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