Initial import

1 files changed, 1652 insertions, 0 deletions

diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c
new file mode 100644
index 000000000..5e80621d9
--- /dev/null
+++ b/arch/powerpc/mm/numa.c
@@ -0,0 +1,1652 @@
+/*
+ * pSeries NUMA support
+ *
+ * Copyright (C) 2002 Anton Blanchard <anton@au.ibm.com>, IBM
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+#define pr_fmt(fmt) "numa: " fmt
+
+#include <linux/threads.h>
+#include <linux/bootmem.h>
+#include <linux/init.h>
+#include <linux/mm.h>
+#include <linux/mmzone.h>
+#include <linux/export.h>
+#include <linux/nodemask.h>
+#include <linux/cpu.h>
+#include <linux/notifier.h>
+#include <linux/memblock.h>
+#include <linux/of.h>
+#include <linux/pfn.h>
+#include <linux/cpuset.h>
+#include <linux/node.h>
+#include <linux/stop_machine.h>
+#include <linux/proc_fs.h>
+#include <linux/seq_file.h>
+#include <linux/uaccess.h>
+#include <linux/slab.h>
+#include <asm/cputhreads.h>
+#include <asm/sparsemem.h>
+#include <asm/prom.h>
+#include <asm/smp.h>
+#include <asm/cputhreads.h>
+#include <asm/topology.h>
+#include <asm/firmware.h>
+#include <asm/paca.h>
+#include <asm/hvcall.h>
+#include <asm/setup.h>
+#include <asm/vdso.h>
+
+static int numa_enabled = 1;
+
+static char *cmdline __initdata;
+
+static int numa_debug;
+#define dbg(args...) if (numa_debug) { printk(KERN_INFO args); }
+
+int numa_cpu_lookup_table[NR_CPUS];
+cpumask_var_t node_to_cpumask_map[MAX_NUMNODES];
+struct pglist_data *node_data[MAX_NUMNODES];
+
+EXPORT_SYMBOL(numa_cpu_lookup_table);
+EXPORT_SYMBOL(node_to_cpumask_map);
+EXPORT_SYMBOL(node_data);
+
+static int min_common_depth;
+static int n_mem_addr_cells, n_mem_size_cells;
+static int form1_affinity;
+
+#define MAX_DISTANCE_REF_POINTS 4
+static int distance_ref_points_depth;
+static const __be32 *distance_ref_points;
+static int distance_lookup_table[MAX_NUMNODES][MAX_DISTANCE_REF_POINTS];
+
+/*
+ * Allocate node_to_cpumask_map based on number of available nodes
+ * Requires node_possible_map to be valid.
+ *
+ * Note: cpumask_of_node() is not valid until after this is done.
+ */
+static void __init setup_node_to_cpumask_map(void)
+{
+	unsigned int node;
+
+	/* setup nr_node_ids if not done yet */
+	if (nr_node_ids == MAX_NUMNODES)
+		setup_nr_node_ids();
+
+	/* allocate the map */
+	for (node = 0; node < nr_node_ids; node++)
+		alloc_bootmem_cpumask_var(&node_to_cpumask_map[node]);
+
+	/* cpumask_of_node() will now work */
+	dbg("Node to cpumask map for %d nodes\n", nr_node_ids);
+}
+
+static int __init fake_numa_create_new_node(unsigned long end_pfn,
+						unsigned int *nid)
+{
+	unsigned long long mem;
+	char *p = cmdline;
+	static unsigned int fake_nid;
+	static unsigned long long curr_boundary;
+
+	/*
+	 * Modify node id, iff we started creating NUMA nodes
+	 * We want to continue from where we left of the last time
+	 */
+	if (fake_nid)
+		*nid = fake_nid;
+	/*
+	 * In case there are no more arguments to parse, the
+	 * node_id should be the same as the last fake node id
+	 * (we've handled this above).
+	 */
+	if (!p)
+		return 0;
+
+	mem = memparse(p, &p);
+	if (!mem)
+		return 0;
+
+	if (mem < curr_boundary)
+		return 0;
+
+	curr_boundary = mem;
+
+	if ((end_pfn << PAGE_SHIFT) > mem) {
+		/*
+		 * Skip commas and spaces
+		 */
+		while (*p == ',' || *p == ' ' || *p == '\t')
+			p++;
+
+		cmdline = p;
+		fake_nid++;
+		*nid = fake_nid;
+		dbg("created new fake_node with id %d\n", fake_nid);
+		return 1;
+	}
+	return 0;
+}
+
+static void reset_numa_cpu_lookup_table(void)
+{
+	unsigned int cpu;
+
+	for_each_possible_cpu(cpu)
+		numa_cpu_lookup_table[cpu] = -1;
+}
+
+static void update_numa_cpu_lookup_table(unsigned int cpu, int node)
+{
+	numa_cpu_lookup_table[cpu] = node;
+}
+
+static void map_cpu_to_node(int cpu, int node)
+{
+	update_numa_cpu_lookup_table(cpu, node);
+
+	dbg("adding cpu %d to node %d\n", cpu, node);
+
+	if (!(cpumask_test_cpu(cpu, node_to_cpumask_map[node])))
+		cpumask_set_cpu(cpu, node_to_cpumask_map[node]);
+}
+
+#if defined(CONFIG_HOTPLUG_CPU) || defined(CONFIG_PPC_SPLPAR)
+static void unmap_cpu_from_node(unsigned long cpu)
+{
+	int node = numa_cpu_lookup_table[cpu];
+
+	dbg("removing cpu %lu from node %d\n", cpu, node);
+
+	if (cpumask_test_cpu(cpu, node_to_cpumask_map[node])) {
+		cpumask_clear_cpu(cpu, node_to_cpumask_map[node]);
+	} else {
+		printk(KERN_ERR "WARNING: cpu %lu not found in node %d\n",
+		       cpu, node);
+	}
+}
+#endif /* CONFIG_HOTPLUG_CPU || CONFIG_PPC_SPLPAR */
+
+/* must hold reference to node during call */
+static const __be32 *of_get_associativity(struct device_node *dev)
+{
+	return of_get_property(dev, "ibm,associativity", NULL);
+}
+
+/*
+ * Returns the property linux,drconf-usable-memory if
+ * it exists (the property exists only in kexec/kdump kernels,
+ * added by kexec-tools)
+ */
+static const __be32 *of_get_usable_memory(struct device_node *memory)
+{
+	const __be32 *prop;
+	u32 len;
+	prop = of_get_property(memory, "linux,drconf-usable-memory", &len);
+	if (!prop || len < sizeof(unsigned int))
+		return NULL;
+	return prop;
+}
+
+int __node_distance(int a, int b)
+{
+	int i;
+	int distance = LOCAL_DISTANCE;
+
+	if (!form1_affinity)
+		return ((a == b) ? LOCAL_DISTANCE : REMOTE_DISTANCE);
+
+	for (i = 0; i < distance_ref_points_depth; i++) {
+		if (distance_lookup_table[a][i] == distance_lookup_table[b][i])
+			break;
+
+		/* Double the distance for each NUMA level */
+		distance *= 2;
+	}
+
+	return distance;
+}
+EXPORT_SYMBOL(__node_distance);
+
+static void initialize_distance_lookup_table(int nid,
+		const __be32 *associativity)
+{
+	int i;
+
+	if (!form1_affinity)
+		return;
+
+	for (i = 0; i < distance_ref_points_depth; i++) {
+		const __be32 *entry;
+
+		entry = &associativity[be32_to_cpu(distance_ref_points[i])];
+		distance_lookup_table[nid][i] = of_read_number(entry, 1);
+	}
+}
+
+/* Returns nid in the range [0..MAX_NUMNODES-1], or -1 if no useful numa
+ * info is found.
