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