Re: [v2,3/4] lib/xe: use debugfs info to implement xe_engine_class_supports_multi_queue()

[Daniel Charles <daniel.charles@intel.com>]

On 4/3/2026 12:13 AM, Xin Wang wrote:
> Update xe_engine_class_supports_multi_queue() to take a device fd and
> use the kernel-reported multi_queue_engine_classes bitmask from debugfs
> when available, with a fallback to the hardcoded default for older KMD.
>
> Propagate the new fd argument through the xe_for_each_multi_queue_engine
> and xe_for_each_multi_queue_engine_class macros and all their call sites.
>
> Signed-off-by: Xin Wang <x.wang@intel.com>
> ---
>   lib/xe/xe_query.c                 | 52 ++++++++++++++++++-------------
>   lib/xe/xe_query.h                 |  8 ++---
>   tests/intel/xe_exec_multi_queue.c |  4 +--
>   tests/intel/xe_exec_threads.c     |  4 +--
>   4 files changed, 38 insertions(+), 30 deletions(-)
>
> diff --git a/lib/xe/xe_query.c b/lib/xe/xe_query.c
> index e13d5e143..3286a3b37 100644
> --- a/lib/xe/xe_query.c
> +++ b/lib/xe/xe_query.c
> @@ -215,28 +215,6 @@ static uint16_t xe_device_query_engine_class_mask(int fd, const char *key)
>   	return mask;
>   }
>   
> -/**
> - * xe_engine_class_supports_multi_queue:
> - * @engine_class: engine class
> - *
> - * Returns true if multi queue supported by engine class or false.
> - */
> -bool xe_engine_class_supports_multi_queue(uint32_t engine_class)
> -{
> -	switch (engine_class) {
> -		case DRM_XE_ENGINE_CLASS_COPY:
> -		case DRM_XE_ENGINE_CLASS_COMPUTE:
> -			return true;
> -		case DRM_XE_ENGINE_CLASS_RENDER:
> -		case DRM_XE_ENGINE_CLASS_VIDEO_DECODE:
> -		case DRM_XE_ENGINE_CLASS_VIDEO_ENHANCE:
> -			return false;
> -		default:
> -			igt_warn("Engine class 0x%x unknown\n", engine_class);
> -			return false;
> -	}
> -}
> -
>   /**
>    * xe_engine_class_string:
>    * @engine_class: engine class
> @@ -338,6 +316,36 @@ bool xe_engine_class_supports_multi_lrc(int fd, uint32_t engine_class)
>   	}
>   }
>   
> +/**
> + * xe_engine_class_supports_multi_queue:
> + * @fd: xe device fd
> + * @engine_class: engine class
> + *
> + * Returns true if multi queue supported by engine class or false.
> + * Uses the kernel-reported bitmask from debugfs when available, otherwise
> + * falls back to the hardcoded per-class default.
> + */
> +bool xe_engine_class_supports_multi_queue(int fd, uint32_t engine_class)
> +{
> +	struct xe_device *xe_dev = find_in_cache(fd);
> +
> +	if (xe_dev && xe_dev->multi_queue_engine_class_mask != UINT16_MAX)
> +		return !!(xe_dev->multi_queue_engine_class_mask & BIT(engine_class));
> +
> +	switch (engine_class) {
> +	case DRM_XE_ENGINE_CLASS_COPY:
> +	case DRM_XE_ENGINE_CLASS_COMPUTE:
> +		return true;
> +	case DRM_XE_ENGINE_CLASS_RENDER:
> +	case DRM_XE_ENGINE_CLASS_VIDEO_DECODE:
> +	case DRM_XE_ENGINE_CLASS_VIDEO_ENHANCE:
> +		return false;
> +	default:
> +		igt_warn("Engine class 0x%x unknown\n", engine_class);
> +		return false;
> +	}
> +}
> +
>   static void xe_device_free(struct xe_device *xe_dev)
>   {
>   	free(xe_dev->config);
> diff --git a/lib/xe/xe_query.h b/lib/xe/xe_query.h
> index 5c26a3e88..8815c6c66 100644
