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 "dax-private.h" 15 #include "bus.h" 16 17 /* Memory resource name used for add_memory_driver_managed(). */ 18 static const char *kmem_name; 19 /* Set if any memory will remain added when the driver will be unloaded. */ 20 static bool any_hotremove_failed; 21 22 static struct range dax_kmem_range(struct dev_dax *dev_dax) 23 { 24 struct range range; 25 26 /* memory-block align the hotplug range */ 27 range.start = ALIGN(dev_dax->range.start, memory_block_size_bytes()); 28 range.end = ALIGN_DOWN(dev_dax->range.end + 1, memory_block_size_bytes()) - 1; 29 return range; 30 } 31 32 int dev_dax_kmem_probe(struct device *dev) 33 { 34 struct dev_dax *dev_dax = to_dev_dax(dev); 35 struct range range = dax_kmem_range(dev_dax); 36 struct resource *new_res; 37 const char *new_res_name; 38 int numa_node; 39 int rc; 40 41 /* 42 * Ensure good NUMA information for the persistent memory. 43 * Without this check, there is a risk that slow memory 44 * could be mixed in a node with faster memory, causing 45 * unavoidable performance issues. 46 */ 47 numa_node = dev_dax->target_node; 48 if (numa_node < 0) { 49 dev_warn(dev, "rejecting DAX region with invalid node: %d\n", 50 numa_node); 51 return -EINVAL; 52 } 53 54 new_res_name = kstrdup(dev_name(dev), GFP_KERNEL); 55 if (!new_res_name) 56 return -ENOMEM; 57 58 /* Region is permanently reserved if hotremove fails. */ 59 new_res = request_mem_region(range.start, range_len(&range), new_res_name); 60 if (!new_res) { 61 dev_warn(dev, "could not reserve region [%#llx-%#llx]\n", range.start, range.end); 62 kfree(new_res_name); 63 return -EBUSY; 64 } 65 66 /* 67 * Set flags appropriate for System RAM. Leave ..._BUSY clear 68 * so that add_memory() can add a child resource. Do not 69 * inherit flags from the parent since it may set new flags 70 * unknown to us that will break add_memory() below. 71 */ 72 new_res->flags = IORESOURCE_SYSTEM_RAM; 73 74 /* 75 * Ensure that future kexec'd kernels will not treat this as RAM 76 * automatically. 77 */ 78 rc = add_memory_driver_managed(numa_node, new_res->start, 79 resource_size(new_res), kmem_name); 80 if (rc) { 81 release_resource(new_res); 82 kfree(new_res); 83 kfree(new_res_name); 84 return rc; 85 } 86 dev_dax->dax_kmem_res = new_res; 87 88 return 0; 89 } 90 91 #ifdef CONFIG_MEMORY_HOTREMOVE 92 static int dev_dax_kmem_remove(struct device *dev) 93 { 94 struct dev_dax *dev_dax = to_dev_dax(dev); 95 struct range range = dax_kmem_range(dev_dax); 96 struct resource *res = dev_dax->dax_kmem_res; 97 const char *res_name = res->name; 98 int rc; 99 100 /* 101 * We have one shot for removing memory, if some memory blocks were not 102 * offline prior to calling this function remove_memory() will fail, and 103 * there is no way to hotremove this memory until reboot because device 104 * unbind will succeed even if we return failure. 105 */ 106 rc = remove_memory(dev_dax->target_node, range.start, range_len(&range)); 107 if (rc) { 108 any_hotremove_failed = true; 109 dev_err(dev, "%#llx-%#llx cannot be hotremoved until the next reboot\n", 110 range.start, range.end); 111 return rc; 112 } 113 114 /* Release and free dax resources */ 115 release_resource(res); 116 kfree(res); 117 kfree(res_name); 118 dev_dax->dax_kmem_res = NULL; 119 120 return 0; 121 } 122 #else 123 static int dev_dax_kmem_remove(struct device *dev) 124 { 125 /* 126 * Without hotremove purposely leak the request_mem_region() for the 127 * device-dax range and return '0' to ->remove() attempts. The removal 128 * of the device from the driver always succeeds, but the region is 129 * permanently pinned as reserved by the unreleased 130 * request_mem_region(). 131 */ 132 any_hotremove_failed = true; 133 return 0; 134 } 135 #endif /* CONFIG_MEMORY_HOTREMOVE */ 136 137 static struct dax_device_driver device_dax_kmem_driver = { 138 .drv = { 139 .probe = dev_dax_kmem_probe, 140 .remove = dev_dax_kmem_remove, 141 }, 142 }; 143 144 static int __init dax_kmem_init(void) 145 { 146 int rc; 147 148 /* Resource name is permanently allocated if any hotremove fails. */ 149 kmem_name = kstrdup_const("System RAM (kmem)", GFP_KERNEL); 150 if (!kmem_name) 151 return -ENOMEM; 152 153 rc = dax_driver_register(&device_dax_kmem_driver); 154 if (rc) 155 kfree_const(kmem_name); 156 return rc; 157 } 158 159 static void __exit dax_kmem_exit(void) 160 { 161 dax_driver_unregister(&device_dax_kmem_driver); 162 if (!any_hotremove_failed) 163 kfree_const(kmem_name); 164 } 165 166 MODULE_AUTHOR("Intel Corporation"); 167 MODULE_LICENSE("GPL v2"); 168 module_init(dax_kmem_init); 169 module_exit(dax_kmem_exit); 170 MODULE_ALIAS_DAX_DEVICE(0); 171