+ */
+static int associativity_to_nid(const __be32 *associativity)
+{
+	int nid = -1;
+
+	if (min_common_depth == -1)
+		goto out;
+
+	if (of_read_number(associativity, 1) >= min_common_depth)
+		nid = of_read_number(&associativity[min_common_depth], 1);
+
+	/* POWER4 LPAR uses 0xffff as invalid node */
+	if (nid == 0xffff || nid >= MAX_NUMNODES)
+		nid = -1;
+
+	if (nid > 0 &&
+	    of_read_number(associativity, 1) >= distance_ref_points_depth)
+		initialize_distance_lookup_table(nid, associativity);
+
+out:
+	return nid;
+}
+
+/* Returns the nid associated with the given device tree node,
+ * or -1 if not found.
+ */
+static int of_node_to_nid_single(struct device_node *device)
+{
+	int nid = -1;
+	const __be32 *tmp;
+
+	tmp = of_get_associativity(device);
+	if (tmp)
+		nid = associativity_to_nid(tmp);
+	return nid;
+}
+
+/* Walk the device tree upwards, looking for an associativity id */
+int of_node_to_nid(struct device_node *device)
+{
+	struct device_node *tmp;
+	int nid = -1;
+
+	of_node_get(device);
+	while (device) {
+		nid = of_node_to_nid_single(device);
+		if (nid != -1)
+			break;
+
+	        tmp = device;
+		device = of_get_parent(tmp);
+		of_node_put(tmp);
+	}
+	of_node_put(device);
+
+	return nid;
+}
+EXPORT_SYMBOL_GPL(of_node_to_nid);
+
+static int __init find_min_common_depth(void)
+{
+	int depth;
+	struct device_node *root;
+
+	if (firmware_has_feature(FW_FEATURE_OPAL))
+		root = of_find_node_by_path("/ibm,opal");
+	else
+		root = of_find_node_by_path("/rtas");
+	if (!root)
+		root = of_find_node_by_path("/");
+
+	/*
+	 * This property is a set of 32-bit integers, each representing
+	 * an index into the ibm,associativity nodes.
+	 *
+	 * With form 0 affinity the first integer is for an SMP configuration
+	 * (should be all 0's) and the second is for a normal NUMA
+	 * configuration. We have only one level of NUMA.
+	 *
+	 * With form 1 affinity the first integer is the most significant
+	 * NUMA boundary and the following are progressively less significant
+	 * boundaries. There can be more than one level of NUMA.
+	 */
+	distance_ref_points = of_get_property(root,
+					"ibm,associativity-reference-points",
+					&distance_ref_points_depth);
+
+	if (!distance_ref_points) {
+		dbg("NUMA: ibm,associativity-reference-points not found.\n");
+		goto err;
+	}
+
+	distance_ref_points_depth /= sizeof(int);
+
+	if (firmware_has_feature(FW_FEATURE_OPAL) ||
+	    firmware_has_feature(FW_FEATURE_TYPE1_AFFINITY)) {
+		dbg("Using form 1 affinity\n");
+		form1_affinity = 1;
+	}
+
+	if (form1_affinity) {
+		depth = of_read_number(distance_ref_points, 1);
+	} else {
+		if (distance_ref_points_depth < 2) {
+			printk(KERN_WARNING "NUMA: "
+				"short ibm,associativity-reference-points\n");
+			goto err;
+		}
+
+		depth = of_read_number(&distance_ref_points[1], 1);
+	}
+
+	/*
+	 * Warn and cap if the hardware supports more than
+	 * MAX_DISTANCE_REF_POINTS domains.
+	 */
+	if (distance_ref_points_depth > MAX_DISTANCE_REF_POINTS) {
+		printk(KERN_WARNING "NUMA: distance array capped at "
+			"%d entries\n", MAX_DISTANCE_REF_POINTS);
+		distance_ref_points_depth = MAX_DISTANCE_REF_POINTS;
+	}
+
+	of_node_put(root);
+	return depth;
+
+err:
+	of_node_put(root);
+	return -1;
+}
+
+static void __init get_n_mem_cells(int *n_addr_cells, int *n_size_cells)
+{
+	struct device_node *memory = NULL;
+
+	memory = of_find_node_by_type(memory, "memory");
+	if (!memory)
+		panic("numa.c: No memory nodes found!");
+
+	*n_addr_cells = of_n_addr_cells(memory);
+	*n_size_cells = of_n_size_cells(memory);
+	of_node_put(memory);
+}
+
+static unsigned long read_n_cells(int n, const __be32 **buf)
+{
+	unsigned long result = 0;
+
+	while (n--) {
+		result = (result << 32) | of_read_number(*buf, 1);
+		(*buf)++;
+	}
+	return result;
+}
+
+/*
+ * Read the next memblock list entry from the ibm,dynamic-memory property
+ * and return the information in the provided of_drconf_cell structure.
+ */
+static void read_drconf_cell(struct of_drconf_cell *drmem, const __be32 **cellp)
+{
+	const __be32 *cp;
+
+	drmem->base_addr = read_n_cells(n_mem_addr_cells, cellp);
+
+	cp = *cellp;
+	drmem->drc_index = of_read_number(cp, 1);
+	drmem->reserved = of_read_number(&cp[1], 1);
+	drmem->aa_index = of_read_number(&cp[2], 1);
+	drmem->flags = of_read_number(&cp[3], 1);
+
+	*cellp = cp + 4;
+}
+
+/*
+ * Retrieve and validate the ibm,dynamic-memory property of the device tree.
