Re: [PATCH v6 5/7] drm/xe/vf: Add bounds checking for queried GGTT base and size

On 8/12/2026 2:43 PM, Satyanarayana K V P wrote:
> Add explicit bounds checks for GGTT base and size which can detect
> and reject invalid configuration data from a misconfigured or
> malfunctioning PF, preventing protocol violations and protecting VF
> initialization.
> 
> Signed-off-by: Satyanarayana K V P <[email protected]>
> Cc: Michal Wajdeczko <[email protected]>
> ---
> V5 -> V6:
> - Updated error codes for unaligned GGTT base and size (Michal W).
> - Fixed review comments (Michal W).
> 
> V4 -> V5:
> - New commit.
> ---
>  drivers/gpu/drm/xe/xe_gt_sriov_vf.c | 13 +++++++++++++
>  1 file changed, 13 insertions(+)
> 
> diff --git a/drivers/gpu/drm/xe/xe_gt_sriov_vf.c b/drivers/gpu/drm/xe/xe_gt_sriov_vf.c
> index 81d68fe5ad7c..d805c064377c 100644
> --- a/drivers/gpu/drm/xe/xe_gt_sriov_vf.c
> +++ b/drivers/gpu/drm/xe/xe_gt_sriov_vf.c
> @@ -488,6 +488,7 @@ u32 xe_gt_sriov_vf_gmdid(struct xe_gt *gt)
>  
>  static int vf_get_ggtt_info(struct xe_gt *gt)
>  {
> +	u64 alignment = xe_vram_alignment(gt_to_xe(gt));
>  	struct xe_tile *tile = gt_to_tile(gt);
>  	struct xe_guc *guc = &gt->uc.guc;
>  	u64 start, size, ggtt_size;
> @@ -526,6 +527,18 @@ static int vf_get_ggtt_info(struct xe_gt *gt)
>  		return -EREMCHG;
>  	}
>  
> +	if (!IS_ALIGNED(start, alignment)) {
> +		xe_gt_sriov_err(gt, "Unaligned GGTT base: %llu, expected %llu\n",
> +				start, ALIGN(start, alignment));
> +		return -EINVAL;
> +	}
> +
> +	if (!IS_ALIGNED(size, alignment)) {
> +		xe_gt_sriov_err(gt, "Unaligned GGTT size %llu, expected %llu\n",
> +				size, ALIGN(size, alignment));
> +		return -EINVAL;
> +	}
> +

as Sashiko pointed out, likely from

commit e904c56ba6e0d4eff5f48a70356fd5d764c2a966
    drm/xe: Rewrite GGTT VF initialization

we are doing some checks too late, including these new one

can you fix the existing check first, then add new ones?

>  	xe_gt_sriov_dbg_verbose(gt, "GGTT %#llx-%#llx = %lluK\n",
>  				start, start + size - 1, size / SZ_1K);
>