[linux-2.6-microblaze.git] / arch / powerpc / mm / numa.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * pSeries NUMA support
 *
 * Copyright (C) 2002 Anton Blanchard <anton@au.ibm.com>, IBM
 */
#define pr_fmt(fmt) "numa: " fmt

#include <linux/threads.h>
#include <linux/memblock.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/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/topology.h>
#include <asm/firmware.h>
#include <asm/paca.h>
#include <asm/hvcall.h>
#include <asm/setup.h>
#include <asm/vdso.h>
#include <asm/drmem.h>

static int numa_enabled = 1;

static char *cmdline __initdata;

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 primary_domain_index;
static int n_mem_addr_cells, n_mem_size_cells;

#define FORM0_AFFINITY 0
#define FORM1_AFFINITY 1
#define FORM2_AFFINITY 2
static int affinity_form;

#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];
static int numa_distance_table[MAX_NUMNODES][MAX_NUMNODES] = {
        [0 ... MAX_NUMNODES - 1] = { [0 ... MAX_NUMNODES - 1] = -1 }
};
static int numa_id_index_table[MAX_NUMNODES] = { [0 ... MAX_NUMNODES - 1] = NUMA_NO_NODE };

/*
 * 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_each_node(node)
                alloc_bootmem_cpumask_var(&node_to_cpumask_map[node]);

        /* cpumask_of_node() will now work */
        pr_debug("Node to cpumask map for %u 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;
                pr_debug("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 map_cpu_to_node(int cpu, int node)
{
        update_numa_cpu_lookup_table(cpu, node);

        if (!(cpumask_test_cpu(cpu, node_to_cpumask_map[node]))) {
                pr_debug("adding cpu %d to node %d\n", cpu, 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];

        if (cpumask_test_cpu(cpu, node_to_cpumask_map[node])) {
                cpumask_clear_cpu(cpu, node_to_cpumask_map[node]);
                pr_debug("removing cpu %lu from node %d\n", cpu, node);
        } else {
                pr_warn("Warning: cpu %lu not found in node %d\n", cpu, node);
        }
}
#endif /* CONFIG_HOTPLUG_CPU || CONFIG_PPC_SPLPAR */

static int __associativity_to_nid(const __be32 *associativity,
                                  int max_array_sz)
{
        int nid;
        /*
         * primary_domain_index is 1 based array index.
         */
        int index = primary_domain_index  - 1;

        if (!numa_enabled || index >= max_array_sz)
                return NUMA_NO_NODE;

        nid = of_read_number(&associativity[index], 1);

        /* POWER4 LPAR uses 0xffff as invalid node */
        if (nid == 0xffff || nid >= nr_node_ids)
                nid = NUMA_NO_NODE;
        return nid;
}
/*
 * Returns nid in the range [0..nr_node_ids], or -1 if no useful NUMA
 * info is found.
 */
static int associativity_to_nid(const __be32 *associativity)
{
        int array_sz = of_read_number(associativity, 1);

        /* Skip the first element in the associativity array */
        return __associativity_to_nid((associativity + 1), array_sz);
}

static int __cpu_form2_relative_distance(__be32 *cpu1_assoc, __be32 *cpu2_assoc)
{
        int dist;
        int node1, node2;

        node1 = associativity_to_nid(cpu1_assoc);
        node2 = associativity_to_nid(cpu2_assoc);

        dist = numa_distance_table[node1][node2];
        if (dist <= LOCAL_DISTANCE)
                return 0;
        else if (dist <= REMOTE_DISTANCE)
                return 1;
        else
                return 2;
}

static int __cpu_form1_relative_distance(__be32 *cpu1_assoc, __be32 *cpu2_assoc)
{
        int dist = 0;

        int i, index;

        for (i = 0; i < distance_ref_points_depth; i++) {
                index = be32_to_cpu(distance_ref_points[i]);
                if (cpu1_assoc[index] == cpu2_assoc[index])
                        break;
                dist++;
        }

        return dist;
}

int cpu_relative_distance(__be32 *cpu1_assoc, __be32 *cpu2_assoc)
{
        /* We should not get called with FORM0 */
        VM_WARN_ON(affinity_form == FORM0_AFFINITY);
        if (affinity_form == FORM1_AFFINITY)
                return __cpu_form1_relative_distance(cpu1_assoc, cpu2_assoc);
        return __cpu_form2_relative_distance(cpu1_assoc, cpu2_assoc);
}