+ *
+ * The layout of the ibm,dynamic-memory property is a number N of memblock
+ * list entries followed by N memblock list entries.  Each memblock list entry
+ * contains information as laid out in the of_drconf_cell struct above.
+ */
+static int of_get_drconf_memory(struct device_node *memory, const __be32 **dm)
+{
+	const __be32 *prop;
+	u32 len, entries;
+
+	prop = of_get_property(memory, "ibm,dynamic-memory", &len);
+	if (!prop || len < sizeof(unsigned int))
+		return 0;
+
+	entries = of_read_number(prop++, 1);
+
+	/* Now that we know the number of entries, revalidate the size
+	 * of the property read in to ensure we have everything
+	 */
+	if (len < (entries * (n_mem_addr_cells + 4) + 1) * sizeof(unsigned int))
+		return 0;
+
+	*dm = prop;
+	return entries;
+}
+
+/*
+ * Retrieve and validate the ibm,lmb-size property for drconf memory
+ * from the device tree.
+ */
+static u64 of_get_lmb_size(struct device_node *memory)
+{
+	const __be32 *prop;
+	u32 len;
+
+	prop = of_get_property(memory, "ibm,lmb-size", &len);
+	if (!prop || len < sizeof(unsigned int))
+		return 0;
+
+	return read_n_cells(n_mem_size_cells, &prop);
+}
+
+struct assoc_arrays {
+	u32	n_arrays;
+	u32	array_sz;
+	const __be32 *arrays;
+};
+
+/*
+ * Retrieve and validate the list of associativity arrays for drconf
+ * memory from the ibm,associativity-lookup-arrays property of the
+ * device tree..
+ *
+ * The layout of the ibm,associativity-lookup-arrays property is a number N
+ * indicating the number of associativity arrays, followed by a number M
+ * indicating the size of each associativity array, followed by a list
+ * of N associativity arrays.
+ */
+static int of_get_assoc_arrays(struct device_node *memory,
+			       struct assoc_arrays *aa)
+{
+	const __be32 *prop;
+	u32 len;
+
+	prop = of_get_property(memory, "ibm,associativity-lookup-arrays", &len);
+	if (!prop || len < 2 * sizeof(unsigned int))
+		return -1;
+
+	aa->n_arrays = of_read_number(prop++, 1);
+	aa->array_sz = of_read_number(prop++, 1);
+
+	/* Now that we know the number of arrays and size of each array,
+	 * revalidate the size of the property read in.
+	 */
+	if (len < (aa->n_arrays * aa->array_sz + 2) * sizeof(unsigned int))
+		return -1;
+
+	aa->arrays = prop;
+	return 0;
+}
+
+/*
+ * This is like of_node_to_nid_single() for memory represented in the
+ * ibm,dynamic-reconfiguration-memory node.
+ */
+static int of_drconf_to_nid_single(struct of_drconf_cell *drmem,
+				   struct assoc_arrays *aa)
+{
+	int default_nid = 0;
+	int nid = default_nid;
+	int index;
+
+	if (min_common_depth > 0 && min_common_depth <= aa->array_sz &&
+	    !(drmem->flags & DRCONF_MEM_AI_INVALID) &&
+	    drmem->aa_index < aa->n_arrays) {
+		index = drmem->aa_index * aa->array_sz + min_common_depth - 1;
+		nid = of_read_number(&aa->arrays[index], 1);
+
+		if (nid == 0xffff || nid >= MAX_NUMNODES)
+			nid = default_nid;
+	}
+
+	return nid;
+}
+
+/*
+ * Figure out to which domain a cpu belongs and stick it there.
+ * Return the id of the domain used.
+ */
+static int numa_setup_cpu(unsigned long lcpu)
+{
+	int nid = -1;
+	struct device_node *cpu;
+
+	/*
+	 * If a valid cpu-to-node mapping is already available, use it
+	 * directly instead of querying the firmware, since it represents
+	 * the most recent mapping notified to us by the platform (eg: VPHN).
+	 */
+	if ((nid = numa_cpu_lookup_table[lcpu]) >= 0) {
+		map_cpu_to_node(lcpu, nid);
+		return nid;
+	}
+
+	cpu = of_get_cpu_node(lcpu, NULL);
+
+	if (!cpu) {
+		WARN_ON(1);
+		if (cpu_present(lcpu))
+			goto out_present;
+		else
+			goto out;
+	}
+
+	nid = of_node_to_nid_single(cpu);
+
+out_present:
+	if (nid < 0 || !node_online(nid))
+		nid = first_online_node;
+
+	map_cpu_to_node(lcpu, nid);
+	of_node_put(cpu);
+out:
+	return nid;
+}
+
+static void verify_cpu_node_mapping(int cpu, int node)
+{
+	int base, sibling, i;
+
+	/* Verify that all the threads in the core belong to the same node */
+	base = cpu_first_thread_sibling(cpu);
+
+	for (i = 0; i < threads_per_core; i++) {
+		sibling = base + i;
+
+		if (sibling == cpu || cpu_is_offline(sibling))
+			continue;
+
+		if (cpu_to_node(sibling) != node) {
+			WARN(1, "CPU thread siblings %d and %d don't belong"
+				" to the same node!\n", cpu, sibling);
+			break;
+		}
+	}
+}
+
+static int cpu_numa_callback(struct notifier_block *nfb, unsigned long action,
+			     void *hcpu)
+{
+	unsigned long lcpu = (unsigned long)hcpu;
+	int ret = NOTIFY_DONE, nid;
+
+	switch (action) {
+	case CPU_UP_PREPARE:
+	case CPU_UP_PREPARE_FROZEN:
+		nid = numa_setup_cpu(lcpu);
+		verify_cpu_node_mapping((int)lcpu, nid);
+		ret = NOTIFY_OK;
+		break;
+#ifdef CONFIG_HOTPLUG_CPU
+	case CPU_DEAD:
+	case CPU_DEAD_FROZEN:
+	case CPU_UP_CANCELED:
+	case CPU_UP_CANCELED_FROZEN:
+		unmap_cpu_from_node(lcpu);
+		ret = NOTIFY_OK;
+		break;
+#endif
+	}
+	return ret;
+}
+
+/*
+ * Check and possibly modify a memory region to enforce the memory limit.
+ *
+ * Returns the size the region should have to enforce the memory limit.
+ * This will either be the original value of size, a truncated value,
+ * or zero. If the returned value of size is 0 the region should be
+ * discarded as it lies wholly above the memory limit.
+ */
+static unsigned long __init numa_enforce_memory_limit(unsigned long start,
+						      unsigned long size)
+{
+	/*
+	 * We use memblock_end_of_DRAM() in here instead of memory_limit because
+	 * we've already adjusted it for the limit and it takes care of
+	 * having memory holes below the limit.  Also, in the case of
+	 * iommu_is_off, memory_limit is not set but is implicitly enforced.
