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 "dax-private.h" 17 #include "bus.h" 18 19 /* 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. 23 */ 24 #define MEMTIER_DEFAULT_DAX_ADISTANCE (MEMTIER_ADISTANCE_DRAM * 5) 25 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; 30 31 static int dax_kmem_range(struct dev_dax *dev_dax, int i, struct range *r) 32 { 33 struct dev_dax_range *dax_range = &dev_dax->ranges[i]; 34 struct range *range = &dax_range->range; 35 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; 41 r->end = range->end; 42 return -ENOSPC; 43 } 44 return 0; 45 } 46 47 struct dax_kmem_data { 48 const char *res_name; 49 int mgid; 50 struct resource *res[]; 51 }; 52 53 static DEFINE_MUTEX(kmem_memory_type_lock); 54 static LIST_HEAD(kmem_memory_types); 55 56 static struct memory_dev_type *kmem_find_alloc_memory_type(int adist) 57 { 58 bool found = false; 59 struct memory_dev_type *mtype; 60 61 mutex_lock(&kmem_memory_type_lock); 62 list_for_each_entry(mtype, &kmem_memory_types, list) { 63 if (mtype->adistance == adist) { 64 found = true; 65 break; 66 } 67 } 68 if (!found) { 69 mtype = alloc_memory_type(adist); 70 if (!IS_ERR(mtype)) 71 list_add(&mtype->list, &kmem_memory_types); 72 } 73 mutex_unlock(&kmem_memory_type_lock); 74 75 return mtype; 76 } 77 78 static void kmem_put_memory_types(void) 79 { 80 struct memory_dev_type *mtype, *mtn; 81 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); 86 } 87 mutex_unlock(&kmem_memory_type_lock); 88 } 89 90 static int dev_dax_kmem_probe(struct dev_dax *dev_dax) 91 { 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; 97 mhp_t mhp_flags; 98 int numa_node; 99 int adist = MEMTIER_DEFAULT_DAX_ADISTANCE; 100 101 /* 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. 106 */ 107 numa_node = dev_dax->target_node; 108 if (numa_node < 0) { 109 dev_warn(dev, "rejecting DAX region with invalid node: %d\n", 110 numa_node); 111 return -EINVAL; 112 } 113 114 mt_calc_adistance(numa_node, &adist); 115 mtype = kmem_find_alloc_memory_type(adist); 116 if (IS_ERR(mtype)) 117 return PTR_ERR(mtype); 118 119 for (i = 0; i < dev_dax->nr_range; i++) { 120 struct range range; 121 122 rc = dax_kmem_range(dev_dax, i, &range); 123 if (rc) { 124 dev_info(dev, "mapping%d: %#llx-%#llx too small after alignment\n", 125 i, range.start, range.end); 126 continue; 127 } 128 total_len += range_len(&range); 129 } 130 131 if (!total_len) { 132 dev_warn(dev, "rejecting DAX region without any memory after alignment\n"); 133 return -EINVAL; 134 } 135 136 init_node_memory_type(numa_node, mtype); 137 138 rc = -ENOMEM; 139 data = kzalloc(struct_size(data, res, dev_dax->nr_range), GFP_KERNEL); 140 if (!data) 141 goto err_dax_kmem_data; 142 143 data->res_name = kstrdup(dev_name(dev), GFP_KERNEL); 144 if (!data->res_name) 145 goto err_res_name; 146 147 rc = memory_group_register_static(numa_node, PFN_UP(total_len)); 148 if (rc < 0) 149 goto err_reg_mgid; 150 data->mgid = rc; 151 152 for (i = 0; i < dev_dax->nr_range; i++) { 153 struct resource *res; 154 struct range range; 155 156 rc = dax_kmem_range(dev_dax, i, &range); 157 if (rc) 158 continue; 159 160 /* Region is permanently reserved if hotremove fails. */ 161 res = request_mem_region(range.start, range_len(&range), data->res_name); 162 if (!res) { 163 dev_warn(dev, "mapping%d: %#llx-%#llx could not reserve region\n", 164 i, range.start, range.end); 165 /* 166 * Once some memory has been onlined we can't 167 * assume that it can be un-onlined safely. 