drivers/dax/kmem.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /* Copyright(c) 2016-2019 Intel Corporation. All rights reserved. */
 #include <linux/memremap.h>
 #include <linux/pagemap.h>
 #include <linux/memory.h>
 #include <linux/module.h>
 #include <linux/device.h>
 #include <linux/pfn_t.h>
 #include <linux/slab.h>
 #include <linux/dax.h>
 #include <linux/fs.h>
 #include <linux/mm.h>
 #include <linux/mman.h>
 #include <linux/memory-tiers.h>
 #include "dax-private.h"
 #include "bus.h"

 /*
  * Default abstract distance assigned to the NUMA node onlined
  * by DAX/kmem if the low level platform driver didn't initialize
  * one for this NUMA node.
  */
 #define MEMTIER_DEFAULT_DAX_ADISTANCE	(MEMTIER_ADISTANCE_DRAM * 5)

 /* Memory resource name used for add_memory_driver_managed(). */
 static const char *kmem_name;
 /* Set if any memory will remain added when the driver will be unloaded. */
 static bool any_hotremove_failed;

 static int dax_kmem_range(struct dev_dax *dev_dax, int i, struct range *r)
 {
 	struct dev_dax_range *dax_range = &dev_dax->ranges[i];
 	struct range *range = &dax_range->range;

 	/* memory-block align the hotplug range */
 	r->start = ALIGN(range->start, memory_block_size_bytes());
 	r->end = ALIGN_DOWN(range->end + 1, memory_block_size_bytes()) - 1;
 	if (r->start >= r->end) {
 		r->start = range->start;
 		r->end = range->end;
 		return -ENOSPC;
 	}
 	return 0;
 }

 struct dax_kmem_data {
 	const char *res_name;
 	int mgid;
 	struct resource *res[];
 };

 static struct memory_dev_type *dax_slowmem_type;
 static int dev_dax_kmem_probe(struct dev_dax *dev_dax)
 {
 	struct device *dev = &dev_dax->dev;
 	unsigned long total_len = 0;
 	struct dax_kmem_data *data;
 	int i, rc, mapped = 0;
 	int numa_node;

 	/*
 	 * Ensure good NUMA information for the persistent memory.
 	 * Without this check, there is a risk that slow memory
 	 * could be mixed in a node with faster memory, causing
 	 * unavoidable performance issues.
 	 */
 	numa_node = dev_dax->target_node;
 	if (numa_node < 0) {
 		dev_warn(dev, "rejecting DAX region with invalid node: %d\n",
 				numa_node);
 		return -EINVAL;
 	}

 	for (i = 0; i < dev_dax->nr_range; i++) {
 		struct range range;

 		rc = dax_kmem_range(dev_dax, i, &range);
 		if (rc) {
 			dev_info(dev, "mapping%d: %#llx-%#llx too small after alignment\n",
 					i, range.start, range.end);
 			continue;
 		}
 		total_len += range_len(&range);
 	}

 	if (!total_len) {
 		dev_warn(dev, "rejecting DAX region without any memory after alignment\n");
 		return -EINVAL;
 	}

 	init_node_memory_type(numa_node, dax_slowmem_type);

 	rc = -ENOMEM;
 	data = kzalloc(struct_size(data, res, dev_dax->nr_range), GFP_KERNEL);
 	if (!data)
 		goto err_dax_kmem_data;

 	data->res_name = kstrdup(dev_name(dev), GFP_KERNEL);
 	if (!data->res_name)
 		goto err_res_name;

 	rc = memory_group_register_static(numa_node, PFN_UP(total_len));
 	if (rc < 0)
 		goto err_reg_mgid;
 	data->mgid = rc;

 	for (i = 0; i < dev_dax->nr_range; i++) {
 		struct resource *res;
 		struct range range;

 		rc = dax_kmem_range(dev_dax, i, &range);
 		if (rc)
 			continue;

 		/* Region is permanently reserved if hotremove fails. */
 		res = request_mem_region(range.start, range_len(&range), data->res_name);
 		if (!res) {
 			dev_warn(dev, "mapping%d: %#llx-%#llx could not reserve region\n",
 					i, range.start, range.end);
 			/*
 			 * Once some memory has been onlined we can't
 			 * assume that it can be un-onlined safely.
 			 */
 			if (mapped)
 				continue;
 			rc = -EBUSY;
 			goto err_request_mem;
 		}
 		data->res[i] = res;

 		/*
 		 * Set flags appropriate for System RAM.  Leave ..._BUSY clear
 		 * so that add_memory() can add a child resource.  Do not
 		 * inherit flags from the parent since it may set new flags
 		 * unknown to us that will break add_memory() below.
 		 */
 		res->flags = IORESOURCE_SYSTEM_RAM;

