Re: [PATCH v4 11/20] drm/xe: Allow CPU address mirror VMA unbind with gpu bindings for madvise

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

On Fri, Jun 13, 2025 at 06:25:49PM +0530, Himal Prasad Ghimiray wrote:
> In the case of the MADVISE ioctl, if the start or end addresses fall
> within a VMA and existing SVM ranges are present, remove the existing
> SVM mappings. Then, continue with ops_parse to create new VMAs by REMAP
> unmapping of old one.
> 
> v2 (Matthew Brost)
> - Use vops flag to call unmapping of ranges in vm_bind_ioctl_ops_parse
> - Rename the function
> 
> Signed-off-by: Himal Prasad Ghimiray <himal.prasad.ghimiray@intel.com>
> ---
>  drivers/gpu/drm/xe/xe_svm.c | 27 +++++++++++++++++++++++++++
>  drivers/gpu/drm/xe/xe_svm.h |  8 ++++++++
>  drivers/gpu/drm/xe/xe_vm.c  |  8 ++++++--
>  3 files changed, 41 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/xe/xe_svm.c b/drivers/gpu/drm/xe/xe_svm.c
> index 19420635f1fa..df6992ee2e2d 100644
> --- a/drivers/gpu/drm/xe/xe_svm.c
> +++ b/drivers/gpu/drm/xe/xe_svm.c
> @@ -935,6 +935,33 @@ bool xe_svm_has_mapping(struct xe_vm *vm, u64 start, u64 end)
>  	return drm_gpusvm_has_mapping(&vm->svm.gpusvm, start, end);
>  }
>  
> +/**
> + * xe_svm_unmap_address_range - UNMAP SVM mappings and ranges
> + * @start: start addr
> + * @end: end addr
> + *
> + * This function UNMAPS svm ranges if start or end address are inside them.
> + */
> +void xe_svm_unmap_address_range(struct xe_vm *vm, u64 start, u64 end)
> +{
> +	struct drm_gpusvm_notifier *notifier, *next;
> +
> +	lockdep_assert_held_write(&vm->lock);
> +
> +	drm_gpusvm_for_each_notifier_safe(notifier, next, &vm->svm.gpusvm, start, end) {
> +		struct drm_gpusvm_range *range, *__next;
> +
> +		drm_gpusvm_for_each_range_safe(range, __next, notifier, start, end) {
> +			if (start > drm_gpusvm_range_start(range) ||
> +			    end < drm_gpusvm_range_end(range)) {
> +				if (IS_DGFX(vm->xe) && xe_svm_range_in_vram(to_xe_range(range)))
> +					drm_gpusvm_range_evict(&vm->svm.gpusvm, range);

I think you could use xe_svm_range_migrate_to_smem here but also I don't
eviction is strickly required here either. This akin to a partial unmap
and we don't evict there. Any reason that I'm missing here?

Matt

> +				__xe_svm_garbage_collector(vm, to_xe_range(range));
> +			}
> +		}
> +	}
> +}
> +
>  /**
>   * xe_svm_bo_evict() - SVM evict BO to system memory
>   * @bo: BO to evict
> diff --git a/drivers/gpu/drm/xe/xe_svm.h b/drivers/gpu/drm/xe/xe_svm.h
> index af8f285b6caa..4e5d42323679 100644
> --- a/drivers/gpu/drm/xe/xe_svm.h
> +++ b/drivers/gpu/drm/xe/xe_svm.h
> @@ -92,6 +92,9 @@ 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);
> +
> +void xe_svm_unmap_address_range(struct xe_vm *vm, u64 start, u64 end);
> +
>  /**
>   * xe_svm_range_has_dma_mapping() - SVM range has DMA mapping
>   * @range: SVM range
> @@ -312,6 +315,11 @@ u8 xe_svm_ranges_zap_ptes_in_range(struct xe_vm *vm, u64 start, u64 end)
>  	return 0;
>  }
>  
> +static inline
> +void xe_svm_unmap_address_range(struct xe_vm *vm, u64 start, u64 end)
> +{
> +}
> +
>  #define xe_svm_assert_in_notifier(...) do {} while (0)
>  #define xe_svm_range_has_dma_mapping(...) false
>  
> diff --git a/drivers/gpu/drm/xe/xe_vm.c b/drivers/gpu/drm/xe/xe_vm.c
> index e059d9810d26..0872df8d0b15 100644
> --- a/drivers/gpu/drm/xe/xe_vm.c
> +++ b/drivers/gpu/drm/xe/xe_vm.c
> @@ -2663,8 +2663,12 @@ static int vm_bind_ioctl_ops_parse(struct xe_vm *vm, struct drm_gpuva_ops *ops,
>  				end = op->base.remap.next->va.addr;
>  
>  			if (xe_vma_is_cpu_addr_mirror(old) &&
> -			    xe_svm_has_mapping(vm, start, end))
> -				return -EBUSY;
> +			    xe_svm_has_mapping(vm, start, end)) {
> +				if (vops->flags & XE_VMA_OPS_FLAG_MADVISE)
> +					xe_svm_unmap_address_range(vm, start, end);
> +				else
> +					return -EBUSY;
> +			}
>  
>  			op->remap.start = xe_vma_start(old);
>  			op->remap.range = xe_vma_size(old);
> -- 
> 2.34.1
>