s390/numa: add core infrastructure

Enable core NUMA support for s390 and add one simple default mode "plain"
that creates one single NUMA node.

This patch contains several changes from Michael Holzheu.

Signed-off-by: Philipp Hachtmann <phacht@linux.vnet.ibm.com>
Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

3 files changed, 204 insertions, 0 deletions

diff --git a/arch/s390/numa/Makefile b/arch/s390/numa/Makefile
new file mode 100644
index 0000000..7e94c8f
--- /dev/null
+++ b/arch/s390/numa/Makefile
@@ -0,0 +1 @@
+obj-y			+= numa.o
diff --git a/arch/s390/numa/numa.c b/arch/s390/numa/numa.c
new file mode 100644
index 0000000..0416a36
--- /dev/null
+++ b/arch/s390/numa/numa.c
@@ -0,0 +1,180 @@
+/*
+ * NUMA support for s390
+ *
+ * Implement NUMA core code.
+ *
+ * Copyright IBM Corp. 2015
+ */
+
+#define KMSG_COMPONENT "numa"
+#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
+
+#include <linux/kernel.h>
+#include <linux/mmzone.h>
+#include <linux/cpumask.h>
+#include <linux/bootmem.h>
+#include <linux/memblock.h>
+#include <linux/slab.h>
+#include <linux/node.h>
+
+#include <asm/numa.h>
+#include "numa_mode.h"
+
+pg_data_t *node_data[MAX_NUMNODES];
+EXPORT_SYMBOL(node_data);
+
+cpumask_var_t node_to_cpumask_map[MAX_NUMNODES];
+EXPORT_SYMBOL(node_to_cpumask_map);
+
+const struct numa_mode numa_mode_plain = {
+	.name = "plain",
+};
+
+static const struct numa_mode *mode = &numa_mode_plain;
+
+int numa_pfn_to_nid(unsigned long pfn)
+{
+	return mode->__pfn_to_nid ? mode->__pfn_to_nid(pfn) : 0;
+}
+
+void numa_update_cpu_topology(void)
+{
+	if (mode->update_cpu_topology)
+		mode->update_cpu_topology();
+}
+
+int __node_distance(int a, int b)
+{
+	return mode->distance ? mode->distance(a, b) : 0;
+}
+
+int numa_debug_enabled;
+
+/*
+ * alloc_node_data() - Allocate node data
+ */
+static __init pg_data_t *alloc_node_data(void)
+{
+	pg_data_t *res;
+
+	res = (pg_data_t *) memblock_alloc(sizeof(pg_data_t), 1);
+	if (!res)
+		panic("Could not allocate memory for node data!\n");
+	memset(res, 0, sizeof(pg_data_t));
+	return res;
+}
+
+/*
+ * numa_setup_memory() - Assign bootmem to nodes
+ *
+ * The memory is first added to memblock without any respect to nodes.
+ * This is fixed before remaining memblock memory is handed over to the
+ * buddy allocator.
+ * An important side effect is that large bootmem allocations might easily
+ * cross node boundaries, which can be needed for large allocations with
+ * smaller memory stripes in each node (i.e. when using NUMA emulation).
+ *
+ * Memory defines nodes:
+ * Therefore this routine also sets the nodes online with memory.
+ */
+static void __init numa_setup_memory(void)
+{
+	unsigned long cur_base, align, end_of_dram;
+	int nid = 0;
+
+	end_of_dram = memblock_end_of_DRAM();
+	align = mode->align ? mode->align() : ULONG_MAX;
+
+	/*
+	 * Step through all available memory and assign it to the nodes
+	 * indicated by the mode implementation.
+	 * All nodes which are seen here will be set online.
+	 */
+	cur_base = 0;
+	do {
+		nid = numa_pfn_to_nid(PFN_DOWN(cur_base));
+		node_set_online(nid);
+		memblock_set_node(cur_base, align, &memblock.memory, nid);
+		cur_base += align;
+	} while (cur_base < end_of_dram);
+
+	/* Allocate and fill out node_data */
+	for (nid = 0; nid < MAX_NUMNODES; nid++)
+		NODE_DATA(nid) = alloc_node_data();
+
+	for_each_online_node(nid) {
+		unsigned long start_pfn, end_pfn;
+		unsigned long t_start, t_end;
+		int i;
+
+		start_pfn = ULONG_MAX;
+		end_pfn = 0;
+		for_each_mem_pfn_range(i, nid, &t_start, &t_end, NULL) {
+			if (t_start < start_pfn)
+				start_pfn = t_start;
+			if (t_end > end_pfn)
+				end_pfn = t_end;
+		}
+		NODE_DATA(nid)->node_spanned_pages = end_pfn - start_pfn;
+		NODE_DATA(nid)->node_id = nid;
+	}
+}
+
+/*
+ * numa_setup() - Earliest initialization
+ *
+ * Assign the mode and call the mode's setup routine.
+ */
+void __init numa_setup(void)
+{
+	pr_info("NUMA mode: %s\n", mode->name);
+	if (mode->setup)
+		mode->setup();
+	numa_setup_memory();
+	memblock_dump_all();
+}
+
+
+/*
+ * numa_init_early() - Initialization initcall
+ *
+ * This runs when only one CPU is online and before the first
+ * topology update is called for by the scheduler.
+ */
+static int __init numa_init_early(void)
+{
+	/* Attach all possible CPUs to node 0 for now. */
+	cpumask_copy(node_to_cpumask_map[0], cpu_possible_mask);
+	return 0;
+}
+early_initcall(numa_init_early);
+
+/*
+ * numa_init_late() - Initialization initcall
+ *
+ * Register NUMA nodes.
+ */
+static int __init numa_init_late(void)
+{
+	int nid;
+
+	for_each_online_node(nid)
+		register_one_node(nid);
+	return 0;
+}
+device_initcall(numa_init_late);
+
+static int __init parse_debug(char *parm)
+{
+	numa_debug_enabled = 1;
+	return 0;
+}
+early_param("numa_debug", parse_debug);
+
+static int __init parse_numa(char *parm)
+{
+	if (strcmp(parm, numa_mode_plain.name) == 0)
+		mode = &numa_mode_plain;
+	return 0;
+}
+early_param("numa", parse_numa);
diff --git a/arch/s390/numa/numa_mode.h b/arch/s390/numa/numa_mode.h
new file mode 100644
index 0000000..7756598
--- /dev/null
+++ b/arch/s390/numa/numa_mode.h
@@ -0,0 +1,23 @@
+/*
+ * NUMA support for s390
+ *
+ * Define declarations used for communication between NUMA mode
+ * implementations and NUMA core functionality.
+ *
+ * Copyright IBM Corp. 2015
+ */
+#ifndef __S390_NUMA_MODE_H
+#define __S390_NUMA_MODE_H
+
+struct numa_mode {
+	char *name;				/* Name of mode */
+	void (*setup)(void);			/* Initizalize mode */
+	void (*update_cpu_topology)(void);	/* Called by topology code */
+	int (*__pfn_to_nid)(unsigned long pfn);	/* PFN to node ID */
+	unsigned long (*align)(void);		/* Minimum node alignment */
+	int (*distance)(int a, int b);		/* Distance between two nodes */
+};
+
+extern const struct numa_mode numa_mode_plain;
+
+#endif /* __S390_NUMA_MODE_H */