Re: [PATCH v4 06/14] cxl/region: Separate region parameter setup and region construction

[Dave Jiang <dave.jiang@intel.com>]

On 11/3/25 11:47 AM, Robert Richter wrote:
> To construct a region, the region parameters such as address range and
> interleaving config need to be determined. This is done while
> constructing the region by inspecting the endpoint decoder
> configuration. The endpoint decoder is passed as a function argument.
> 
> With address translation the endpoint decoder data is no longer
> sufficient to extract the region parameters as some of the information
> is obtained using other methods such as using firmware calls.
> 
> In a first step, separate code to determine the region parameters from
> the region construction. Temporarily store all the data to create the
> region in the new struct cxl_region_context. Once the region data is
> determined and struct cxl_region_context is filled, construct the
> region.
> 
> Patch is a prerequisite to implement address translation. The code
> separation helps to later extend it to determine region parameters
> using other methods as needed, esp. to support address translation.
> 
> Reviewed-by: Gregory Price <gourry@gourry.net>
> Signed-off-by: Robert Richter <rrichter@amd.com>

Just a small thing below, otherwise
Reviewed-by: Dave Jiang <dave.jiang@intel.com>

> ---
>  drivers/cxl/core/core.h   |  9 +++++++++
>  drivers/cxl/core/region.c | 32 +++++++++++++++++++++-----------
>  2 files changed, 30 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/cxl/core/core.h b/drivers/cxl/core/core.h
> index 1fb66132b777..2bc37f3aee21 100644
> --- a/drivers/cxl/core/core.h
> +++ b/drivers/cxl/core/core.h
> @@ -19,6 +19,15 @@ enum cxl_detach_mode {
>  };
>  
>  #ifdef CONFIG_CXL_REGION
> +
> +struct cxl_region_context {
> +	struct cxl_endpoint_decoder *cxled;
> +	struct cxl_memdev *cxlmd;

cxlmd may not be needed.

struct cxl_memdev *cxlmd = cxled_to_memdev(cxlr_ctx->cxled);

which you used later on in this patch to init the cxlmd member :)

DJ

> +	struct range hpa_range;
> +	int interleave_ways;
> +	int interleave_granularity;
> +};
> +
>  extern struct device_attribute dev_attr_create_pmem_region;
>  extern struct device_attribute dev_attr_create_ram_region;
>  extern struct device_attribute dev_attr_delete_region;
> diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
> index d3557d9d5b0f..2cfc29a2b588 100644
> --- a/drivers/cxl/core/region.c
> +++ b/drivers/cxl/core/region.c
> @@ -3448,11 +3448,12 @@ static int cxl_extended_linear_cache_resize(struct cxl_region *cxlr,
>  }
>  
>  static int __construct_region(struct cxl_region *cxlr,
> -			      struct cxl_endpoint_decoder *cxled)
> +			      struct cxl_region_context *ctx)
>  {
> +	struct cxl_endpoint_decoder *cxled = ctx->cxled;
>  	struct cxl_root_decoder *cxlrd = cxlr->cxlrd;
> -	struct cxl_memdev *cxlmd = cxled_to_memdev(cxled);
> -	struct range *hpa_range = &cxled->cxld.hpa_range;
> +	struct cxl_memdev *cxlmd = ctx->cxlmd;
> +	struct range *hpa_range = &ctx->hpa_range;
>  	struct cxl_region_params *p;
>  	struct resource *res;
>  	int rc;
> @@ -3501,8 +3502,8 @@ static int __construct_region(struct cxl_region *cxlr,
>  	}
>  
>  	p->res = res;
> -	p->interleave_ways = cxled->cxld.interleave_ways;
> -	p->interleave_granularity = cxled->cxld.interleave_granularity;
> +	p->interleave_ways = ctx->interleave_ways;
> +	p->interleave_granularity = ctx->interleave_granularity;
>  	p->state = CXL_CONFIG_INTERLEAVE_ACTIVE;
>  
>  	rc = sysfs_update_group(&cxlr->dev.kobj, get_cxl_region_target_group());
> @@ -3522,9 +3523,10 @@ static int __construct_region(struct cxl_region *cxlr,
>  
>  /* Establish an empty region covering the given HPA range */
>  static struct cxl_region *construct_region(struct cxl_root_decoder *cxlrd,
> -					   struct cxl_endpoint_decoder *cxled)
> +					   struct cxl_region_context *ctx)
>  {
> -	struct cxl_memdev *cxlmd = cxled_to_memdev(cxled);
> +	struct cxl_endpoint_decoder *cxled = ctx->cxled;
> +	struct cxl_memdev *cxlmd = ctx->cxlmd;
>  	struct cxl_port *port = cxlrd_to_port(cxlrd);
>  	struct cxl_dev_state *cxlds = cxlmd->cxlds;
>  	int rc, part = READ_ONCE(cxled->part);
> @@ -3543,7 +3545,7 @@ static struct cxl_region *construct_region(struct cxl_root_decoder *cxlrd,
>  		return cxlr;
>  	}
>  
> -	rc = __construct_region(cxlr, cxled);
> +	rc = __construct_region(cxlr, ctx);
>  	if (rc) {
>  		devm_release_action(port->uport_dev, unregister_region, cxlr);
>  		return ERR_PTR(rc);
> @@ -3568,11 +3570,19 @@ cxl_find_region_by_range(struct cxl_root_decoder *cxlrd,
>  
>  int cxl_add_to_region(struct cxl_endpoint_decoder *cxled)
>  {
> -	struct range *hpa_range = &cxled->cxld.hpa_range;
> +	struct cxl_region_context ctx;
>  	struct cxl_region_params *p;
>  	bool attach = false;
>  	int rc;
>  
> +	ctx = (struct cxl_region_context) {
> +		.cxled = cxled,
> +		.cxlmd = cxled_to_memdev(cxled),
> +		.hpa_range = cxled->cxld.hpa_range,
> +		.interleave_ways = cxled->cxld.interleave_ways,
> +		.interleave_granularity = cxled->cxld.interleave_granularity,
> +	};
> +
>  	struct cxl_root_decoder *cxlrd __free(put_cxl_root_decoder) =
>  		cxl_find_root_decoder(cxled);
>  	if (!cxlrd)
> @@ -3585,9 +3595,9 @@ int cxl_add_to_region(struct cxl_endpoint_decoder *cxled)
>  	 */
>  	mutex_lock(&cxlrd->range_lock);
>  	struct cxl_region *cxlr __free(put_cxl_region) =
> -		cxl_find_region_by_range(cxlrd, hpa_range);
> +		cxl_find_region_by_range(cxlrd, &ctx.hpa_range);
>  	if (!cxlr)
> -		cxlr = construct_region(cxlrd, cxled);
> +		cxlr = construct_region(cxlrd, &ctx);
>  	mutex_unlock(&cxlrd->range_lock);
>  
>  	rc = PTR_ERR_OR_ZERO(cxlr);