+	 */
+
+	if (start + size <= memblock_end_of_DRAM())
+		return size;
+
+	if (start >= memblock_end_of_DRAM())
+		return 0;
+
+	return memblock_end_of_DRAM() - start;
+}
+
+/*
+ * Reads the counter for a given entry in
+ * linux,drconf-usable-memory property
+ */
+static inline int __init read_usm_ranges(const __be32 **usm)
+{
+	/*
+	 * For each lmb in ibm,dynamic-memory a corresponding
+	 * entry in linux,drconf-usable-memory property contains
+	 * a counter followed by that many (base, size) duple.
+	 * read the counter from linux,drconf-usable-memory
+	 */
+	return read_n_cells(n_mem_size_cells, usm);
+}
+
+/*
+ * Extract NUMA information from the ibm,dynamic-reconfiguration-memory
+ * node.  This assumes n_mem_{addr,size}_cells have been set.
+ */
+static void __init parse_drconf_memory(struct device_node *memory)
+{
+	const __be32 *uninitialized_var(dm), *usm;
+	unsigned int n, rc, ranges, is_kexec_kdump = 0;
+	unsigned long lmb_size, base, size, sz;
+	int nid;
+	struct assoc_arrays aa = { .arrays = NULL };
+
+	n = of_get_drconf_memory(memory, &dm);
+	if (!n)
+		return;
+
+	lmb_size = of_get_lmb_size(memory);
+	if (!lmb_size)
+		return;
+
+	rc = of_get_assoc_arrays(memory, &aa);
+	if (rc)
+		return;
+
+	/* check if this is a kexec/kdump kernel */
+	usm = of_get_usable_memory(memory);
+	if (usm != NULL)
+		is_kexec_kdump = 1;
+
+	for (; n != 0; --n) {
+		struct of_drconf_cell drmem;
+
+		read_drconf_cell(&drmem, &dm);
+
+		/* skip this block if the reserved bit is set in flags (0x80)
+		   or if the block is not assigned to this partition (0x8) */
+		if ((drmem.flags & DRCONF_MEM_RESERVED)
+		    || !(drmem.flags & DRCONF_MEM_ASSIGNED))
+			continue;
+
+		base = drmem.base_addr;
+		size = lmb_size;
+		ranges = 1;
+
+		if (is_kexec_kdump) {
+			ranges = read_usm_ranges(&usm);
+			if (!ranges) /* there are no (base, size) duple */
+				continue;
+		}
+		do {
+			if (is_kexec_kdump) {
+				base = read_n_cells(n_mem_addr_cells, &usm);
+				size = read_n_cells(n_mem_size_cells, &usm);
+			}
+			nid = of_drconf_to_nid_single(&drmem, &aa);
+			fake_numa_create_new_node(
+				((base + size) >> PAGE_SHIFT),
+					   &nid);
+			node_set_online(nid);
+			sz = numa_enforce_memory_limit(base, size);
+			if (sz)
+				memblock_set_node(base, sz,
+						  &memblock.memory, nid);
+		} while (--ranges);
+	}
+}
+
+static int __init parse_numa_properties(void)
+{
+	struct device_node *memory;
+	int default_nid = 0;
+	unsigned long i;
+
+	if (numa_enabled == 0) {
+		printk(KERN_WARNING "NUMA disabled by user\n");
+		return -1;
+	}
+
+	min_common_depth = find_min_common_depth();
+
+	if (min_common_depth < 0)
+		return min_common_depth;
+
+	dbg("NUMA associativity depth for CPU/Memory: %d\n", min_common_depth);
+
+	/*
+	 * Even though we connect cpus to numa domains later in SMP
+	 * init, we need to know the node ids now. This is because
+	 * each node to be onlined must have NODE_DATA etc backing it.
+	 */
+	for_each_present_cpu(i) {
+		struct device_node *cpu;
+		int nid;
+
+		cpu = of_get_cpu_node(i, NULL);
+		BUG_ON(!cpu);
+		nid = of_node_to_nid_single(cpu);
+		of_node_put(cpu);
+
+		/*
+		 * Don't fall back to default_nid yet -- we will plug
+		 * cpus into nodes once the memory scan has discovered
+		 * the topology.
+		 */
+		if (nid < 0)
+			continue;
+		node_set_online(nid);
+	}
+
+	get_n_mem_cells(&n_mem_addr_cells, &n_mem_size_cells);
+
+	for_each_node_by_type(memory, "memory") {
+		unsigned long start;
+		unsigned long size;
+		int nid;
+		int ranges;
+		const __be32 *memcell_buf;
+		unsigned int len;
+
+		memcell_buf = of_get_property(memory,
+			"linux,usable-memory", &len);
+		if (!memcell_buf || len <= 0)
+			memcell_buf = of_get_property(memory, "reg", &len);
+		if (!memcell_buf || len <= 0)
+			continue;
+
+		/* ranges in cell */
+		ranges = (len >> 2) / (n_mem_addr_cells + n_mem_size_cells);
+new_range:
+		/* these are order-sensitive, and modify the buffer pointer */
+		start = read_n_cells(n_mem_addr_cells, &memcell_buf);
+		size = read_n_cells(n_mem_size_cells, &memcell_buf);
+
+		/*
+		 * Assumption: either all memory nodes or none will
+		 * have associativity properties.  If none, then
+		 * everything goes to default_nid.
+		 */
+		nid = of_node_to_nid_single(memory);
+		if (nid < 0)
+			nid = default_nid;
+
+		fake_numa_create_new_node(((start + size) >> PAGE_SHIFT), &nid);
+		node_set_online(nid);
+
+		if (!(size = numa_enforce_memory_limit(start, size))) {
+			if (--ranges)
+				goto new_range;
+			else
+				continue;
+		}
+
+		memblock_set_node(start, size, &memblock.memory, nid);
+
+		if (--ranges)
+			goto new_range;
+	}
+
+	/*
+	 * Now do the same thing for each MEMBLOCK listed in the
+	 * ibm,dynamic-memory property in the
+	 * ibm,dynamic-reconfiguration-memory node.
