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

[Niranjana Vishwanathapura <niranjana.vishwanathapura@intel.com>]

On Mon, Jan 19, 2026 at 05:57:29PM +0100, Thomas Hellström wrote:
>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?
>

Hmm...I think only checking and setting of 'q->multi_queue.priority'
in guc_exec_queue_set_multi_queue_priority() is a potential issue
(as the rest is handled by message handling queue and guc ct backend).
I think we can fix it with a simple spicklock in this function.

>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.

Yah, ability to dynamically change multi-queue priority is a requirement
from the Compute UMD team.

Niranjana

>
>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
>