drivers/cxl/mem.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /* Copyright(c) 2022 Intel Corporation. All rights reserved. */
 #include <linux/debugfs.h>
 #include <linux/device.h>
 #include <linux/module.h>
 #include <linux/pci.h>

 #include "cxlmem.h"
 #include "cxlpci.h"

 /**
  * DOC: cxl mem
  *
  * CXL memory endpoint devices and switches are CXL capable devices that are
  * participating in CXL.mem protocol. Their functionality builds on top of the
  * CXL.io protocol that allows enumerating and configuring components via
  * standard PCI mechanisms.
  *
  * The cxl_mem driver owns kicking off the enumeration of this CXL.mem
  * capability. With the detection of a CXL capable endpoint, the driver will
  * walk up to find the platform specific port it is connected to, and determine
  * if there are intervening switches in the path. If there are switches, a
  * secondary action is to enumerate those (implemented in cxl_core). Finally the
  * cxl_mem driver adds the device it is bound to as a CXL endpoint-port for use
  * in higher level operations.
  */

 static void enable_suspend(void *data)
 {
 	cxl_mem_active_dec();
 }

 static void remove_debugfs(void *dentry)
 {
 	debugfs_remove_recursive(dentry);
 }

 static int cxl_mem_dpa_show(struct seq_file *file, void *data)
 {
 	struct device *dev = file->private;
 	struct cxl_memdev *cxlmd = to_cxl_memdev(dev);

 	cxl_dpa_debug(file, cxlmd->cxlds);

 	return 0;
 }

 static int devm_cxl_add_endpoint(struct device *host, struct cxl_memdev *cxlmd,
 				 struct cxl_dport *parent_dport)
 {
 	struct cxl_port *parent_port = parent_dport->port;
 	struct cxl_port *endpoint, *iter, *down;
 	int rc;

 	/*
 	 * Now that the path to the root is established record all the
 	 * intervening ports in the chain.
 	 */
 	for (iter = parent_port, down = NULL; !is_cxl_root(iter);
 	     down = iter, iter = to_cxl_port(iter->dev.parent)) {
 		struct cxl_ep *ep;

 		ep = cxl_ep_load(iter, cxlmd);
 		ep->next = down;
 	}

 	/* Note: endpoint port component registers are derived from @cxlds */
 	endpoint = devm_cxl_add_port(host, &cxlmd->dev, CXL_RESOURCE_NONE,
 				     parent_dport);
 	if (IS_ERR(endpoint))
 		return PTR_ERR(endpoint);

 	rc = cxl_endpoint_autoremove(cxlmd, endpoint);
 	if (rc)
 		return rc;

 	if (!endpoint->dev.driver) {
 		dev_err(&cxlmd->dev, "%s failed probe\n",
 			dev_name(&endpoint->dev));
 		return -ENXIO;
 	}

 	return 0;
 }

 static int cxl_debugfs_poison_inject(void *data, u64 dpa)
 {
 	struct cxl_memdev *cxlmd = data;

 	return cxl_inject_poison(cxlmd, dpa);
 }

 DEFINE_DEBUGFS_ATTRIBUTE(cxl_poison_inject_fops, NULL,
 			 cxl_debugfs_poison_inject, "%llx\n");

 static int cxl_debugfs_poison_clear(void *data, u64 dpa)
 {
 	struct cxl_memdev *cxlmd = data;

 	return cxl_clear_poison(cxlmd, dpa);
 }

 DEFINE_DEBUGFS_ATTRIBUTE(cxl_poison_clear_fops, NULL,
 			 cxl_debugfs_poison_clear, "%llx\n");

 static int cxl_mem_probe(struct device *dev)
 {
 	struct cxl_memdev *cxlmd = to_cxl_memdev(dev);
 	struct cxl_memdev_state *mds = to_cxl_memdev_state(cxlmd->cxlds);
 	struct cxl_dev_state *cxlds = cxlmd->cxlds;
 	struct device *endpoint_parent;
 	struct cxl_port *parent_port;
 	struct cxl_dport *dport;
 	struct dentry *dentry;
 	int rc;

 	if (!cxlds->media_ready)
 		return -EBUSY;