+	 */
+	memory = of_find_node_by_path("/ibm,dynamic-reconfiguration-memory");
+	if (memory)
+		parse_drconf_memory(memory);
+
+	return 0;
+}
+
+static void __init setup_nonnuma(void)
+{
+	unsigned long top_of_ram = memblock_end_of_DRAM();
+	unsigned long total_ram = memblock_phys_mem_size();
+	unsigned long start_pfn, end_pfn;
+	unsigned int nid = 0;
+	struct memblock_region *reg;
+
+	printk(KERN_DEBUG "Top of RAM: 0x%lx, Total RAM: 0x%lx\n",
+	       top_of_ram, total_ram);
+	printk(KERN_DEBUG "Memory hole size: %ldMB\n",
+	       (top_of_ram - total_ram) >> 20);
+
+	for_each_memblock(memory, reg) {
+		start_pfn = memblock_region_memory_base_pfn(reg);
+		end_pfn = memblock_region_memory_end_pfn(reg);
+
+		fake_numa_create_new_node(end_pfn, &nid);
+		memblock_set_node(PFN_PHYS(start_pfn),
+				  PFN_PHYS(end_pfn - start_pfn),
+				  &memblock.memory, nid);
+		node_set_online(nid);
+	}
+}
+
+void __init dump_numa_cpu_topology(void)
+{
+	unsigned int node;
+	unsigned int cpu, count;
+
+	if (min_common_depth == -1 || !numa_enabled)
+		return;
+
+	for_each_online_node(node) {
+		printk(KERN_DEBUG "Node %d CPUs:", node);
+
+		count = 0;
+		/*
+		 * If we used a CPU iterator here we would miss printing
+		 * the holes in the cpumap.
+		 */
+		for (cpu = 0; cpu < nr_cpu_ids; cpu++) {
+			if (cpumask_test_cpu(cpu,
+					node_to_cpumask_map[node])) {
+				if (count == 0)
+					printk(" %u", cpu);
+				++count;
+			} else {
+				if (count > 1)
+					printk("-%u", cpu - 1);
+				count = 0;
+			}
+		}
+
+		if (count > 1)
+			printk("-%u", nr_cpu_ids - 1);
+		printk("\n");
+	}
+}
+
+static void __init dump_numa_memory_topology(void)
+{
+	unsigned int node;
+	unsigned int count;
+
+	if (min_common_depth == -1 || !numa_enabled)
+		return;
+
+	for_each_online_node(node) {
+		unsigned long i;
+
+		printk(KERN_DEBUG "Node %d Memory:", node);
+
+		count = 0;
+
+		for (i = 0; i < memblock_end_of_DRAM();
+		     i += (1 << SECTION_SIZE_BITS)) {
+			if (early_pfn_to_nid(i >> PAGE_SHIFT) == node) {
+				if (count == 0)
+					printk(" 0x%lx", i);
+				++count;
+			} else {
+				if (count > 0)
+					printk("-0x%lx", i);
+				count = 0;
+			}
+		}
+
+		if (count > 0)
+			printk("-0x%lx", i);
+		printk("\n");
+	}
+}
+
+static struct notifier_block ppc64_numa_nb = {
+	.notifier_call = cpu_numa_callback,
+	.priority = 1 /* Must run before sched domains notifier. */
+};
+
+/* Initialize NODE_DATA for a node on the local memory */
+static void __init setup_node_data(int nid, u64 start_pfn, u64 end_pfn)
+{
+	u64 spanned_pages = end_pfn - start_pfn;
+	const size_t nd_size = roundup(sizeof(pg_data_t), SMP_CACHE_BYTES);
+	u64 nd_pa;
+	void *nd;
+	int tnid;
+
+	if (spanned_pages)
+		pr_info("Initmem setup node %d [mem %#010Lx-%#010Lx]\n",
+			nid, start_pfn << PAGE_SHIFT,
+			(end_pfn << PAGE_SHIFT) - 1);
+	else
+		pr_info("Initmem setup node %d\n", nid);
+
+	nd_pa = memblock_alloc_try_nid(nd_size, SMP_CACHE_BYTES, nid);
+	nd = __va(nd_pa);
+
+	/* report and initialize */
+	pr_info("  NODE_DATA [mem %#010Lx-%#010Lx]\n",
+		nd_pa, nd_pa + nd_size - 1);
+	tnid = early_pfn_to_nid(nd_pa >> PAGE_SHIFT);
+	if (tnid != nid)
+		pr_info("    NODE_DATA(%d) on node %d\n", nid, tnid);
+
+	node_data[nid] = nd;
+	memset(NODE_DATA(nid), 0, sizeof(pg_data_t));
+	NODE_DATA(nid)->node_id = nid;
+	NODE_DATA(nid)->node_start_pfn = start_pfn;
+	NODE_DATA(nid)->node_spanned_pages = spanned_pages;
+}
+
+void __init initmem_init(void)
+{
+	int nid, cpu;
+
+	max_low_pfn = memblock_end_of_DRAM() >> PAGE_SHIFT;
+	max_pfn = max_low_pfn;
+
+	if (parse_numa_properties())
+		setup_nonnuma();
+	else
+		dump_numa_memory_topology();
+
+	memblock_dump_all();
+
+	/*
+	 * Reduce the possible NUMA nodes to the online NUMA nodes,
+	 * since we do not support node hotplug. This ensures that  we
+	 * lower the maximum NUMA node ID to what is actually present.
+	 */
+	nodes_and(node_possible_map, node_possible_map, node_online_map);
+
+	for_each_online_node(nid) {
+		unsigned long start_pfn, end_pfn;
+
+		get_pfn_range_for_nid(nid, &start_pfn, &end_pfn);
+		setup_node_data(nid, start_pfn, end_pfn);
+		sparse_memory_present_with_active_regions(nid);
+	}
+
+	sparse_init();
+
+	setup_node_to_cpumask_map();
+
+	reset_numa_cpu_lookup_table();
+	register_cpu_notifier(&ppc64_numa_nb);
+	/*
+	 * We need the numa_cpu_lookup_table to be accurate for all CPUs,
+	 * even before we online them, so that we can use cpu_to_{node,mem}
+	 * early in boot, cf. smp_prepare_cpus().
+	 */
+	for_each_present_cpu(cpu) {
+		numa_setup_cpu((unsigned long)cpu);
+	}
+}
+
+static int __init early_numa(char *p)
+{
+	if (!p)
+		return 0;
+
+	if (strstr(p, "off"))
+		numa_enabled = 0;
+
+	if (strstr(p, "debug"))
+		numa_debug = 1;
+
+	p = strstr(p, "fake=");
+	if (p)
+		cmdline = p + strlen("fake=");
+
+	return 0;
+}
+early_param("numa", early_numa);
+
+static bool topology_updates_enabled = true;
+
+static int __init early_topology_updates(char *p)
+{
+	if (!p)
+		return 0;
+
+	if (!strcmp(p, "off")) {
+		pr_info("Disabling topology updates\n");
+		topology_updates_enabled = false;
+	}
+
+	return 0;
+}
+early_param("topology_updates", early_topology_updates);
+
+#ifdef CONFIG_MEMORY_HOTPLUG
+/*
+ * Find the node associated with a hot added memory section for
+ * memory represented in the device tree by the property
+ * ibm,dynamic-reconfiguration-memory/ibm,dynamic-memory.
