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>
11 #include <linux/fs.h>
12 #include <linux/mm.h>
13 #include <linux/mman.h>
14 #include <linux/memory-tiers.h>
15 #include <linux/memory_hotplug.h>
16 #include <linux/string_helpers.h>
17 #include "dax-private.h"
18 #include "bus.h"
19
20 /*
21 * Default abstract distance assigned to the NUMA node onlined
22 * by DAX/kmem if the low level platform driver didn't initialize
23 * one for this NUMA node.
24 */
25 #define MEMTIER_DEFAULT_DAX_ADISTANCE (MEMTIER_ADISTANCE_DRAM * 5)
26
27 /* Memory resource name used for add_memory_driver_managed(). */
28 static const char *kmem_name;
29 /* Set if any memory will remain added when the driver will be unloaded. */
30 static bool any_hotremove_failed;
31
dax_kmem_range(struct dev_dax * dev_dax,int i,struct range * r)32 static int dax_kmem_range(struct dev_dax *dev_dax, int i, struct range *r)
33 {
34 struct dev_dax_range *dax_range = &dev_dax->ranges[i];
35 struct range *range = &dax_range->range;
36
37 /* memory-block align the hotplug range */
38 r->start = ALIGN(range->start, memory_block_size_bytes());
39 r->end = ALIGN_DOWN(range->end + 1, memory_block_size_bytes()) - 1;
40 if (r->start >= r->end) {
41 r->start = range->start;
42 r->end = range->end;
43 return -ENOSPC;
44 }
45 return 0;
46 }
47
48 struct dax_kmem_data {
49 const char *res_name;
50 int mgid;
51 struct resource *res[];
52 };
53
54 static DEFINE_MUTEX(kmem_memory_type_lock);
55 static LIST_HEAD(kmem_memory_types);
56
kmem_find_alloc_memory_type(int adist)57 static struct memory_dev_type *kmem_find_alloc_memory_type(int adist)
58 {
59 guard(mutex)(&kmem_memory_type_lock);
60 return mt_find_alloc_memory_type(adist, &kmem_memory_types);
61 }
62
kmem_put_memory_types(void)63 static void kmem_put_memory_types(void)
64 {
65 guard(mutex)(&kmem_memory_type_lock);
66 mt_put_memory_types(&kmem_memory_types);
67 }
68
dev_dax_kmem_probe(struct dev_dax * dev_dax)69 static int dev_dax_kmem_probe(struct dev_dax *dev_dax)
70 {
71 struct device *dev = &dev_dax->dev;
72 unsigned long total_len = 0, orig_len = 0;
73 struct dax_kmem_data *data;
74 struct memory_dev_type *mtype;
75 int i, rc, mapped = 0;
76 mhp_t mhp_flags;
77 int numa_node;
78 int adist = MEMTIER_DEFAULT_DAX_ADISTANCE;
79
80 /*
81 * Ensure good NUMA information for the persistent memory.
82 * Without this check, there is a risk that slow memory
83 * could be mixed in a node with faster memory, causing
84 * unavoidable performance issues.
85 */
86 numa_node = dev_dax->target_node;
87 if (numa_node < 0) {
88 dev_warn(dev, "rejecting DAX region with invalid node: %d\n",
89 numa_node);
90 return -EINVAL;
91 }
92
93 mt_calc_adistance(numa_node, &adist);
94 mtype = kmem_find_alloc_memory_type(adist);
95 if (IS_ERR(mtype))
96 return PTR_ERR(mtype);
97
98 for (i = 0; i < dev_dax->nr_range; i++) {
99 struct range range;
100
101 orig_len += range_len(&dev_dax->ranges[i].range);
102 rc = dax_kmem_range(dev_dax, i, &range);
103 if (rc) {
104 dev_info(dev, "mapping%d: %#llx-%#llx too small after alignment\n",
105 i, range.start, range.end);
106 continue;
107 }
108 total_len += range_len(&range);
109 }
110
111 if (!total_len) {
112 dev_warn(dev, "rejecting DAX region without any memory after alignment\n");
113 return -EINVAL;
114 } else if (total_len != orig_len) {
115 char buf[16];
116
117 string_get_size(orig_len - total_len, 1, STRING_UNITS_2,
118 buf, sizeof(buf));
119 dev_warn(dev, "DAX region truncated by %s due to alignment\n", buf);
120 }
121
122 init_node_memory_type(numa_node, mtype);
123
124 rc = -ENOMEM;
125 data = kzalloc(struct_size(data, res, dev_dax->nr_range), GFP_KERNEL);
126 if (!data)
127 goto err_dax_kmem_data;
128
129 data->res_name = kstrdup(dev_name(dev), GFP_KERNEL);
130 if (!data->res_name)
131 goto err_res_name;
132
133 rc = memory_group_register_static(numa_node, PFN_UP(total_len));
134 if (rc < 0)
135 goto err_reg_mgid;
136 data->mgid = rc;
137
138 for (i = 0; i < dev_dax->nr_range; i++) {
139 struct resource *res;
140 struct range range;
141
142 rc = dax_kmem_range(dev_dax, i, &range);
143 if (rc)
144 continue;
145
146 /* Region is permanently reserved if hotremove fails. */
147 res = request_mem_region(range.start, range_len(&range), data->res_name);
148 if (!res) {
149 dev_warn(dev, "mapping%d: %#llx-%#llx could not reserve region\n",
150 i, range.start, range.end);
151 /*
152 * Once some memory has been onlined we can't
153 * assume that it can be un-onlined safely.
