Re: [PATCH v5 4/6] drm/xe/vf: Add bounds checking for queried GGTT base and size

On 8/10/2026 12:14 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]>
> ---
> V4 -> V5:
> - New commit.
> ---
>  drivers/gpu/drm/xe/xe_gt_sriov_vf.c | 20 ++++++++++++++++++++
>  1 file changed, 20 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..65e48f135801 100644
> --- a/drivers/gpu/drm/xe/xe_gt_sriov_vf.c
> +++ b/drivers/gpu/drm/xe/xe_gt_sriov_vf.c
> @@ -486,8 +486,16 @@ u32 xe_gt_sriov_vf_gmdid(struct xe_gt *gt)
>  	return value;
>  }
>  
> +static u64 vf_get_ggtt_alignment(struct xe_gt *gt)
> +{
> +	struct xe_device *xe = gt_to_xe(gt);
> +
> +	return IS_DGFX(xe) && xe->info.vram_flags & XE_VRAM_FLAGS_NEED64K ? SZ_64K : SZ_4K;
> +}

I guess it's time to extract this logic to some common helper
(maybe in xe_ggtt.c or xe_device.c) as we repeat that in:


xe_gt_sriov_pf_config.c:446:
	return IS_DGFX(xe) && xe->info.vram_flags & XE_VRAM_FLAGS_NEED64K ? SZ_64K : SZ_4K;

xe_ggtt.c:423:
	if (IS_DGFX(xe) && xe->info.vram_flags & XE_VRAM_FLAGS_NEED64K)
		ggtt->flags |= XE_GGTT_FLAGS_64K;

display/xe_initial_plane.c:48:
	u64 page_size = xe->info.vram_flags & XE_VRAM_FLAGS_NEED64K ? SZ_64K : SZ_4K;


xe_bo.c-4057-
	u32 page_size = max_t(u32, PAGE_SIZE,
		xe->info.vram_flags & XE_VRAM_FLAGS_NEED64K ? SZ_64K : SZ_4K);

xe_query.c-291
	mem_regions->mem_regions[mem_regions->num_mem_regions].min_page_size =
			xe->info.vram_flags & XE_VRAM_FLAGS_NEED64K ?
			SZ_64K : PAGE_SIZE;

xe_query.c-357-
	config->info[DRM_XE_QUERY_CONFIG_MIN_ALIGNMENT] =
		xe->info.vram_flags & XE_VRAM_FLAGS_NEED64K ? SZ_64K : SZ_4K;

...


> +
>  static int vf_get_ggtt_info(struct xe_gt *gt)
>  {
> +	u64 alignment = vf_get_ggtt_alignment(gt);
>  	struct xe_tile *tile = gt_to_tile(gt);
>  	struct xe_guc *guc = &gt->uc.guc;
>  	u64 start, size, ggtt_size;
> @@ -526,6 +534,18 @@ static int vf_get_ggtt_info(struct xe_gt *gt)
>  		return -EREMCHG;
>  	}
>  
> +	if (size % alignment) {

IS_ALIGNED(size, alignment)

> +		xe_gt_sriov_err(gt, "Unexpected GGTT alignment for size: %llu != %llu\n",

	"Unaligned GGTT size (%llu != %llu)"
or
	"Unaligned GGTT size %llu, expected %llu"

> +				size, (size / alignment) * alignment);

size, ALIGN(size, alignment)

> +		return -EREMCHG;
> +	}
> +
> +	if (start % alignment) {
> +		xe_gt_sriov_err(gt, "Unexpected GGTT alignment for base: %llu != %llu\n",
> +				start, (start / alignment) * alignment);
> +		return -EREMCHG;

ditto

and maybe check base first?

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