+ */
+static int hot_add_drconf_scn_to_nid(struct device_node *memory,
+				     unsigned long scn_addr)
+{
+	const __be32 *dm;
+	unsigned int drconf_cell_cnt, rc;
+	unsigned long lmb_size;
+	struct assoc_arrays aa;
+	int nid = -1;
+
+	drconf_cell_cnt = of_get_drconf_memory(memory, &dm);
+	if (!drconf_cell_cnt)
+		return -1;
+
+	lmb_size = of_get_lmb_size(memory);
+	if (!lmb_size)
+		return -1;
+
+	rc = of_get_assoc_arrays(memory, &aa);
+	if (rc)
+		return -1;
+
+	for (; drconf_cell_cnt != 0; --drconf_cell_cnt) {
+		struct of_drconf_cell drmem;
+
+		read_drconf_cell(&drmem, &dm);
+
+		/* skip this block if it is reserved or not assigned to
+		 * this partition */
+		if ((drmem.flags & DRCONF_MEM_RESERVED)
+		    || !(drmem.flags & DRCONF_MEM_ASSIGNED))
+			continue;
+
+		if ((scn_addr < drmem.base_addr)
+		    || (scn_addr >= (drmem.base_addr + lmb_size)))
+			continue;
+
+		nid = of_drconf_to_nid_single(&drmem, &aa);
+		break;
+	}
+
+	return nid;
+}
+
+/*
+ * Find the node associated with a hot added memory section for memory
+ * represented in the device tree as a node (i.e. memory@XXXX) for
+ * each memblock.
+ */
+static int hot_add_node_scn_to_nid(unsigned long scn_addr)
+{
+	struct device_node *memory;
+	int nid = -1;
+
+	for_each_node_by_type(memory, "memory") {
+		unsigned long start, size;
+		int ranges;
+		const __be32 *memcell_buf;
+		unsigned int len;
+
+		memcell_buf = of_get_property(memory, "reg", &len);
+		if (!memcell_buf || len <= 0)
+			continue;
+
+		/* ranges in cell */
+		ranges = (len >> 2) / (n_mem_addr_cells + n_mem_size_cells);
+
+		while (ranges--) {
+			start = read_n_cells(n_mem_addr_cells, &memcell_buf);
+			size = read_n_cells(n_mem_size_cells, &memcell_buf);
+
+			if ((scn_addr < start) || (scn_addr >= (start + size)))
+				continue;
+
+			nid = of_node_to_nid_single(memory);
+			break;
+		}
+
+		if (nid >= 0)
+			break;
+	}
+
+	of_node_put(memory);
+
+	return nid;
+}
+
+/*
+ * Find the node associated with a hot added memory section.  Section
+ * corresponds to a SPARSEMEM section, not an MEMBLOCK.  It is assumed that
+ * sections are fully contained within a single MEMBLOCK.
+ */
+int hot_add_scn_to_nid(unsigned long scn_addr)
+{
+	struct device_node *memory = NULL;
+	int nid, found = 0;
+
+	if (!numa_enabled || (min_common_depth < 0))
+		return first_online_node;
+
+	memory = of_find_node_by_path("/ibm,dynamic-reconfiguration-memory");
+	if (memory) {
+		nid = hot_add_drconf_scn_to_nid(memory, scn_addr);
+		of_node_put(memory);
+	} else {
+		nid = hot_add_node_scn_to_nid(scn_addr);
+	}
+
+	if (nid < 0 || !node_online(nid))
+		nid = first_online_node;
+
+	if (NODE_DATA(nid)->node_spanned_pages)
+		return nid;
+
+	for_each_online_node(nid) {
+		if (NODE_DATA(nid)->node_spanned_pages) {
+			found = 1;
+			break;
+		}
+	}
+
+	BUG_ON(!found);
+	return nid;
+}
+
+static u64 hot_add_drconf_memory_max(void)
+{
+        struct device_node *memory = NULL;
+        unsigned int drconf_cell_cnt = 0;
+        u64 lmb_size = 0;
+	const __be32 *dm = NULL;
+
+        memory = of_find_node_by_path("/ibm,dynamic-reconfiguration-memory");
+        if (memory) {
+                drconf_cell_cnt = of_get_drconf_memory(memory, &dm);
+                lmb_size = of_get_lmb_size(memory);
+                of_node_put(memory);
+        }
+        return lmb_size * drconf_cell_cnt;
+}
+
+/*
+ * memory_hotplug_max - return max address of memory that may be added
+ *
+ * This is currently only used on systems that support drconfig memory
+ * hotplug.
+ */
+u64 memory_hotplug_max(void)
+{
+        return max(hot_add_drconf_memory_max(), memblock_end_of_DRAM());
+}
+#endif /* CONFIG_MEMORY_HOTPLUG */
+
+/* Virtual Processor Home Node (VPHN) support */
+#ifdef CONFIG_PPC_SPLPAR
+
+#include "vphn.h"
+
+struct topology_update_data {
+	struct topology_update_data *next;
+	unsigned int cpu;
+	int old_nid;
+	int new_nid;
+};
+
+static u8 vphn_cpu_change_counts[NR_CPUS][MAX_DISTANCE_REF_POINTS];
+static cpumask_t cpu_associativity_changes_mask;
+static int vphn_enabled;
+static int prrn_enabled;
+static void reset_topology_timer(void);
+
+/*
+ * Store the current values of the associativity change counters in the
+ * hypervisor.
+ */
+static void setup_cpu_associativity_change_counters(void)
+{
+	int cpu;
+
+	/* The VPHN feature supports a maximum of 8 reference points */
+	BUILD_BUG_ON(MAX_DISTANCE_REF_POINTS > 8);
+
+	for_each_possible_cpu(cpu) {
+		int i;
+		u8 *counts = vphn_cpu_change_counts[cpu];
+		volatile u8 *hypervisor_counts = lppaca[cpu].vphn_assoc_counts;
+
+		for (i = 0; i < distance_ref_points_depth; i++)
+			counts[i] = hypervisor_counts[i];
+	}
+}
+
+/*
+ * The hypervisor maintains a set of 8 associativity change counters in
+ * the VPA of each cpu that correspond to the associativity levels in the
+ * ibm,associativity-reference-points property. When an associativity
+ * level changes, the corresponding counter is incremented.
+ *
+ * Set a bit in cpu_associativity_changes_mask for each cpu whose home
+ * node associativity levels have changed.
