1 // SPDX-License-Identifier: GPL-2.0
2 /* Copyright(c) 2016-2019 Intel Corporation. All rights reserved. */
3 #include <linux/memremap.h>
4 #include <linux/pagemap.h>
5 #include <linux/memory.h>
6 #include <linux/module.h>
7 #include <linux/device.h>
8 #include <linux/pfn_t.h>
9 #include <linux/slab.h>
10 #include <linux/dax.h>
13 #include <linux/mman.h>
14 #include <linux/memory-tiers.h>
15 #include <linux/memory_hotplug.h>
16 #include "dax-private.h"
20 * Default abstract distance assigned to the NUMA node onlined
21 * by DAX/kmem if the low level platform driver didn't initialize
22 * one for this NUMA node.
24 #define MEMTIER_DEFAULT_DAX_ADISTANCE (MEMTIER_ADISTANCE_DRAM * 5)
26 /* Memory resource name used for add_memory_driver_managed(). */
27 static const char *kmem_name;
28 /* Set if any memory will remain added when the driver will be unloaded. */
29 static bool any_hotremove_failed;
31 static int dax_kmem_range(struct dev_dax *dev_dax, int i, struct range *r)
33 struct dev_dax_range *dax_range = &dev_dax->ranges[i];
34 struct range *range = &dax_range->range;
36 /* memory-block align the hotplug range */
37 r->start = ALIGN(range->start, memory_block_size_bytes());
38 r->end = ALIGN_DOWN(range->end + 1, memory_block_size_bytes()) - 1;
39 if (r->start >= r->end) {
40 r->start = range->start;
47 struct dax_kmem_data {
50 struct resource *res[];
53 static DEFINE_MUTEX(kmem_memory_type_lock);
54 static LIST_HEAD(kmem_memory_types);
56 static struct memory_dev_type *kmem_find_alloc_memory_type(int adist)
59 struct memory_dev_type *mtype;
61 mutex_lock(&kmem_memory_type_lock);
62 list_for_each_entry(mtype, &kmem_memory_types, list) {
63 if (mtype->adistance == adist) {
69 mtype = alloc_memory_type(adist);
71 list_add(&mtype->list, &kmem_memory_types);
73 mutex_unlock(&kmem_memory_type_lock);
78 static void kmem_put_memory_types(void)
80 struct memory_dev_type *mtype, *mtn;
82 mutex_lock(&kmem_memory_type_lock);
83 list_for_each_entry_safe(mtype, mtn, &kmem_memory_types, list) {
84 list_del(&mtype->list);
85 put_memory_type(mtype);
87 mutex_unlock(&kmem_memory_type_lock);
90 static int dev_dax_kmem_probe(struct dev_dax *dev_dax)
92 struct device *dev = &dev_dax->dev;
93 unsigned long total_len = 0;
94 struct dax_kmem_data *data;
95 struct memory_dev_type *mtype;
96 int i, rc, mapped = 0;
99 int adist = MEMTIER_DEFAULT_DAX_ADISTANCE;
102 * Ensure good NUMA information for the persistent memory.
103 * Without this check, there is a risk that slow memory
104 * could be mixed in a node with faster memory, causing
105 * unavoidable performance issues.
107 numa_node = dev_dax->target_node;
109 dev_warn(dev, "rejecting DAX region with invalid node: %d\n",
114 mt_calc_adistance(numa_node, &adist);
115 mtype = kmem_find_alloc_memory_type(adist);
117 return PTR_ERR(mtype);
119 for (i = 0; i < dev_dax->nr_range; i++) {
122 rc = dax_kmem_range(dev_dax, i, &range);
124 dev_info(dev, "mapping%d: %#llx-%#llx too small after alignment\n",
125 i, range.start, range.end);
128 total_len += range_len(&range);
132 dev_warn(dev, "rejecting DAX region without any memory after alignment\n");
136 init_node_memory_type(numa_node, mtype);
139 data = kzalloc(struct_size(data, res, dev_dax->nr_range), GFP_KERNEL);
141 goto err_dax_kmem_data;
143 data->res_name = kstrdup(dev_name(dev), GFP_KERNEL);
147 rc = memory_group_register_static(numa_node, PFN_UP(total_len));
152 for (i = 0; i < dev_dax->nr_range; i++) {
153 struct resource *res;
156 rc = dax_kmem_range(dev_dax, i, &range);
160 /* Region is permanently reserved if hotremove fails. */
161 res = request_mem_region(range.start, range_len(&range), data->res_name);
163 dev_warn(dev, "mapping%d: %#llx-%#llx could not reserve region\n",
164 i, range.start, range.end);
166 * Once some memory has been onlined we can't
167 * assume that it can be un-onlined safely.
