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 int numa_node; 26 int rc; 27 28 /* 29 * Ensure good NUMA information for the persistent memory. 30 * Without this check, there is a risk that slow memory 31 * could be mixed in a node with faster memory, causing 32 * unavoidable performance issues. 33 */ 34 numa_node = dev_dax->target_node; 35 if (numa_node < 0) { 36 dev_warn(dev, "rejecting DAX region %pR with invalid node: %d\n", 37 res, numa_node); 38 return -EINVAL; 39 } 40 41 /* Hotplug starting at the beginning of the next block: */ 42 kmem_start = ALIGN(res->start, memory_block_size_bytes()); 43 44 kmem_size = resource_size(res); 45 /* Adjust the size down to compensate for moving up kmem_start: */ 46 kmem_size -= kmem_start - res->start; 47 /* Align the size down to cover only complete blocks: */ 48 kmem_size &= ~(memory_block_size_bytes() - 1); 49 kmem_end = kmem_start + kmem_size; 50 51 /* Region is permanently reserved. Hot-remove not yet implemented. */ 52 new_res = request_mem_region(kmem_start, kmem_size, dev_name(dev)); 53 if (!new_res) { 54 dev_warn(dev, "could not reserve region [%pa-%pa]\n", 55 &kmem_start, &kmem_end); 56 return -EBUSY; 57 } 58 59 /* 60 * Set flags appropriate for System RAM. Leave ..._BUSY clear 61 * so that add_memory() can add a child resource. Do not 62 * inherit flags from the parent since it may set new flags 63 * unknown to us that will break add_memory() below. 64 */ 65 new_res->flags = IORESOURCE_SYSTEM_RAM; 66 new_res->name = dev_name(dev); 67 68 rc = add_memory(numa_node, new_res->start, resource_size(new_res)); 69 if (rc) 70 return rc; 71 72 return 0; 73 } 74 75 static int dev_dax_kmem_remove(struct device *dev) 76 { 77 /* 78 * Purposely leak the request_mem_region() for the device-dax 79 * range and return '0' to ->remove() attempts. The removal of 80 * the device from the driver always succeeds, but the region 81 * is permanently pinned as reserved by the unreleased 82 * request_mem_region(). 83 */ 84 return 0; 85 } 86 87 static struct dax_device_driver device_dax_kmem_driver = { 88 .drv = { 89 .probe = dev_dax_kmem_probe, 90 .remove = dev_dax_kmem_remove, 91 }, 92 }; 93 94 static int __init dax_kmem_init(void) 95 { 96 return dax_driver_register(&device_dax_kmem_driver); 97 } 98 99 static void __exit dax_kmem_exit(void) 100 { 101 dax_driver_unregister(&device_dax_kmem_driver); 102 } 103 104 MODULE_AUTHOR("Intel Corporation"); 105 MODULE_LICENSE("GPL v2"); 106 module_init(dax_kmem_init); 107 module_exit(dax_kmem_exit); 108 MODULE_ALIAS_DAX_DEVICE(0); 109