Re: [PATCH] drm/xe/uapi: loosen used tracking restriction

[Rodrigo Vivi <rodrigo.vivi@intel.com>]

On Fri, Sep 19, 2025 at 01:20:53PM +0100, Matthew Auld wrote:
> Currently this is hidden behind perfmon_capable() since this is
> technically an info leak, given that this is a system wide metric.
> However the granularity reported here is always PAGE_SIZE aligned, which
> matches what the core kernel is already willing to expose to userspace
> if querying how many free RAM pages there are on the system, and that
> doesn't need any special privileges. In addition other drm drivers seem
> happy to expose this.
> 
> The motivation here if with oneAPI where they want to use the system
> wide 'used' reporting here, so not the per-client fdinfo stats. This has
> also come up with some perf overlay applications wanting this
> information.
> 
> Fixes: 1105ac15d2a1 ("drm/xe/uapi: restrict system wide accounting")
> Signed-off-by: Matthew Auld <matthew.auld@intel.com>
> Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
> Cc: Joshua Santosh <joshua.santosh.ranjan@intel.com>
> Cc: José Roberto de Souza <jose.souza@intel.com>
> Cc: Matthew Brost <matthew.brost@intel.com>
> Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
> Cc: <stable@vger.kernel.org> # v6.8+

Acked-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

> ---
>  drivers/gpu/drm/xe/xe_query.c | 15 ++++++---------
>  1 file changed, 6 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/gpu/drm/xe/xe_query.c b/drivers/gpu/drm/xe/xe_query.c
> index e1b603aba61b..2e9ff33ed2fe 100644
> --- a/drivers/gpu/drm/xe/xe_query.c
> +++ b/drivers/gpu/drm/xe/xe_query.c
> @@ -276,8 +276,7 @@ static int query_mem_regions(struct xe_device *xe,
>  	mem_regions->mem_regions[0].instance = 0;
>  	mem_regions->mem_regions[0].min_page_size = PAGE_SIZE;
>  	mem_regions->mem_regions[0].total_size = man->size << PAGE_SHIFT;
> -	if (perfmon_capable())
> -		mem_regions->mem_regions[0].used = ttm_resource_manager_usage(man);
> +	mem_regions->mem_regions[0].used = ttm_resource_manager_usage(man);
>  	mem_regions->num_mem_regions = 1;
>  
>  	for (i = XE_PL_VRAM0; i <= XE_PL_VRAM1; ++i) {
> @@ -293,13 +292,11 @@ static int query_mem_regions(struct xe_device *xe,
>  			mem_regions->mem_regions[mem_regions->num_mem_regions].total_size =
>  				man->size;
>  
> -			if (perfmon_capable()) {
> -				xe_ttm_vram_get_used(man,
> -					&mem_regions->mem_regions
> -					[mem_regions->num_mem_regions].used,
> -					&mem_regions->mem_regions
> -					[mem_regions->num_mem_regions].cpu_visible_used);
> -			}
> +			xe_ttm_vram_get_used(man,
> +					     &mem_regions->mem_regions
> +					     [mem_regions->num_mem_regions].used,
> +					     &mem_regions->mem_regions
> +					     [mem_regions->num_mem_regions].cpu_visible_used);
>  
>  			mem_regions->mem_regions[mem_regions->num_mem_regions].cpu_visible_size =
>  				xe_ttm_vram_get_cpu_visible_size(man);
> -- 
> 2.51.0
>