172 goto err_request_mem;
177 * Set flags appropriate for System RAM. Leave ..._BUSY clear
178 * so that add_memory() can add a child resource. Do not
179 * inherit flags from the parent since it may set new flags
180 * unknown to us that will break add_memory() below.
182 res->flags = IORESOURCE_SYSTEM_RAM;
184 mhp_flags = MHP_NID_IS_MGID;
185 if (dev_dax->memmap_on_memory)
186 mhp_flags |= MHP_MEMMAP_ON_MEMORY;
189 * Ensure that future kexec'd kernels will not treat
190 * this as RAM automatically.
192 rc = add_memory_driver_managed(data->mgid, range.start,
193 range_len(&range), kmem_name, mhp_flags);
196 dev_warn(dev, "mapping%d: %#llx-%#llx memory add failed\n",
197 i, range.start, range.end);
198 remove_resource(res);
203 goto err_request_mem;
208 dev_set_drvdata(dev, data);
213 memory_group_unregister(data->mgid);
215 kfree(data->res_name);
219 clear_node_memory_type(numa_node, mtype);
223 #ifdef CONFIG_MEMORY_HOTREMOVE
224 static void dev_dax_kmem_remove(struct dev_dax *dev_dax)
227 int node = dev_dax->target_node;
228 struct device *dev = &dev_dax->dev;
229 struct dax_kmem_data *data = dev_get_drvdata(dev);
232 * We have one shot for removing memory, if some memory blocks were not
233 * offline prior to calling this function remove_memory() will fail, and
234 * there is no way to hotremove this memory until reboot because device
235 * unbind will succeed even if we return failure.
237 for (i = 0; i < dev_dax->nr_range; i++) {
241 rc = dax_kmem_range(dev_dax, i, &range);
245 rc = remove_memory(range.start, range_len(&range));
247 remove_resource(data->res[i]);
253 any_hotremove_failed = true;
255 "mapping%d: %#llx-%#llx cannot be hotremoved until the next reboot\n",
256 i, range.start, range.end);
259 if (success >= dev_dax->nr_range) {
260 memory_group_unregister(data->mgid);
261 kfree(data->res_name);
263 dev_set_drvdata(dev, NULL);
265 * Clear the memtype association on successful unplug.
266 * If not, we have memory blocks left which can be
267 * offlined/onlined later. We need to keep memory_dev_type
268 * for that. This implies this reference will be around
271 clear_node_memory_type(node, NULL);
275 static void dev_dax_kmem_remove(struct dev_dax *dev_dax)
278 * Without hotremove purposely leak the request_mem_region() for the
279 * device-dax range and return '0' to ->remove() attempts. The removal
280 * of the device from the driver always succeeds, but the region is
281 * permanently pinned as reserved by the unreleased
282 * request_mem_region().
284 any_hotremove_failed = true;
286 #endif /* CONFIG_MEMORY_HOTREMOVE */
288 static struct dax_device_driver device_dax_kmem_driver = {
289 .probe = dev_dax_kmem_probe,
290 .remove = dev_dax_kmem_remove,
291 .type = DAXDRV_KMEM_TYPE,
294 static int __init dax_kmem_init(void)
298 /* Resource name is permanently allocated if any hotremove fails. */
299 kmem_name = kstrdup_const("System RAM (kmem)", GFP_KERNEL);
303 rc = dax_driver_register(&device_dax_kmem_driver);
305 goto error_dax_driver;
310 kmem_put_memory_types();
311 kfree_const(kmem_name);
315 static void __exit dax_kmem_exit(void)
317 dax_driver_unregister(&device_dax_kmem_driver);
318 if (!any_hotremove_failed)
319 kfree_const(kmem_name);
320 kmem_put_memory_types();
323 MODULE_AUTHOR("Intel Corporation");
324 MODULE_LICENSE("GPL v2");
325 module_init(dax_kmem_init);
326 module_exit(dax_kmem_exit);
327 MODULE_ALIAS_DAX_DEVICE(0);