/* 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);
}

int __node_distance(int a, int b)
{
        int i;
        int distance = LOCAL_DISTANCE;

        if (affinity_form == FORM2_AFFINITY)
                return numa_distance_table[a][b];
        else if (affinity_form == FORM0_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);

/* 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 = NUMA_NO_NODE;
        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)
{
        int nid = NUMA_NO_NODE;

        of_node_get(device);
        while (device) {
                nid = of_node_to_nid_single(device);
                if (nid != -1)
                        break;

                device = of_get_next_parent(device);
        }
        of_node_put(device);

        return nid;
}
EXPORT_SYMBOL(of_node_to_nid);

static void __initialize_form1_numa_distance(const __be32 *associativity,
                                             int max_array_sz)
{
        int i, nid;

        if (affinity_form != FORM1_AFFINITY)
                return;

        nid = __associativity_to_nid(associativity, max_array_sz);
        if (nid != NUMA_NO_NODE) {
                for (i = 0; i < distance_ref_points_depth; i++) {
                        const __be32 *entry;
                        int index = be32_to_cpu(distance_ref_points[i]) - 1;

                        /*
                         * broken hierarchy, return with broken distance table
                         */
                        if (WARN(index >= max_array_sz, "Broken ibm,associativity property"))
                                return;

                        entry = &associativity[index];
                        distance_lookup_table[nid][i] = of_read_number(entry, 1);
                }
        }
}

static void initialize_form1_numa_distance(const __be32 *associativity)
{
        int array_sz;

        array_sz = of_read_number(associativity, 1);
        /* Skip the first element in the associativity array */
        __initialize_form1_numa_distance(associativity + 1, array_sz);
}

/*
 * Used to update distance information w.r.t newly added node.
 */
void update_numa_distance(struct device_node *node)
{
        int nid;

        if (affinity_form == FORM0_AFFINITY)
                return;
        else if (affinity_form == FORM1_AFFINITY) {
                const __be32 *associativity;

                associativity = of_get_associativity(node);
                if (!associativity)
                        return;

                initialize_form1_numa_distance(associativity);
                return;
        }

        /* FORM2 affinity  */
        nid = of_node_to_nid_single(node);
        if (nid == NUMA_NO_NODE)
                return;

        /*
         * With FORM2 we expect NUMA distance of all possible NUMA
         * nodes to be provided during boot.
         */
        WARN(numa_distance_table[nid][nid] == -1,
             "NUMA distance details for node %d not provided\n", nid);
}

/*
 * ibm,numa-lookup-index-table= {N, domainid1, domainid2, ..... domainidN}
 * ibm,numa-distance-table = { N, 1, 2, 4, 5, 1, 6, .... N elements}
 */
static void initialize_form2_numa_distance_lookup_table(void)
{
        int i, j;
        struct device_node *root;
        const __u8 *numa_dist_table;
        const __be32 *numa_lookup_index;
        int numa_dist_table_length;
        int max_numa_index, distance_index;

        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("/");

        numa_lookup_index = of_get_property(root, "ibm,numa-lookup-index-table", NULL);
        max_numa_index = of_read_number(&numa_lookup_index[0], 1);

        /* first element of the array is the size and is encode-int */
        numa_dist_table = of_get_property(root, "ibm,numa-distance-table", NULL);
        numa_dist_table_length = of_read_number((const __be32 *)&numa_dist_table[0], 1);
        /* Skip the size which is encoded int */
        numa_dist_table += sizeof(__be32);

        pr_debug("numa_dist_table_len = %d, numa_dist_indexes_len = %d\n",
                 numa_dist_table_length, max_numa_index);

        for (i = 0; i < max_numa_index; i++)
                /* +1 skip the max_numa_index in the property */
                numa_id_index_table[i] = of_read_number(&numa_lookup_index[i + 1], 1);


        if (numa_dist_table_length != max_numa_index * max_numa_index) {
                WARN(1, "Wrong NUMA distance information\n");
                /* consider everybody else just remote. */
                for (i = 0;  i < max_numa_index; i++) {
                        for (j = 0; j < max_numa_index; j++) {
                                int nodeA = numa_id_index_table[i];
                                int nodeB = numa_id_index_table[j];

