Re: [PATCH v1 13/29] cxl: Introduce callback to translate an HPA range from a port to its parent

[Gregory Price]

On Tue, Jan 07, 2025 at 03:09:59PM +0100, Robert Richter wrote:
> To enable address translation, the endpoint's HPA range must be
> translated to each of the parent port's address ranges up to the root
> decoder. Traverse the decoder and port hierarchy from the endpoint up
> to the root port and apply platform specific translation functions to
> determine the next HPA range of the parent port where needed:
> 
>   if (cxl_port->to_hpa)
>     hpa = cxl_port->to_hpa(cxl_decoder, hpa)
> 
> The root port's HPA range is equivalent to the system's SPA range.
> 
> Introduce a callback to translate an HPA range from a port to its
> parent.
> 
> Signed-off-by: Robert Richter <rrichter@xxxxxxx>

Assuming prior patch holds

Reviewed-by: Gregory Price <gourry@xxxxxxxxxx>

> ---
>  drivers/cxl/cxl.h | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
> index be7685fe8a23..49280e0f8840 100644
> --- a/drivers/cxl/cxl.h
> +++ b/drivers/cxl/cxl.h
> @@ -601,6 +601,7 @@ struct cxl_dax_region {
>   * @parent_dport: dport that points to this port in the parent
>   * @decoder_ida: allocator for decoder ids
>   * @reg_map: component and ras register mapping parameters
> + * @to_hpa: Callback to translate a child port's decoder address to the port's HPA address range
>   * @nr_dports: number of entries in @dports
>   * @hdm_end: track last allocated HDM decoder instance for allocation ordering
>   * @commit_end: cursor to track highest committed decoder for commit ordering
> @@ -621,6 +622,7 @@ struct cxl_port {
>  	struct cxl_dport *parent_dport;
>  	struct ida decoder_ida;
>  	struct cxl_register_map reg_map;
> +	cxl_to_hpa_fn to_hpa;
>  	int nr_dports;
>  	int hdm_end;
>  	int commit_end;
> -- 
> 2.39.5
>