1 files changed, 530 insertions, 0 deletions
diff --git a/arch/s390/numa/mode_emu.c b/arch/s390/numa/mode_emu.c
new file mode 100644
index 000000000000..7de4e2f780d7
--- /dev/null
+++ b/arch/s390/numa/mode_emu.c
@@ -0,0 +1,530 @@
+/*
+ * NUMA support for s390
+ *
+ * NUMA emulation (aka fake NUMA) distributes the available memory to nodes
+ * without using real topology information about the physical memory of the
+ * machine.
+ *
+ * It distributes the available CPUs to nodes while respecting the original
+ * machine topology information. This is done by trying to avoid to separate
+ * CPUs which reside on the same book or even on the same MC.
+ *
+ * Because the current Linux scheduler code requires a stable cpu to node
+ * mapping, cores are pinned to nodes when the first CPU thread is set online.
+ *
+ * Copyright IBM Corp. 2015
+ */
+
+#define KMSG_COMPONENT "numa_emu"
+#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
+
+#include <linux/kernel.h>
+#include <linux/cpumask.h>
+#include <linux/memblock.h>
+#include <linux/node.h>
+#include <linux/memory.h>
+#include <linux/slab.h>
+#include <asm/smp.h>
+#include <asm/topology.h>
+#include "numa_mode.h"
+#include "toptree.h"
+
+/* Distances between the different system components */
+#define DIST_EMPTY	0
+#define DIST_CORE	1
+#define DIST_MC		2
+#define DIST_BOOK	3
+#define DIST_MAX	4
+
+/* Node distance reported to common code */
+#define EMU_NODE_DIST	10
+
+/* Node ID for free (not yet pinned) cores */
+#define NODE_ID_FREE	-1
+
+/* Different levels of toptree */
+enum toptree_level {CORE, MC, BOOK, NODE, TOPOLOGY};
+
+/* The two toptree IDs */
+enum {TOPTREE_ID_PHYS, TOPTREE_ID_NUMA};
+
+/* Number of NUMA nodes */
+static int emu_nodes = 1;
+/* NUMA stripe size */
+static unsigned long emu_size;
+
+/*
+ * Node to core pinning information updates are protected by
+ * "sched_domains_mutex".
+ */
+static struct {
+	s32 to_node_id[CONFIG_NR_CPUS];	/* Pinned core to node mapping */
+	int total;			/* Total number of pinned cores */
+	int per_node_target;		/* Cores per node without extra cores */
+	int per_node[MAX_NUMNODES];	/* Number of cores pinned to node */
+} *emu_cores;
+
+/*
+ * Pin a core to a node
+ */
+static void pin_core_to_node(int core_id, int node_id)
+{
+	if (emu_cores->to_node_id[core_id] == NODE_ID_FREE) {
+		emu_cores->per_node[node_id]++;
+		emu_cores->to_node_id[core_id] = node_id;
+		emu_cores->total++;
+	} else {
+		WARN_ON(emu_cores->to_node_id[core_id] != node_id);
+	}
+}
+
+/*
+ * Number of pinned cores of a node
+ */
+static int cores_pinned(struct toptree *node)
+{
+	return emu_cores->per_node[node->id];
+}
+
+/*
+ * ID of the node where the core is pinned (or NODE_ID_FREE)
+ */
+static int core_pinned_to_node_id(struct toptree *core)
+{
+	return emu_cores->to_node_id[core->id];
+}
+
+/*
+ * Number of cores in the tree that are not yet pinned
+ */
+static int cores_free(struct toptree *tree)
+{
+	struct toptree *core;
+	int count = 0;
+
+	toptree_for_each(core, tree, CORE) {
+		if (core_pinned_to_node_id(core) == NODE_ID_FREE)
+			count++;
+	}
+	return count;
+}
+
+/*
+ * Return node of core
+ */
+static struct toptree *core_node(struct toptree *core)
+{
+	return core->parent->parent->parent;
+}
+
+/*
+ * Return book of core
+ */
+static struct toptree *core_book(struct toptree *core)
+{
+	return core->parent->parent;
+}
+
+/*
+ * Return mc of core
+ */
+static struct toptree *core_mc(struct toptree *core)
+{
+	return core->parent;
+}
+
+/*
+ * Distance between two cores
+ */
+static int dist_core_to_core(struct toptree *core1, struct toptree *core2)
+{
+	if (core_book(core1)->id != core_book(core2)->id)
+		return DIST_BOOK;
+	if (core_mc(core1)->id != core_mc(core2)->id)
+		return DIST_MC;
+	/* Same core or sibling on same MC */
+	return DIST_CORE;
+}
+
+/*
+ * Distance of a node to a core
+ */
+static int dist_node_to_core(struct toptree *node, struct toptree *core)
+{
+	struct toptree *core_node;
+	int dist_min = DIST_MAX;
+
+	toptree_for_each(core_node, node, CORE)
+		dist_min = min(dist_min, dist_core_to_core(core_node, core));
+	return dist_min == DIST_MAX ? DIST_EMPTY : dist_min;
+}
+
+/*
+ * Unify will delete empty nodes, therefore recreate nodes.
