Re: [PATCH v3 08/19] drm/xe/svm: Add xe_svm_ranges_zap_ptes_in_range() for PTE zapping

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

On Tue, May 27, 2025 at 10:09:52PM +0530, Himal Prasad Ghimiray wrote:
> Introduce xe_svm_ranges_zap_ptes_in_range(), a function to zap page table
> entries (PTEs) for all SVM ranges within a user-specified address range.
> 
> Signed-off-by: Himal Prasad Ghimiray <himal.prasad.ghimiray@intel.com>
> ---
>  drivers/gpu/drm/xe/xe_svm.c | 43 +++++++++++++++++++++++++++++++++++++
>  drivers/gpu/drm/xe/xe_svm.h |  7 ++++++
>  2 files changed, 50 insertions(+)
> 
> diff --git a/drivers/gpu/drm/xe/xe_svm.c b/drivers/gpu/drm/xe/xe_svm.c
> index 59e73187114d..a4d53c24fcbc 100644
> --- a/drivers/gpu/drm/xe/xe_svm.c
> +++ b/drivers/gpu/drm/xe/xe_svm.c
> @@ -1006,6 +1006,49 @@ int xe_svm_range_get_pages(struct xe_vm *vm, struct xe_svm_range *range,
>  	return err;
>  }
>  
> +/**
> + * xe_svm_ranges_zap_ptes_in_range - clear ptes of svm ranges in input range
> + * @vm: Pointer to the xe_vm structure
> + * @start: Start of the input range
> + * @end: End of the input range
> + *
> + * This function removes the page table entries (PTEs) associated
> + * with the svm ranges within the given input start amnd end
> + *
> + * Return: tile_mask for which gt's need to be tlb invalidated.
> + */
> +u8 xe_svm_ranges_zap_ptes_in_range(struct xe_vm *vm, u64 start, u64 end)
> +{
> +	struct drm_gpusvm_notifier *notifier;
> +	struct xe_svm_range *range;
> +	u64 adj_start, adj_end;
> +	struct xe_tile *tile;
> +	u8 tile_mask = 0;
> +	u8 id;
> +
> +	down_write(&vm->svm.gpusvm.notifier_lock);

xe_svm_notifier_lock

> +
> +	drm_gpusvm_for_each_notifier(notifier, &vm->svm.gpusvm, start, end) {
> +		struct drm_gpusvm_range *r = NULL;
> +
> +		adj_start = max(start, notifier->itree.start);
> +		adj_end = min(end, notifier->itree.last + 1);
> +		drm_gpusvm_for_each_range(r, notifier, adj_start, adj_end) {
> +			range = to_xe_range(r);
> +			for_each_tile(tile, vm->xe, id) {
> +				if (xe_pt_zap_ptes_range(tile, vm, range)) {
> +					tile_mask |= BIT(id);
> +					range->tile_invalidated |= BIT(id);
> +				}
> +			}
> +		}
> +	}
> +
> +	up_write(&vm->svm.gpusvm.notifier_lock);
> +

xe_svm_notifier_unlock

Matt

> +	return tile_mask;
> +}
> +
>  #if IS_ENABLED(CONFIG_DRM_XE_DEVMEM_MIRROR)
>  
>  static struct drm_pagemap_device_addr
> diff --git a/drivers/gpu/drm/xe/xe_svm.h b/drivers/gpu/drm/xe/xe_svm.h
> index 19ce4f2754a7..af8f285b6caa 100644
> --- a/drivers/gpu/drm/xe/xe_svm.h
> +++ b/drivers/gpu/drm/xe/xe_svm.h
> @@ -91,6 +91,7 @@ bool xe_svm_range_validate(struct xe_vm *vm,
>  
>  u64 xe_svm_find_vma_start(struct xe_vm *vm, u64 addr, u64 end,  struct xe_vma *vma);
>  
> +u8 xe_svm_ranges_zap_ptes_in_range(struct xe_vm *vm, u64 start, u64 end);
>  /**
>   * xe_svm_range_has_dma_mapping() - SVM range has DMA mapping
>   * @range: SVM range
> @@ -305,6 +306,12 @@ u64 xe_svm_find_vma_start(struct xe_vm *vm, u64 addr, u64 end, struct xe_vma *vm
>  	return ULONG_MAX;
>  }
>  
> +static inline
> +u8 xe_svm_ranges_zap_ptes_in_range(struct xe_vm *vm, u64 start, u64 end)
> +{
> +	return 0;
> +}
> +
>  #define xe_svm_assert_in_notifier(...) do {} while (0)
>  #define xe_svm_range_has_dma_mapping(...) false
>  
> -- 
> 2.34.1
>