                                if (nodeA == nodeB)
                                        numa_distance_table[nodeA][nodeB] = LOCAL_DISTANCE;
                                else
                                        numa_distance_table[nodeA][nodeB] = REMOTE_DISTANCE;
                        }
                }
        }

        distance_index = 0;
        for (i = 0;  i < max_numa_index; i++) {
                for (j = 0; j < max_numa_index; j++) {
                        int nodeA = numa_id_index_table[i];
                        int nodeB = numa_id_index_table[j];

                        numa_distance_table[nodeA][nodeB] = numa_dist_table[distance_index++];
                        pr_debug("dist[%d][%d]=%d ", nodeA, nodeB, numa_distance_table[nodeA][nodeB]);
                }
        }
        of_node_put(root);
}

static int __init find_primary_domain_index(void)
{
        int index;
        struct device_node *root;

        /*
         * Check for which form of affinity.
         */
        if (firmware_has_feature(FW_FEATURE_OPAL)) {
                affinity_form = FORM1_AFFINITY;
        } else if (firmware_has_feature(FW_FEATURE_FORM2_AFFINITY)) {
                pr_debug("Using form 2 affinity\n");
                affinity_form = FORM2_AFFINITY;
        } else if (firmware_has_feature(FW_FEATURE_FORM1_AFFINITY)) {
                pr_debug("Using form 1 affinity\n");
                affinity_form = FORM1_AFFINITY;
        } else
                affinity_form = FORM0_AFFINITY;

        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) {
                pr_debug("ibm,associativity-reference-points not found.\n");
                goto err;
        }

        distance_ref_points_depth /= sizeof(int);
        if (affinity_form == FORM0_AFFINITY) {
                if (distance_ref_points_depth < 2) {
                        pr_warn("short ibm,associativity-reference-points\n");
                        goto err;
                }

                index = of_read_number(&distance_ref_points[1], 1);
        } else {
                /*
                 * Both FORM1 and FORM2 affinity find the primary domain details
                 * at the same offset.
                 */
                index = of_read_number(distance_ref_points, 1);
        }
        /*
         * Warn and cap if the hardware supports more than
         * MAX_DISTANCE_REF_POINTS domains.
         */
        if (distance_ref_points_depth > MAX_DISTANCE_REF_POINTS) {
                pr_warn("distance array capped at %d entries\n",
                        MAX_DISTANCE_REF_POINTS);
                distance_ref_points_depth = MAX_DISTANCE_REF_POINTS;
        }

        of_node_put(root);
        return index;

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;
}

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 assoc_arrays *aa)
{
        struct device_node *memory;
        const __be32 *prop;
        u32 len;

        memory = of_find_node_by_path("/ibm,dynamic-reconfiguration-memory");
        if (!memory)
                return -1;

        prop = of_get_property(memory, "ibm,associativity-lookup-arrays", &len);
        if (!prop || len < 2 * sizeof(unsigned int)) {
                of_node_put(memory);
                return -1;
        }

        aa->n_arrays = of_read_number(prop++, 1);
        aa->array_sz = of_read_number(prop++, 1);

        of_node_put(memory);

        /* 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;
}

static int get_nid_and_numa_distance(struct drmem_lmb *lmb)
{
        struct assoc_arrays aa = { .arrays = NULL };
        int default_nid = NUMA_NO_NODE;
        int nid = default_nid;
        int rc, index;

        if ((primary_domain_index < 0) || !numa_enabled)
                return default_nid;

        rc = of_get_assoc_arrays(&aa);
        if (rc)
                return default_nid;

        if (primary_domain_index <= aa.array_sz &&
            !(lmb->flags & DRCONF_MEM_AI_INVALID) && lmb->aa_index < aa.n_arrays) {
                const __be32 *associativity;

                index = lmb->aa_index * aa.array_sz;
                associativity = &aa.arrays[index];
                nid = __associativity_to_nid(associativity, aa.array_sz);
                if (nid > 0 && affinity_form == FORM1_AFFINITY) {
                        /*
                         * lookup array associativity entries have
                         * no length of the array as the first element.
                         */
                        __initialize_form1_numa_distance(associativity, aa.array_sz);
                }
        }
        return nid;
}