+ *
+ * Returns the number of cpus with unhandled associativity changes.
+ */
+static int update_cpu_associativity_changes_mask(void)
+{
+	int cpu;
+	cpumask_t *changes = &cpu_associativity_changes_mask;
+
+	for_each_possible_cpu(cpu) {
+		int i, changed = 0;
+		u8 *counts = vphn_cpu_change_counts[cpu];
+		volatile u8 *hypervisor_counts = lppaca[cpu].vphn_assoc_counts;
+
+		for (i = 0; i < distance_ref_points_depth; i++) {
+			if (hypervisor_counts[i] != counts[i]) {
+				counts[i] = hypervisor_counts[i];
+				changed = 1;
+			}
+		}
+		if (changed) {
+			cpumask_or(changes, changes, cpu_sibling_mask(cpu));
+			cpu = cpu_last_thread_sibling(cpu);
+		}
+	}
+
+	return cpumask_weight(changes);
+}
+
+/*
+ * Retrieve the new associativity information for a virtual processor's
+ * home node.
+ */
+static long hcall_vphn(unsigned long cpu, __be32 *associativity)
+{
+	long rc;
+	long retbuf[PLPAR_HCALL9_BUFSIZE] = {0};
+	u64 flags = 1;
+	int hwcpu = get_hard_smp_processor_id(cpu);
+
+	rc = plpar_hcall9(H_HOME_NODE_ASSOCIATIVITY, retbuf, flags, hwcpu);
+	vphn_unpack_associativity(retbuf, associativity);
+
+	return rc;
+}
+
+static long vphn_get_associativity(unsigned long cpu,
+					__be32 *associativity)
+{
+	long rc;
+
+	rc = hcall_vphn(cpu, associativity);
+
+	switch (rc) {
+	case H_FUNCTION:
+		printk(KERN_INFO
+			"VPHN is not supported. Disabling polling...\n");
+		stop_topology_update();
+		break;
+	case H_HARDWARE:
+		printk(KERN_ERR
+			"hcall_vphn() experienced a hardware fault "
+			"preventing VPHN. Disabling polling...\n");
+		stop_topology_update();
+	}
+
+	return rc;
+}
+
+/*
+ * Update the CPU maps and sysfs entries for a single CPU when its NUMA
+ * characteristics change. This function doesn't perform any locking and is
+ * only safe to call from stop_machine().
+ */
+static int update_cpu_topology(void *data)
+{
+	struct topology_update_data *update;
+	unsigned long cpu;
+
+	if (!data)
+		return -EINVAL;
+
+	cpu = smp_processor_id();
+
+	for (update = data; update; update = update->next) {
+		int new_nid = update->new_nid;
+		if (cpu != update->cpu)
+			continue;
+
+		unmap_cpu_from_node(cpu);
+		map_cpu_to_node(cpu, new_nid);
+		set_cpu_numa_node(cpu, new_nid);
+		set_cpu_numa_mem(cpu, local_memory_node(new_nid));
+		vdso_getcpu_init();
+	}
+
+	return 0;
+}
+
+static int update_lookup_table(void *data)
+{
+	struct topology_update_data *update;
+
+	if (!data)
+		return -EINVAL;
+
+	/*
+	 * Upon topology update, the numa-cpu lookup table needs to be updated
+	 * for all threads in the core, including offline CPUs, to ensure that
+	 * future hotplug operations respect the cpu-to-node associativity
+	 * properly.
+	 */
+	for (update = data; update; update = update->next) {
+		int nid, base, j;
+
+		nid = update->new_nid;
+		base = cpu_first_thread_sibling(update->cpu);
+
+		for (j = 0; j < threads_per_core; j++) {
+			update_numa_cpu_lookup_table(base + j, nid);
+		}
+	}
+
+	return 0;
+}
+
+/*
+ * Update the node maps and sysfs entries for each cpu whose home node
+ * has changed. Returns 1 when the topology has changed, and 0 otherwise.
+ */
+int arch_update_cpu_topology(void)
+{
+	unsigned int cpu, sibling, changed = 0;
+	struct topology_update_data *updates, *ud;
+	__be32 associativity[VPHN_ASSOC_BUFSIZE] = {0};
+	cpumask_t updated_cpus;
+	struct device *dev;
+	int weight, new_nid, i = 0;
+
+	if (!prrn_enabled && !vphn_enabled)
+		return 0;
+
+	weight = cpumask_weight(&cpu_associativity_changes_mask);
+	if (!weight)
+		return 0;
+
+	updates = kzalloc(weight * (sizeof(*updates)), GFP_KERNEL);
+	if (!updates)
+		return 0;
+
+	cpumask_clear(&updated_cpus);
+
+	for_each_cpu(cpu, &cpu_associativity_changes_mask) {
+		/*
+		 * If siblings aren't flagged for changes, updates list
+		 * will be too short. Skip on this update and set for next
+		 * update.
+		 */
+		if (!cpumask_subset(cpu_sibling_mask(cpu),
+					&cpu_associativity_changes_mask)) {
+			pr_info("Sibling bits not set for associativity "
+					"change, cpu%d\n", cpu);
+			cpumask_or(&cpu_associativity_changes_mask,
+					&cpu_associativity_changes_mask,
+					cpu_sibling_mask(cpu));
+			cpu = cpu_last_thread_sibling(cpu);
+			continue;
+		}
+
+		/* Use associativity from first thread for all siblings */
+		vphn_get_associativity(cpu, associativity);
+		new_nid = associativity_to_nid(associativity);
+		if (new_nid < 0 || !node_online(new_nid))
+			new_nid = first_online_node;
+
+		if (new_nid == numa_cpu_lookup_table[cpu]) {
+			cpumask_andnot(&cpu_associativity_changes_mask,
+					&cpu_associativity_changes_mask,
+					cpu_sibling_mask(cpu));
+			cpu = cpu_last_thread_sibling(cpu);
+			continue;
+		}
+
+		for_each_cpu(sibling, cpu_sibling_mask(cpu)) {
+			ud = &updates[i++];
+			ud->cpu = sibling;
+			ud->new_nid = new_nid;
+			ud->old_nid = numa_cpu_lookup_table[sibling];
+			cpumask_set_cpu(sibling, &updated_cpus);
+			if (i < weight)
+				ud->next = &updates[i];
+		}
+		cpu = cpu_last_thread_sibling(cpu);
+	}
+
+	pr_debug("Topology update for the following CPUs:\n");
+	if (cpumask_weight(&updated_cpus)) {
+		for (ud = &updates[0]; ud; ud = ud->next) {
+			pr_debug("cpu %d moving from node %d "
+					  "to %d\n", ud->cpu,
+					  ud->old_nid, ud->new_nid);
+		}
+	}
+
+	/*
+	 * In cases where we have nothing to update (because the updates list
+	 * is too short or because the new topology is same as the old one),
+	 * skip invoking update_cpu_topology() via stop-machine(). This is
+	 * necessary (and not just a fast-path optimization) since stop-machine
+	 * can end up electing a random CPU to run update_cpu_topology(), and
+	 * thus trick us into setting up incorrect cpu-node mappings (since
+	 * 'updates' is kzalloc()'ed).