 		/*
 		 * Ensure that future kexec'd kernels will not treat
 		 * this as RAM automatically.
 		 */
 		rc = add_memory_driver_managed(data->mgid, range.start,
 				range_len(&range), kmem_name, MHP_NID_IS_MGID);

 		if (rc) {
 			dev_warn(dev, "mapping%d: %#llx-%#llx memory add failed\n",
 					i, range.start, range.end);
 			remove_resource(res);
 			kfree(res);
 			data->res[i] = NULL;
 			if (mapped)
 				continue;
 			goto err_request_mem;
 		}
 		mapped++;
 	}

 	dev_set_drvdata(dev, data);

 	return 0;

 err_request_mem:
 	memory_group_unregister(data->mgid);
 err_reg_mgid:
 	kfree(data->res_name);
 err_res_name:
 	kfree(data);
 err_dax_kmem_data:
 	clear_node_memory_type(numa_node, dax_slowmem_type);
 	return rc;
 }

 #ifdef CONFIG_MEMORY_HOTREMOVE
 static void dev_dax_kmem_remove(struct dev_dax *dev_dax)
 {
 	int i, success = 0;
 	int node = dev_dax->target_node;
 	struct device *dev = &dev_dax->dev;
 	struct dax_kmem_data *data = dev_get_drvdata(dev);

 	/*
 	 * We have one shot for removing memory, if some memory blocks were not
 	 * offline prior to calling this function remove_memory() will fail, and
 	 * there is no way to hotremove this memory until reboot because device
 	 * unbind will succeed even if we return failure.
 	 */
 	for (i = 0; i < dev_dax->nr_range; i++) {
 		struct range range;
 		int rc;

 		rc = dax_kmem_range(dev_dax, i, &range);
 		if (rc)
 			continue;

 		rc = remove_memory(range.start, range_len(&range));
 		if (rc == 0) {
 			remove_resource(data->res[i]);
 			kfree(data->res[i]);
 			data->res[i] = NULL;
 			success++;
 			continue;
 		}
 		any_hotremove_failed = true;
 		dev_err(dev,
 			"mapping%d: %#llx-%#llx cannot be hotremoved until the next reboot\n",
 				i, range.start, range.end);
 	}

 	if (success >= dev_dax->nr_range) {
 		memory_group_unregister(data->mgid);
 		kfree(data->res_name);
 		kfree(data);
 		dev_set_drvdata(dev, NULL);
 		/*
 		 * Clear the memtype association on successful unplug.
 		 * If not, we have memory blocks left which can be
 		 * offlined/onlined later. We need to keep memory_dev_type
 		 * for that. This implies this reference will be around
 		 * till next reboot.
 		 */
 		clear_node_memory_type(node, dax_slowmem_type);
 	}
 }
 #else
 static void dev_dax_kmem_remove(struct dev_dax *dev_dax)
 {
 	/*
 	 * Without hotremove purposely leak the request_mem_region() for the
 	 * device-dax range and return '0' to ->remove() attempts. The removal
 	 * of the device from the driver always succeeds, but the region is
 	 * permanently pinned as reserved by the unreleased
 	 * request_mem_region().
 	 */
 	any_hotremove_failed = true;
 }
 #endif /* CONFIG_MEMORY_HOTREMOVE */

 static struct dax_device_driver device_dax_kmem_driver = {
 	.probe = dev_dax_kmem_probe,
 	.remove = dev_dax_kmem_remove,
 	.type = DAXDRV_KMEM_TYPE,
 };

 static int __init dax_kmem_init(void)
 {
 	int rc;

 	/* Resource name is permanently allocated if any hotremove fails. */
 	kmem_name = kstrdup_const("System RAM (kmem)", GFP_KERNEL);
 	if (!kmem_name)
 		return -ENOMEM;

 	dax_slowmem_type = alloc_memory_type(MEMTIER_DEFAULT_DAX_ADISTANCE);
 	if (IS_ERR(dax_slowmem_type)) {
 		rc = PTR_ERR(dax_slowmem_type);
 		goto err_dax_slowmem_type;
 	}

 	rc = dax_driver_register(&device_dax_kmem_driver);
 	if (rc)
 		goto error_dax_driver;

 	return rc;

 error_dax_driver:
 	destroy_memory_type(dax_slowmem_type);
 err_dax_slowmem_type:
 	kfree_const(kmem_name);
 	return rc;
 }

 static void __exit dax_kmem_exit(void)
 {
 	dax_driver_unregister(&device_dax_kmem_driver);
 	if (!any_hotremove_failed)
 		kfree_const(kmem_name);
 	destroy_memory_type(dax_slowmem_type);
 }

