x86-64, NUMA: Implement generic node distance handling

Node distance either used direct node comparison, ACPI PXM comparison
or ACPI SLIT table lookup.  This patch implements generic node
distance handling.  NUMA init methods can call numa_set_distance() to
set distance between nodes and the common __node_distance()
implementation will report the set distance.

Due to the way NUMA emulation is implemented, the generic node
distance handling is used only when emulation is not used.  Later
patches will update NUMA emulation to use the generic distance
mechanism.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Cyrill Gorcunov <gorcunov@gmail.com>
Cc: Shaohui Zheng <shaohui.zheng@intel.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: H. Peter Anvin <hpa@linux.intel.com>

2 files changed, 106 insertions, 16 deletions

diff --git a/arch/x86/mm/numa_64.c b/arch/x86/mm/numa_64.c
index 8b1f178a866e..a3621f2953d6 100644
--- a/arch/x86/mm/numa_64.c
+++ b/arch/x86/mm/numa_64.c
@@ -45,6 +45,13 @@ static unsigned long __initdata nodemap_size;
 
 static struct numa_meminfo numa_meminfo __initdata;
 
+static int numa_distance_cnt;
+static u8 *numa_distance;
+
+#ifdef CONFIG_NUMA_EMU
+static bool numa_emu_dist;
+#endif
+
 /*
  * Given a shift value, try to populate memnodemap[]
  * Returns :
@@ -357,6 +364,92 @@ static void __init numa_nodemask_from_meminfo(nodemask_t *nodemask,
 }
 
 /*
+ * Reset distance table.  The current table is freed.  The next
+ * numa_set_distance() call will create a new one.
+ */
+static void __init numa_reset_distance(void)
+{
+	size_t size;
+
+	size = numa_distance_cnt * sizeof(numa_distance[0]);
+	memblock_x86_free_range(__pa(numa_distance),
+				__pa(numa_distance) + size);
+	numa_distance = NULL;
+	numa_distance_cnt = 0;
+}
+
+/*
+ * Set the distance between node @from to @to to @distance.  If distance
+ * table doesn't exist, one which is large enough to accomodate all the
+ * currently known nodes will be created.
+ */
+void __init numa_set_distance(int from, int to, int distance)
+{
+	if (!numa_distance) {
+		nodemask_t nodes_parsed;
+		size_t size;
+		int i, j, cnt = 0;
+		u64 phys;
+
+		/* size the new table and allocate it */
+		nodes_parsed = numa_nodes_parsed;
+		numa_nodemask_from_meminfo(&nodes_parsed, &numa_meminfo);
+
+		for_each_node_mask(i, nodes_parsed)
+			cnt = i;
+		size = ++cnt * sizeof(numa_distance[0]);
+
+		phys = memblock_find_in_range(0,
+					      (u64)max_pfn_mapped << PAGE_SHIFT,
+					      size, PAGE_SIZE);
+		if (phys == MEMBLOCK_ERROR) {
+			pr_warning("NUMA: Warning: can't allocate distance table!\n");
+			/* don't retry until explicitly reset */
+			numa_distance = (void *)1LU;
+			return;
+		}
+		memblock_x86_reserve_range(phys, phys + size, "NUMA DIST");
+
+		numa_distance = __va(phys);
+		numa_distance_cnt = cnt;
+
+		/* fill with the default distances */
+		for (i = 0; i < cnt; i++)
+			for (j = 0; j < cnt; j++)
+				numa_distance[i * cnt + j] = i == j ?
+					LOCAL_DISTANCE : REMOTE_DISTANCE;
+		printk(KERN_DEBUG "NUMA: Initialized distance table, cnt=%d\n", cnt);
+	}
+
+	if (from >= numa_distance_cnt || to >= numa_distance_cnt) {
+		printk_once(KERN_DEBUG "NUMA: Debug: distance out of bound, from=%d to=%d distance=%d\n",
+			    from, to, distance);
+		return;
+	}
+
+	if ((u8)distance != distance ||
+	    (from == to && distance != LOCAL_DISTANCE)) {
+		pr_warn_once("NUMA: Warning: invalid distance parameter, from=%d to=%d distance=%d\n",
+			     from, to, distance);
+		return;
+	}
+
+	numa_distance[from * numa_distance_cnt + to] = distance;
+}
+
+int __node_distance(int from, int to)
+{
+#if defined(CONFIG_ACPI_NUMA) && defined(CONFIG_NUMA_EMU)
+	if (numa_emu_dist)
+		return acpi_emu_node_distance(from, to);
+#endif
+	if (from >= numa_distance_cnt || to >= numa_distance_cnt)
+		return from == to ? LOCAL_DISTANCE : REMOTE_DISTANCE;
+	return numa_distance[from * numa_distance_cnt + to];
+}
+EXPORT_SYMBOL(__node_distance);
+
+/*
  * Sanity check to catch more bad NUMA configurations (they are amazingly
  * common).  Make sure the nodes cover all memory.
  */
@@ -826,6 +919,7 @@ static int __init numa_emulation(unsigned long start_pfn,
 	setup_physnodes(addr, max_addr);
 	fake_physnodes(acpi, amd, num_nodes);
 	numa_init_array();
+	numa_emu_dist = true;
 	return 0;
 }
 #endif /* CONFIG_NUMA_EMU */
@@ -869,6 +963,7 @@ void __init initmem_init(void)
 		nodes_clear(node_online_map);
 		memset(&numa_meminfo, 0, sizeof(numa_meminfo));
 		remove_all_active_ranges();
+		numa_reset_distance();
 