/*
 * This is like of_node_to_nid_single() for memory represented in the
 * ibm,dynamic-reconfiguration-memory node.
 */
int of_drconf_to_nid_single(struct drmem_lmb *lmb)
{
        struct assoc_arrays aa = { .arrays = NULL };
        int default_nid = NUMA_NO_NODE;
        int nid = default_nid;
        int rc, index;

        if ((primary_domain_index < 0) || !numa_enabled)
                return default_nid;

        rc = of_get_assoc_arrays(&aa);
        if (rc)
                return default_nid;

        if (primary_domain_index <= aa.array_sz &&
            !(lmb->flags & DRCONF_MEM_AI_INVALID) && lmb->aa_index < aa.n_arrays) {
                const __be32 *associativity;

                index = lmb->aa_index * aa.array_sz;
                associativity = &aa.arrays[index];
                nid = __associativity_to_nid(associativity, aa.array_sz);
        }
        return nid;
}

#ifdef CONFIG_PPC_SPLPAR

static int __vphn_get_associativity(long lcpu, __be32 *associativity)
{
        long rc, hwid;

        /*
         * On a shared lpar, device tree will not have node associativity.
         * At this time lppaca, or its __old_status field may not be
         * updated. Hence kernel cannot detect if its on a shared lpar. So
         * request an explicit associativity irrespective of whether the
         * lpar is shared or dedicated. Use the device tree property as a
         * fallback. cpu_to_phys_id is only valid between
         * smp_setup_cpu_maps() and smp_setup_pacas().
         */
        if (firmware_has_feature(FW_FEATURE_VPHN)) {
                if (cpu_to_phys_id)
                        hwid = cpu_to_phys_id[lcpu];
                else
                        hwid = get_hard_smp_processor_id(lcpu);

                rc = hcall_vphn(hwid, VPHN_FLAG_VCPU, associativity);
                if (rc == H_SUCCESS)
                        return 0;
        }

        return -1;
}

static int vphn_get_nid(long lcpu)
{
        __be32 associativity[VPHN_ASSOC_BUFSIZE] = {0};


        if (!__vphn_get_associativity(lcpu, associativity))
                return associativity_to_nid(associativity);

        return NUMA_NO_NODE;

}
#else

static int __vphn_get_associativity(long lcpu, __be32 *associativity)
{
        return -1;
}

static int vphn_get_nid(long unused)
{
        return NUMA_NO_NODE;
}
#endif  /* CONFIG_PPC_SPLPAR */

/*
 * 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)
{
        struct device_node *cpu;
        int fcpu = cpu_first_thread_sibling(lcpu);
        int nid = NUMA_NO_NODE;

        if (!cpu_present(lcpu)) {
                set_cpu_numa_node(lcpu, first_online_node);
                return first_online_node;
        }

        /*
         * 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).
         * Since cpu_to_node binding remains the same for all threads in the
         * core. If a valid cpu-to-node mapping is already available, for
         * the first thread in the core, use it.
         */
        nid = numa_cpu_lookup_table[fcpu];
        if (nid >= 0) {
                map_cpu_to_node(lcpu, nid);
                return nid;
        }

        nid = vphn_get_nid(lcpu);
        if (nid != NUMA_NO_NODE)
                goto out_present;

        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);
        of_node_put(cpu);

out_present:
        if (nid < 0 || !node_possible(nid))
                nid = first_online_node;

        /*
         * Update for the first thread of the core. All threads of a core
         * have to be part of the same node. This not only avoids querying
         * for every other thread in the core, but always avoids a case
         * where virtual node associativity change causes subsequent threads
         * of a core to be associated with different nid. However if first
         * thread is already online, expect it to have a valid mapping.
         */
        if (fcpu != lcpu) {
                WARN_ON(cpu_online(fcpu));
                map_cpu_to_node(fcpu, nid);
        }

        map_cpu_to_node(lcpu, nid);
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;
                }
        }
}

/* Must run before sched domains notifier. */
static int ppc_numa_cpu_prepare(unsigned int cpu)
{
        int nid;

        nid = numa_setup_cpu(cpu);
        verify_cpu_node_mapping(cpu, nid);
        return 0;
}

static int ppc_numa_cpu_dead(unsigned int cpu)
{
#ifdef CONFIG_HOTPLUG_CPU
        unmap_cpu_from_node(cpu);
#endif
        return 0;
}

/*
 * 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 int __init numa_setup_drmem_lmb(struct drmem_lmb *lmb,
                                        const __be32 **usm,
                                        void *data)
{
        unsigned int ranges, is_kexec_kdump = 0;
        unsigned long base, size, sz;
        int nid;