+	 *
+	 * And for the similar reason, we will skip all the following updating.
+	 */
+	if (!cpumask_weight(&updated_cpus))
+		goto out;
+
+	stop_machine(update_cpu_topology, &updates[0], &updated_cpus);
+
+	/*
+	 * Update the numa-cpu lookup table with the new mappings, even for
+	 * offline CPUs. It is best to perform this update from the stop-
+	 * machine context.
+	 */
+	stop_machine(update_lookup_table, &updates[0],
+					cpumask_of(raw_smp_processor_id()));
+
+	for (ud = &updates[0]; ud; ud = ud->next) {
+		unregister_cpu_under_node(ud->cpu, ud->old_nid);
+		register_cpu_under_node(ud->cpu, ud->new_nid);
+
+		dev = get_cpu_device(ud->cpu);
+		if (dev)
+			kobject_uevent(&dev->kobj, KOBJ_CHANGE);
+		cpumask_clear_cpu(ud->cpu, &cpu_associativity_changes_mask);
+		changed = 1;
+	}
+
+out:
+	kfree(updates);
+	return changed;
+}
+
+static void topology_work_fn(struct work_struct *work)
+{
+	rebuild_sched_domains();
+}
+static DECLARE_WORK(topology_work, topology_work_fn);
+
+static void topology_schedule_update(void)
+{
+	schedule_work(&topology_work);
+}
+
+static void topology_timer_fn(unsigned long ignored)
+{
+	if (prrn_enabled && cpumask_weight(&cpu_associativity_changes_mask))
+		topology_schedule_update();
+	else if (vphn_enabled) {
+		if (update_cpu_associativity_changes_mask() > 0)
+			topology_schedule_update();
+		reset_topology_timer();
+	}
+}
+static struct timer_list topology_timer =
+	TIMER_INITIALIZER(topology_timer_fn, 0, 0);
+
+static void reset_topology_timer(void)
+{
+	topology_timer.data = 0;
+	topology_timer.expires = jiffies + 60 * HZ;
+	mod_timer(&topology_timer, topology_timer.expires);
+}
+
+#ifdef CONFIG_SMP
+
+static void stage_topology_update(int core_id)
+{
+	cpumask_or(&cpu_associativity_changes_mask,
+		&cpu_associativity_changes_mask, cpu_sibling_mask(core_id));
+	reset_topology_timer();
+}
+
+static int dt_update_callback(struct notifier_block *nb,
+				unsigned long action, void *data)
+{
+	struct of_reconfig_data *update = data;
+	int rc = NOTIFY_DONE;
+
+	switch (action) {
+	case OF_RECONFIG_UPDATE_PROPERTY:
+		if (!of_prop_cmp(update->dn->type, "cpu") &&
+		    !of_prop_cmp(update->prop->name, "ibm,associativity")) {
+			u32 core_id;
+			of_property_read_u32(update->dn, "reg", &core_id);
+			stage_topology_update(core_id);
+			rc = NOTIFY_OK;
+		}
+		break;
+	}
+
+	return rc;
+}
+
+static struct notifier_block dt_update_nb = {
+	.notifier_call = dt_update_callback,
+};
+
+#endif
+
+/*
+ * Start polling for associativity changes.
+ */
+int start_topology_update(void)
+{
+	int rc = 0;
+
+	if (firmware_has_feature(FW_FEATURE_PRRN)) {
+		if (!prrn_enabled) {
+			prrn_enabled = 1;
+			vphn_enabled = 0;
+#ifdef CONFIG_SMP
+			rc = of_reconfig_notifier_register(&dt_update_nb);
+#endif
+		}
+	} else if (firmware_has_feature(FW_FEATURE_VPHN) &&
+		   lppaca_shared_proc(get_lppaca())) {
+		if (!vphn_enabled) {
+			prrn_enabled = 0;
+			vphn_enabled = 1;
+			setup_cpu_associativity_change_counters();
+			init_timer_deferrable(&topology_timer);
+			reset_topology_timer();
+		}
+	}
+
+	return rc;
+}
+
+/*
+ * Disable polling for VPHN associativity changes.
+ */
+int stop_topology_update(void)
+{
+	int rc = 0;
+
+	if (prrn_enabled) {
+		prrn_enabled = 0;
+#ifdef CONFIG_SMP
+		rc = of_reconfig_notifier_unregister(&dt_update_nb);
+#endif
+	} else if (vphn_enabled) {
+		vphn_enabled = 0;
+		rc = del_timer_sync(&topology_timer);
+	}
+
+	return rc;
+}
+
+int prrn_is_enabled(void)
+{
+	return prrn_enabled;
+}
+
+static int topology_read(struct seq_file *file, void *v)
+{
+	if (vphn_enabled || prrn_enabled)
+		seq_puts(file, "on\n");
+	else
+		seq_puts(file, "off\n");
+
+	return 0;
+}
+
+static int topology_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, topology_read, NULL);
+}
+
+static ssize_t topology_write(struct file *file, const char __user *buf,
+			      size_t count, loff_t *off)
+{
+	char kbuf[4]; /* "on" or "off" plus null. */
+	int read_len;
+
+	read_len = count < 3 ? count : 3;
+	if (copy_from_user(kbuf, buf, read_len))
+		return -EINVAL;
+
+	kbuf[read_len] = '\0';
+
+	if (!strncmp(kbuf, "on", 2))
+		start_topology_update();
+	else if (!strncmp(kbuf, "off", 3))
+		stop_topology_update();
+	else
+		return -EINVAL;
+
+	return count;
+}
+
+static const struct file_operations topology_ops = {
+	.read = seq_read,
+	.write = topology_write,
+	.open = topology_open,
+	.release = single_release
+};
+
+static int topology_update_init(void)
+{
+	/* Do not poll for changes if disabled at boot */
+	if (topology_updates_enabled)
+		start_topology_update();
+
+	if (!proc_create("powerpc/topology_updates", 0644, NULL, &topology_ops))
+		return -ENOMEM;
+
+	return 0;
+}
+device_initcall(topology_update_init);
+#endif /* CONFIG_PPC_SPLPAR */