// SPDX-License-Identifier: GPL-2.0 /* Copyright(c) 2016-2019 Intel Corporation. All rights reserved. */ #include <linux/memremap.h> #include <linux/pagemap.h> #include <linux/memory.h> #include <linux/module.h> #include <linux/device.h> #include <linux/pfn_t.h> #include <linux/slab.h> #include <linux/dax.h> #include <linux/fs.h> #include <linux/mm.h> #include <linux/mman.h> #include "dax-private.h" #include "bus.h" int dev_dax_kmem_probe(struct device *dev) { struct dev_dax *dev_dax = to_dev_dax(dev); struct resource *res = &dev_dax->region->res; resource_size_t kmem_start; resource_size_t kmem_size; resource_size_t kmem_end; struct resource *new_res; int numa_node; int rc; /* * Ensure good NUMA information for the persistent memory. * Without this check, there is a risk that slow memory * could be mixed in a node with faster memory, causing * unavoidable performance issues. */ numa_node = dev_dax->target_node; if (numa_node < 0) { dev_warn(dev, "rejecting DAX region %pR with invalid node: %d\n", res, numa_node); return -EINVAL; } /* Hotplug starting at the beginning of the next block: */ kmem_start = ALIGN(res->start, memory_block_size_bytes()); kmem_size = resource_size(res); /* Adjust the size down to compensate for moving up kmem_start: */ kmem_size -= kmem_start - res->start; /* Align the size down to cover only complete blocks: */ kmem_size &= ~(memory_block_size_bytes() - 1); kmem_end = kmem_start + kmem_size; /* Region is permanently reserved. Hot-remove not yet implemented. */ new_res = request_mem_region(kmem_start, kmem_size, dev_name(dev)); if (!new_res) { dev_warn(dev, "could not reserve region [%pa-%pa]\n", &kmem_start, &kmem_end); return -EBUSY; } /* * Set flags appropriate for System RAM. Leave ..._BUSY clear * so that add_memory() can add a child resource. Do not * inherit flags from the parent since it may set new flags * unknown to us that will break add_memory() below. */ new_res->flags = IORESOURCE_SYSTEM_RAM; new_res->name = dev_name(dev); rc = add_memory(numa_node, new_res->start, resource_size(new_res)); if (rc) { release_resource(new_res); kfree(new_res); return rc; } dev_dax->dax_kmem_res = new_res; return 0; } #ifdef CONFIG_MEMORY_HOTREMOVE static int dev_dax_kmem_remove(struct device *dev) { struct dev_dax *dev_dax = to_dev_dax(dev); struct resource *res = dev_dax->dax_kmem_res; resource_size_t kmem_start = res->start; resource_size_t kmem_size = resource_size(res); int rc; /* * We have one shot for removing memory, if some memory blocks were not * offline prior to calling this function remove_memory() will fail, and * there is no way to hotremove this memory until reboot because device * unbind will succeed even if we return failure. */ rc = remove_memory(dev_dax->target_node, kmem_start, kmem_size); if (rc) { dev_err(dev, "DAX region %pR cannot be hotremoved until the next reboot\n", res); return rc; } /* Release and free dax resources */ release_resource(res); kfree(res); dev_dax->dax_kmem_res = NULL; return 0; } #else static int dev_dax_kmem_remove(struct device *dev) { /* * Without hotremove purposely leak the request_mem_region() for the * device-dax range and return '0' to ->remove() attempts. The removal * of the device from the driver always succeeds, but the region is * permanently pinned as reserved by the unreleased * request_mem_region(). */ return 0; } #endif /* CONFIG_MEMORY_HOTREMOVE */ static struct dax_device_driver device_dax_kmem_driver = { .drv = { .probe = dev_dax_kmem_probe, .remove = dev_dax_kmem_remove, }, }; static int __init dax_kmem_init(void) { return dax_driver_register(&device_dax_kmem_driver); } static void __exit dax_kmem_exit(void) { dax_driver_unregister(&device_dax_kmem_driver); } MODULE_AUTHOR("Intel Corporation"); MODULE_LICENSE("GPL v2"); module_init(dax_kmem_init); module_exit(dax_kmem_exit); MODULE_ALIAS_DAX_DEVICE(0);