Re: [PATCH v6 06/17] drm/xe/multi_queue: Add exec_queue set_property ioctl support

["Thomas Hellström" <thomas.hellstrom@linux.intel.com>]

Hi,

On Wed, 2025-12-10 at 17:02 -0800, Niranjana Vishwanathapura wrote:
> This patch adds support for exec_queue set_property ioctl.
> It is derived from the original work which is part of
> https://patchwork.freedesktop.org/series/112188/
> 
> Currently only DRM_XE_EXEC_QUEUE_SET_PROPERTY_MULTI_QUEUE_PRIORITY
> property can be dynamically set.
> 
> v2: Check for and update kernel-doc which property this ioctl
>     supports (Matt Brost)
> 
> Signed-off-by: Matthew Brost <matthew.brost@intel.com>
> Signed-off-by: Pallavi Mishra <pallavi.mishra@intel.com>
> Signed-off-by: Niranjana Vishwanathapura
> <niranjana.vishwanathapura@intel.com>
> Reviewed-by: Matthew Brost <matthew.brost@intel.com>

Two questions on this patch:

1) I don't see any locking to protect the exec-queue / lrc state.
Perhaps I missed it, but couldn't this blow up if someone runs two
set_property ioctls in parallel on the same exec-queue? Looks like at
least the set_priority is doing non-atomic RMW assignments?

2) Do we really need this to be mutable? In i915 assuming that lrc /
context configuration could change created horrendous locking
constructs that were later fixed by making it immutable at first
command sumbission. I don't exactly remember the details but do we need
to change properties after first submission? If not I suggest blocking
that.