 	/*
 	 * Someone is trying to reattach this device after it lost its port
 	 * connection (an endpoint port previously registered by this memdev was
 	 * disabled). This racy check is ok because if the port is still gone,
 	 * no harm done, and if the port hierarchy comes back it will re-trigger
 	 * this probe. Port rescan and memdev detach work share the same
 	 * single-threaded workqueue.
 	 */
 	if (work_pending(&cxlmd->detach_work))
 		return -EBUSY;

 	dentry = cxl_debugfs_create_dir(dev_name(dev));
 	debugfs_create_devm_seqfile(dev, "dpamem", dentry, cxl_mem_dpa_show);

 	if (test_bit(CXL_POISON_ENABLED_INJECT, mds->poison.enabled_cmds))
 		debugfs_create_file("inject_poison", 0200, dentry, cxlmd,
 				    &cxl_poison_inject_fops);
 	if (test_bit(CXL_POISON_ENABLED_CLEAR, mds->poison.enabled_cmds))
 		debugfs_create_file("clear_poison", 0200, dentry, cxlmd,
 				    &cxl_poison_clear_fops);

 	rc = devm_add_action_or_reset(dev, remove_debugfs, dentry);
 	if (rc)
 		return rc;

 	rc = devm_cxl_enumerate_ports(cxlmd);
 	if (rc)
 		return rc;

 	parent_port = cxl_mem_find_port(cxlmd, &dport);
 	if (!parent_port) {
 		dev_err(dev, "CXL port topology not found\n");
 		return -ENXIO;
 	}

 	if (dport->rch)
 		endpoint_parent = parent_port->uport_dev;
 	else
 		endpoint_parent = &parent_port->dev;

 	cxl_setup_parent_dport(dev, dport);

 	device_lock(endpoint_parent);
 	if (!endpoint_parent->driver) {
 		dev_err(dev, "CXL port topology %s not enabled\n",
 			dev_name(endpoint_parent));
 		rc = -ENXIO;
 		goto unlock;
 	}

 	rc = devm_cxl_add_endpoint(endpoint_parent, cxlmd, dport);
 unlock:
 	device_unlock(endpoint_parent);
 	put_device(&parent_port->dev);
 	if (rc)
 		return rc;

 	if (resource_size(&cxlds->pmem_res) && IS_ENABLED(CONFIG_CXL_PMEM)) {
 		rc = devm_cxl_add_nvdimm(cxlmd);
 		if (rc == -ENODEV)
 			dev_info(dev, "PMEM disabled by platform\n");
 		else
 			return rc;
 	}

 	/*
 	 * The kernel may be operating out of CXL memory on this device,
 	 * there is no spec defined way to determine whether this device
 	 * preserves contents over suspend, and there is no simple way
 	 * to arrange for the suspend image to avoid CXL memory which
 	 * would setup a circular dependency between PCI resume and save
 	 * state restoration.
 	 *
 	 * TODO: support suspend when all the regions this device is
 	 * hosting are locked and covered by the system address map,
 	 * i.e. platform firmware owns restoring the HDM configuration
 	 * that it locked.
 	 */
 	cxl_mem_active_inc();
 	return devm_add_action_or_reset(dev, enable_suspend, NULL);
 }

 static ssize_t trigger_poison_list_store(struct device *dev,
 					 struct device_attribute *attr,
 					 const char *buf, size_t len)
 {
 	bool trigger;
 	int rc;

 	if (kstrtobool(buf, &trigger) || !trigger)
 		return -EINVAL;

 	rc = cxl_trigger_poison_list(to_cxl_memdev(dev));

 	return rc ? rc : len;
 }
 static DEVICE_ATTR_WO(trigger_poison_list);

 static umode_t cxl_mem_visible(struct kobject *kobj, struct attribute *a, int n)
 {
 	if (a == &dev_attr_trigger_poison_list.attr) {
 		struct device *dev = kobj_to_dev(kobj);
 		struct cxl_memdev *cxlmd = to_cxl_memdev(dev);
 		struct cxl_memdev_state *mds =
 			to_cxl_memdev_state(cxlmd->cxlds);

 		if (!test_bit(CXL_POISON_ENABLED_LIST,
 			      mds->poison.enabled_cmds))
 			return 0;
 	}
 	return a->mode;
 }

 static struct attribute *cxl_mem_attrs[] = {
 	&dev_attr_trigger_poison_list.attr,
 	NULL
 };

 static struct attribute_group cxl_mem_group = {
 	.attrs = cxl_mem_attrs,
 	.is_visible = cxl_mem_visible,
 };

 __ATTRIBUTE_GROUPS(cxl_mem);

 static struct cxl_driver cxl_mem_driver = {
 	.name = "cxl_mem",
 	.probe = cxl_mem_probe,
 	.id = CXL_DEVICE_MEMORY_EXPANDER,
 	.drv = {
 		.dev_groups = cxl_mem_groups,
 	},
 };

 module_cxl_driver(cxl_mem_driver);