 MODULE_AUTHOR("Intel Corporation");
 MODULE_LICENSE("GPL v2");
 module_init(dax_kmem_init);
 module_exit(dax_kmem_exit);
 MODULE_ALIAS_DAX_DEVICE(0);
	// SPDX-License-Identifier: GPL-2.0
	/* Copyright(c) 2016-2019 Intel Corporation. All rights reserved. */
	#include <linux/memremap.h>
	#include <linux/pagemap.h>
	#include <linux/memory.h>
	#include <linux/module.h>
	#include <linux/device.h>
	#include <linux/pfn_t.h>
	#include <linux/slab.h>
	#include <linux/dax.h>
	#include <linux/fs.h>
	#include <linux/mm.h>
	#include <linux/mman.h>
	#include <linux/memory-tiers.h>
	#include "dax-private.h"
	#include "bus.h"

	/*
	* Default abstract distance assigned to the NUMA node onlined
	* by DAX/kmem if the low level platform driver didn't initialize
	* one for this NUMA node.
	*/
	#define MEMTIER_DEFAULT_DAX_ADISTANCE (MEMTIER_ADISTANCE_DRAM * 5)

	/* Memory resource name used for add_memory_driver_managed(). */
	static const char *kmem_name;
	/* Set if any memory will remain added when the driver will be unloaded. */
	static bool any_hotremove_failed;

	static int dax_kmem_range(struct dev_dax dev_dax, int i, struct range r)
	{
	struct dev_dax_range *dax_range = &dev_dax->ranges[i];
	struct range *range = &dax_range->range;

	/* memory-block align the hotplug range */
	r->start = ALIGN(range->start, memory_block_size_bytes());
	r->end = ALIGN_DOWN(range->end + 1, memory_block_size_bytes()) - 1;
	if (r->start >= r->end) {
	r->start = range->start;
	r->end = range->end;
	return -ENOSPC;
	}
	return 0;
	}

	struct dax_kmem_data {
	const char *res_name;
	int mgid;
	struct resource *res[];
	};

	static struct memory_dev_type *dax_slowmem_type;
	static int dev_dax_kmem_probe(struct dev_dax *dev_dax)
	{
	struct device *dev = &dev_dax->dev;
	unsigned long total_len = 0;
	struct dax_kmem_data *data;
	int i, rc, mapped = 0;
	int numa_node;

	/*
	* Ensure good NUMA information for the persistent memory.
	* Without this check, there is a risk that slow memory
	* could be mixed in a node with faster memory, causing
	* unavoidable performance issues.
	*/
	numa_node = dev_dax->target_node;
	if (numa_node < 0) {
	dev_warn(dev, "rejecting DAX region with invalid node: %d\n",
	numa_node);
	return -EINVAL;
	}

	for (i = 0; i < dev_dax->nr_range; i++) {
	struct range range;

	rc = dax_kmem_range(dev_dax, i, &range);
	if (rc) {
	dev_info(dev, "mapping%d: %#llx-%#llx too small after alignment\n",
	i, range.start, range.end);
	continue;
	}
	total_len += range_len(&range);
	}

	if (!total_len) {
	dev_warn(dev, "rejecting DAX region without any memory after alignment\n");
	return -EINVAL;
	}

	init_node_memory_type(numa_node, dax_slowmem_type);

	rc = -ENOMEM;
	data = kzalloc(struct_size(data, res, dev_dax->nr_range), GFP_KERNEL);
	if (!data)
	goto err_dax_kmem_data;

	data->res_name = kstrdup(dev_name(dev), GFP_KERNEL);
	if (!data->res_name)
	goto err_res_name;

	rc = memory_group_register_static(numa_node, PFN_UP(total_len));
	if (rc < 0)
	goto err_reg_mgid;
	data->mgid = rc;

	for (i = 0; i < dev_dax->nr_range; i++) {
	struct resource *res;
	struct range range;

	rc = dax_kmem_range(dev_dax, i, &range);
	if (rc)
	continue;

	/* Region is permanently reserved if hotremove fails. */
	res = request_mem_region(range.start, range_len(&range), data->res_name);
	if (!res) {
	dev_warn(dev, "mapping%d: %#llx-%#llx could not reserve region\n",
	i, range.start, range.end);
	/*
	* Once some memory has been onlined we can't
	* assume that it can be un-onlined safely.
	*/
	if (mapped)
	continue;
	rc = -EBUSY;
	goto err_request_mem;
	}
	data->res[i] = res;

	/*
	* Set flags appropriate for System RAM. Leave ..._BUSY clear
	* so that add_memory() can add a child resource. Do not
	* inherit flags from the parent since it may set new flags
	* unknown to us that will break add_memory() below.
	*/
	res->flags = IORESOURCE_SYSTEM_RAM;