        /*
         * Skip this block if the reserved bit is set in flags (0x80)
         * or if the block is not assigned to this partition (0x8)
         */
        if ((lmb->flags & DRCONF_MEM_RESERVED)
            || !(lmb->flags & DRCONF_MEM_ASSIGNED))
                return 0;

        if (*usm)
                is_kexec_kdump = 1;

        base = lmb->base_addr;
        size = drmem_lmb_size();
        ranges = 1;

        if (is_kexec_kdump) {
                ranges = read_usm_ranges(usm);
                if (!ranges) /* there are no (base, size) duple */
                        return 0;
        }

        do {
                if (is_kexec_kdump) {
                        base = read_n_cells(n_mem_addr_cells, usm);
                        size = read_n_cells(n_mem_size_cells, usm);
                }

                nid = get_nid_and_numa_distance(lmb);
                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);

        return 0;
}

static int __init parse_numa_properties(void)
{
        struct device_node *memory;
        int default_nid = 0;
        unsigned long i;
        const __be32 *associativity;

        if (numa_enabled == 0) {
                pr_warn("disabled by user\n");
                return -1;
        }

        primary_domain_index = find_primary_domain_index();

        if (primary_domain_index < 0) {
                /*
                 * if we fail to parse primary_domain_index from device tree
                 * mark the numa disabled, boot with numa disabled.
                 */
                numa_enabled = false;
                return primary_domain_index;
        }

        pr_debug("associativity depth for CPU/Memory: %d\n", primary_domain_index);

        /*
         * If it is FORM2 initialize the distance table here.
         */
        if (affinity_form == FORM2_AFFINITY)
                initialize_form2_numa_distance_lookup_table();

        /*
         * 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) {
                __be32 vphn_assoc[VPHN_ASSOC_BUFSIZE];
                struct device_node *cpu;
                int nid = NUMA_NO_NODE;

                memset(vphn_assoc, 0, VPHN_ASSOC_BUFSIZE * sizeof(__be32));

                if (__vphn_get_associativity(i, vphn_assoc) == 0) {
                        nid = associativity_to_nid(vphn_assoc);
                        initialize_form1_numa_distance(vphn_assoc);
                } else {

                        /*
                         * Don't fall back to default_nid yet -- we will plug
                         * cpus into nodes once the memory scan has discovered
                         * the topology.
                         */
                        cpu = of_get_cpu_node(i, NULL);
                        BUG_ON(!cpu);

                        associativity = of_get_associativity(cpu);
                        if (associativity) {
                                nid = associativity_to_nid(associativity);
                                initialize_form1_numa_distance(associativity);
                        }
                        of_node_put(cpu);
                }

                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.
                 */
                associativity = of_get_associativity(memory);
                if (associativity) {
                        nid = associativity_to_nid(associativity);
                        initialize_form1_numa_distance(associativity);
                } else
                        nid = default_nid;

                fake_numa_create_new_node(((start + size) >> PAGE_SHIFT), &nid);
                node_set_online(nid);

                size = numa_enforce_memory_limit(start, size);
                if (size)
                        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) {
                walk_drmem_lmbs(memory, NULL, numa_setup_drmem_lmb);
                of_node_put(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;
        int i;

        pr_debug("Top of RAM: 0x%lx, Total RAM: 0x%lx\n", top_of_ram, total_ram);
        pr_debug("Memory hole size: %ldMB\n", (top_of_ram - total_ram) >> 20);

        for_each_mem_pfn_range(i, MAX_NUMNODES, &start_pfn, &end_pfn, NULL) {
                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 (!numa_enabled)
                return;

        for_each_online_node(node) {
                pr_info("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)
                                        pr_cont(" %u", cpu);
                                ++count;
                        } else {
                                if (count > 1)
                                        pr_cont("-%u", cpu - 1);
                                count = 0;
                        }
                }

                if (count > 1)
                        pr_cont("-%u", nr_cpu_ids - 1);
                pr_cont("\n");
        }
}

/* 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;

        nd_pa = memblock_phys_alloc_try_nid(nd_size, SMP_CACHE_BYTES, nid);
        if (!nd_pa)
                panic("Cannot allocate %zu bytes for node %d data\n",
                      nd_size, 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;
}

static void __init find_possible_nodes(void)
{
        struct device_node *rtas;
        const __be32 *domains = NULL;
        int prop_length, max_nodes;
        u32 i;

        if (!numa_enabled)
                return;

        rtas = of_find_node_by_path("/rtas");
        if (!rtas)
                return;

