Re: [PATCH v4 02/20] drm/xe/uapi: Add madvise interface

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

On Fri, Jun 13, 2025 at 06:25:40PM +0530, Himal Prasad Ghimiray wrote:
> This commit introduces a new madvise interface to support
> driver-specific ioctl operations. The madvise interface allows for more
> efficient memory management by providing hints to the driver about the
> expected memory usage and pte update policy for gpuvma.
> 
> v2 (Matthew/Thomas)
> - Drop num_ops support
> - Drop purgeable support
> - Add kernel-docs
> - IOWR/IOW
> 
> Cc: Matthew Brost <matthew.brost@intel.com>
> Signed-off-by: Himal Prasad Ghimiray <himal.prasad.ghimiray@intel.com>
> Acked-by: José Roberto de Souza <jose.souza@intel.com>
> ---
>  include/uapi/drm/xe_drm.h | 118 ++++++++++++++++++++++++++++++++++++++
>  1 file changed, 118 insertions(+)
> 
> diff --git a/include/uapi/drm/xe_drm.h b/include/uapi/drm/xe_drm.h
> index 6a702ba7817c..b5f8d11faaa8 100644
> --- a/include/uapi/drm/xe_drm.h
> +++ b/include/uapi/drm/xe_drm.h
> @@ -81,6 +81,7 @@ extern "C" {
>   *  - &DRM_IOCTL_XE_EXEC
>   *  - &DRM_IOCTL_XE_WAIT_USER_FENCE
>   *  - &DRM_IOCTL_XE_OBSERVATION
> + *  - &DRM_IOCTL_XE_MADVISE
>   */
>  
>  /*
> @@ -102,6 +103,7 @@ extern "C" {
>  #define DRM_XE_EXEC			0x09
>  #define DRM_XE_WAIT_USER_FENCE		0x0a
>  #define DRM_XE_OBSERVATION		0x0b
> +#define DRM_XE_MADVISE			0x0c
>  
>  /* Must be kept compact -- no holes */
>  
> @@ -117,6 +119,7 @@ extern "C" {
>  #define DRM_IOCTL_XE_EXEC			DRM_IOW(DRM_COMMAND_BASE + DRM_XE_EXEC, struct drm_xe_exec)
>  #define DRM_IOCTL_XE_WAIT_USER_FENCE		DRM_IOWR(DRM_COMMAND_BASE + DRM_XE_WAIT_USER_FENCE, struct drm_xe_wait_user_fence)
>  #define DRM_IOCTL_XE_OBSERVATION		DRM_IOW(DRM_COMMAND_BASE + DRM_XE_OBSERVATION, struct drm_xe_observation_param)
> +#define DRM_IOCTL_XE_MADVISE			DRM_IOW(DRM_COMMAND_BASE + DRM_XE_MADVISE, struct drm_xe_madvise)
>  
>  /**
>   * DOC: Xe IOCTL Extensions
> @@ -1970,6 +1973,121 @@ struct drm_xe_query_eu_stall {
>  	__u64 sampling_rates[];
>  };
>  
> +/**
> + * struct drm_xe_madvise - Input of &DRM_IOCTL_XE_MADVISE
> + *
> + * This structure is used to set memory attributes for a virtual address range
> + * in a VM. The type of attribute is specified by @type, and the corresponding
> + * union member is used to provide additional parameters for @type.
> + *
> + * Supported attribute types:
> + * - DRM_XE_VMA_ATTR_PREFERRED_LOC: Set preferred memory location.
> + * - DRM_XE_VMA_ATTR_ATOMIC: Set atomic access policy.
> + * - DRM_XE_VMA_ATTR_PAT: Set page attribute table index.
> + *
> + * Example:
> + *
> + * .. code-block:: C
> + *
> + * struct drm_xe_madvise madvise = {
> + *          .vm_id = vm_id,
> + *          .start = 0x100000,
> + *          .range = 0x2000,
> + *          .type = DRM_XE_VMA_ATTR_ATOMIC,
> + *          .atomic_val = DRM_XE_VMA_ATOMIC_DEVICE,
> + *         };
> + *
> + * ioctl(fd, DRM_IOCTL_XE_MADVISE, &madvise);
> + *
> + */
> +struct drm_xe_madvise {
> +	/** @extensions: Pointer to the first extension struct, if any */
> +	__u64 extensions;
> +
> +	/** @start: start of the virtual address range */
> +	__u64 start;
> +
> +	/** @size: size of the virtual address range */
> +	__u64 range;
> +
> +	/** @vm_id: vm_id of the virtual range */
> +	__u32 vm_id;
> +
> +#define DRM_XE_VMA_ATTR_PREFERRED_LOC	0
> +#define DRM_XE_VMA_ATTR_ATOMIC		1
> +#define DRM_XE_VMA_ATTR_PAT		2
> +	/** @type: type of attribute */
> +	__u32 type;
> +
> +	union {

