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// 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"
/* Memory resource name used for add_memory_driver_managed(). */
static const char *kmem_name;
/* Set if any memory will remain added when the driver will be unloaded. */
static bool any_hotremove_failed;
static struct range dax_kmem_range(struct dev_dax *dev_dax)
{
struct range range;
/* memory-block align the hotplug range */
range.start = ALIGN(dev_dax->range.start, memory_block_size_bytes());
range.end = ALIGN_DOWN(dev_dax->range.end + 1, memory_block_size_bytes()) - 1;
return range;
}
int dev_dax_kmem_probe(struct device *dev)
{
struct dev_dax *dev_dax = to_dev_dax(dev);
struct range range = dax_kmem_range(dev_dax);
struct resource *res;
char *res_name;
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 with invalid node: %d\n",
numa_node);
return -EINVAL;
}
res_name = kstrdup(dev_name(dev), GFP_KERNEL);
if (!res_name)
return -ENOMEM;
/* Region is permanently reserved if hotremove fails. */
res = request_mem_region(range.start, range_len(&range), res_name);
if (!res) {
dev_warn(dev, "could not reserve region [%#llx-%#llx]\n", range.start, range.end);
kfree(res_name);
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.
*/
res->flags = IORESOURCE_SYSTEM_RAM;
/*
* Ensure that future kexec'd kernels will not treat this as RAM
* automatically.
*/
rc = add_memory_driver_managed(numa_node, range.start, range_len(&range), kmem_name);
if (rc) {
release_mem_region(range.start, range_len(&range));
kfree(res_name);
return rc;
}
dev_set_drvdata(dev, res_name);
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 range range = dax_kmem_range(dev_dax);
const char *res_name = dev_get_drvdata(dev);
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, range.start, range_len(&range));
if (rc) {
any_hotremove_failed = true;
dev_err(dev, "%#llx-%#llx cannot be hotremoved until the next reboot\n",
range.start, range.end);
return rc;
}
/* Release and free dax resources */
release_mem_region(range.start, range_len(&range));
kfree(res_name);
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().
*/
any_hotremove_failed = true;
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)
{
int rc;
/* Resource name is permanently allocated if any hotremove fails. */
kmem_name = kstrdup_const("System RAM (kmem)", GFP_KERNEL);
if (!kmem_name)
return -ENOMEM;
rc = dax_driver_register(&device_dax_kmem_driver);
if (rc)
kfree_const(kmem_name);
return rc;
}
static void __exit dax_kmem_exit(void)
{
dax_driver_unregister(&device_dax_kmem_driver);
if (!any_hotremove_failed)
kfree_const(kmem_name);
}
MODULE_AUTHOR("Intel Corporation");
MODULE_LICENSE("GPL v2");
module_init(dax_kmem_init);
module_exit(dax_kmem_exit);
MODULE_ALIAS_DAX_DEVICE(0);
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