+ */
+static void toptree_unify_tree(struct toptree *tree)
+{
+	int nid;
+
+	toptree_unify(tree);
+	for (nid = 0; nid < emu_nodes; nid++)
+		toptree_get_child(tree, nid);
+}
+
+/*
+ * Find the best/nearest node for a given core and ensure that no node
+ * gets more than "emu_cores->per_node_target + extra" cores.
+ */
+static struct toptree *node_for_core(struct toptree *numa, struct toptree *core,
+				     int extra)
+{
+	struct toptree *node, *node_best = NULL;
+	int dist_cur, dist_best, cores_target;
+
+	cores_target = emu_cores->per_node_target + extra;
+	dist_best = DIST_MAX;
+	node_best = NULL;
+	toptree_for_each(node, numa, NODE) {
+		/* Already pinned cores must use their nodes */
+		if (core_pinned_to_node_id(core) == node->id) {
+			node_best = node;
+			break;
+		}
+		/* Skip nodes that already have enough cores */
+		if (cores_pinned(node) >= cores_target)
+			continue;
+		dist_cur = dist_node_to_core(node, core);
+		if (dist_cur < dist_best) {
+			dist_best = dist_cur;
+			node_best = node;
+		}
+	}
+	return node_best;
+}
+
+/*
+ * Find the best node for each core with respect to "extra" core count
+ */
+static void toptree_to_numa_single(struct toptree *numa, struct toptree *phys,
+				   int extra)
+{
+	struct toptree *node, *core, *tmp;
+
+	toptree_for_each_safe(core, tmp, phys, CORE) {
+		node = node_for_core(numa, core, extra);
+		if (!node)
+			return;
+		toptree_move(core, node);
+		pin_core_to_node(core->id, node->id);
+	}
+}
+
+/*
+ * Move structures of given level to specified NUMA node
+ */
+static void move_level_to_numa_node(struct toptree *node, struct toptree *phys,
+				    enum toptree_level level, bool perfect)
+{
+	int cores_free, cores_target = emu_cores->per_node_target;
+	struct toptree *cur, *tmp;
+
+	toptree_for_each_safe(cur, tmp, phys, level) {
+		cores_free = cores_target - toptree_count(node, CORE);
+		if (perfect) {
+			if (cores_free == toptree_count(cur, CORE))
+				toptree_move(cur, node);
+		} else {
+			if (cores_free >= toptree_count(cur, CORE))
+				toptree_move(cur, node);
+		}
+	}
+}
+
+/*
+ * Move structures of a given level to NUMA nodes. If "perfect" is specified
+ * move only perfectly fitting structures. Otherwise move also smaller
+ * than needed structures.
