Re: [PATCH i-g-t v6 2/9] lib/xe: Add purgeable memory ioctl support

["Sharma, Nishit" <nishit.sharma@intel.com>]

On 3/25/2026 6:14 PM, Arvind Yadav wrote:
> Add xe_vm_madvise_purgeable() helper function to support purgeable
> memory management through the XE madvise ioctl. This allows applications
> to hint to the kernel about buffer object usage patterns for better
> memory management under pressure.
>
> The function provides a clean interface to:
> - Mark buffer objects as DONTNEED (purgeable)
> - Mark buffer objects as WILLNEED (not purgeable)
>
> Returns the retained value directly (1 if backing store exists, 0 if
> purged).
>
> Also update __xe_vm_madvise() to reject purgeable state operations
> and direct users to the dedicated helper.

Here you can also mention why this new ioctl when __xe_vm_madvise() 
already available.

You can mention the changes required.

>
> v2:
>    - retained must be initialized to 0(Thomas)
>
> v5:
>    - Rename retained to retained_ptr. (Jose)
>
> Cc: Nishit Sharma <nishit.sharma@intel.com>
> Cc: Matthew Brost <matthew.brost@intel.com>
> Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
> Cc: Himal Prasad Ghimiray <himal.prasad.ghimiray@intel.com>
> Cc: Pravalika Gurram <pravalika.gurram@intel.com>
> Signed-off-by: Arvind Yadav <arvind.yadav@intel.com>
> ---
>   lib/xe/xe_ioctl.c | 33 +++++++++++++++++++++++++++++++++
>   lib/xe/xe_ioctl.h |  2 ++
>   2 files changed, 35 insertions(+)
>
> diff --git a/lib/xe/xe_ioctl.c b/lib/xe/xe_ioctl.c
> index ea3f2fcaa..955607f93 100644
> --- a/lib/xe/xe_ioctl.c
> +++ b/lib/xe/xe_ioctl.c
> @@ -785,6 +785,9 @@ int __xe_vm_madvise(int fd, uint32_t vm, uint64_t addr, uint64_t range,
>   	case DRM_XE_MEM_RANGE_ATTR_PAT:
>   		madvise.pat_index.val = op_val;
>   		break;
> +	case DRM_XE_VMA_ATTR_PURGEABLE_STATE:
> +		/* Purgeable state handled by xe_vm_madvise_purgeable */
> +		return -EINVAL;
>   	default:
>   		igt_warn("Unknown attribute\n");
>   		return -EINVAL;
> @@ -821,6 +824,36 @@ void xe_vm_madvise(int fd, uint32_t vm, uint64_t addr, uint64_t range,
>   				      instance), 0);
>   }
>   
> +/**
> + * xe_vm_madvise_purgeable:
> + * @fd: xe device fd
> + * @vm_id: vm_id of the virtual range
> + * @start: start of the virtual address range
> + * @range: size of the virtual address range
> + * @state: purgeable state (DRM_XE_VMA_PURGEABLE_STATE_WILLNEED or DONTNEED)
> + *
> + * Sets the purgeable state for a virtual memory range. This allows applications
> + * to hint to the kernel about buffer object usage patterns for better memory management.
> + *
> + * Returns: retained value (1 if backing store exists, 0 if purged)
> + */
> +uint32_t xe_vm_madvise_purgeable(int fd, uint32_t vm_id, uint64_t start,
> +				 uint64_t range, uint32_t state)
> +{
> +	uint32_t retained_val = 0;
> +	struct drm_xe_madvise madvise = {
> +		.vm_id = vm_id,
> +		.start = start,
> +		.range = range,
> +		.type = DRM_XE_VMA_ATTR_PURGEABLE_STATE,
> +		.purge_state_val.val = state,
> +		.purge_state_val.retained_ptr = (uint64_t)(uintptr_t)&retained_val,
> +	};
> +
> +	igt_assert_eq(igt_ioctl(fd, DRM_IOCTL_XE_MADVISE, &madvise), 0);
> +	return retained_val;
> +}
> +
>   #define	BIND_SYNC_VAL	0x686868
>   void xe_vm_bind_lr_sync(int fd, uint32_t vm, uint32_t bo, uint64_t offset,
>   			uint64_t addr, uint64_t size, uint32_t flags)
> diff --git a/lib/xe/xe_ioctl.h b/lib/xe/xe_ioctl.h
> index b62d259fd..a02d68cfe 100644
> --- a/lib/xe/xe_ioctl.h
> +++ b/lib/xe/xe_ioctl.h
> @@ -108,6 +108,8 @@ int __xe_vm_madvise(int fd, uint32_t vm, uint64_t addr, uint64_t range, uint64_t
>   		    uint32_t type, uint32_t op_val, uint16_t policy, uint16_t instance);
>   void xe_vm_madvise(int fd, uint32_t vm, uint64_t addr, uint64_t range, uint64_t ext,
>   		   uint32_t type, uint32_t op_val, uint16_t policy, uint16_t instance);
> +uint32_t xe_vm_madvise_purgeable(int fd, uint32_t vm_id, uint64_t start,
> +				 uint64_t range, uint32_t state);
>   int xe_vm_number_vmas_in_range(int fd, struct drm_xe_vm_query_mem_range_attr *vmas_attr);
>   int xe_vm_vma_attrs(int fd, struct drm_xe_vm_query_mem_range_attr *vmas_attr,
>   		    struct drm_xe_mem_range_attr *mem_attr);

with above change in commit message LGTM:

Reviewed-by: Nishit Sharma <nishit.sharma@intel.com>