Re: [PATCH v2] drm/xe/pf: Always expose VRAM provisioning data on discrete GPUs

[Michal Wajdeczko <michal.wajdeczko@intel.com>]

On 10/16/2025 2:22 PM, Lukasz Laguna wrote:
> Currently, VRAM provisioning data is only exposed if the device supports
> LMTT. While it should not be possible to modify VRAM provisioning on
> platforms without LMTT, it is still useful to be able to read the VRAM
> provisioning data on all discrete GPU platforms.
> 
> Expose the VRAM debugfs attributes whenever running on dGFX, adjusting
> file permissions to read only when LMTT is not available.
> 
> Fixes: 921ddb37d87c ("drm/xe/pf: Don't allow LMEM provisioning if LMTT isn't available on the device")

all our current DGFX SR-IOV platforms are using LMTT, so IMO there is nothing to fix

> Signed-off-by: Lukasz Laguna <lukasz.laguna@intel.com>
> ---
> v2:
>  - add extra protection against changing the LMEM provisioning (Piotr)
> ---
>  drivers/gpu/drm/xe/xe_gt_sriov_pf_config.c    | 3 ++-
>  drivers/gpu/drm/xe/xe_tile_sriov_pf_debugfs.c | 9 ++++++---
>  2 files changed, 8 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/xe/xe_gt_sriov_pf_config.c b/drivers/gpu/drm/xe/xe_gt_sriov_pf_config.c
> index b2e5c52978e6..c0c0215c0703 100644
> --- a/drivers/gpu/drm/xe/xe_gt_sriov_pf_config.c
> +++ b/drivers/gpu/drm/xe/xe_gt_sriov_pf_config.c
> @@ -1548,7 +1548,8 @@ int xe_gt_sriov_pf_config_set_lmem(struct xe_gt *gt, unsigned int vfid, u64 size
>  {
>  	int err;
>  
> -	xe_gt_assert(gt, xe_device_has_lmtt(gt_to_xe(gt)));
> +	if (!xe_device_has_lmtt(gt_to_xe(gt)))
> +		return -EPERM;
>  
>  	mutex_lock(xe_gt_sriov_pf_master_mutex(gt));
>  	if (vfid)
> diff --git a/drivers/gpu/drm/xe/xe_tile_sriov_pf_debugfs.c b/drivers/gpu/drm/xe/xe_tile_sriov_pf_debugfs.c
> index c8df18af4d00..6ba2332c77d4 100644
> --- a/drivers/gpu/drm/xe/xe_tile_sriov_pf_debugfs.c
> +++ b/drivers/gpu/drm/xe/xe_tile_sriov_pf_debugfs.c
> @@ -165,14 +165,17 @@ DEFINE_SRIOV_TILE_CONFIG_DEBUGFS_ATTRIBUTE(vram, lmem, u64, "%llu\n");
>  
>  static void pf_add_config_attrs(struct xe_tile *tile, struct dentry *dent, unsigned int vfid)
>  {
> +	struct xe_device *xe = tile->xe;
> +
>  	xe_tile_assert(tile, tile == extract_tile(dent));
>  	xe_tile_assert(tile, vfid == extract_vfid(dent));
>  
>  	debugfs_create_file_unsafe(vfid ? "ggtt_quota" : "ggtt_spare",
>  				   0644, dent, dent, &ggtt_fops);
> -	if (xe_device_has_lmtt(tile->xe))
> +	if (IS_DGFX(xe))
>  		debugfs_create_file_unsafe(vfid ? "vram_quota" : "vram_spare",
> -					   0644, dent, dent, &vram_fops);
> +					   xe_device_has_lmtt(xe) ? 0644 : 0444,
> +					   dent, dent, &vram_fops);

for platforms without LMTT, does it make sense to expose PF's "spare" attribute?
>  }
>  
>  static void pf_populate_tile(struct xe_tile *tile, struct dentry *dent, unsigned int vfid)
> @@ -188,7 +191,7 @@ static void pf_populate_tile(struct xe_tile *tile, struct dentry *dent, unsigned
>  		drm_debugfs_create_files(pf_ggtt_info,
>  					 ARRAY_SIZE(pf_ggtt_info),
>  					 dent, minor);
> -		if (xe_device_has_lmtt(xe))
> +		if (IS_DGFX(xe))
>  			drm_debugfs_create_files(pf_vram_info,
>  						 ARRAY_SIZE(pf_vram_info),
>  						 dent, minor);