Re: [PATCH v3 1/3] drm/xe: add VM_BIND DECOMPRESS uapi flag

[Matthew Brost <matthew.brost@intel.com>]

On Wed, Oct 15, 2025 at 04:17:07PM +0530, Nitin Gote wrote:
> Add a new VM_BIND flag, DRM_XE_VM_BIND_FLAG_DECOMPRESS, that lets userspace
> express intent for the driver to perform on-device in-place decompression
> for the GPU mapping created by a MAP bind operation.
> 
> This flag is used by subsequent driver changes to trigger scheduling of
> GPU work that resolves compressed VRAM pages into an uncompressed PAT
> VM mapping.
> 
> Behavior and semantics:
> - Valid only for DRM_XE_VM_BIND_OP_MAP. IOCTLs using this flag on other ops
>   are rejected (-EINVAL).
> - The bind's pat_index must select the device "no-compression" PAT entry;
>   otherwise the ioctl is rejected (-EINVAL).
> - Only meaningful for VRAM-backed BOs on devices that support Flat CCS and
>   the required hardware generation (driver will return -EOPNOTSUPP if not).
> - On success the driver schedules a migrate/resolve and installs the
>   returned dma_fence into the BO's kernel reservation
>   (DMA_RESV_USAGE_KERNEL).
> 
> v2: Add kernel doc (Matt)
> 
> Cc: Matthew Brost <matthew.brost@intel.com>
> Cc: Matthew Auld <matthew.auld@intel.com>
> Signed-off-by: Nitin Gote <nitin.r.gote@intel.com>
> ---
>  include/uapi/drm/xe_drm.h | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/include/uapi/drm/xe_drm.h b/include/uapi/drm/xe_drm.h
> index 40ff19f52a8d..07bd63651a7e 100644
> --- a/include/uapi/drm/xe_drm.h
> +++ b/include/uapi/drm/xe_drm.h
> @@ -1013,6 +1013,13 @@ struct drm_xe_vm_destroy {
>   *    valid on VMs with DRM_XE_VM_CREATE_FLAG_FAULT_MODE set. The CPU address
>   *    mirror flag are only valid for DRM_XE_VM_BIND_OP_MAP operations, the BO
>   *    handle MBZ, and the BO offset MBZ.
> + *  - DRM_XE_VM_BIND_FLAG_DECOMPRESS - Request on-device decompression for a MAP.
> + *    When set on a MAP bind operation, request the driver schedule an on-device
> + *    in-place decompression (via the migrate/resolve path) for the GPU mapping
> + *    created by this bind. Only valid for DRM_XE_VM_BIND_OP_MAP; usage on
> + *    other ops is rejected. The bind's pat_index must select the device's
> + *    "no-compression" PAT. Only meaningful for VRAM-backed BOs on devices that
> + *    support Flat CCS and the required HW generation XE2+.

Reviewed-by: Matthew Brost <matthew.brost@intel.com>

Since this uAPI, I believe we should get a UMD ack here too ahead or merging.

Matt

>   *
>   * The @prefetch_mem_region_instance for %DRM_XE_VM_BIND_OP_PREFETCH can also be:
>   *  - %DRM_XE_CONSULT_MEM_ADVISE_PREF_LOC, which ensures prefetching occurs in
> @@ -1119,6 +1126,7 @@ struct drm_xe_vm_bind_op {
>  #define DRM_XE_VM_BIND_FLAG_DUMPABLE	(1 << 3)
>  #define DRM_XE_VM_BIND_FLAG_CHECK_PXP	(1 << 4)
>  #define DRM_XE_VM_BIND_FLAG_CPU_ADDR_MIRROR	(1 << 5)
> +#define DRM_XE_VM_BIND_FLAG_DECOMPRESS	(1 << 6)
>  	/** @flags: Bind flags */
>  	__u32 flags;
>  
> -- 
> 2.25.1
>