// 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 <linux/memory-tiers.h>
#include <linux/memory_hotplug.h>
#include "dax-private.h"
#include "bus.h"
/*
* Default abstract distance assigned to the NUMA node onlined
* by DAX/kmem if the low level platform driver didn't initialize
* one for this NUMA node.
*/
#define MEMTIER_DEFAULT_DAX_ADISTANCE (MEMTIER_ADISTANCE_DRAM * 5)
/* 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 int dax_kmem_range(struct dev_dax *dev_dax, int i, struct range *r)
{
struct dev_dax_range *dax_range = &dev_dax->ranges[i];
struct range *range = &dax_range->range;
/* memory-block align the hotplug range */
r->start = ALIGN(range->start, memory_block_size_bytes());
r->end = ALIGN_DOWN(range->end + 1, memory_block_size_bytes()) - 1;
if (r->start >= r->end) {
r->start = range->start;
r->end = range->end;
return -ENOSPC;
}
return 0;
}
struct dax_kmem_data {
const char *res_name;
int mgid;
struct resource *res[];
};
static DEFINE_MUTEX(kmem_memory_type_lock);
static LIST_HEAD(kmem_memory_types);
static struct memory_dev_type *kmem_find_alloc_memory_type(int adist)
{
guard(mutex)(&kmem_memory_type_lock);
return mt_find_alloc_memory_type(adist, &kmem_memory_types);
}
static void kmem_put_memory_types(void)
{
guard(mutex)(&kmem_memory_type_lock);
mt_put_memory_types(&kmem_memory_types);
}
static int dev_dax_kmem_probe(struct dev_dax *dev_dax)
{
struct device *dev = &dev_dax->dev;
unsigned long total_len = 0;
struct dax_kmem_data *data;
struct memory_dev_type *mtype;
int i, rc, mapped = 0;
mhp_t mhp_flags;
int numa_node;
int adist = MEMTIER_DEFAULT_DAX_ADISTANCE;
/*
* 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;
}
mt_calc_adistance(numa_node, &adist);
mtype = kmem_find_alloc_memory_type(adist);
if (IS_ERR(mtype))
return PTR_ERR(mtype);
for (i = 0; i < dev_dax->nr_range; i++) {
struct range range;
rc = dax_kmem_range(dev_dax, i, &range);
if (rc) {
dev_info(dev, "mapping%d: %#llx-%#llx too small after alignment\n",
i, range.start, range.end);
continue;
}
total_len += range_len(&range);
}
if (!total_len) {
dev_warn(dev, "rejecting DAX region without any memory after alignment\n");
return -EINVAL;
}
init_node_memory_type(numa_node, mtype);
rc = -ENOMEM;
data = kzalloc(struct_size(data, res, dev_dax->nr_range), GFP_KERNEL);
if (!data)
goto err_dax_kmem_data;
data->res_name = kstrdup(dev_name(dev), GFP_KERNEL);
if (!data->res_name)
goto err_res_name;
rc = memory_group_register_static(numa_node, PFN_UP(total_len));
if (rc < 0)
goto err_reg_mgid;
data->mgid = rc;
for (i = 0; i < dev_dax->nr_range; i++) {
struct resource *res;
struct range range;
rc = dax_kmem_range(dev_dax, i, &range);
if (rc)
continue;
/* Region is permanently reserved if hotremove fails. */
res = request_mem_region(range.start, range_len(&range), data->res_name);
if (!res) {
dev_warn(dev, "mapping%d: %#llx-%#llx could not reserve region\n",
i, range.start, range.end);
/*
* Once some memory has been onlined we can't
* assume that it can be un-onlined safely.
*/
if (mapped)
continue;
rc = -EBUSY;
goto err_request_mem;
}
data->res[i] = res;
/*
* 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;
mhp_flags = MHP_NID_IS_MGID;
if (dev_dax->memmap_on_memory)
mhp_flags |= MHP_MEMMAP_ON_MEMORY;
/*
* Ensure that future kexec'd kernels will not treat
* this as RAM automatically.
*/
rc = add_memory_driver_managed(data->mgid, range.start,
range_len(&range), kmem_name, mhp_flags);
if (rc) {
dev_warn(dev, "mapping%d: %#llx-%#llx memory add failed\n",
i, range.start, range.end);
remove_resource(res);
kfree(res);
data->res[i] = NULL;
if (mapped)
continue;
goto err_request_mem;
}
mapped++;
}
dev_set_drvdata(dev, data);
return 0;
err_request_mem:
memory_group_unregister(data->mgid);
err_reg_mgid:
kfree(data->res_name);
err_res_name:
kfree(data);
err_dax_kmem_data:
clear_node_memory_type(numa_node, mtype);
return rc;
}
#ifdef CONFIG_MEMORY_HOTREMOVE
static void dev_dax_kmem_remove(struct dev_dax *dev_dax)
{
int i, success = 0;
int node = dev_dax->target_node;
struct device *dev = &dev_dax->dev;
struct dax_kmem_data *data = dev_get_drvdata(dev);
/*
* 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.
*/
for (i = 0; i < dev_dax->nr_range; i++) {
struct range range;
int rc;
rc = dax_kmem_range(dev_dax, i, &range);
if (rc)
continue;
rc = remove_memory(range.start, range_len(&range));
if (rc == 0) {
remove_resource(data->res[i]);
kfree(data->res[i]);
data->res[i] = NULL;
success++;
continue;
}
any_hotremove_failed = true;
dev_err(dev,
"mapping%d: %#llx-%#llx cannot be hotremoved until the next reboot\n",
i, range.start, range.end);
}
if (success >= dev_dax->nr_range) {
memory_group_unregister(data->mgid);
kfree(data->res_name);
kfree(data);
dev_set_drvdata(dev, NULL);
/*
* Clear the memtype association on successful unplug.
* If not, we have memory blocks left which can be
* offlined/onlined later. We need to keep memory_dev_type
* for that. This implies this reference will be around
* till next reboot.
*/
clear_node_memory_type(node, NULL);
}
}
#else
static void dev_dax_kmem_remove(struct dev_dax *dev_dax)
{
/*
* 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;
}
#endif /* CONFIG_MEMORY_HOTREMOVE */
static struct dax_device_driver device_dax_kmem_driver = {
.probe = dev_dax_kmem_probe,
.remove = dev_dax_kmem_remove,
.type = DAXDRV_KMEM_TYPE,
};
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)
goto error_dax_driver;
return rc;
error_dax_driver:
kmem_put_memory_types();
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);
kmem_put_memory_types();
}
MODULE_AUTHOR("Intel Corporation");
MODULE_DESCRIPTION("KMEM DAX: map dax-devices as System-RAM");
MODULE_LICENSE("GPL v2");
module_init(dax_kmem_init);
module_exit(dax_kmem_exit);
MODULE_ALIAS_DAX_DEVICE(0);
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