Re: [PATCH v1 23/29] cxl/region: Use root decoders interleaving parameters to create a region

[Alison Schofield]

On Tue, Jan 07, 2025 at 03:10:09PM +0100, Robert Richter wrote:
> Endpoints requiring address translation might not be aware of the
> system's interleaving configuration. Instead, interleaving can be
> configured on an upper memory domain (from an endpoint view) and thus
> is not visible to the endpoint. For region creation this might cause
> an invalid interleaving config that does not match the CFMWS entries.
> 
> Use the interleaving configuration of the root decoders to create a
> region which bases on CFMWS entries. This always matches the system's
> interleaving configuration and is independent of the underlying memory
> topology.

This sounds like a restriction, more restrictive than present.

Won't it block all region interleave ways greater than root decoder
interleave ways? ie. disallows 2, 2+2, 2+2+2, 4, etc.


> 
> Signed-off-by: Robert Richter <rrichter@xxxxxxx>
> ---
>  drivers/cxl/core/region.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
> index e218f0be2409..c3322bae05b9 100644
> --- a/drivers/cxl/core/region.c
> +++ b/drivers/cxl/core/region.c
> @@ -3477,8 +3477,8 @@ static struct cxl_region *construct_region(struct cxl_root_decoder *cxlrd,
>  	}
>  
>  	p->res = res;
> -	p->interleave_ways = cxled->cxld.interleave_ways;
> -	p->interleave_granularity = cxled->cxld.interleave_granularity;
> +	p->interleave_ways = cxlrd->cxlsd.cxld.interleave_ways;
> +	p->interleave_granularity = cxlrd->cxlsd.cxld.interleave_granularity;
>  	p->state = CXL_CONFIG_INTERLEAVE_ACTIVE;
>  
>  	rc = sysfs_update_group(&cxlr->dev.kobj, get_cxl_region_target_group());
> -- 
> 2.39.5
>