 MODULE_LICENSE("GPL v2");
 MODULE_IMPORT_NS(CXL);
 MODULE_ALIAS_CXL(CXL_DEVICE_MEMORY_EXPANDER);
 /*
  * create_endpoint() wants to validate port driver attach immediately after
  * endpoint registration.
  */
 MODULE_SOFTDEP("pre: cxl_port");
	// SPDX-License-Identifier: GPL-2.0-only
	/* Copyright(c) 2022 Intel Corporation. All rights reserved. */
	#include <linux/debugfs.h>
	#include <linux/device.h>
	#include <linux/module.h>
	#include <linux/pci.h>

	#include "cxlmem.h"
	#include "cxlpci.h"

	/**
	* DOC: cxl mem
	*
	* CXL memory endpoint devices and switches are CXL capable devices that are
	* participating in CXL.mem protocol. Their functionality builds on top of the
	* CXL.io protocol that allows enumerating and configuring components via
	* standard PCI mechanisms.
	*
	* The cxl_mem driver owns kicking off the enumeration of this CXL.mem
	* capability. With the detection of a CXL capable endpoint, the driver will
	* walk up to find the platform specific port it is connected to, and determine
	* if there are intervening switches in the path. If there are switches, a
	* secondary action is to enumerate those (implemented in cxl_core). Finally the
	* cxl_mem driver adds the device it is bound to as a CXL endpoint-port for use
	* in higher level operations.
	*/

	static void enable_suspend(void *data)
	{
	cxl_mem_active_dec();
	}

	static void remove_debugfs(void *dentry)
	{
	debugfs_remove_recursive(dentry);
	}

	static int cxl_mem_dpa_show(struct seq_file file, void data)
	{
	struct device *dev = file->private;
	struct cxl_memdev *cxlmd = to_cxl_memdev(dev);

	cxl_dpa_debug(file, cxlmd->cxlds);

	return 0;
	}

	static int devm_cxl_add_endpoint(struct device host, struct cxl_memdev cxlmd,
	struct cxl_dport *parent_dport)
	{
	struct cxl_port *parent_port = parent_dport->port;
	struct cxl_port endpoint, iter, *down;
	int rc;

	/*
	* Now that the path to the root is established record all the
	* intervening ports in the chain.
	*/
	for (iter = parent_port, down = NULL; !is_cxl_root(iter);
	down = iter, iter = to_cxl_port(iter->dev.parent)) {
	struct cxl_ep *ep;

	ep = cxl_ep_load(iter, cxlmd);
	ep->next = down;
	}

	/* Note: endpoint port component registers are derived from @cxlds */
	endpoint = devm_cxl_add_port(host, &cxlmd->dev, CXL_RESOURCE_NONE,
	parent_dport);
	if (IS_ERR(endpoint))
	return PTR_ERR(endpoint);

	rc = cxl_endpoint_autoremove(cxlmd, endpoint);
	if (rc)
	return rc;

	if (!endpoint->dev.driver) {
	dev_err(&cxlmd->dev, "%s failed probe\n",
	dev_name(&endpoint->dev));
	return -ENXIO;
	}

	return 0;
	}

	static int cxl_debugfs_poison_inject(void *data, u64 dpa)
	{
	struct cxl_memdev *cxlmd = data;

	return cxl_inject_poison(cxlmd, dpa);
	}

	DEFINE_DEBUGFS_ATTRIBUTE(cxl_poison_inject_fops, NULL,
	cxl_debugfs_poison_inject, "%llx\n");

	static int cxl_debugfs_poison_clear(void *data, u64 dpa)
	{
	struct cxl_memdev *cxlmd = data;

	return cxl_clear_poison(cxlmd, dpa);
	}

	DEFINE_DEBUGFS_ATTRIBUTE(cxl_poison_clear_fops, NULL,
	cxl_debugfs_poison_clear, "%llx\n");

	static int cxl_mem_probe(struct device *dev)
	{
	struct cxl_memdev *cxlmd = to_cxl_memdev(dev);
	struct cxl_memdev_state *mds = to_cxl_memdev_state(cxlmd->cxlds);
	struct cxl_dev_state *cxlds = cxlmd->cxlds;
	struct device *endpoint_parent;
	struct cxl_port *parent_port;
	struct cxl_dport *dport;
	struct dentry *dentry;
	int rc;

	if (!cxlds->media_ready)
	return -EBUSY;

