drivers/base, mm: move arch_numa.c to mm/

arch_numa.c implements boot time discovery and initialization of NUMA
topology on architectures that select GENERIC_ARCH_NUMA (currently arm64
and riscv).

Since this is step in the initialization of the memory management
subsystem, it's logical to have arch_numa.c in mm/ alongside numa.c,
numa_memblks.c and numa_emulation.c.

Move arch_numa.c to mm/ and add its F: entry to "MEMBLOCK AND MEMORY
MANAGEMENT INITIALIZATION" in MAINTAINERS.

Link: https://lore.kernel.org/20260806-arch-numa-v1-1-968ec128121e@kernel.org
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
Acked-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Acked-by: Danilo Krummrich <dakr@kernel.org>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Alexandre Ghiti <alex@ghiti.fr>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

3 files changed, 383 insertions, 0 deletions

diff --git a/mm/Kconfig b/mm/Kconfig
index 331daf7fcfab..8a24c130d008 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -1463,6 +1463,13 @@ config NUMA_EMU
 	  into virtual nodes when booted with "numa=fake=N", where N is the
 	  number of nodes. This is only useful for debugging.
 
+config GENERIC_ARCH_NUMA
+	bool
+	select NUMA_MEMBLKS
+	help
+	  Enable support for generic NUMA implementation. Currently, RISC-V
+	  and ARM64 use it.
+
 config ARCH_HAS_USER_SHADOW_STACK
 	bool
 	help
diff --git a/mm/Makefile b/mm/Makefile
index ab37ef428d98..e7245cb88c66 100644
--- a/mm/Makefile
+++ b/mm/Makefile
@@ -122,6 +122,7 @@ obj-$(CONFIG_CMA)	+= cma.o
 obj-$(CONFIG_NUMA) += numa.o
 obj-$(CONFIG_NUMA_MEMBLKS) += numa_memblks.o
 obj-$(CONFIG_NUMA_EMU) += numa_emulation.o
+obj-$(CONFIG_GENERIC_ARCH_NUMA) += arch_numa.o
 obj-$(CONFIG_BALLOON) += balloon.o
 obj-$(CONFIG_PAGE_EXTENSION) += page_ext.o
 obj-$(CONFIG_PAGE_TABLE_CHECK) += page_table_check.o
diff --git a/mm/arch_numa.c b/mm/arch_numa.c
new file mode 100644
index 000000000000..442ea239bba7
--- /dev/null
+++ b/mm/arch_numa.c
@@ -0,0 +1,375 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * NUMA support, based on the x86 implementation.
+ *
+ * Copyright (C) 2015 Cavium Inc.
+ * Author: Ganapatrao Kulkarni <gkulkarni@cavium.com>
+ */
+
+#define pr_fmt(fmt) "NUMA: " fmt
+
+#include <linux/acpi.h>
+#include <linux/memblock.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/numa_memblks.h>
+
+#include <asm/sections.h>
+
+static int cpu_to_node_map[NR_CPUS] = { [0 ... NR_CPUS-1] = NUMA_NO_NODE };
+
+bool numa_off;
+
+static __init int numa_parse_early_param(char *opt)
+{
+	if (!opt)
+		return -EINVAL;
+	if (str_has_prefix(opt, "off"))
+		numa_off = true;
+	if (!strncmp(opt, "fake=", 5))
+		return numa_emu_cmdline(opt + 5);
+
+	return 0;
+}
+early_param("numa", numa_parse_early_param);
+
+cpumask_var_t node_to_cpumask_map[MAX_NUMNODES];
+EXPORT_SYMBOL(node_to_cpumask_map);
+
+#ifdef CONFIG_DEBUG_PER_CPU_MAPS
+
+/*
+ * Returns a pointer to the bitmask of CPUs on Node 'node'.
+ */
+const struct cpumask *cpumask_of_node(int node)
+{
+
+	if (node == NUMA_NO_NODE)
+		return cpu_all_mask;
+
+	if (WARN_ON(node < 0 || node >= nr_node_ids))
+		return cpu_none_mask;
+
+	if (WARN_ON(node_to_cpumask_map[node] == NULL))
+		return cpu_online_mask;
+
+	return node_to_cpumask_map[node];
+}
+EXPORT_SYMBOL(cpumask_of_node);
+
+#endif
+
+#ifndef CONFIG_NUMA_EMU
+static void numa_update_cpu(unsigned int cpu, bool remove)
+{
+	int nid = cpu_to_node(cpu);
+
+	if (nid == NUMA_NO_NODE)
+		return;
+
+	if (remove)
+		cpumask_clear_cpu(cpu, node_to_cpumask_map[nid]);