 		if (numa_init[i]() < 0)
 			continue;
diff --git a/arch/x86/mm/srat_64.c b/arch/x86/mm/srat_64.c
index 4f8e6cde9bf6..d2f53f35d86a 100644
--- a/arch/x86/mm/srat_64.c
+++ b/arch/x86/mm/srat_64.c
@@ -50,9 +50,16 @@ static __init inline int srat_disabled(void)
 /* Callback for SLIT parsing */
 void __init acpi_numa_slit_init(struct acpi_table_slit *slit)
 {
+	int i, j;
 	unsigned length;
 	unsigned long phys;
 
+	for (i = 0; i < slit->locality_count; i++)
+		for (j = 0; j < slit->locality_count; j++)
+			numa_set_distance(pxm_to_node(i), pxm_to_node(j),
+				slit->entry[slit->locality_count * i + j]);
+
+	/* acpi_slit is used only by emulation */
 	length = slit->header.length;
 	phys = memblock_find_in_range(0, max_pfn_mapped<<PAGE_SHIFT, length,
 		 PAGE_SIZE);
@@ -313,29 +320,17 @@ void __init acpi_fake_nodes(const struct bootnode *fake_nodes, int num_nodes)
 			node_set(i, numa_nodes_parsed);
 }
 
-static int null_slit_node_compare(int a, int b)
-{
-	return node_to_pxm(a) == node_to_pxm(b);
-}
-#else
-static int null_slit_node_compare(int a, int b)
-{
-	return a == b;
-}
-#endif /* CONFIG_NUMA_EMU */
-
-int __node_distance(int a, int b)
+int acpi_emu_node_distance(int a, int b)
 {
 	int index;
 
 	if (!acpi_slit)
-		return null_slit_node_compare(a, b) ? LOCAL_DISTANCE :
-						      REMOTE_DISTANCE;
+		return node_to_pxm(a) == node_to_pxm(b) ?
+			LOCAL_DISTANCE : REMOTE_DISTANCE;
 	index = acpi_slit->locality_count * node_to_pxm(a);
 	return acpi_slit->entry[index + node_to_pxm(b)];
 }
-
-EXPORT_SYMBOL(__node_distance);
+#endif /* CONFIG_NUMA_EMU */
 
 #if defined(CONFIG_MEMORY_HOTPLUG_SPARSE) || defined(CONFIG_ACPI_HOTPLUG_MEMORY)
 int memory_add_physaddr_to_nid(u64 start)