154 */
155 if (mapped)
156 continue;
157 rc = -EBUSY;
158 goto err_request_mem;
159 }
160 data->res[i] = res;
161
162 /*
163 * Set flags appropriate for System RAM. Leave ..._BUSY clear
164 * so that add_memory() can add a child resource. Do not
165 * inherit flags from the parent since it may set new flags
166 * unknown to us that will break add_memory() below.
167 */
168 res->flags = IORESOURCE_SYSTEM_RAM;
169
170 mhp_flags = MHP_NID_IS_MGID;
171 if (dev_dax->memmap_on_memory)
172 mhp_flags |= MHP_MEMMAP_ON_MEMORY;
173
174 /*
175 * Ensure that future kexec'd kernels will not treat
176 * this as RAM automatically.
177 */
178 rc = add_memory_driver_managed(data->mgid, range.start,
179 range_len(&range), kmem_name, mhp_flags);
180
181 if (rc) {
182 dev_warn(dev, "mapping%d: %#llx-%#llx memory add failed\n",
183 i, range.start, range.end);
184 remove_resource(res);
185 kfree(res);
186 data->res[i] = NULL;
187 if (mapped)
188 continue;
189 goto err_request_mem;
190 }
191 mapped++;
192 }
193
194 dev_set_drvdata(dev, data);
195
196 return 0;
197
198 err_request_mem:
199 memory_group_unregister(data->mgid);
200 err_reg_mgid:
201 kfree(data->res_name);
202 err_res_name:
203 kfree(data);
204 err_dax_kmem_data:
205 clear_node_memory_type(numa_node, mtype);
206 return rc;
207 }
208
209 #ifdef CONFIG_MEMORY_HOTREMOVE
dev_dax_kmem_remove(struct dev_dax * dev_dax)210 static void dev_dax_kmem_remove(struct dev_dax *dev_dax)
211 {
212 int i, success = 0;
213 int node = dev_dax->target_node;
214 struct device *dev = &dev_dax->dev;
215 struct dax_kmem_data *data = dev_get_drvdata(dev);
216
217 /*
218 * We have one shot for removing memory, if some memory blocks were not
219 * offline prior to calling this function remove_memory() will fail, and
220 * there is no way to hotremove this memory until reboot because device
221 * unbind will succeed even if we return failure.
222 */
223 for (i = 0; i < dev_dax->nr_range; i++) {
224 struct range range;
225 int rc;
226
227 rc = dax_kmem_range(dev_dax, i, &range);
228 if (rc)
229 continue;
230
231 rc = remove_memory(range.start, range_len(&range));
232 if (rc == 0) {
233 remove_resource(data->res[i]);
234 kfree(data->res[i]);
235 data->res[i] = NULL;
236 success++;
237 continue;
238 }
239 any_hotremove_failed = true;
240 dev_err(dev,
241 "mapping%d: %#llx-%#llx cannot be hotremoved until the next reboot\n",
242 i, range.start, range.end);
243 }
244
245 if (success >= dev_dax->nr_range) {
246 memory_group_unregister(data->mgid);
247 kfree(data->res_name);
248 kfree(data);
249 dev_set_drvdata(dev, NULL);
250 /*
251 * Clear the memtype association on successful unplug.
252 * If not, we have memory blocks left which can be
253 * offlined/onlined later. We need to keep memory_dev_type
254 * for that. This implies this reference will be around
255 * till next reboot.
256 */
257 clear_node_memory_type(node, NULL);
258 }
259 }
260 #else
dev_dax_kmem_remove(struct dev_dax * dev_dax)261 static void dev_dax_kmem_remove(struct dev_dax *dev_dax)
262 {
263 /*
264 * Without hotremove purposely leak the request_mem_region() for the
265 * device-dax range and return '0' to ->remove() attempts. The removal
266 * of the device from the driver always succeeds, but the region is
267 * permanently pinned as reserved by the unreleased
268 * request_mem_region().
269 */
270 any_hotremove_failed = true;
271 }
272 #endif /* CONFIG_MEMORY_HOTREMOVE */
273
274 static struct dax_device_driver device_dax_kmem_driver = {
275 .probe = dev_dax_kmem_probe,
276 .remove = dev_dax_kmem_remove,
277 .type = DAXDRV_KMEM_TYPE,
278 };
279
dax_kmem_init(void)280 static int __init dax_kmem_init(void)
281 {
282 int rc;
283
284 /* Resource name is permanently allocated if any hotremove fails. */
285 kmem_name = kstrdup_const("System RAM (kmem)", GFP_KERNEL);
286 if (!kmem_name)
287 return -ENOMEM;
288
289 rc = dax_driver_register(&device_dax_kmem_driver);
290 if (rc)
291 goto error_dax_driver;
292
293 return rc;
294
295 error_dax_driver:
296 kmem_put_memory_types();
297 kfree_const(kmem_name);
298 return rc;
299 }
300
dax_kmem_exit(void)301 static void __exit dax_kmem_exit(void)
302 {
303 dax_driver_unregister(&device_dax_kmem_driver);
304 if (!any_hotremove_failed)
305 kfree_const(kmem_name);
306 kmem_put_memory_types();
307 }
308
309 MODULE_AUTHOR("Intel Corporation");
310 MODULE_DESCRIPTION("KMEM DAX: map dax-devices as System-RAM");
311 MODULE_LICENSE("GPL v2");
312 module_init(dax_kmem_init);
313 module_exit(dax_kmem_exit);
314 MODULE_ALIAS_DAX_DEVICE(0);
315