	/*
	* Ensure that future kexec'd kernels will not treat
	* this as RAM automatically.
	*/
	rc = add_memory_driver_managed(data->mgid, range.start,
	range_len(&range), kmem_name, MHP_NID_IS_MGID);

	if (rc) {
	dev_warn(dev, "mapping%d: %#llx-%#llx memory add failed\n",
	i, range.start, range.end);
	remove_resource(res);
	kfree(res);
	data->res[i] = NULL;
	if (mapped)
	continue;
	goto err_request_mem;
	}
	mapped++;
	}

	dev_set_drvdata(dev, data);

	return 0;

	err_request_mem:
	memory_group_unregister(data->mgid);
	err_reg_mgid:
	kfree(data->res_name);
	err_res_name:
	kfree(data);
	err_dax_kmem_data:
	clear_node_memory_type(numa_node, dax_slowmem_type);
	return rc;
	}

	#ifdef CONFIG_MEMORY_HOTREMOVE
	static void dev_dax_kmem_remove(struct dev_dax *dev_dax)
	{
	int i, success = 0;
	int node = dev_dax->target_node;
	struct device *dev = &dev_dax->dev;
	struct dax_kmem_data *data = dev_get_drvdata(dev);

	/*
	* We have one shot for removing memory, if some memory blocks were not
	* offline prior to calling this function remove_memory() will fail, and
	* there is no way to hotremove this memory until reboot because device
	* unbind will succeed even if we return failure.
	*/
	for (i = 0; i < dev_dax->nr_range; i++) {
	struct range range;
	int rc;

	rc = dax_kmem_range(dev_dax, i, &range);
	if (rc)
	continue;

	rc = remove_memory(range.start, range_len(&range));
	if (rc == 0) {
	remove_resource(data->res[i]);
	kfree(data->res[i]);
	data->res[i] = NULL;
	success++;
	continue;
	}
	any_hotremove_failed = true;
	dev_err(dev,
	"mapping%d: %#llx-%#llx cannot be hotremoved until the next reboot\n",
	i, range.start, range.end);
	}

	if (success >= dev_dax->nr_range) {
	memory_group_unregister(data->mgid);
	kfree(data->res_name);
	kfree(data);
	dev_set_drvdata(dev, NULL);
	/*
	* Clear the memtype association on successful unplug.
	* If not, we have memory blocks left which can be
	* offlined/onlined later. We need to keep memory_dev_type
	* for that. This implies this reference will be around
	* till next reboot.
	*/
	clear_node_memory_type(node, dax_slowmem_type);
	}
	}
	#else
	static void dev_dax_kmem_remove(struct dev_dax *dev_dax)
	{
	/*
	* Without hotremove purposely leak the request_mem_region() for the
	* device-dax range and return '0' to ->remove() attempts. The removal
	* of the device from the driver always succeeds, but the region is
	* permanently pinned as reserved by the unreleased
	* request_mem_region().
	*/
	any_hotremove_failed = true;
	}
	#endif /* CONFIG_MEMORY_HOTREMOVE */

	static struct dax_device_driver device_dax_kmem_driver = {
	.probe = dev_dax_kmem_probe,
	.remove = dev_dax_kmem_remove,
	.type = DAXDRV_KMEM_TYPE,
	};

	static int __init dax_kmem_init(void)
	{
	int rc;

	/* Resource name is permanently allocated if any hotremove fails. */
	kmem_name = kstrdup_const("System RAM (kmem)", GFP_KERNEL);
	if (!kmem_name)
	return -ENOMEM;

	dax_slowmem_type = alloc_memory_type(MEMTIER_DEFAULT_DAX_ADISTANCE);
	if (IS_ERR(dax_slowmem_type)) {
	rc = PTR_ERR(dax_slowmem_type);
	goto err_dax_slowmem_type;
	}

	rc = dax_driver_register(&device_dax_kmem_driver);
	if (rc)
	goto error_dax_driver;

	return rc;

	error_dax_driver:
	destroy_memory_type(dax_slowmem_type);
	err_dax_slowmem_type:
	kfree_const(kmem_name);
	return rc;
	}

	static void __exit dax_kmem_exit(void)
	{
	dax_driver_unregister(&device_dax_kmem_driver);
	if (!any_hotremove_failed)
	kfree_const(kmem_name);
	destroy_memory_type(dax_slowmem_type);
	}

	MODULE_AUTHOR("Intel Corporation");
	MODULE_LICENSE("GPL v2");
	module_init(dax_kmem_init);
	module_exit(dax_kmem_exit);
	MODULE_ALIAS_DAX_DEVICE(0);