Commit d01149bb authored by Robert Richter's avatar Robert Richter Committed by Dave Jiang
Browse files

cxl/region: Use region data to get the root decoder 



To find a region's root decoder, the endpoint's HPA range is used to
search the matching decoder by its range. With address translation the
endpoint decoder's range is in a different address space and thus
cannot be used to determine the root decoder.

The region parameters are encapsulated within struct cxl_region_context
and may include the translated Host Physical Address (HPA) range. Use
this context to identify the root decoder rather than relying on the
endpoint.

Modify cxl_find_root_decoder() and add the region context as
parameter. Rename this function to get_cxl_root_decoder() as a
counterpart to put_cxl_root_decoder(). Simplify the implementation by
removing function cxl_port_find_switch_decode(). The function is
unnecessary because it is not referenced or utilized elsewhere in the
code.

Reviewed-by: default avatarDave Jiang <dave.jiang@intel.com>
Reviewed-by: default avatarJonathan Cameron <jonathan.cameron@huawei.com>
Reviewed-by: default avatarAlison Schofield <alison.schofield@intel.com>
Tested-by: default avatarGregory Price <gourry@gourry.net>
Signed-off-by: default avatarRobert Richter <rrichter@amd.com>
Link: https://patch.msgid.link/20260114164837.1076338-8-rrichter@amd.com


Signed-off-by: default avatarDave Jiang <dave.jiang@intel.com>
parent 1fd6c38f

drivers/cxl/core/region.c

+24 −26
Original line number Diff line number Diff line
@@ -3469,47 +3469,44 @@ static int devm_cxl_add_dax_region(struct cxl_region *cxlr) 
	return rc;

}



static int match_decoder_by_range(struct device *dev, const void *data)

static int match_root_decoder(struct device *dev, const void *data)

{

	const struct range *r1, *r2 = data;

	struct cxl_decoder *cxld;

	struct cxl_root_decoder *cxlrd;



	if (!is_switch_decoder(dev))

	if (!is_root_decoder(dev))

		return 0;



	cxld = to_cxl_decoder(dev);

	r1 = &cxld->hpa_range;

	return range_contains(r1, r2);

}

	cxlrd = to_cxl_root_decoder(dev);

	r1 = &cxlrd->cxlsd.cxld.hpa_range;



static struct cxl_decoder *

cxl_port_find_switch_decoder(struct cxl_port *port, struct range *hpa_range)

{

	struct device *cxld_dev = device_find_child(&port->dev, hpa_range,

						    match_decoder_by_range);



	return cxld_dev ? to_cxl_decoder(cxld_dev) : NULL;

	return range_contains(r1, r2);

}



/*

 * Note, when finished with the device, drop the reference with

 * put_device() or use the put_cxl_root_decoder helper.

 */

static struct cxl_root_decoder *

cxl_find_root_decoder(struct cxl_endpoint_decoder *cxled)

get_cxl_root_decoder(struct cxl_endpoint_decoder *cxled,

		     struct cxl_region_context *ctx)

{

	struct cxl_memdev *cxlmd = cxled_to_memdev(cxled);

	struct cxl_port *port = cxled_to_port(cxled);

	struct cxl_root *cxl_root __free(put_cxl_root) = find_cxl_root(port);

	struct cxl_decoder *root, *cxld = &cxled->cxld;

	struct range *hpa_range = &cxld->hpa_range;

	struct device *cxlrd_dev;



	root = cxl_port_find_switch_decoder(&cxl_root->port, hpa_range);

	if (!root) {

	cxlrd_dev = device_find_child(&cxl_root->port.dev, &ctx->hpa_range,

				      match_root_decoder);

	if (!cxlrd_dev) {

		dev_err(cxlmd->dev.parent,

			"%s:%s no CXL window for range %#llx:%#llx\n",

			dev_name(&cxlmd->dev), dev_name(&cxld->dev),

			hpa_range->start, hpa_range->end);

		return NULL;

			dev_name(&cxlmd->dev), dev_name(&cxled->cxld.dev),

			ctx->hpa_range.start, ctx->hpa_range.end);

		return ERR_PTR(-ENXIO);

	}



	return to_cxl_root_decoder(&root->dev);

	return to_cxl_root_decoder(cxlrd_dev);

}



static int match_region_by_range(struct device *dev, const void *data)
@@ -3706,9 +3703,10 @@ int cxl_add_to_region(struct cxl_endpoint_decoder *cxled) 
	};



	struct cxl_root_decoder *cxlrd __free(put_cxl_root_decoder) =

		cxl_find_root_decoder(cxled);

	if (!cxlrd)

		return -ENXIO;

		get_cxl_root_decoder(cxled, &ctx);



	if (IS_ERR(cxlrd))

		return PTR_ERR(cxlrd);



	/*

	 * Ensure that, if multiple threads race to construct_region()