
>                                  svm_range_unmap_from_gpus(pchild, s, l, trigger);
>                          mutex_unlock(&pchild->lock);
>                  }
> -               s = max(start, prange->start);
> -               l = min(last, prange->last);
> +               s = svm_range_align_start(prange, start);
> +               l = svm_range_align_last(prange, last);
>                  if (l >= s)
>                          svm_range_unmap_from_gpus(prange, s, l, trigger);
>          }
> --
> 2.35.1
>