Nit: I'd make this union is same order as the defines (e.g., preferred location
first, atomic second, pat third).

> +		/**
> +		 * @atomic: Atomic access policy
> +		 *
> +		 * Used when @type == DRM_XE_VMA_ATTR_ATOMIC.
> +		 *
> +		 * Supported values for @atomic.val:
> +		 * - DRM_XE_VMA_ATOMIC_UNDEFINED: Undefined or default behaviour
> +		 *   Support both GPU and CPU atomic operations for system allocator
> +		 *   Support GPU atomic operations for normal(bo) allocator
> +		 * - DRM_XE_VMA_ATOMIC_DEVICE: Support GPU atomic operations
> +		 * - DRM_XE_VMA_ATOMIC_GLOBAL: Support both GPU and CPU atomic operations
> +		 * - DRM_XE_VMA_ATOMIC_CPU: Support CPU atomic
> +		 */
> +		struct {
> +#define DRM_XE_VMA_ATOMIC_UNDEFINED	0
> +#define DRM_XE_VMA_ATOMIC_DEVICE	1
> +#define DRM_XE_VMA_ATOMIC_GLOBAL	2
> +#define DRM_XE_VMA_ATOMIC_CPU		3
> +			/** @atomic.val: value of atomic operation */
> +			__u32 val;
> +
> +			/** @atomic.reserved: Reserved */
> +			__u32 reserved;
> +		} atomic;
> +
> +		/**
> +		 * @pat_index: Page attribute table index
> +		 *
> +		 * Used when @type == DRM_XE_VMA_ATTR_PAT.
> +		 */
> +		struct {
> +			/** @pat_index.val: PAT index value */
> +			__u32 val;
> +
> +			/** @pat_index.reserved: Reserved */
> +			__u32 reserved;
> +		} pat_index;
> +
> +		/**
> +		 * @preferred_mem_loc: preferred memory location
> +		 *
> +		 * Used when @type == DRM_XE_VMA_ATTR_PREFERRED_LOC
> +		 *
> +		 * Supported values for @preferred_mem_loc.devmem_fd:
> +		 * - DRM_XE_PREFERRED_LOC_DEFAULT_DEVICE: set vram of faulting tile as preferred loc
> +		 * - DRM_XE_PREFERRED_LOC_DEFAULT_SYSTEM: set smem as preferred loc
> +		 *
> +		 * Supported values for @preferred_mem_loc.migration_policy:
> +		 * - DRM_XE_MIGRATE_ALL_PAGES
> +		 * - DRM_XE_MIGRATE_ONLY_SYSTEM_PAGES
> +		 */
> +		struct {
> +#define DRM_XE_PREFERRED_LOC_DEFAULT_DEVICE	0
> +#define DRM_XE_PREFERRED_LOC_DEFAULT_SYSTEM	-1
> +			/** @preferred_mem_loc.devmem_fd: fd for preferred loc */
> +			__u32 devmem_fd;
> +
> +#define DRM_XE_MIGRATE_ALL_PAGES		0
> +#define DRM_XE_MIGRATE_ONLY_SYSTEM_PAGES	1

I'd double check with Thomas / maintainers if they want this (migration_policy)
to be included in this version as still more or less unused in this series.

> +			/** @preferred_mem_loc.migration_policy: Page migration policy */
> +			__u32 migration_policy;

Could we future proof a little, maybe migration_policy is a __u16 (or __u8?) and
stick a reserved __u16 in here?

Matt

> +		} preferred_mem_loc;
> +	};
> +
> +	/** @reserved: Reserved */
> +	__u64 reserved[2];
> +};
> +
>  #if defined(__cplusplus)
>  }
>  #endif
> -- 
> 2.34.1
>