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 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 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 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 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 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 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 }; 279 280 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 } 300 301 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