numa_emulation.c | Explore in Territory

// 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/numa_memblks.h>
#include <asm/numa.h>

#define FAKE_NODE_MIN_SIZE …
#define FAKE_NODE_MIN_HASH_MASK …

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

int __init numa_emu_cmdline(char *str)
{ … }

static int __init emu_find_memblk_by_nid(int nid, const struct numa_meminfo *mi)
{ … }

static u64 __init mem_hole_size(u64 start, u64 end)
{ … }

/*
 * 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)
{ … }

/*
 * 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)
{ … }

/*
 * 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)
{ … }

static u64 uniform_size(u64 max_addr, u64 base, u64 hole, int nr_nodes)
{ … }

/*
 * 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_uniform(struct numa_meminfo *ei,
					      struct numa_meminfo *pi,
					      u64 addr, u64 max_addr, u64 size,
					      int nr_nodes, struct numa_memblk *pblk,
					      int nid)
{ … }

static int __init split_nodes_size_interleave(struct numa_meminfo *ei,
					      struct numa_meminfo *pi,
					      u64 addr, u64 max_addr, u64 size)
{ … }

static int __init setup_emu2phys_nid(int *dfl_phys_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)
{ … }

#ifndef CONFIG_DEBUG_PER_CPU_MAPS
void numa_add_cpu(unsigned 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(unsigned 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(unsigned int cpu, bool enable)
{ … }

void numa_add_cpu(unsigned int cpu)
{ … }

void numa_remove_cpu(unsigned int cpu)
{ … }
#endif	/* !CONFIG_DEBUG_PER_CPU_MAPS */
linux/mm/numa_emulation.c
