// SPDX-License-Identifier: GPL-2.0
/*
 * NUMA emulation
 */
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/topology.h>
#include <linux/memblock.h>
#include <linux/bootmem.h>
#include <asm/dma.h>

#include "numa_internal.h"

static int emu_nid_to_phys[MAX_NUMNODES];
static char *emu_cmdline __initdata;

void __init numa_emu_cmdline(char *str)
{
        emu_cmdline = str;
}

static int __init emu_find_memblk_by_nid(int nid, const struct numa_meminfo *mi)
{
        int i;

        for (i = 0; i < mi->nr_blks; i++)
                if (mi->blk[i].nid == nid)
                        return i;
        return -ENOENT;
}

static u64 __init mem_hole_size(u64 start, u64 end)
{
        unsigned long start_pfn = PFN_UP(start);
        unsigned long end_pfn = PFN_DOWN(end);

        if (start_pfn < end_pfn)
                return PFN_PHYS(absent_pages_in_range(start_pfn, end_pfn));
        return 0;
}

/*
 * Sets up nid to range from @start to @end.  The return value is -errno if
 * something went wrong, 0 otherwise.
 */
static int __init emu_setup_memblk(struct numa_meminfo *ei,
                                   struct numa_meminfo *pi,
                                   int nid, int phys_blk, u64 size)
{
        struct numa_memblk *eb = &ei->blk[ei->nr_blks];
        struct numa_memblk *pb = &pi->blk[phys_blk];

        if (ei->nr_blks >= NR_NODE_MEMBLKS) {
                pr_err("NUMA: Too many emulated memblks, failing emulation\n");
                return -EINVAL;
        }

        ei->nr_blks++;
        eb->start = pb->start;
        eb->end = pb->start + size;
        eb->nid = nid;

        if (emu_nid_to_phys[nid] == NUMA_NO_NODE)
                emu_nid_to_phys[nid] = nid;

        pb->start += size;
        if (pb->start >= pb->end) {
                WARN_ON_ONCE(pb->start > pb->end);
                numa_remove_memblk_from(phys_blk, pi);
        }

        printk(KERN_INFO "Faking node %d at [mem %#018Lx-%#018Lx] (%LuMB)\n",
               nid, eb->start, eb->end - 1, (eb->end - eb->start) >> 20);
        return 0;
}

/*
 * Sets up nr_nodes fake nodes interleaved over physical nodes ranging from addr
 * to max_addr.
 *
 * Returns zero on success or negative on error.
 */
static int __init split_nodes_interleave(struct numa_meminfo *ei,
                                         struct numa_meminfo *pi,
                                         u64 addr, u64 max_addr, int nr_nodes)
{
        nodemask_t physnode_mask = numa_nodes_parsed;
        u64 size;
        int big;
        int nid = 0;
        int i, ret;

        if (nr_nodes <= 0)
                return -1;
        if (nr_nodes > MAX_NUMNODES) {
                pr_info("numa=fake=%d too large, reducing to %d\n",
                        nr_nodes, MAX_NUMNODES);
                nr_nodes = MAX_NUMNODES;
        }

        /*
         * Calculate target node size.  x86_32 freaks on __udivdi3() so do
         * the division in ulong number of pages and convert back.
         */
        size = max_addr - addr - mem_hole_size(addr, max_addr);
        size = PFN_PHYS((unsigned long)(size >> PAGE_SHIFT) / nr_nodes);

        /*
         * Calculate the number of big nodes that can be allocated as a result
         * of consolidating the remainder.
         */
        big = ((size & ~FAKE_NODE_MIN_HASH_MASK) * nr_nodes) /
                FAKE_NODE_MIN_SIZE;

        size &= FAKE_NODE_MIN_HASH_MASK;
        if (!size) {
                pr_err("Not enough memory for each node.  "
                        "NUMA emulation disabled.\n");
                return -1;
        }

        /*
         * Continue to fill physical nodes with fake nodes until there is no
         * memory left on any of them.
         */
        while (nodes_weight(physnode_mask)) {
                for_each_node_mask(i, physnode_mask) {
                        u64 dma32_end = PFN_PHYS(MAX_DMA32_PFN);
                        u64 start, limit, end;
                        int phys_blk;

                        phys_blk = emu_find_memblk_by_nid(i, pi);
                        if (phys_blk < 0) {
                                node_clear(i, physnode_mask);
                                continue;
                        }
                        start = pi->blk[phys_blk].start;
                        limit = pi->blk[phys_blk].end;
                        end = start + size;