        /*
         * ibm,current-associativity-domains is a fairly recent property. If
         * it doesn't exist, then fallback on ibm,max-associativity-domains.
         * Current denotes what the platform can support compared to max
         * which denotes what the Hypervisor can support.
         *
         * If the LPAR is migratable, new nodes might be activated after a LPM,
         * so we should consider the max number in that case.
         */
        if (!of_get_property(of_root, "ibm,migratable-partition", NULL))
                domains = of_get_property(rtas,
                                          "ibm,current-associativity-domains",
                                          &prop_length);
        if (!domains) {
                domains = of_get_property(rtas, "ibm,max-associativity-domains",
                                        &prop_length);
                if (!domains)
                        goto out;
        }

        max_nodes = of_read_number(&domains[primary_domain_index], 1);
        pr_info("Partition configured for %d NUMA nodes.\n", max_nodes);

        for (i = 0; i < max_nodes; i++) {
                if (!node_possible(i))
                        node_set(i, node_possible_map);
        }

        prop_length /= sizeof(int);
        if (prop_length > primary_domain_index + 2)
                coregroup_enabled = 1;

out:
        of_node_put(rtas);
}

void __init mem_topology_setup(void)
{
        int cpu;

        /*
         * Linux/mm assumes node 0 to be online at boot. However this is not
         * true on PowerPC, where node 0 is similar to any other node, it
         * could be cpuless, memoryless node. So force node 0 to be offline
         * for now. This will prevent cpuless, memoryless node 0 showing up
         * unnecessarily as online. If a node has cpus or memory that need
         * to be online, then node will anyway be marked online.
         */
        node_set_offline(0);

        if (parse_numa_properties())
                setup_nonnuma();

        /*
         * Modify the set of possible NUMA nodes to reflect information
         * available about the set of online nodes, and the set of nodes
         * that we expect to make use of for this platform's affinity
         * calculations.
         */
        nodes_and(node_possible_map, node_possible_map, node_online_map);

        find_possible_nodes();

        setup_node_to_cpumask_map();

        reset_numa_cpu_lookup_table();

        for_each_possible_cpu(cpu) {
                /*
                 * Powerpc with CONFIG_NUMA always used to have a node 0,
                 * even if it was memoryless or cpuless. For all cpus that
                 * are possible but not present, cpu_to_node() would point
                 * to node 0. To remove a cpuless, memoryless dummy node,
                 * powerpc need to make sure all possible but not present
                 * cpu_to_node are set to a proper node.
                 */
                numa_setup_cpu(cpu);
        }
}

void __init initmem_init(void)
{
        int nid;

        max_low_pfn = memblock_end_of_DRAM() >> PAGE_SHIFT;
        max_pfn = max_low_pfn;

        memblock_dump_all();

        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_init();

        /*
         * 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().
         * _nocalls() + manual invocation is used because cpuhp is not yet
         * initialized for the boot CPU.
         */
        cpuhp_setup_state_nocalls(CPUHP_POWER_NUMA_PREPARE, "powerpc/numa:prepare",
                                  ppc_numa_cpu_prepare, ppc_numa_cpu_dead);
}

static int __init early_numa(char *p)
{
        if (!p)
                return 0;

        if (strstr(p, "off"))
                numa_enabled = 0;

        p = strstr(p, "fake=");
        if (p)
                cmdline = p + strlen("fake=");

        return 0;
}
early_param("numa", early_numa);

#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(unsigned long scn_addr)
{
        struct drmem_lmb *lmb;
        unsigned long lmb_size;
        int nid = NUMA_NO_NODE;

        lmb_size = drmem_lmb_size();

        for_each_drmem_lmb(lmb) {
                /* skip this block if it is reserved or not assigned to
                 * this partition */
                if ((lmb->flags & DRCONF_MEM_RESERVED)
                    || !(lmb->flags & DRCONF_MEM_ASSIGNED))
                        continue;

                if ((scn_addr < lmb->base_addr)
                    || (scn_addr >= (lmb->base_addr + lmb_size)))
                        continue;

                nid = of_drconf_to_nid_single(lmb);
                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 = NUMA_NO_NODE;