> --- a/lib/xe/xe_query.h
> +++ b/lib/xe/xe_query.h
> @@ -113,10 +113,10 @@ struct xe_device {
>   
>   #define xe_for_each_multi_queue_engine(__fd, __hwe)	\
>   	xe_for_each_engine(__fd, __hwe)			\
> -		for_if(xe_engine_class_supports_multi_queue((__hwe)->engine_class))
> -#define xe_for_each_multi_queue_engine_class(__class)			\
> +		for_if(xe_engine_class_supports_multi_queue(__fd, (__hwe)->engine_class))
> +#define xe_for_each_multi_queue_engine_class(__fd, __class)		\
>   	xe_for_each_engine_class(__class)				\
> -		for_if(xe_engine_class_supports_multi_queue(__class))
> +		for_if(xe_engine_class_supports_multi_queue(__fd, __class))
>   
>   #define XE_IS_CLASS_SYSMEM(__region) ((__region)->mem_class == DRM_XE_MEM_REGION_CLASS_SYSMEM)
>   #define XE_IS_CLASS_VRAM(__region) ((__region)->mem_class == DRM_XE_MEM_REGION_CLASS_VRAM)
> @@ -161,7 +161,7 @@ uint32_t xe_get_default_alignment(int fd);
>   uint32_t xe_va_bits(int fd);
>   uint16_t xe_dev_id(int fd);
>   int xe_supports_faults(int fd);
> -bool xe_engine_class_supports_multi_queue(uint32_t engine_class);
> +bool xe_engine_class_supports_multi_queue(int fd, uint32_t engine_class);
>   bool xe_engine_class_supports_multi_lrc(int fd, uint32_t engine_class);
>   const char *xe_engine_class_string(uint32_t engine_class);
>   const char *xe_engine_class_short_string(uint32_t engine_class);
> diff --git a/tests/intel/xe_exec_multi_queue.c b/tests/intel/xe_exec_multi_queue.c
> index f987f8d6a..b5ded0633 100644
> --- a/tests/intel/xe_exec_multi_queue.c
> +++ b/tests/intel/xe_exec_multi_queue.c
> @@ -1052,7 +1052,7 @@ int igt_main()
>   
>   	igt_subtest_f("sanity")
>   		xe_for_each_gt(fd, gt)
> -			xe_for_each_multi_queue_engine_class(class)
> +			xe_for_each_multi_queue_engine_class(fd, class)
>   				test_sanity(fd, gt, class);
>   
>   	igt_subtest_f("exec-sanity")
> @@ -1061,7 +1061,7 @@ int igt_main()
>   
>   	igt_subtest_f("virtual")
>   		xe_for_each_gt(fd, gt)
> -			xe_for_each_multi_queue_engine_class(class)
> +			xe_for_each_multi_queue_engine_class(fd, class)
>   				test_exec_virtual(fd, gt, class);
>   
>   	igt_subtest_f("priority")
> diff --git a/tests/intel/xe_exec_threads.c b/tests/intel/xe_exec_threads.c
> index f082a0eda..ab9565beb 100644
> --- a/tests/intel/xe_exec_threads.c
> +++ b/tests/intel/xe_exec_threads.c
> @@ -1141,7 +1141,7 @@ static void threads(int fd, int flags)
>   	int gt;
>   
>   	xe_for_each_engine(fd, hwe) {
> -		if ((flags & MULTI_QUEUE) && !xe_engine_class_supports_multi_queue(hwe->engine_class))
> +		if ((flags & MULTI_QUEUE) && !xe_engine_class_supports_multi_queue(fd, hwe->engine_class))
>   			continue;
>   		++n_engines;
>   	}
> @@ -1170,7 +1170,7 @@ static void threads(int fd, int flags)
>   	}
>   
>   	xe_for_each_engine(fd, hwe) {
> -		if ((flags & MULTI_QUEUE) && !xe_engine_class_supports_multi_queue(hwe->engine_class))
> +		if ((flags & MULTI_QUEUE) && !xe_engine_class_supports_multi_queue(fd, hwe->engine_class))
>   			continue;
>   		threads_data[i].mutex = &mutex;
>   		threads_data[i].cond = &cond;
Reviewed-by:Daniel Charles <daniel.charles@intel.com>