+ */
+static void move_level_to_numa(struct toptree *numa, struct toptree *phys,
+			       enum toptree_level level, bool perfect)
+{
+	struct toptree *node;
+
+	toptree_for_each(node, numa, NODE)
+		move_level_to_numa_node(node, phys, level, perfect);
+}
+
+/*
+ * For the first run try to move the big structures
+ */
+static void toptree_to_numa_first(struct toptree *numa, struct toptree *phys)
+{
+	struct toptree *core;
+
+	/* Always try to move perfectly fitting structures first */
+	move_level_to_numa(numa, phys, BOOK, true);
+	move_level_to_numa(numa, phys, BOOK, false);
+	move_level_to_numa(numa, phys, MC, true);
+	move_level_to_numa(numa, phys, MC, false);
+	/* Now pin all the moved cores */
+	toptree_for_each(core, numa, CORE)
+		pin_core_to_node(core->id, core_node(core)->id);
+}
+
+/*
+ * Allocate new topology and create required nodes
+ */
+static struct toptree *toptree_new(int id, int nodes)
+{
+	struct toptree *tree;
+	int nid;
+
+	tree = toptree_alloc(TOPOLOGY, id);
+	if (!tree)
+		goto fail;
+	for (nid = 0; nid < nodes; nid++) {
+		if (!toptree_get_child(tree, nid))
+			goto fail;
+	}
+	return tree;
+fail:
+	panic("NUMA emulation could not allocate topology");
+}
+
+/*
+ * Allocate and initialize core to node mapping
+ */
+static void create_core_to_node_map(void)
+{
+	int i;
+
+	emu_cores = kzalloc(sizeof(*emu_cores), GFP_KERNEL);
+	if (emu_cores == NULL)
+		panic("Could not allocate cores to node memory");
+	for (i = 0; i < ARRAY_SIZE(emu_cores->to_node_id); i++)
+		emu_cores->to_node_id[i] = NODE_ID_FREE;
+}
+
+/*
+ * Move cores from physical topology into NUMA target topology
+ * and try to keep as much of the physical topology as possible.
+ */
+static struct toptree *toptree_to_numa(struct toptree *phys)
+{
+	static int first = 1;
+	struct toptree *numa;
+	int cores_total;
+
+	cores_total = emu_cores->total + cores_free(phys);
+	emu_cores->per_node_target = cores_total / emu_nodes;
+	numa = toptree_new(TOPTREE_ID_NUMA, emu_nodes);
+	if (first) {
+		toptree_to_numa_first(numa, phys);
+		first = 0;
+	}
+	toptree_to_numa_single(numa, phys, 0);
+	toptree_to_numa_single(numa, phys, 1);
+	toptree_unify_tree(numa);
+
+	WARN_ON(cpumask_weight(&phys->mask));
+	return numa;
+}
+
+/*
+ * Create a toptree out of the physical topology that we got from the hypervisor
+ */
+static struct toptree *toptree_from_topology(void)
+{
+	struct toptree *phys, *node, *book, *mc, *core;
+	struct cpu_topology_s390 *top;
+	int cpu;
+
+	phys = toptree_new(TOPTREE_ID_PHYS, 1);
+
+	for_each_online_cpu(cpu) {
+		top = &per_cpu(cpu_topology, cpu);
+		node = toptree_get_child(phys, 0);
+		book = toptree_get_child(node, top->book_id);
+		mc = toptree_get_child(book, top->socket_id);
+		core = toptree_get_child(mc, top->core_id);
+		if (!book || !mc || !core)
+			panic("NUMA emulation could not allocate memory");
+		cpumask_set_cpu(cpu, &core->mask);
+		toptree_update_mask(mc);
+	}
+	return phys;
+}
+
+/*
+ * Add toptree core to topology and create correct CPU masks
+ */
+static void topology_add_core(struct toptree *core)
+{
+	struct cpu_topology_s390 *top;
+	int cpu;
+
+	for_each_cpu(cpu, &core->mask) {
+		top = &per_cpu(cpu_topology, cpu);
+		cpumask_copy(&top->thread_mask, &core->mask);
+		cpumask_copy(&top->core_mask, &core_mc(core)->mask);
+		cpumask_copy(&top->book_mask, &core_book(core)->mask);
+		cpumask_set_cpu(cpu, node_to_cpumask_map[core_node(core)->id]);
+		top->node_id = core_node(core)->id;
+	}
+}
+
+/*
+ * Apply toptree to topology and create CPU masks
+ */
+static void toptree_to_topology(struct toptree *numa)
+{
+	struct toptree *core;
+	int i;
+
+	/* Clear all node masks */
+	for (i = 0; i < MAX_NUMNODES; i++)
+		cpumask_clear(node_to_cpumask_map[i]);
+
+	/* Rebuild all masks */
+	toptree_for_each(core, numa, CORE)
+		topology_add_core(core);
+}
+
+/*
+ * Show the node to core mapping
+ */
+static void print_node_to_core_map(void)
+{
+	int nid, cid;
+
+	if (!numa_debug_enabled)
+		return;
+	printk(KERN_DEBUG "NUMA node to core mapping\n");
+	for (nid = 0; nid < emu_nodes; nid++) {
+		printk(KERN_DEBUG "  node %3d: ", nid);
+		for (cid = 0; cid < ARRAY_SIZE(emu_cores->to_node_id); cid++) {
+			if (emu_cores->to_node_id[cid] == nid)
+				printk(KERN_CONT "%d ", cid);
+		}
+		printk(KERN_CONT "\n");
+	}
+}
+
+/*
+ * Transfer physical topology into a NUMA topology and modify CPU masks
+ * according to the NUMA topology.
