Re: [PATCH v2 0/4] Introduce PF-mem VRAM regions

[Matthew Auld <matthew.auld@intel.com>]

On 21/08/2026 10:45, Piórkowski, Piotr wrote:
> From: Piotr Piórkowski <piotr.piorkowski@intel.com>
> 
> This series lays the groundwork for PF-mem regions: VRAM regions
> dedicated to kernel-only allocations, where buffers are allocated
> exclusively by the kernel driver and are never exposed to userspace
> workloads.
> 
> Today a tile exposes a single VRAM region shared by both kernel and
> userspace allocations. Some use cases need a separate VRAM region
> carved out of a tile and reserved for the kernel driver only. For

Do you have a sketch in mind for how this will look? Do you take the 
normal VRAM region and reserve a contig piece of it using the allocator, 
forming your kernel-only region? Or do you partition VRAM into two 
different regions?  How do you choose the offset and size? Does this 
come from the KMD or is this fw/hw?

> example, on an SR-IOV PF most of the tile VRAM is provisioned to VFs;
> the kernel driver still needs its own allocations, which must come from
> a region reserved for the kernel and kept apart from the VRAM handed
> out to VFs. That reserved kernel region is what PF-mem provides.
> 
> To support this, the VRAM region abstraction needs a way to distinguish
> regions by purpose, dedicated TTM placements so the BO paths can route
> and evict such buffers correctly, and helpers to create a region from a
> caller-provided parent, offset, and size.
> 
> v1 -> v2:
>   - Add comments explaining why PF-mem is excluded from user BO eviction
>     (Sashiko).
>   - Resolve xe_ttm_vram_mgr_alloc_sgt() physical address via
>     xe_map_resource_to_region() instead of the tile's
>     VRAM region (Sashiko).
>   - Enforce page alignment on offset/size and guard against a NULL
>     parent BAR mapping (Sashiko)
> 
> Piotr Piórkowski (4):
>    drm/xe/vram: Add binding information to VRAM regions
>    drm/xe/ttm: Add PF-mem VRAM placement types for TTM
>    drm/xe/vram: Add initial support for PF-mem regions
>    drm/xe/kunit: Add tests for PF-mem regions
> 
>   drivers/gpu/drm/xe/tests/xe_vram.c   | 115 +++++++++++++++++++++++++++
>   drivers/gpu/drm/xe/xe_bo.c           |  16 +++-
>   drivers/gpu/drm/xe/xe_bo.h           |  17 ++++
>   drivers/gpu/drm/xe/xe_bo_evict.c     |   7 +-
>   drivers/gpu/drm/xe/xe_pm.c           |   4 +-
>   drivers/gpu/drm/xe/xe_res_cursor.h   |   9 ++-
>   drivers/gpu/drm/xe/xe_tile.c         |  10 ++-
>   drivers/gpu/drm/xe/xe_ttm_vram_mgr.c |   9 +--
>   drivers/gpu/drm/xe/xe_vram.c         |  90 +++++++++++++++++++--
>   drivers/gpu/drm/xe/xe_vram.h         |  10 ++-
>   drivers/gpu/drm/xe/xe_vram_types.h   |  14 +++-
>   11 files changed, 275 insertions(+), 26 deletions(-)
>   create mode 100644 drivers/gpu/drm/xe/tests/xe_vram.c
>