Re: [PATCH v5 1/6] drm/xe/xe_gt_pagefault: Disallow writes to read-only VMAs

[Gwan-gyeong Mun <gwan-gyeong.mun@intel.com>]

On 3/4/25 7:08 PM, Jonathan Cavitt wrote:
> The page fault handler should reject write/atomic access to read only
> VMAs.  Add code to handle this in handle_pagefault after the VMA lookup.
> 
> Fixes: 3d420e9fa848 ("drm/xe: Rework GPU page fault handling")
> Signed-off-by: Jonathan Cavitt <jonathan.cavitt@intel.com>
> Suggested-by: Matthew Brost <matthew.brost@intel.com>
> ---
>   drivers/gpu/drm/xe/xe_gt_pagefault.c | 5 +++++
>   1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/gpu/drm/xe/xe_gt_pagefault.c b/drivers/gpu/drm/xe/xe_gt_pagefault.c
> index 17d69039b866..f608a765fa7c 100644
> --- a/drivers/gpu/drm/xe/xe_gt_pagefault.c
> +++ b/drivers/gpu/drm/xe/xe_gt_pagefault.c
> @@ -235,6 +235,11 @@ static int handle_pagefault(struct xe_gt *gt, struct pagefault *pf)
>   		goto unlock_vm;
>   	}
>   
> +	if (xe_vma_read_only(vma) && pf->access_type != ACCESS_TYPE_READ) {
one question, if the PTE Present bit is disabled and the page fault is 
caused by atomic load/store eu instruction, will the GuC deliver 
pagefault request to KMD with ACCESS_TYPE_READ/ACCESS_TYPE_WRITE Fault 
type instead of ACCESS_TYPE_ATOMIC?

G.G.
> +		err = -EPERM;
> +		goto unlock_vm;
> +	}
> +
>   	err = handle_vma_pagefault(gt, pf, vma);
>   
>   unlock_vm: