Commit 6e099264 authored by Dan Williams's avatar Dan Williams
Browse files

cxl/region: Add volatile region creation support 



Expand the region creation infrastructure to enable 'ram'
(volatile-memory) regions. The internals of create_pmem_region_store()
and create_pmem_region_show() are factored out into helpers
__create_region() and __create_region_show() for the 'ram' case to
reuse.

Reviewed-by: default avatarVishal Verma <vishal.l.verma@intel.com>
Reviewed-by: default avatarGregory Price <gregory.price@memverge.com>
Reviewed-by: default avatarDave Jiang <dave.jiang@intel.com>
Reviewed-by: default avatarIra Weiny <ira.weiny@intel.com>
Reviewed-by: default avatarJonathan Cameron <Jonathan.Cameron@huawei.com>
Tested-by: default avatarFan Ni <fan.ni@samsung.com>
Link: https://lore.kernel.org/r/167601995775.1924368.352616146815830591.stgit@dwillia2-xfh.jf.intel.com


Signed-off-by: default avatarDan Williams <dan.j.williams@intel.com>
parent 1b9b7a6f

Documentation/ABI/testing/sysfs-bus-cxl

+11 −11
Original line number Diff line number Diff line
@@ -285,20 +285,20 @@ Description: 
		interleave_granularity).





What:		/sys/bus/cxl/devices/decoderX.Y/create_pmem_region

Date:		May, 2022

KernelVersion:	v6.0

What:		/sys/bus/cxl/devices/decoderX.Y/create_{pmem,ram}_region

Date:		May, 2022, January, 2023

KernelVersion:	v6.0 (pmem), v6.3 (ram)

Contact:	linux-cxl@vger.kernel.org

Description:

		(RW) Write a string in the form 'regionZ' to start the process

		of defining a new persistent memory region (interleave-set)

		within the decode range bounded by root decoder 'decoderX.Y'.

		The value written must match the current value returned from

		reading this attribute. An atomic compare exchange operation is

		done on write to assign the requested id to a region and

		allocate the region-id for the next creation attempt. EBUSY is

		returned if the region name written does not match the current

		cached value.

		of defining a new persistent, or volatile memory region

		(interleave-set) within the decode range bounded by root decoder

		'decoderX.Y'. The value written must match the current value

		returned from reading this attribute. An atomic compare exchange

		operation is done on write to assign the requested id to a

		region and allocate the region-id for the next creation attempt.

		EBUSY is returned if the region name written does not match the

		current cached value.





What:		/sys/bus/cxl/devices/decoderX.Y/delete_region

drivers/cxl/core/core.h

+1 −0
Original line number Diff line number Diff line
@@ -11,6 +11,7 @@ extern struct attribute_group cxl_base_attribute_group; 


#ifdef CONFIG_CXL_REGION

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;

extern struct device_attribute dev_attr_region;

extern const struct device_type cxl_pmem_region_type;

drivers/cxl/core/port.c

+13 −1
Original line number Diff line number Diff line
@@ -294,6 +294,7 @@ static struct attribute *cxl_decoder_root_attrs[] = { 
	&dev_attr_cap_type3.attr,

	&dev_attr_target_list.attr,

	SET_CXL_REGION_ATTR(create_pmem_region)

	SET_CXL_REGION_ATTR(create_ram_region)

	SET_CXL_REGION_ATTR(delete_region)

	NULL,

};
@@ -305,6 +306,13 @@ static bool can_create_pmem(struct cxl_root_decoder *cxlrd) 
	return (cxlrd->cxlsd.cxld.flags & flags) == flags;

}



static bool can_create_ram(struct cxl_root_decoder *cxlrd)

{

	unsigned long flags = CXL_DECODER_F_TYPE3 | CXL_DECODER_F_RAM;



	return (cxlrd->cxlsd.cxld.flags & flags) == flags;

}



static umode_t cxl_root_decoder_visible(struct kobject *kobj, struct attribute *a, int n)

{

	struct device *dev = kobj_to_dev(kobj);
@@ -313,7 +321,11 @@ static umode_t cxl_root_decoder_visible(struct kobject *kobj, struct attribute * 
	if (a == CXL_REGION_ATTR(create_pmem_region) && !can_create_pmem(cxlrd))

		return 0;



	if (a == CXL_REGION_ATTR(delete_region) && !can_create_pmem(cxlrd))

	if (a == CXL_REGION_ATTR(create_ram_region) && !can_create_ram(cxlrd))

		return 0;



	if (a == CXL_REGION_ATTR(delete_region) &&

	    !(can_create_pmem(cxlrd) || can_create_ram(cxlrd)))

		return 0;



	return a->mode;

drivers/cxl/core/region.c

+58 −13
Original line number Diff line number Diff line
@@ -1689,6 +1689,15 @@ static struct cxl_region *devm_cxl_add_region(struct cxl_root_decoder *cxlrd, 
	struct device *dev;

	int rc;



	switch (mode) {

	case CXL_DECODER_RAM:

	case CXL_DECODER_PMEM:

		break;

	default:

		dev_err(&cxlrd->cxlsd.cxld.dev, "unsupported mode %d\n", mode);

		return ERR_PTR(-EINVAL);

	}



	cxlr = cxl_region_alloc(cxlrd, id);

	if (IS_ERR(cxlr))

		return cxlr;
@@ -1717,12 +1726,38 @@ static struct cxl_region *devm_cxl_add_region(struct cxl_root_decoder *cxlrd, 
	return ERR_PTR(rc);

}



static ssize_t __create_region_show(struct cxl_root_decoder *cxlrd, char *buf)

{

	return sysfs_emit(buf, "region%u\n", atomic_read(&cxlrd->region_id));

}



static ssize_t create_pmem_region_show(struct device *dev,

				       struct device_attribute *attr, char *buf)

{

	struct cxl_root_decoder *cxlrd = to_cxl_root_decoder(dev);

	return __create_region_show(to_cxl_root_decoder(dev), buf);

}



	return sysfs_emit(buf, "region%u\n", atomic_read(&cxlrd->region_id));

static ssize_t create_ram_region_show(struct device *dev,

				      struct device_attribute *attr, char *buf)

{

	return __create_region_show(to_cxl_root_decoder(dev), buf);

}



static struct cxl_region *__create_region(struct cxl_root_decoder *cxlrd,

					  enum cxl_decoder_mode mode, int id)

{

	int rc;



	rc = memregion_alloc(GFP_KERNEL);

	if (rc < 0)

		return ERR_PTR(rc);



	if (atomic_cmpxchg(&cxlrd->region_id, id, rc) != id) {

		memregion_free(rc);

		return ERR_PTR(-EBUSY);

	}



	return devm_cxl_add_region(cxlrd, id, mode, CXL_DECODER_EXPANDER);

}



static ssize_t create_pmem_region_store(struct device *dev,
@@ -1731,29 +1766,39 @@ static ssize_t create_pmem_region_store(struct device *dev, 
{

	struct cxl_root_decoder *cxlrd = to_cxl_root_decoder(dev);

	struct cxl_region *cxlr;

	int id, rc;

	int rc, id;



	rc = sscanf(buf, "region%d\n", &id);

	if (rc != 1)

		return -EINVAL;



	rc = memregion_alloc(GFP_KERNEL);

	if (rc < 0)

		return rc;

	cxlr = __create_region(cxlrd, CXL_DECODER_PMEM, id);

	if (IS_ERR(cxlr))

		return PTR_ERR(cxlr);



	if (atomic_cmpxchg(&cxlrd->region_id, id, rc) != id) {

		memregion_free(rc);

		return -EBUSY;

	return len;

}

DEVICE_ATTR_RW(create_pmem_region);



static ssize_t create_ram_region_store(struct device *dev,

				       struct device_attribute *attr,

				       const char *buf, size_t len)

{

	struct cxl_root_decoder *cxlrd = to_cxl_root_decoder(dev);

	struct cxl_region *cxlr;

	int rc, id;



	rc = sscanf(buf, "region%d\n", &id);

	if (rc != 1)

		return -EINVAL;



	cxlr = devm_cxl_add_region(cxlrd, id, CXL_DECODER_PMEM,

				   CXL_DECODER_EXPANDER);

	cxlr = __create_region(cxlrd, CXL_DECODER_RAM, id);

	if (IS_ERR(cxlr))

		return PTR_ERR(cxlr);



	return len;

}

DEVICE_ATTR_RW(create_pmem_region);

DEVICE_ATTR_RW(create_ram_region);



static ssize_t region_show(struct device *dev, struct device_attribute *attr,

			   char *buf)