1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
|
// 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 "dax-private.h"
#include "bus.h"
/* 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;
struct resource *res[];
};
static int dev_dax_kmem_probe(struct dev_dax *dev_dax)
{
struct device *dev = &dev_dax->dev;
struct dax_kmem_data *data;
int rc = -ENOMEM;
int i, 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;
}
data = kzalloc(sizeof(*data) + sizeof(struct resource *) * dev_dax->nr_range, GFP_KERNEL);
if (!data)
return -ENOMEM;
data->res_name = kstrdup(dev_name(dev), GFP_KERNEL);
if (!data->res_name)
goto err_res_name;
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) {
dev_info(dev, "mapping%d: %#llx-%#llx too small after alignment\n",
i, range.start, range.end);
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(numa_node, range.start,
range_len(&range), kmem_name, MHP_NONE);
if (rc) {
dev_warn(dev, "mapping%d: %#llx-%#llx memory add failed\n",
i, range.start, range.end);
release_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:
kfree(data->res_name);
err_res_name:
kfree(data);
return rc;
}
#ifdef CONFIG_MEMORY_HOTREMOVE
static int dev_dax_kmem_remove(struct dev_dax *dev_dax)
{
int i, success = 0;
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(dev_dax->target_node, range.start,
range_len(&range));
if (rc == 0) {
release_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) {
kfree(data->res_name);
kfree(data);
dev_set_drvdata(dev, NULL);
}
return 0;
}
#else
static int 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;
return 0;
}
#endif /* CONFIG_MEMORY_HOTREMOVE */
static struct dax_device_driver device_dax_kmem_driver = {
.probe = dev_dax_kmem_probe,
.remove = dev_dax_kmem_remove,
};
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;
rc = dax_driver_register(&device_dax_kmem_driver);
if (rc)
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);
}
MODULE_AUTHOR("Intel Corporation");
MODULE_LICENSE("GPL v2");
module_init(dax_kmem_init);
module_exit(dax_kmem_exit);
MODULE_ALIAS_DAX_DEVICE(0);
|
