Re: [PATCH v3 11/19] drm/xe: Allow CPU address mirror VMA unbind with gpu bindings for madvise

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

On Tue, May 27, 2025 at 10:09:55PM +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.
> 
> Signed-off-by: Himal Prasad Ghimiray <himal.prasad.ghimiray@intel.com>
> ---
>  drivers/gpu/drm/xe/xe_svm.c | 25 +++++++++++++++++++++++++
>  drivers/gpu/drm/xe/xe_svm.h |  8 ++++++++
>  drivers/gpu/drm/xe/xe_vm.c  | 18 +++++++++++++++++-
>  3 files changed, 50 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/xe/xe_svm.c b/drivers/gpu/drm/xe/xe_svm.c
> index a4d53c24fcbc..5691bb9dbf26 100644
> --- a/drivers/gpu/drm/xe/xe_svm.c
> +++ b/drivers/gpu/drm/xe/xe_svm.c
> @@ -942,6 +942,31 @@ 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_range_clean_if_addr_within - Clean SVM mappings and ranges
> + * @start: start addr
> + * @end: end addr
> + *
> + * This function cleans up svm ranges if start or end address are inside them.
> + */
> +void xe_svm_range_clean_if_addr_within(struct xe_vm *vm, u64 start, u64 end)
> +{
> +	struct drm_gpusvm_notifier *notifier, *next;
> +

lockdep_assert(vm lock in write mode);

> +	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);

Why evict here? I don't think that is required.

> +				__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..b36f70ab3d03 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_range_clean_if_addr_within(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_range_clean_if_addr_within(struct xe_vm *vm, u64 start, u64 end)
> +{
> +}

Maybe...

s/xe_svm_range_clean_if_addr_within/s/xe_svm_unmap_address_range

Or if you can think of something better but don't really like
xe_svm_range_clean_if_addr_within.

> +
>  #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 c220bf904ee0..8208409485f6 100644
> --- a/drivers/gpu/drm/xe/xe_vm.c
> +++ b/drivers/gpu/drm/xe/xe_vm.c
> @@ -2359,6 +2359,22 @@ vm_bind_ioctl_ops_create(struct xe_vm *vm, struct xe_vma_ops *vops,
>  			op->map.pat_index = pat_index;
>  			op->map.invalidate_on_bind =
>  				__xe_vm_needs_clear_scratch_pages(vm, flags);
> +		} else if (__op->op == DRM_GPUVA_OP_REMAP) {
> +			struct xe_vma *old =
> +				gpuva_to_vma(op->base.remap.unmap->va);
> +			u64 start = xe_vma_start(old), end = xe_vma_end(old);
> +
> +			if (op->base.remap.prev)
> +				start = op->base.remap.prev->va.addr +
> +					op->base.remap.prev->va.range;
> +			if (op->base.remap.next)
> +				end = op->base.remap.next->va.addr;
> +
> +			if (xe_vma_is_cpu_addr_mirror(old) &&
> +			    xe_svm_has_mapping(vm, start, end)) {
> +				drm_gpuva_ops_free(&vm->gpuvm, ops);
> +				return ERR_PTR(-EBUSY);
> +			}

How about dropping this.

>  		} else if (__op->op == DRM_GPUVA_OP_PREFETCH) {
>  			struct xe_vma *vma = gpuva_to_vma(op->base.prefetch.va);
>  			struct xe_svm_range *svm_range;
> @@ -2662,7 +2678,7 @@ static int vm_bind_ioctl_ops_parse(struct xe_vm *vm, struct drm_gpuva_ops *ops,
>  
>  			if (xe_vma_is_cpu_addr_mirror(old) &&
>  			    xe_svm_has_mapping(vm, start, end))
> -				return -EBUSY;
> +				xe_svm_range_clean_if_addr_within(vm, start, end);
>

And here add a flag to xe_vma_ops which says we are in madvise.

e.g. XE_VMA_OPS_FLAG_MADVISE

Then...

if (xe_vma_is_cpu_addr_mirror(old) &&
    xe_svm_has_mapping(vm, start, end)) {
	if (vops->flags & XE_VMA_OPS_FLAG_MADVISE)
		xe_svm_range_clean_if_addr_within(vm, start, end);
	else 
		return -EBUSY;
}

Matt
  
>  			op->remap.start = xe_vma_start(old);
>  			op->remap.range = xe_vma_size(old);
> -- 
> 2.34.1
>