Re: [PATCH v2] drm/xe: restrict multi-lrc to VCS/VECS engines

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

On Wed, Feb 18, 2026 at 11:38:23PM +0000, Xin Wang wrote:
> Tighten uapi validation to restrict multi-lrc support to VIDEO_DECODE and
> VIDEO_ENHANCE engines only. This check should have been in place from the
> start, as the driver typically avoids allowing uapi cases that we have
> no userspace consumer for.
> 

This will break IGTs but that is likely fine as long as those are fixed.

> Additionally, the GuC firmware on ModSched platforms no longer supports
> multi-lrc on non-media engines.
> 
> V2:
>  - correct the typo (Shuicheng)
>  - move the check earlier to avoid VM lookup (Shuicheng, Matt)
>  - remove the graphics version check (Matt)
>  - input more details in the commit info (Matt)
> 
> Cc: Shuicheng Lin <shuicheng.lin@intel.com>
> Cc: Matt Roper <matthew.d.roper@intel.com>
> Signed-off-by: Xin Wang <x.wang@intel.com>
> ---
>  drivers/gpu/drm/xe/xe_exec_queue.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/drivers/gpu/drm/xe/xe_exec_queue.c b/drivers/gpu/drm/xe/xe_exec_queue.c
> index 66d0e10ee2c4..36bf570ab221 100644
> --- a/drivers/gpu/drm/xe/xe_exec_queue.c
> +++ b/drivers/gpu/drm/xe/xe_exec_queue.c
> @@ -1184,6 +1184,12 @@ int xe_exec_queue_create_ioctl(struct drm_device *dev, void *data,
>  		if (XE_IOCTL_DBG(xe, !hwe))
>  			return -EINVAL;
>  
> +		/* multi-lrc is only supported on VIDEO_DECODE and VIDEO_ENHANCE engines */
> +		if (XE_IOCTL_DBG(xe, args->width > 1 &&
> +				 eci[0].engine_class != DRM_XE_ENGINE_CLASS_VIDEO_DECODE &&
> +				 eci[0].engine_class != DRM_XE_ENGINE_CLASS_VIDEO_ENHANCE))
> +			return -EOPNOTSUPP;

Would it be better to store a multi-lrc enable class mask in xe->info
and populate from xe_device_desc in xe_pci.c?

Matt  

> +
>  		vm = xe_vm_lookup(xef, args->vm_id);
>  		if (XE_IOCTL_DBG(xe, !vm))
>  			return -ENOENT;
> -- 
> 2.43.0
>