+	else
+		cpumask_set_cpu(cpu, node_to_cpumask_map[nid]);
+}
+
+void numa_add_cpu(unsigned int cpu)
+{
+	numa_update_cpu(cpu, false);
+}
+
+void numa_remove_cpu(unsigned int cpu)
+{
+	numa_update_cpu(cpu, true);
+}
+#endif
+
+void numa_clear_node(unsigned int cpu)
+{
+	numa_remove_cpu(cpu);
+	set_cpu_numa_node(cpu, 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.
+ * (Use CONFIG_DEBUG_PER_CPU_MAPS to check this.)
+ */
+static void __init setup_node_to_cpumask_map(void)
+{
+	int node;
+
+	/* setup nr_node_ids if not done yet */
+	if (nr_node_ids == MAX_NUMNODES)
+		setup_nr_node_ids();
+
+	/* allocate and clear the mapping */
+	for (node = 0; node < nr_node_ids; node++) {
+		alloc_bootmem_cpumask_var(&node_to_cpumask_map[node]);
+		cpumask_clear(node_to_cpumask_map[node]);
+	}
+
+	/* cpumask_of_node() will now work */
+	pr_debug("Node to cpumask map for %u nodes\n", nr_node_ids);
+}
+
+/*
+ * Set the cpu to node and mem mapping
+ */
+void numa_store_cpu_info(unsigned int cpu)
+{
+	set_cpu_numa_node(cpu, cpu_to_node_map[cpu]);
+}
+
+void __init early_map_cpu_to_node(unsigned int cpu, int nid)
+{
+	/* fallback to node 0 */
+	if (nid < 0 || nid >= MAX_NUMNODES || numa_off)
+		nid = 0;
+
+	cpu_to_node_map[cpu] = nid;
+
+	/*
+	 * We should set the numa node of cpu0 as soon as possible, because it
+	 * has already been set up online before. cpu_to_node(0) will soon be
+	 * called.
+	 */
+	if (!cpu)
+		set_cpu_numa_node(cpu, nid);
+}
+
+#ifdef CONFIG_HAVE_SETUP_PER_CPU_AREA
+unsigned long __per_cpu_offset[NR_CPUS] __read_mostly;
+EXPORT_SYMBOL(__per_cpu_offset);
+
+int early_cpu_to_node(int cpu)
+{
+	return cpu_to_node_map[cpu];
+}
+
+static int __init pcpu_cpu_distance(unsigned int from, unsigned int to)
+{
+	return node_distance(early_cpu_to_node(from), early_cpu_to_node(to));
+}
+
+void __init setup_per_cpu_areas(void)
+{
+	unsigned long delta;
+	unsigned int cpu;
+	int rc = -EINVAL;
+
+	if (pcpu_chosen_fc != PCPU_FC_PAGE) {
+		/*
+		 * Always reserve area for module percpu variables.  That's
+		 * what the legacy allocator did.
+		 */
+		rc = pcpu_embed_first_chunk(PERCPU_MODULE_RESERVE,
+					    PERCPU_DYNAMIC_RESERVE, PAGE_SIZE,
+					    pcpu_cpu_distance,
+					    early_cpu_to_node);
+#ifdef CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK
+		if (rc < 0)
+			pr_warn("PERCPU: %s allocator failed (%d), falling back to page size\n",
+				   pcpu_fc_names[pcpu_chosen_fc], rc);
+#endif
+	}
+
+#ifdef CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK
+	if (rc < 0)
+		rc = pcpu_page_first_chunk(PERCPU_MODULE_RESERVE, early_cpu_to_node);
+#endif
+	if (rc < 0)
+		panic("Failed to initialize percpu areas (err=%d).", rc);
+
+	delta = (unsigned long)pcpu_base_addr - (unsigned long)__per_cpu_start;
+	for_each_possible_cpu(cpu)
+		__per_cpu_offset[cpu] = delta + pcpu_unit_offsets[cpu];
+}
+#endif
+
+/*
+ * Initialize NODE_DATA for a node on the local memory
+ */
+static void __init setup_node_data(int nid, u64 start_pfn, u64 end_pfn)
+{
+	if (start_pfn >= end_pfn)
+		pr_info("Initmem setup node %d [<memory-less node>]\n", nid);
+
+	alloc_node_data(nid);
+
+	NODE_DATA(nid)->node_id = nid;
+	NODE_DATA(nid)->node_start_pfn = start_pfn;
+	NODE_DATA(nid)->node_spanned_pages = end_pfn - start_pfn;
+}
+
+static int __init numa_register_nodes(void)
+{
+	int nid;
+
+	/* Check the validity of the memblock/node mapping */
+	if (!memblock_validate_numa_coverage(0))
+		return -EINVAL;
+
+	/* Finally register nodes. */
+	for_each_node_mask(nid, numa_nodes_parsed) {