                        if (nid < big)
                                end += FAKE_NODE_MIN_SIZE;

                        /*
                         * Continue to add memory to this fake node if its
                         * non-reserved memory is less than the per-node size.
                         */
                        while (end - start - mem_hole_size(start, end) < size) {
                                end += FAKE_NODE_MIN_SIZE;
                                if (end > limit) {
                                        end = limit;
                                        break;
                                }
                        }

                        /*
                         * If there won't be at least FAKE_NODE_MIN_SIZE of
                         * non-reserved memory in ZONE_DMA32 for the next node,
                         * this one must extend to the boundary.
                         */
                        if (end < dma32_end && dma32_end - end -
                            mem_hole_size(end, dma32_end) < FAKE_NODE_MIN_SIZE)
                                end = dma32_end;

                        /*
                         * If there won't be enough non-reserved memory for the
                         * next node, this one must extend to the end of the
                         * physical node.
                         */
                        if (limit - end - mem_hole_size(end, limit) < size)
                                end = limit;

                        ret = emu_setup_memblk(ei, pi, nid++ % nr_nodes,
                                               phys_blk,
                                               min(end, limit) - start);
                        if (ret < 0)
                                return ret;
                }
        }
        return 0;
}

/*
 * Returns the end address of a node so that there is at least `size' amount of
 * non-reserved memory or `max_addr' is reached.
 */
static u64 __init find_end_of_node(u64 start, u64 max_addr, u64 size)
{
        u64 end = start + size;

        while (end - start - mem_hole_size(start, end) < size) {
                end += FAKE_NODE_MIN_SIZE;
                if (end > max_addr) {
                        end = max_addr;
                        break;
                }
        }
        return end;
}

/*
 * Sets up fake nodes of `size' interleaved over physical nodes ranging from
 * `addr' to `max_addr'.
 *
 * Returns zero on success or negative on error.
 */
static int __init split_nodes_size_interleave(struct numa_meminfo *ei,
                                              struct numa_meminfo *pi,
                                              u64 addr, u64 max_addr, u64 size)
{
        nodemask_t physnode_mask = numa_nodes_parsed;
        u64 min_size;
        int nid = 0;
        int i, ret;

        if (!size)
                return -1;
        /*
         * The limit on emulated nodes is MAX_NUMNODES, so the size per node is
         * increased accordingly if the requested size is too small.  This
         * creates a uniform distribution of node sizes across the entire
         * machine (but not necessarily over physical nodes).
         */
        min_size = (max_addr - addr - mem_hole_size(addr, max_addr)) / MAX_NUMNODES;
        min_size = max(min_size, FAKE_NODE_MIN_SIZE);
        if ((min_size & FAKE_NODE_MIN_HASH_MASK) < min_size)
                min_size = (min_size + FAKE_NODE_MIN_SIZE) &
                                                FAKE_NODE_MIN_HASH_MASK;
        if (size < min_size) {
                pr_err("Fake node size %LuMB too small, increasing to %LuMB\n",
                        size >> 20, min_size >> 20);
                size = min_size;
        }
        size &= FAKE_NODE_MIN_HASH_MASK;

        /*
         * Fill physical nodes with fake nodes of size until there is no memory
         * left on any of them.
         */
        while (nodes_weight(physnode_mask)) {
                for_each_node_mask(i, physnode_mask) {
                        u64 dma32_end = PFN_PHYS(MAX_DMA32_PFN);
                        u64 start, limit, end;
                        int phys_blk;

                        phys_blk = emu_find_memblk_by_nid(i, pi);
                        if (phys_blk < 0) {
                                node_clear(i, physnode_mask);
                                continue;
                        }
                        start = pi->blk[phys_blk].start;
                        limit = pi->blk[phys_blk].end;

                        end = find_end_of_node(start, limit, size);
                        /*
                         * If there won't be at least FAKE_NODE_MIN_SIZE of
                         * non-reserved memory in ZONE_DMA32 for the next node,
                         * this one must extend to the boundary.
                         */
                        if (end < dma32_end && dma32_end - end -
                            mem_hole_size(end, dma32_end) < FAKE_NODE_MIN_SIZE)
                                end = dma32_end;

                        /*
                         * If there won't be enough non-reserved memory for the
                         * next node, this one must extend to the end of the
                         * physical node.
                         */
                        if (limit - end - mem_hole_size(end, limit) < size)
                                end = limit;