	/*
	* Someone is trying to reattach this device after it lost its port
	* connection (an endpoint port previously registered by this memdev was
	* disabled). This racy check is ok because if the port is still gone,
	* no harm done, and if the port hierarchy comes back it will re-trigger
	* this probe. Port rescan and memdev detach work share the same
	* single-threaded workqueue.
	*/
	if (work_pending(&cxlmd->detach_work))
	return -EBUSY;

	dentry = cxl_debugfs_create_dir(dev_name(dev));
	debugfs_create_devm_seqfile(dev, "dpamem", dentry, cxl_mem_dpa_show);

	if (test_bit(CXL_POISON_ENABLED_INJECT, mds->poison.enabled_cmds))
	debugfs_create_file("inject_poison", 0200, dentry, cxlmd,
	&cxl_poison_inject_fops);
	if (test_bit(CXL_POISON_ENABLED_CLEAR, mds->poison.enabled_cmds))
	debugfs_create_file("clear_poison", 0200, dentry, cxlmd,
	&cxl_poison_clear_fops);

	rc = devm_add_action_or_reset(dev, remove_debugfs, dentry);
	if (rc)
	return rc;

	rc = devm_cxl_enumerate_ports(cxlmd);
	if (rc)
	return rc;

	parent_port = cxl_mem_find_port(cxlmd, &dport);
	if (!parent_port) {
	dev_err(dev, "CXL port topology not found\n");
	return -ENXIO;
	}

	if (dport->rch)
	endpoint_parent = parent_port->uport_dev;
	else
	endpoint_parent = &parent_port->dev;

	cxl_setup_parent_dport(dev, dport);

	device_lock(endpoint_parent);
	if (!endpoint_parent->driver) {
	dev_err(dev, "CXL port topology %s not enabled\n",
	dev_name(endpoint_parent));
	rc = -ENXIO;
	goto unlock;
	}

	rc = devm_cxl_add_endpoint(endpoint_parent, cxlmd, dport);
	unlock:
	device_unlock(endpoint_parent);
	put_device(&parent_port->dev);
	if (rc)
	return rc;

	if (resource_size(&cxlds->pmem_res) && IS_ENABLED(CONFIG_CXL_PMEM)) {
	rc = devm_cxl_add_nvdimm(cxlmd);
	if (rc == -ENODEV)
	dev_info(dev, "PMEM disabled by platform\n");
	else
	return rc;
	}

	/*
	* The kernel may be operating out of CXL memory on this device,
	* there is no spec defined way to determine whether this device
	* preserves contents over suspend, and there is no simple way
	* to arrange for the suspend image to avoid CXL memory which
	* would setup a circular dependency between PCI resume and save
	* state restoration.
	*
	* TODO: support suspend when all the regions this device is
	* hosting are locked and covered by the system address map,
	* i.e. platform firmware owns restoring the HDM configuration
	* that it locked.
	*/
	cxl_mem_active_inc();
	return devm_add_action_or_reset(dev, enable_suspend, NULL);
	}

	static ssize_t trigger_poison_list_store(struct device *dev,
	struct device_attribute *attr,
	const char *buf, size_t len)
	{
	bool trigger;
	int rc;

	if (kstrtobool(buf, &trigger) \|\| !trigger)
	return -EINVAL;

	rc = cxl_trigger_poison_list(to_cxl_memdev(dev));

	return rc ? rc : len;
	}
	static DEVICE_ATTR_WO(trigger_poison_list);

	static umode_t cxl_mem_visible(struct kobject kobj, struct attribute a, int n)
	{
	if (a == &dev_attr_trigger_poison_list.attr) {
	struct device *dev = kobj_to_dev(kobj);
	struct cxl_memdev *cxlmd = to_cxl_memdev(dev);
	struct cxl_memdev_state *mds =
	to_cxl_memdev_state(cxlmd->cxlds);

	if (!test_bit(CXL_POISON_ENABLED_LIST,
	mds->poison.enabled_cmds))
	return 0;
	}
	return a->mode;
	}

	static struct attribute *cxl_mem_attrs[] = {
	&dev_attr_trigger_poison_list.attr,
	NULL
	};

	static struct attribute_group cxl_mem_group = {
	.attrs = cxl_mem_attrs,
	.is_visible = cxl_mem_visible,
	};

	__ATTRIBUTE_GROUPS(cxl_mem);

	static struct cxl_driver cxl_mem_driver = {
	.name = "cxl_mem",
	.probe = cxl_mem_probe,
	.id = CXL_DEVICE_MEMORY_EXPANDER,
	.drv = {
	.dev_groups = cxl_mem_groups,
	},
	};

	module_cxl_driver(cxl_mem_driver);

	MODULE_LICENSE("GPL v2");
	MODULE_IMPORT_NS(CXL);
	MODULE_ALIAS_CXL(CXL_DEVICE_MEMORY_EXPANDER);
	/*
	* create_endpoint() wants to validate port driver attach immediately after
	* endpoint registration.
	*/
	MODULE_SOFTDEP("pre: cxl_port");