+		unsigned long start_pfn, end_pfn;
+
+		get_pfn_range_for_nid(nid, &start_pfn, &end_pfn);
+		setup_node_data(nid, start_pfn, end_pfn);
+		node_set_online(nid);
+	}
+
+	/* Setup online nodes to actual nodes*/
+	node_possible_map = numa_nodes_parsed;
+
+	return 0;
+}
+
+static int __init numa_init(int (*init_func)(void))
+{
+	int ret;
+
+	ret = numa_memblks_init(init_func, /* memblock_force_top_down */ false);
+	if (ret < 0)
+		goto out_free_distance;
+
+	if (nodes_empty(numa_nodes_parsed)) {
+		pr_info("No NUMA configuration found\n");
+		ret = -EINVAL;
+		goto out_free_distance;
+	}
+
+	ret = numa_register_nodes();
+	if (ret < 0)
+		goto out_free_distance;
+
+	setup_node_to_cpumask_map();
+
+	return 0;
+out_free_distance:
+	numa_reset_distance();
+	return ret;
+}
+
+/**
+ * dummy_numa_init() - Fallback dummy NUMA init
+ *
+ * Used if there's no underlying NUMA architecture, NUMA initialization
+ * fails, or NUMA is disabled on the command line.
+ *
+ * Must online at least one node (node 0) and add memory blocks that cover all
+ * allowed memory. It is unlikely that this function fails.
+ *
+ * Return: 0 on success, -errno on failure.
+ */
+static int __init dummy_numa_init(void)
+{
+	phys_addr_t start = memblock_start_of_DRAM();
+	phys_addr_t end = memblock_end_of_DRAM() - 1;
+	int ret;
+
+	if (numa_off)
+		pr_info("NUMA disabled\n"); /* Forced off on command line. */
+	pr_info("Faking a node at [mem %pap-%pap]\n", &start, &end);
+
+	ret = numa_add_memblk(0, start, end + 1);
+	if (ret) {
+		pr_err("NUMA init failed\n");
+		return ret;
+	}
+	node_set(0, numa_nodes_parsed);
+
+	numa_off = true;
+	return 0;
+}
+
+#ifdef CONFIG_ACPI_NUMA
+static int __init arch_acpi_numa_init(void)
+{
+	int ret;
+
+	ret = acpi_numa_init();
+	if (ret) {
+		pr_debug("Failed to initialise from firmware\n");
+		return ret;
+	}
+
+	return srat_disabled() ? -EINVAL : 0;
+}
+#else
+static int __init arch_acpi_numa_init(void)
+{
+	return -EOPNOTSUPP;
+}
+#endif
+
+/**
+ * arch_numa_init() - Initialize NUMA
+ *
+ * Try each configured NUMA initialization method until one succeeds. The
+ * last fallback is dummy single node config encompassing whole memory.
+ */
+void __init arch_numa_init(void)
+{
+	if (!numa_off) {
+		if (!acpi_disabled && !numa_init(arch_acpi_numa_init))
+			return;
+		if (acpi_disabled && !numa_init(of_numa_init))
+			return;
+	}
+
+	numa_init(dummy_numa_init);
+}
+
+#ifdef CONFIG_NUMA_EMU
+void __init numa_emu_update_cpu_to_node(int *emu_nid_to_phys,
+					unsigned int nr_emu_nids)
+{
+	int i, j;
+
+	/*
+	 * Transform cpu_to_node_map 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(cpu_to_node_map); i++) {
+		if (cpu_to_node_map[i] == NUMA_NO_NODE)
+			continue;
+		for (j = 0; j < nr_emu_nids; j++)
+			if (cpu_to_node_map[i] == emu_nid_to_phys[j])
+				break;
+		cpu_to_node_map[i] = j < nr_emu_nids ? j : 0;
+	}
+}
+
+u64 __init numa_emu_dma_end(void)
+{
+	return memblock_start_of_DRAM() + SZ_4G;
+}
+
+void debug_cpumask_set_cpu(unsigned int cpu, int node, bool enable)
+{
+	struct cpumask *mask;
+
+	if (node == NUMA_NO_NODE)
+		return;
+
+	mask = node_to_cpumask_map[node];
+	if (!cpumask_available(mask)) {
+		pr_err("node_to_cpumask_map[%i] NULL\n", node);
+		dump_stack();
+		return;
+	}
+
+	if (enable)
+		cpumask_set_cpu(cpu, mask);
+	else
+		cpumask_clear_cpu(cpu, mask);
+
+	pr_debug("%s cpu %d node %d: mask now %*pbl\n",
+		 enable ? "numa_add_cpu" : "numa_remove_cpu",
+		 cpu, node, cpumask_pr_args(mask));
+}
+#endif /* CONFIG_NUMA_EMU */