Re: [PATCH v2 08/15] cxl/region: Use the endpoint's SPA range to find a region

[Gregory Price]

On Tue, Feb 18, 2025 at 02:23:49PM +0100, Robert Richter wrote:
> To find the correct region and root port of an endpoint of a system
> needing address translation, the endpoint's HPA range must be
> translated to each of the parent port address ranges up to the root
> decoder.
> 
> Use the calculated SPA range of an endpoint to find the endpoint's
> region.
>
> Signed-off-by: Robert Richter <rrichter@xxxxxxx>

May be worth noting that cxl_endpoint_initialize() will set
cxled->spa_range regardless of whether HPA=SPA or not, and so it will
always contain the correct value at this point - even if translation
was not required.

Reviewed-by: Gregory Price <gourry@xxxxxxxxxx>

> ---
>  drivers/cxl/core/region.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
> index 6d5ede5b4c43..ffe6038249ed 100644
> --- a/drivers/cxl/core/region.c
> +++ b/drivers/cxl/core/region.c
> @@ -3535,7 +3535,6 @@ static struct cxl_region *construct_region(struct cxl_root_decoder *cxlrd,
>  
>  static int cxl_endpoint_decoder_add(struct cxl_endpoint_decoder *cxled)
>  {
> -	struct range *hpa = &cxled->cxld.hpa_range;
>  	struct cxl_root_decoder *cxlrd = cxled->cxlrd;
>  	struct cxl_region_params *p;
>  	struct cxl_region *cxlr;
> @@ -3547,7 +3546,7 @@ static int cxl_endpoint_decoder_add(struct cxl_endpoint_decoder *cxled)
>  	 * one does the construction and the others add to that.
>  	 */
>  	mutex_lock(&cxlrd->range_lock);
> -	cxlr = cxl_find_region_by_range(cxlrd, hpa);
> +	cxlr = cxl_find_region_by_range(cxlrd, &cxled->spa_range);
>  	if (!cxlr)
>  		cxlr = construct_region(cxlrd, cxled);
>  	mutex_unlock(&cxlrd->range_lock);
> -- 
> 2.39.5
>