Re: [PATCH v7 02/20] drm/gpuvm: Helper to get range of unmap from a remap op.

[Danilo Krummrich]

On 10/10/23 15:37, Sarah Walker wrote:
> From: Donald Robson <donald.robson@xxxxxxxxxx>
>
> Determining the start and range of the unmap stage of a remap op is a
> common piece of code currently implemented by multiple drivers. Add a
> helper for this.
>
> Changes since v6:
> - Remove use of __always_inline
>
> Signed-off-by: Donald Robson <donald.robson@xxxxxxxxxx>
> Signed-off-by: Sarah Walker <sarah.walker@xxxxxxxxxx>
> ---
>   include/drm/drm_gpuvm.h | 27 +++++++++++++++++++++++++++
>   1 file changed, 27 insertions(+)
>
> diff --git a/include/drm/drm_gpuvm.h b/include/drm/drm_gpuvm.h
> index c7ed6bf441d4..932e942da921 100644
> --- a/include/drm/drm_gpuvm.h
> +++ b/include/drm/drm_gpuvm.h
> @@ -702,4 +702,31 @@ void drm_gpuva_remap(struct drm_gpuva *prev,
>   
>   void drm_gpuva_unmap(struct drm_gpuva_op_unmap *op);
>   
> +/**
> + * drm_gpuva_op_remap_get_unmap_range() - Helper to get the start and range of

Not a strong opinion on that, but maybe drm_gpuva_op_remap_to_unmap_range() would
be a bit better.

> + * the unmap stage of a remap op.
> + * @op: Remap op.
> + * @start_addr: Output pointer for the start of the required unmap.
> + * @range: Output pointer for the length of the required unmap.
> + *
> + * These parameters can then be used by the caller to unmap memory pages that
> + * are no longer required.

I think we should be a bit more precise on what this is good for. Maybe something
like: "The given start address and range will be set such that they represent the
range of the address space that was previously covered by the mapping getting
re-mapped, but is empty now."

> + */
> +static inline void
> +drm_gpuva_op_remap_get_unmap_range(const struct drm_gpuva_op_remap *op,
> +				   u64 *start_addr, u64 *range)
> +{
> +	const u64 va_start = op->prev ?
> +			     op->prev->va.addr + op->prev->va.range :
> +			     op->unmap->va->va.addr;
> +	const u64 va_end = op->next ?
> +			   op->next->va.addr :
> +			   op->unmap->va->va.addr + op->unmap->va->va.range;
> +
> +	if (start_addr)
> +		*start_addr = va_start;
> +	if (range)
> +		*range = va_end - va_start;
> +}
> +
>   #endif /* __DRM_GPUVM_H__ */