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-rw-r--r--drivers/dax/kmem.c285
1 files changed, 285 insertions, 0 deletions
diff --git a/drivers/dax/kmem.c b/drivers/dax/kmem.c
new file mode 100644
index 0000000000..c57acb73e3
--- /dev/null
+++ b/drivers/dax/kmem.c
@@ -0,0 +1,285 @@
+// 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 "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 struct memory_dev_type *dax_slowmem_type;
+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;
+ int i, rc, mapped = 0;
+ int numa_node;
+
+ /*
+ * 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;
+ }
+
+ 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, dax_slowmem_type);
+
+ 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;
+
+ /*
+ * 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_NID_IS_MGID);
+
+ 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, dax_slowmem_type);
+ 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, dax_slowmem_type);
+ }
+}
+#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;
+
+ dax_slowmem_type = alloc_memory_type(MEMTIER_DEFAULT_DAX_ADISTANCE);
+ if (IS_ERR(dax_slowmem_type)) {
+ rc = PTR_ERR(dax_slowmem_type);
+ goto err_dax_slowmem_type;
+ }
+
+ rc = dax_driver_register(&device_dax_kmem_driver);
+ if (rc)
+ goto error_dax_driver;
+
+ return rc;
+
+error_dax_driver:
+ put_memory_type(dax_slowmem_type);
+err_dax_slowmem_type:
+ 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);
+ put_memory_type(dax_slowmem_type);
+}
+
+MODULE_AUTHOR("Intel Corporation");
+MODULE_LICENSE("GPL v2");
+module_init(dax_kmem_init);
+module_exit(dax_kmem_exit);
+MODULE_ALIAS_DAX_DEVICE(0);