                        ret = emu_setup_memblk(ei, pi, nid++ % MAX_NUMNODES,
                                               phys_blk,
                                               min(end, limit) - start);
                        if (ret < 0)
                                return ret;
                }
        }
        return 0;
}

int __init setup_emu2phys_nid(int *dfl_phys_nid)
{
        int i, max_emu_nid = 0;

        *dfl_phys_nid = NUMA_NO_NODE;
        for (i = 0; i < ARRAY_SIZE(emu_nid_to_phys); i++) {
                if (emu_nid_to_phys[i] != NUMA_NO_NODE) {
                        max_emu_nid = i;
                        if (*dfl_phys_nid == NUMA_NO_NODE)
                                *dfl_phys_nid = emu_nid_to_phys[i];
                }
        }

        return max_emu_nid;
}

/**
 * numa_emulation - Emulate NUMA nodes
 * @numa_meminfo: NUMA configuration to massage
 * @numa_dist_cnt: The size of the physical NUMA distance table
 *
 * Emulate NUMA nodes according to the numa=fake kernel parameter.
 * @numa_meminfo contains the physical memory configuration and is modified
 * to reflect the emulated configuration on success.  @numa_dist_cnt is
 * used to determine the size of the physical distance table.
 *
 * On success, the following modifications are made.
 *
 * - @numa_meminfo is updated to reflect the emulated nodes.
 *
 * - __apicid_to_node[] is updated such that APIC IDs are mapped to the
 *   emulated nodes.
 *
 * - NUMA distance table is rebuilt to represent distances between emulated
 *   nodes.  The distances are determined considering how emulated nodes
 *   are mapped to physical nodes and match the actual distances.
 *
 * - emu_nid_to_phys[] reflects how emulated nodes are mapped to physical
 *   nodes.  This is used by numa_add_cpu() and numa_remove_cpu().
 *
 * If emulation is not enabled or fails, emu_nid_to_phys[] is filled with
 * identity mapping and no other modification is made.
 */
void __init numa_emulation(struct numa_meminfo *numa_meminfo, int numa_dist_cnt)
{
        static struct numa_meminfo ei __initdata;
        static struct numa_meminfo pi __initdata;
        const u64 max_addr = PFN_PHYS(max_pfn);
        u8 *phys_dist = NULL;
        size_t phys_size = numa_dist_cnt * numa_dist_cnt * sizeof(phys_dist[0]);
        int max_emu_nid, dfl_phys_nid;
        int i, j, ret;

        if (!emu_cmdline)
                goto no_emu;

        memset(&ei, 0, sizeof(ei));
        pi = *numa_meminfo;

        for (i = 0; i < MAX_NUMNODES; i++)
                emu_nid_to_phys[i] = NUMA_NO_NODE;

        /*
         * If the numa=fake command-line contains a 'M' or 'G', it represents
         * the fixed node size.  Otherwise, if it is just a single number N,
         * split the system RAM into N fake nodes.
         */
        if (strchr(emu_cmdline, 'M') || strchr(emu_cmdline, 'G')) {
                u64 size;

                size = memparse(emu_cmdline, &emu_cmdline);
                ret = split_nodes_size_interleave(&ei, &pi, 0, max_addr, size);
        } else {
                unsigned long n;

                n = simple_strtoul(emu_cmdline, &emu_cmdline, 0);
                ret = split_nodes_interleave(&ei, &pi, 0, max_addr, n);
        }
        if (*emu_cmdline == ':')
                emu_cmdline++;

        if (ret < 0)
                goto no_emu;

        if (numa_cleanup_meminfo(&ei) < 0) {
                pr_warning("NUMA: Warning: constructed meminfo invalid, disabling emulation\n");
                goto no_emu;
        }

        /* copy the physical distance table */
        if (numa_dist_cnt) {
                u64 phys;

                phys = memblock_find_in_range(0, PFN_PHYS(max_pfn_mapped),
                                              phys_size, PAGE_SIZE);
                if (!phys) {
                        pr_warning("NUMA: Warning: can't allocate copy of distance table, disabling emulation\n");
                        goto no_emu;
                }
                memblock_reserve(phys, phys_size);
                phys_dist = __va(phys);

                for (i = 0; i < numa_dist_cnt; i++)
                        for (j = 0; j < numa_dist_cnt; j++)
                                phys_dist[i * numa_dist_cnt + j] =
                                        node_distance(i, j);
        }