+ *
+ * Must be called with "sched_domains_mutex" lock held.
+ */
+static void emu_update_cpu_topology(void)
+{
+	struct toptree *phys, *numa;
+
+	if (emu_cores == NULL)
+		create_core_to_node_map();
+	phys = toptree_from_topology();
+	numa = toptree_to_numa(phys);
+	toptree_free(phys);
+	toptree_to_topology(numa);
+	toptree_free(numa);
+	print_node_to_core_map();
+}
+
+/*
+ * If emu_size is not set, use CONFIG_EMU_SIZE. Then round to minimum
+ * alignment (needed for memory hotplug).
+ */
+static unsigned long emu_setup_size_adjust(unsigned long size)
+{
+	size = size ? : CONFIG_EMU_SIZE;
+	size = roundup(size, memory_block_size_bytes());
+	return size;
+}
+
+/*
+ * If we have not enough memory for the specified nodes, reduce the node count.
+ */
+static int emu_setup_nodes_adjust(int nodes)
+{
+	int nodes_max;
+
+	nodes_max = memblock.memory.total_size / emu_size;
+	nodes_max = max(nodes_max, 1);
+	if (nodes_max >= nodes)
+		return nodes;
+	pr_warn("Not enough memory for %d nodes, reducing node count\n", nodes);
+	return nodes_max;
+}
+
+/*
+ * Early emu setup
+ */
+static void emu_setup(void)
+{
+	emu_size = emu_setup_size_adjust(emu_size);
+	emu_nodes = emu_setup_nodes_adjust(emu_nodes);
+	pr_info("Creating %d nodes with memory stripe size %ld MB\n",
+		emu_nodes, emu_size >> 20);
+}
+
+/*
+ * Return node id for given page number
+ */
+static int emu_pfn_to_nid(unsigned long pfn)
+{
+	return (pfn / (emu_size >> PAGE_SHIFT)) % emu_nodes;
+}
+
+/*
+ * Return stripe size
+ */
+static unsigned long emu_align(void)
+{
+	return emu_size;
+}
+
+/*
+ * Return distance between two nodes
+ */
+static int emu_distance(int node1, int node2)
+{
+	return (node1 != node2) * EMU_NODE_DIST;
+}
+
+/*
+ * Define callbacks for generic s390 NUMA infrastructure
+ */
+const struct numa_mode numa_mode_emu = {
+	.name = "emu",
+	.setup = emu_setup,
+	.update_cpu_topology = emu_update_cpu_topology,
+	.__pfn_to_nid = emu_pfn_to_nid,
+	.align = emu_align,
+	.distance = emu_distance,
+};
+
+/*
+ * Kernel parameter: emu_nodes=<n>
+ */
+static int __init early_parse_emu_nodes(char *p)
+{
+	int count;
+
+	if (kstrtoint(p, 0, &count) != 0 || count <= 0)
+		return 0;
+	if (count <= 0)
+		return 0;
+	emu_nodes = min(count, MAX_NUMNODES);
+	return 0;
+}
+early_param("emu_nodes", early_parse_emu_nodes);
+
+/*
+ * Kernel parameter: emu_size=[<n>[k|M|G|T]]
+ */
+static int __init early_parse_emu_size(char *p)
+{
+	emu_size = memparse(p, NULL);
+	return 0;
+}
+early_param("emu_size", early_parse_emu_size);