[PATCH v5 09/23] drm/xe/svm: Add xe_svm_ranges_zap_ptes_in_range() for PTE zapping

Matthew Brost matthew.brost at intel.com
Tue Jul 29 03:42:35 UTC 2025


On Tue, Jul 22, 2025 at 07:05:12PM +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.
> 
> -v2 (Matthew Brost)
> Lock should be called even for tlb_invalidation
> 
> v3(Matthew Brost)
> - Update comment
> - s/notifier->itree.start/drm_gpusvm_notifier_start
> - s/notifier->itree.last + 1/drm_gpusvm_notifier_end
> - use WRITE_ONCE
> 
> Cc: Matthew Brost <matthew.brost at intel.com>

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

> Signed-off-by: Himal Prasad Ghimiray <himal.prasad.ghimiray at intel.com>
> ---
>  drivers/gpu/drm/xe/xe_pt.c  | 14 ++++++++++-
>  drivers/gpu/drm/xe/xe_svm.c | 50 +++++++++++++++++++++++++++++++++++++
>  drivers/gpu/drm/xe/xe_svm.h |  8 ++++++
>  3 files changed, 71 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/xe/xe_pt.c b/drivers/gpu/drm/xe/xe_pt.c
> index 1bf0cf81513c..b499006df2cf 100644
> --- a/drivers/gpu/drm/xe/xe_pt.c
> +++ b/drivers/gpu/drm/xe/xe_pt.c
> @@ -950,7 +950,19 @@ bool xe_pt_zap_ptes_range(struct xe_tile *tile, struct xe_vm *vm,
>  	struct xe_pt *pt = vm->pt_root[tile->id];
>  	u8 pt_mask = (range->tile_present & ~range->tile_invalidated);
>  
> -	xe_svm_assert_in_notifier(vm);
> +	/*
> +	 * Locking rules:
> +	 *
> +	 * - notifier_lock (write): full protection against page table changes
> +	 *   and MMU notifier invalidations.
> +	 *
> +	 * - notifier_lock (read) + vm_lock (write): combined protection against
> +	 *   invalidations and concurrent page table modifications. (e.g., madvise)
> +	 *
> +	 */
> +	lockdep_assert(lockdep_is_held_type(&vm->svm.gpusvm.notifier_lock, 0) ||
> +		       (lockdep_is_held_type(&vm->svm.gpusvm.notifier_lock, 1) &&
> +		       lockdep_is_held_type(&vm->lock, 0)));
>  
>  	if (!(pt_mask & BIT(tile->id)))
>  		return false;
> diff --git a/drivers/gpu/drm/xe/xe_svm.c b/drivers/gpu/drm/xe/xe_svm.c
> index ce8a71b80811..c093dc453e32 100644
> --- a/drivers/gpu/drm/xe/xe_svm.c
> +++ b/drivers/gpu/drm/xe/xe_svm.c
> @@ -1025,6 +1025,56 @@ 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 and 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;
> +
> +	lockdep_assert(lockdep_is_held_type(&vm->svm.gpusvm.notifier_lock, 1) &&
> +		       lockdep_is_held_type(&vm->lock, 0));
> +
> +	drm_gpusvm_for_each_notifier(notifier, &vm->svm.gpusvm, start, end) {
> +		struct drm_gpusvm_range *r = NULL;
> +
> +		adj_start = max(start, drm_gpusvm_notifier_start(notifier));
> +		adj_end = min(end, drm_gpusvm_notifier_end(notifier));
> +		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);
> +					/*
> +					 * WRITE_ONCE pairs with READ_ONCE in
> +					 * xe_vm_has_valid_gpu_mapping().
> +					 * Must not fail after setting
> +					 * tile_invalidated and before
> +					 * TLB invalidation.
> +					 */
> +					WRITE_ONCE(range->tile_invalidated,
> +						   range->tile_invalidated | BIT(id));
> +				}
> +			}
> +		}
> +	}
> +
> +	return tile_mask;
> +}
> +
>  #if IS_ENABLED(CONFIG_DRM_XE_PAGEMAP)
>  
>  /**
> diff --git a/drivers/gpu/drm/xe/xe_svm.h b/drivers/gpu/drm/xe/xe_svm.h
> index 754d56b4d255..b0da0e85f0b8 100644
> --- a/drivers/gpu/drm/xe/xe_svm.h
> +++ b/drivers/gpu/drm/xe/xe_svm.h
> @@ -92,6 +92,8 @@ u64 xe_svm_find_vma_start(struct xe_vm *vm, u64 addr, u64 end,  struct xe_vma *v
>  
>  void xe_svm_unmap_address_range(struct xe_vm *vm, u64 start, u64 end);
>  
> +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
> @@ -310,6 +312,12 @@ void xe_svm_unmap_address_range(struct xe_vm *vm, u64 start, u64 end)
>  {
>  }
>  
> +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
> 


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