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