On 15/10/2025 01:09, Adrián Larumbe wrote:
> In the MMU's page fault ISR for a heap object, determine whether the
> faulting address belongs to a 2MiB block that was already mapped by
> checking its corresponding sgt in the Panfrost BO.
> 
> This is done in preparation for a future commit in which the MMU mapping
> helper might fail, but the page array is left populated, so this cannot
> be used as a check for an early bail-out.
> 
> Signed-off-by: Adrián Larumbe <[email protected]>

Reviewed-by: Steven Price <[email protected]>

> ---
>  drivers/gpu/drm/panfrost/panfrost_mmu.c | 11 ++++++-----
>  1 file changed, 6 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/gpu/drm/panfrost/panfrost_mmu.c 
> b/drivers/gpu/drm/panfrost/panfrost_mmu.c
> index cf272b167feb..ba32d99ed854 100644
> --- a/drivers/gpu/drm/panfrost/panfrost_mmu.c
> +++ b/drivers/gpu/drm/panfrost/panfrost_mmu.c
> @@ -600,10 +600,12 @@ static int panfrost_mmu_map_fault_addr(struct 
> panfrost_device *pfdev, int as,
>               refcount_set(&bo->base.pages_use_count, 1);
>       } else {
>               pages = bo->base.pages;
> -             if (pages[page_offset]) {
> -                     /* Pages are already mapped, bail out. */
> -                     goto out;
> -             }
> +     }
> +
> +     sgt = &bo->sgts[page_offset / (SZ_2M / PAGE_SIZE)];
> +     if (sgt->sgl) {
> +             /* Pages are already mapped, bail out. */
> +             goto out;
>       }
>  
>       mapping = bo->base.base.filp->f_mapping;
> @@ -625,7 +627,6 @@ static int panfrost_mmu_map_fault_addr(struct 
> panfrost_device *pfdev, int as,
>               }
>       }
>  
> -     sgt = &bo->sgts[page_offset / (SZ_2M / PAGE_SIZE)];
>       ret = sg_alloc_table_from_pages(sgt, pages + page_offset,
>                                       NUM_FAULT_PAGES, 0, SZ_2M, GFP_KERNEL);
>       if (ret)

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