        /*
         * Determine the max emulated nid and the default phys nid to use
         * for unmapped nodes.
         */
        max_emu_nid = setup_emu2phys_nid(&dfl_phys_nid);

        /* commit */
        *numa_meminfo = ei;

        /* Make sure numa_nodes_parsed only contains emulated nodes */
        nodes_clear(numa_nodes_parsed);
        for (i = 0; i < ARRAY_SIZE(ei.blk); i++)
                if (ei.blk[i].start != ei.blk[i].end &&
                    ei.blk[i].nid != NUMA_NO_NODE)
                        node_set(ei.blk[i].nid, numa_nodes_parsed);

        /*
         * Transform __apicid_to_node table to use emulated nids by
         * reverse-mapping phys_nid.  The maps should always exist but fall
         * back to zero just in case.
         */
        for (i = 0; i < ARRAY_SIZE(__apicid_to_node); i++) {
                if (__apicid_to_node[i] == NUMA_NO_NODE)
                        continue;
                for (j = 0; j < ARRAY_SIZE(emu_nid_to_phys); j++)
                        if (__apicid_to_node[i] == emu_nid_to_phys[j])
                                break;
                __apicid_to_node[i] = j < ARRAY_SIZE(emu_nid_to_phys) ? j : 0;
        }

        /* make sure all emulated nodes are mapped to a physical node */
        for (i = 0; i < ARRAY_SIZE(emu_nid_to_phys); i++)
                if (emu_nid_to_phys[i] == NUMA_NO_NODE)
                        emu_nid_to_phys[i] = dfl_phys_nid;

        /* transform distance table */
        numa_reset_distance();
        for (i = 0; i < max_emu_nid + 1; i++) {
                for (j = 0; j < max_emu_nid + 1; j++) {
                        int physi = emu_nid_to_phys[i];
                        int physj = emu_nid_to_phys[j];
                        int dist;

                        if (get_option(&emu_cmdline, &dist) == 2)
                                ;
                        else if (physi >= numa_dist_cnt || physj >= numa_dist_cnt)
                                dist = physi == physj ?
                                        LOCAL_DISTANCE : REMOTE_DISTANCE;
                        else
                                dist = phys_dist[physi * numa_dist_cnt + physj];

                        numa_set_distance(i, j, dist);
                }
        }

        /* free the copied physical distance table */
        if (phys_dist)
                memblock_free(__pa(phys_dist), phys_size);
        return;

no_emu:
        /* No emulation.  Build identity emu_nid_to_phys[] for numa_add_cpu() */
        for (i = 0; i < ARRAY_SIZE(emu_nid_to_phys); i++)
                emu_nid_to_phys[i] = i;
}

#ifndef CONFIG_DEBUG_PER_CPU_MAPS
void numa_add_cpu(int cpu)
{
        int physnid, nid;

        nid = early_cpu_to_node(cpu);
        BUG_ON(nid == NUMA_NO_NODE || !node_online(nid));

        physnid = emu_nid_to_phys[nid];

        /*
         * Map the cpu to each emulated node that is allocated on the physical
         * node of the cpu's apic id.
         */
        for_each_online_node(nid)
                if (emu_nid_to_phys[nid] == physnid)
                        cpumask_set_cpu(cpu, node_to_cpumask_map[nid]);
}

void numa_remove_cpu(int cpu)
{
        int i;

        for_each_online_node(i)
                cpumask_clear_cpu(cpu, node_to_cpumask_map[i]);
}
#else   /* !CONFIG_DEBUG_PER_CPU_MAPS */
static void numa_set_cpumask(int cpu, bool enable)
{
        int nid, physnid;

        nid = early_cpu_to_node(cpu);
        if (nid == NUMA_NO_NODE) {
                /* early_cpu_to_node() already emits a warning and trace */
                return;
        }

        physnid = emu_nid_to_phys[nid];

        for_each_online_node(nid) {
                if (emu_nid_to_phys[nid] != physnid)
                        continue;

                debug_cpumask_set_cpu(cpu, nid, enable);
        }
}

void numa_add_cpu(int cpu)
{
        numa_set_cpumask(cpu, true);
}

void numa_remove_cpu(int cpu)
{
        numa_set_cpumask(cpu, false);
}
#endif  /* !CONFIG_DEBUG_PER_CPU_MAPS */