[PATCH i-g-t 0/7] Future-proof GT ID handling for Xe

[Matthew Brost]

On Mon, Jun 30, 2025 at 09:35:30AM -0700, Matt Roper wrote:
> Current Intel platforms fall into one of three cases:
>  * Single tile, single GT (primary)
>  * Multiple tiles, one GT each (primary)
>  * Single tile, two GTs (primary+media)
> 
> In all three cases, the GTs are always consecutive (0 and 1) and the
> GT's uapi ID matches its index in the xe_query GT list.  Future
> platforms could potentially have multiple tiles with multiple GTs each,
> and/or could introduce new types of GTs.  In either case, it's possible
> that there might be "holes" in the set of GT IDs returned by the GT
> query (e.g., 0, 2, 3 if a multi-tile platform only media on the second
> tile; or 0, 2 if a single-tile platform introduced a new type of GT, but
> lacked media).
> 

I think in the future we may logically remap GTs too for various
reasons. For this to work, the gt_id returned to user space really just
needs to be an opaque handle which the KMD can assign whatever value to.

I haven't looked through this series (or KMD) but it seems like step in
the right direction for logical remapping, right?

Matt

> We need to break IGT's assumption that the uapi ID used to represent a
> GT always matches its index in the GT query.  This series shouldn't have
> any functional impact on today's Intel platforms; the goal is to just
> future-proof the code for new types of platforms that could show up in
> the future.  Similar refactoring and cleanup is happening on the xe.ko
> side at https://patchwork.freedesktop.org/series/150192/  although this
> series does not depend on the kernel work.
> 
> 
> Matt Roper (7):
>   lib/xe: Track valid GT IDs
>   lib/xe: Don't assume GT ID matches location in GT query list
>   lib/xe: Populate vram_size[] and visible_vram_size[] by GT ID
>   lib/xe: Ensure GT loops iterate over all GTs properly
>   tests/intel/xe_query: Look up GT reference clock correctly
>   lib/xe: Add xe_dev_max_gt()
>   tests/xe: Don't assume max GT ID is num_gt - 1
> 
>  lib/xe/xe_query.c        | 78 ++++++++++++++++++++++++++++++----------
>  lib/xe/xe_query.h        | 10 ++++--
>  lib/xe/xe_util.c         |  7 ++--
>  tests/intel/xe_compute.c | 47 ++++++++++++------------
>  tests/intel/xe_gt_freq.c |  8 ++---
>  tests/intel/xe_query.c   | 13 +++----
>  6 files changed, 103 insertions(+), 60 deletions(-)
> 
> -- 
> 2.49.0
>