Thanks,
Thomas




> ---
>  drivers/gpu/drm/xe/xe_device.c     |  2 ++
>  drivers/gpu/drm/xe/xe_exec_queue.c | 35
> ++++++++++++++++++++++++++++++
>  drivers/gpu/drm/xe/xe_exec_queue.h |  2 ++
>  include/uapi/drm/xe_drm.h          | 26 ++++++++++++++++++++++
>  4 files changed, 65 insertions(+)
> 
> diff --git a/drivers/gpu/drm/xe/xe_device.c
> b/drivers/gpu/drm/xe/xe_device.c
> index 1197f914ef77..7a498c8db7b1 100644
> --- a/drivers/gpu/drm/xe/xe_device.c
> +++ b/drivers/gpu/drm/xe/xe_device.c
> @@ -207,6 +207,8 @@ static const struct drm_ioctl_desc xe_ioctls[] =
> {
>  	DRM_IOCTL_DEF_DRV(XE_MADVISE, xe_vm_madvise_ioctl,
> DRM_RENDER_ALLOW),
>  	DRM_IOCTL_DEF_DRV(XE_VM_QUERY_MEM_RANGE_ATTRS,
> xe_vm_query_vmas_attrs_ioctl,
>  			  DRM_RENDER_ALLOW),
> +	DRM_IOCTL_DEF_DRV(XE_EXEC_QUEUE_SET_PROPERTY,
> xe_exec_queue_set_property_ioctl,
> +			  DRM_RENDER_ALLOW),
>  };
>  
>  static long xe_drm_ioctl(struct file *file, unsigned int cmd,
> unsigned long arg)
> diff --git a/drivers/gpu/drm/xe/xe_exec_queue.c
> b/drivers/gpu/drm/xe/xe_exec_queue.c
> index d0082eb45a4a..d738a9fea1e1 100644
> --- a/drivers/gpu/drm/xe/xe_exec_queue.c
> +++ b/drivers/gpu/drm/xe/xe_exec_queue.c
> @@ -790,6 +790,41 @@ static const xe_exec_queue_set_property_fn
> exec_queue_set_property_funcs[] = {
>  							exec_queue_s
> et_multi_queue_priority,
>  };
>  
> +int xe_exec_queue_set_property_ioctl(struct drm_device *dev, void
> *data,
> +				     struct drm_file *file)
> +{
> +	struct xe_device *xe = to_xe_device(dev);
> +	struct xe_file *xef = to_xe_file(file);
> +	struct drm_xe_exec_queue_set_property *args = data;
> +	struct xe_exec_queue *q;
> +	int ret;
> +	u32 idx;
> +
> +	if (XE_IOCTL_DBG(xe, args->reserved[0] || args-
> >reserved[1]))
> +		return -EINVAL;
> +
> +	if (XE_IOCTL_DBG(xe, args->property !=
> +			
> DRM_XE_EXEC_QUEUE_SET_PROPERTY_MULTI_QUEUE_PRIORITY))
> +		return -EINVAL;
> +
> +	q = xe_exec_queue_lookup(xef, args->exec_queue_id);
> +	if (XE_IOCTL_DBG(xe, !q))
> +		return -ENOENT;
> +
> +	idx = array_index_nospec(args->property,
> +				
> ARRAY_SIZE(exec_queue_set_property_funcs));
> +	ret = exec_queue_set_property_funcs[idx](xe, q, args-
> >value);
> +	if (XE_IOCTL_DBG(xe, ret))
> +		goto err_post_lookup;
> +
> +	xe_exec_queue_put(q);
> +	return 0;
> +
> + err_post_lookup:
> +	xe_exec_queue_put(q);
> +	return ret;
> +}
> +
>  static int exec_queue_user_ext_check(struct xe_exec_queue *q, u64
> properties)
>  {
>  	u64 secondary_queue_valid_props =
> BIT_ULL(DRM_XE_EXEC_QUEUE_SET_PROPERTY_MULTI_GROUP) |
> diff --git a/drivers/gpu/drm/xe/xe_exec_queue.h
> b/drivers/gpu/drm/xe/xe_exec_queue.h
> index e6daa40003f2..ffcc1feb879e 100644
> --- a/drivers/gpu/drm/xe/xe_exec_queue.h
> +++ b/drivers/gpu/drm/xe/xe_exec_queue.h
> @@ -125,6 +125,8 @@ int xe_exec_queue_destroy_ioctl(struct drm_device
> *dev, void *data,
>  				struct drm_file *file);
>  int xe_exec_queue_get_property_ioctl(struct drm_device *dev, void
> *data,
>  				     struct drm_file *file);
> +int xe_exec_queue_set_property_ioctl(struct drm_device *dev, void
> *data,
> +				     struct drm_file *file);
>  enum xe_exec_queue_priority
> xe_exec_queue_device_get_max_priority(struct xe_device *xe);
>  
>  void xe_exec_queue_last_fence_put(struct xe_exec_queue *e, struct
> xe_vm *vm);
> diff --git a/include/uapi/drm/xe_drm.h b/include/uapi/drm/xe_drm.h
> index fd79d78de2e9..705081bf0d81 100644
> --- a/include/uapi/drm/xe_drm.h
> +++ b/include/uapi/drm/xe_drm.h
> @@ -106,6 +106,7 @@ extern "C" {
>  #define DRM_XE_OBSERVATION		0x0b
>  #define DRM_XE_MADVISE			0x0c
>  #define DRM_XE_VM_QUERY_MEM_RANGE_ATTRS	0x0d
> +#define DRM_XE_EXEC_QUEUE_SET_PROPERTY	0x0e
>  
>  /* Must be kept compact -- no holes */
>  
> @@ -123,6 +124,7 @@ extern "C" {
>  #define
> DRM_IOCTL_XE_OBSERVATION		DRM_IOW(DRM_COMMAND_BASE + DRM_XE_OBSERVATION,structdrm_xe_observation_param)
>  #define
> DRM_IOCTL_XE_MADVISE			DRM_IOW(DRM_COMMAND_BASE + DRM_XE_MADVISE, structdrm_xe_madvise)
>  #define
> DRM_IOCTL_XE_VM_QUERY_MEM_RANGE_ATTRS	DRM_IOWR(DRM_COMMAND_BASE + DRM_XE_VM_QUERY_MEM_RANGE_ATTRS,structdrm_xe_vm_query_mem_range_attr)
> +#define
> DRM_IOCTL_XE_EXEC_QUEUE_SET_PROPERTY	DRM_IOW(DRM_COMMAND_BASE + DRM_XE_EXEC_QUEUE_SET_PROPERTY,structdrm_xe_exec_queue_set_property)
>  
>  /**
>   * DOC: Xe IOCTL Extensions
> @@ -2315,6 +2317,30 @@ struct drm_xe_vm_query_mem_range_attr {
>  
>  };
>  
> +/**
> + * struct drm_xe_exec_queue_set_property - exec queue set property
> + *
> + * Sets execution queue properties dynamically.
> + * Currently only
> %DRM_XE_EXEC_QUEUE_SET_PROPERTY_MULTI_QUEUE_PRIORITY
> + * property can be dynamically set.
> + */
> +struct drm_xe_exec_queue_set_property {
> +	/** @extensions: Pointer to the first extension struct, if
> any */
> +	__u64 extensions;
> +
> +	/** @exec_queue_id: Exec queue ID */
> +	__u32 exec_queue_id;
> +
> +	/** @property: property to set */
> +	__u32 property;
> +
> +	/** @value: property value */
> +	__u64 value;
> +
> +	/** @reserved: Reserved */
> +	__u64 reserved[2];
> +};
> +
>  #if defined(__cplusplus)
>  }
>  #endif