168 */ 169 if (mapped) 170 continue; 171 rc = -EBUSY; 172 goto err_request_mem; 173 } 174 data->res[i] = res; 175 176 /* 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. 181 */ 182 res->flags = IORESOURCE_SYSTEM_RAM; 183 184 mhp_flags = MHP_NID_IS_MGID; 185 if (dev_dax->memmap_on_memory) 186 mhp_flags |= MHP_MEMMAP_ON_MEMORY; 187 188 /* 189 * Ensure that future kexec'd kernels will not treat 190 * this as RAM automatically. 191 */ 192 rc = add_memory_driver_managed(data->mgid, range.start, 193 range_len(&range), kmem_name, mhp_flags); 194 195 if (rc) { 196 dev_warn(dev, "mapping%d: %#llx-%#llx memory add failed\n", 197 i, range.start, range.end); 198 remove_resource(res); 199 kfree(res); 200 data->res[i] = NULL; 201 if (mapped) 202 continue; 203 goto err_request_mem; 204 } 205 mapped++; 206 } 207 208 dev_set_drvdata(dev, data); 209 210 return 0; 211 212 err_request_mem: 213 memory_group_unregister(data->mgid); 214 err_reg_mgid: 215 kfree(data->res_name); 216 err_res_name: 217 kfree(data); 218 err_dax_kmem_data: 219 clear_node_memory_type(numa_node, mtype); 220 return rc; 221 } 222 223 #ifdef CONFIG_MEMORY_HOTREMOVE 224 static void dev_dax_kmem_remove(struct dev_dax *dev_dax) 225 { 226 int i, success = 0; 227 int node = dev_dax->target_node; 228 struct device *dev = &dev_dax->dev; 229 struct dax_kmem_data *data = dev_get_drvdata(dev); 230 231 /* 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. 236 */ 237 for (i = 0; i < dev_dax->nr_range; i++) { 238 struct range range; 239 int rc; 240 241 rc = dax_kmem_range(dev_dax, i, &range); 242 if (rc) 243 continue; 244 245 rc = remove_memory(range.start, range_len(&range)); 246 if (rc == 0) { 247 remove_resource(data->res[i]); 248 kfree(data->res[i]); 249 data->res[i] = NULL; 250 success++; 251 continue; 252 } 253 any_hotremove_failed = true; 254 dev_err(dev, 255 "mapping%d: %#llx-%#llx cannot be hotremoved until the next reboot\n", 256 i, range.start, range.end); 257 } 258 259 if (success >= dev_dax->nr_range) { 260 memory_group_unregister(data->mgid); 261 kfree(data->res_name); 262 kfree(data); 263 dev_set_drvdata(dev, NULL); 264 /* 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 269 * till next reboot. 270 */ 271 clear_node_memory_type(node, NULL); 272 } 273 } 274 #else 275 static void dev_dax_kmem_remove(struct dev_dax *dev_dax) 276 { 277 /* 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(). 283 */ 284 any_hotremove_failed = true; 285 } 286 #endif /* CONFIG_MEMORY_HOTREMOVE */ 287 288 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, 292 }; 293 294 static int __init dax_kmem_init(void) 295 { 296 int rc; 297 298 /* Resource name is permanently allocated if any hotremove fails. */ 299 kmem_name = kstrdup_const("System RAM (kmem)", GFP_KERNEL); 300 if (!kmem_name) 301 return -ENOMEM; 302 303 rc = dax_driver_register(&device_dax_kmem_driver); 304 if (rc) 305 goto error_dax_driver; 306 307 return rc; 308 309 error_dax_driver: 310 kmem_put_memory_types(); 311 kfree_const(kmem_name); 312 return rc; 313 } 314 315 static void __exit dax_kmem_exit(void) 316 { 317 dax_driver_unregister(&device_dax_kmem_driver); 318 if (!any_hotremove_failed) 319 kfree_const(kmem_name); 320 kmem_put_memory_types(); 321 } 322 323 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); 328