Commit d6602e25 authored by Dave Jiang's avatar Dave Jiang
Browse files

cxl/region: Add support to indicate region has extended linear cache 



Add a region sysfs attribute to show the size of the extended linear
cache if there is any. The attribute is invisible when the cache
size is 0, which indicates it does not exist.

Moved the cxl_region_visible() location in order to pick up the
new sysfs attribute definition.

[ dj: Fixed spelling errors noted by Benjamin ]

Reviewed-by: default avatarAlison Schofield <alison.schofield@intel.com>
Reviewed-by: default avatarBen Cheatham <benjamin.cheatham@amd.com>
Reviewed-by: default avatarJonathan Cameron <jonathan.cameron@huawei.com>
Link: https://patch.msgid.link/20251022203052.4078527-1-dave.jiang@intel.com


Signed-off-by: default avatarDave Jiang <dave.jiang@intel.com>
parent f0c5d3bc

Documentation/ABI/testing/sysfs-bus-cxl

+10 −1
Original line number Diff line number Diff line
@@ -496,8 +496,17 @@ Description: 
		changed, only freed by writing 0. The kernel makes no guarantees

		that data is maintained over an address space freeing event, and

		there is no guarantee that a free followed by an allocate

		results in the same address being allocated.

		results in the same address being allocated. If extended linear

		cache is present, the size indicates extended linear cache size

		plus the CXL region size.



What:		/sys/bus/cxl/devices/regionZ/extended_linear_cache_size

Date:		October, 2025

KernelVersion:	v6.19

Contact:	linux-cxl@vger.kernel.org

Description:

		(RO) The size of extended linear cache, if there is an extended

		linear cache. Otherwise the attribute will not be visible.



What:		/sys/bus/cxl/devices/regionZ/mode

Date:		January, 2023

drivers/cxl/core/region.c

+44 −15
Original line number Diff line number Diff line
@@ -461,21 +461,6 @@ static ssize_t commit_show(struct device *dev, struct device_attribute *attr, 
}

static DEVICE_ATTR_RW(commit);



static umode_t cxl_region_visible(struct kobject *kobj, struct attribute *a,

				  int n)

{

	struct device *dev = kobj_to_dev(kobj);

	struct cxl_region *cxlr = to_cxl_region(dev);



	/*

	 * Support tooling that expects to find a 'uuid' attribute for all

	 * regions regardless of mode.

	 */

	if (a == &dev_attr_uuid.attr && cxlr->mode != CXL_PARTMODE_PMEM)

		return 0444;

	return a->mode;

}



static ssize_t interleave_ways_show(struct device *dev,

				    struct device_attribute *attr, char *buf)

{
@@ -754,6 +739,21 @@ static ssize_t size_show(struct device *dev, struct device_attribute *attr, 
}

static DEVICE_ATTR_RW(size);



static ssize_t extended_linear_cache_size_show(struct device *dev,

					       struct device_attribute *attr,

					       char *buf)

{

	struct cxl_region *cxlr = to_cxl_region(dev);

	struct cxl_region_params *p = &cxlr->params;

	ssize_t rc;



	ACQUIRE(rwsem_read_intr, rwsem)(&cxl_rwsem.region);

	if ((rc = ACQUIRE_ERR(rwsem_read_intr, &rwsem)))

		return rc;

	return sysfs_emit(buf, "%#llx\n", p->cache_size);

}

static DEVICE_ATTR_RO(extended_linear_cache_size);



static struct attribute *cxl_region_attrs[] = {

	&dev_attr_uuid.attr,

	&dev_attr_commit.attr,
@@ -762,9 +762,34 @@ static struct attribute *cxl_region_attrs[] = { 
	&dev_attr_resource.attr,

	&dev_attr_size.attr,

	&dev_attr_mode.attr,

	&dev_attr_extended_linear_cache_size.attr,

	NULL,

};



static umode_t cxl_region_visible(struct kobject *kobj, struct attribute *a,

				  int n)

{

	struct device *dev = kobj_to_dev(kobj);

	struct cxl_region *cxlr = to_cxl_region(dev);



	/*

	 * Support tooling that expects to find a 'uuid' attribute for all

	 * regions regardless of mode.

	 */

	if (a == &dev_attr_uuid.attr && cxlr->mode != CXL_PARTMODE_PMEM)

		return 0444;



	/*

	 * Don't display extended linear cache attribute if there is no

	 * extended linear cache.

	 */

	if (a == &dev_attr_extended_linear_cache_size.attr &&

	    cxlr->params.cache_size == 0)

		return 0;



	return a->mode;

}



static const struct attribute_group cxl_region_group = {

	.attrs = cxl_region_attrs,

	.is_visible = cxl_region_visible,
@@ -3479,6 +3504,10 @@ static int __construct_region(struct cxl_region *cxlr, 
			 "Extended linear cache calculation failed rc:%d\n", rc);

	}



	rc = sysfs_update_group(&cxlr->dev.kobj, &cxl_region_group);

	if (rc)

		return rc;



	rc = insert_resource(cxlrd->res, res);

	if (rc) {

		/*