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