[PATCH v5 19/23] drm/xe/vm: Add helper to check for default VMA memory attributes

[Matthew Brost]

On Tue, Jul 22, 2025 at 07:05:22PM +0530, Himal Prasad Ghimiray wrote:
> Introduce a new helper function `xe_vma_has_default_mem_attrs()` to
> determine whether a VMA's memory attributes are set to their default
> values. This includes checks for atomic access, PAT index, and preferred
> location.
> 
> Also, add a new field `default_pat_index` to `struct xe_vma_mem_attr`
> to track the initial PAT index set during the first bind. This helps
> distinguish between default and user-modified pat index, such as those
> changed via madvise.
> 
> Signed-off-by: Himal Prasad Ghimiray <himal.prasad.ghimiray at intel.com>

Ah, I see how you restore the default pat_index here. Different than how
I was thinking but it makes sense.

Reviewed-by: Matthew Brost <matthew.brost at intel.com>

> ---
>  drivers/gpu/drm/xe/xe_vm.c       | 24 ++++++++++++++++++++++++
>  drivers/gpu/drm/xe/xe_vm.h       |  2 ++
>  drivers/gpu/drm/xe/xe_vm_types.h |  6 ++++++
>  3 files changed, 32 insertions(+)
> 
> diff --git a/drivers/gpu/drm/xe/xe_vm.c b/drivers/gpu/drm/xe/xe_vm.c
> index 5dc7cd7769f8..d3f08bf9a3ee 100644
> --- a/drivers/gpu/drm/xe/xe_vm.c
> +++ b/drivers/gpu/drm/xe/xe_vm.c
> @@ -2592,6 +2592,29 @@ static int xe_vma_op_commit(struct xe_vm *vm, struct xe_vma_op *op)
>  	return err;
>  }
>  
> +/**
> + * xe_vma_has_default_mem_attrs - Check if a VMA has default memory attributes
> + * @vma: Pointer to the xe_vma structure to check
> + *
> + * This function determines whether the given VMA (Virtual Memory Area)
> + * has its memory attributes set to their default values. Specifically,
> + * it checks the following conditions:
> + *
> + * - `atomic_access` is `DRM_XE_VMA_ATOMIC_UNDEFINED`
> + * - `pat_index` is equal to `default_pat_index`
> + * - `preferred_loc.devmem_fd` is `DRM_XE_PREFERRED_LOC_DEFAULT_DEVICE`
> + * - `preferred_loc.migration_policy` is `DRM_XE_MIGRATE_ALL_PAGES`
> + *
> + * Return: true if all attributes are at their default values, false otherwise.
> + */
> +bool xe_vma_has_default_mem_attrs(struct xe_vma *vma)
> +{
> +	return (vma->attr.atomic_access == DRM_XE_ATOMIC_UNDEFINED &&
> +		vma->attr.pat_index ==  vma->attr.default_pat_index &&
> +		vma->attr.preferred_loc.devmem_fd == DRM_XE_PREFERRED_LOC_DEFAULT_DEVICE &&
> +		vma->attr.preferred_loc.migration_policy == DRM_XE_MIGRATE_ALL_PAGES);
> +}
> +
>  static int vm_bind_ioctl_ops_parse(struct xe_vm *vm, struct drm_gpuva_ops *ops,
>  				   struct xe_vma_ops *vops)
>  {
> @@ -2624,6 +2647,7 @@ static int vm_bind_ioctl_ops_parse(struct xe_vm *vm, struct drm_gpuva_ops *ops,
>  					.migration_policy = DRM_XE_MIGRATE_ALL_PAGES,
>  				},
>  				.atomic_access = DRM_XE_ATOMIC_UNDEFINED,
> +				.default_pat_index = op->map.pat_index,
>  				.pat_index = op->map.pat_index,
>  			};
>  
> diff --git a/drivers/gpu/drm/xe/xe_vm.h b/drivers/gpu/drm/xe/xe_vm.h
> index d5bc09ae640c..a4db843de540 100644
> --- a/drivers/gpu/drm/xe/xe_vm.h
> +++ b/drivers/gpu/drm/xe/xe_vm.h
> @@ -66,6 +66,8 @@ static inline bool xe_vm_is_closed_or_banned(struct xe_vm *vm)
>  struct xe_vma *
>  xe_vm_find_overlapping_vma(struct xe_vm *vm, u64 start, u64 range);
>  
> +bool xe_vma_has_default_mem_attrs(struct xe_vma *vma);
> +
>  /**
>   * xe_vm_has_scratch() - Whether the vm is configured for scratch PTEs
>   * @vm: The vm
> diff --git a/drivers/gpu/drm/xe/xe_vm_types.h b/drivers/gpu/drm/xe/xe_vm_types.h
> index 81d92d886578..351242c92c12 100644
> --- a/drivers/gpu/drm/xe/xe_vm_types.h
> +++ b/drivers/gpu/drm/xe/xe_vm_types.h
> @@ -103,8 +103,14 @@ struct xe_vma_mem_attr {
>  	 */
>  	u32 atomic_access;
>  
> +	/**
> +	 * @default_pat_index: The pat index for VMA set during first bind by user.
> +	 */
> +	u16 default_pat_index;
> +
>  	/**
>  	 * @pat_index: The pat index to use when encoding the PTEs for this vma.
> +	 * same as default_pat_index unless overwritten by madvise.
>  	 */
>  	u16 pat_index;
>  };
> -- 
> 2.34.1
>