        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;

        if (!numa_enabled)
                return first_online_node;

        memory = of_find_node_by_path("/ibm,dynamic-reconfiguration-memory");
        if (memory) {
                nid = hot_add_drconf_scn_to_nid(scn_addr);
                of_node_put(memory);
        } else {
                nid = hot_add_node_scn_to_nid(scn_addr);
        }

        if (nid < 0 || !node_possible(nid))
                nid = first_online_node;

        return nid;
}

static u64 hot_add_drconf_memory_max(void)
{
        struct device_node *memory = NULL;
        struct device_node *dn = NULL;
        const __be64 *lrdr = NULL;

        dn = of_find_node_by_path("/rtas");
        if (dn) {
                lrdr = of_get_property(dn, "ibm,lrdr-capacity", NULL);
                of_node_put(dn);
                if (lrdr)
                        return be64_to_cpup(lrdr);
        }

        memory = of_find_node_by_path("/ibm,dynamic-reconfiguration-memory");
        if (memory) {
                of_node_put(memory);
                return drmem_lmb_memory_max();
        }
        return 0;
}

/*
 * 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
static int topology_inited;

/*
 * Retrieve the new associativity information for a virtual processor's
 * home node.
 */
static long vphn_get_associativity(unsigned long cpu,
                                        __be32 *associativity)
{
        long rc;

        rc = hcall_vphn(get_hard_smp_processor_id(cpu),
                                VPHN_FLAG_VCPU, associativity);

        switch (rc) {
        case H_SUCCESS:
                pr_debug("VPHN hcall succeeded. Reset polling...\n");
                goto out;

        case H_FUNCTION:
                pr_err_ratelimited("VPHN unsupported. Disabling polling...\n");
                break;
        case H_HARDWARE:
                pr_err_ratelimited("hcall_vphn() experienced a hardware fault "
                        "preventing VPHN. Disabling polling...\n");
                break;
        case H_PARAMETER:
                pr_err_ratelimited("hcall_vphn() was passed an invalid parameter. "
                        "Disabling polling...\n");
                break;
        default:
                pr_err_ratelimited("hcall_vphn() returned %ld. Disabling polling...\n"
                        , rc);
                break;
        }
out:
        return rc;
}

int find_and_online_cpu_nid(int cpu)
{
        __be32 associativity[VPHN_ASSOC_BUFSIZE] = {0};
        int new_nid;

        /* Use associativity from first thread for all siblings */
        if (vphn_get_associativity(cpu, associativity))
                return cpu_to_node(cpu);

        new_nid = associativity_to_nid(associativity);
        if (new_nid < 0 || !node_possible(new_nid))
                new_nid = first_online_node;

        if (NODE_DATA(new_nid) == NULL) {
#ifdef CONFIG_MEMORY_HOTPLUG
                /*
                 * Need to ensure that NODE_DATA is initialized for a node from
                 * available memory (see memblock_alloc_try_nid). If unable to
                 * init the node, then default to nearest node that has memory
                 * installed. Skip onlining a node if the subsystems are not
                 * yet initialized.
                 */
                if (!topology_inited || try_online_node(new_nid))
                        new_nid = first_online_node;
#else
                /*
                 * Default to using the nearest node that has memory installed.
                 * Otherwise, it would be necessary to patch the kernel MM code
                 * to deal with more memoryless-node error conditions.
                 */
                new_nid = first_online_node;
#endif
        }

        pr_debug("%s:%d cpu %d nid %d\n", __FUNCTION__, __LINE__,
                cpu, new_nid);
        return new_nid;
}

int cpu_to_coregroup_id(int cpu)
{
        __be32 associativity[VPHN_ASSOC_BUFSIZE] = {0};
        int index;

        if (cpu < 0 || cpu > nr_cpu_ids)
                return -1;

        if (!coregroup_enabled)
                goto out;

        if (!firmware_has_feature(FW_FEATURE_VPHN))
                goto out;

        if (vphn_get_associativity(cpu, associativity))
                goto out;

        index = of_read_number(associativity, 1);
        if (index > primary_domain_index + 1)
                return of_read_number(&associativity[index - 1], 1);

out:
        return cpu_to_core_id(cpu);
}

static int topology_update_init(void)
{
        topology_inited = 1;
        return 0;
}
device_initcall(topology_update_init);
#endif /* CONFIG_PPC_SPLPAR */