[PATCH] x86-64: Don't enable NUMA for a single node in K8 NUMA scanning

[mirror_ubuntu-artful-kernel.git] / arch / x86_64 / mm / k8topology.c

/* 
 * AMD K8 NUMA support.
 * Discover the memory map and associated nodes.
 * 
 * This version reads it directly from the K8 northbridge.
 * 
 * Copyright 2002,2003 Andi Kleen, SuSE Labs.
 */
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/string.h>
#include <linux/module.h>
#include <linux/nodemask.h>
#include <asm/io.h>
#include <linux/pci_ids.h>
#include <asm/types.h>
#include <asm/mmzone.h>
#include <asm/proto.h>
#include <asm/e820.h>
#include <asm/pci-direct.h>
#include <asm/numa.h>

static __init int find_northbridge(void)
{
	int num; 

	for (num = 0; num < 32; num++) { 
		u32 header;
		
		header = read_pci_config(0, num, 0, 0x00);  
		if (header != (PCI_VENDOR_ID_AMD | (0x1100<<16)))
			continue; 	

		header = read_pci_config(0, num, 1, 0x00); 
		if (header != (PCI_VENDOR_ID_AMD | (0x1101<<16)))
			continue;	
		return num; 
	} 

	return -1; 	
}

int __init k8_scan_nodes(unsigned long start, unsigned long end)
{ 
	unsigned long prevbase;
	struct bootnode nodes[8];
	int nodeid, i, nb; 
	unsigned char nodeids[8];
	int found = 0;
	u32 reg;
	unsigned numnodes;
	unsigned dualcore = 0;

	if (!early_pci_allowed())
		return -1;

	nb = find_northbridge(); 
	if (nb < 0) 
		return nb;

	printk(KERN_INFO "Scanning NUMA topology in Northbridge %d\n", nb); 

	reg = read_pci_config(0, nb, 0, 0x60); 
	numnodes = ((reg >> 4) & 0xF) + 1;
	if (numnodes <= 1)
		return -1;

	printk(KERN_INFO "Number of nodes %d\n", numnodes);

	memset(&nodes,0,sizeof(nodes)); 
	prevbase = 0;
	for (i = 0; i < 8; i++) { 
		unsigned long base,limit; 
		u32 nodeid;
		
		/* Undefined before E stepping, but hopefully 0 */
		dualcore |= ((read_pci_config(0, nb, 3, 0xe8) >> 12) & 3) == 1;
		base = read_pci_config(0, nb, 1, 0x40 + i*8);
		limit = read_pci_config(0, nb, 1, 0x44 + i*8);

		nodeid = limit & 7; 
		nodeids[i] = nodeid;
		if ((base & 3) == 0) { 
			if (i < numnodes)
				printk("Skipping disabled node %d\n", i); 
			continue;
		} 
		if (nodeid >= numnodes) {
			printk("Ignoring excess node %d (%lx:%lx)\n", nodeid,
			       base, limit); 
			continue;
		} 

		if (!limit) { 
			printk(KERN_INFO "Skipping node entry %d (base %lx)\n", i,
			       base);
			continue;
		}
		if ((base >> 8) & 3 || (limit >> 8) & 3) {
			printk(KERN_ERR "Node %d using interleaving mode %lx/%lx\n", 
			       nodeid, (base>>8)&3, (limit>>8) & 3); 
			return -1; 
		}	
		if (node_isset(nodeid, node_possible_map)) {
			printk(KERN_INFO "Node %d already present. Skipping\n", 
			       nodeid);
			continue;
		}

		limit >>= 16; 
		limit <<= 24; 
		limit |= (1<<24)-1;
		limit++;

		if (limit > end_pfn << PAGE_SHIFT)
			limit = end_pfn << PAGE_SHIFT;
		if (limit <= base)
			continue; 
			
		base >>= 16;
		base <<= 24; 

		if (base < start) 
			base = start; 
		if (limit > end) 
			limit = end; 
		if (limit == base) { 
			printk(KERN_ERR "Empty node %d\n", nodeid); 
			continue; 
		}
		if (limit < base) { 
			printk(KERN_ERR "Node %d bogus settings %lx-%lx.\n",
			       nodeid, base, limit); 			       
			continue;
		} 
		
		/* Could sort here, but pun for now. Should not happen anyroads. */
		if (prevbase > base) { 
			printk(KERN_ERR "Node map not sorted %lx,%lx\n",
			       prevbase,base);
			return -1;
		}
			
		printk(KERN_INFO "Node %d MemBase %016lx Limit %016lx\n", 
		       nodeid, base, limit); 
		
		found++;
		
		nodes[nodeid].start = base; 
		nodes[nodeid].end = limit;
		e820_register_active_regions(nodeid,
				nodes[nodeid].start >> PAGE_SHIFT,
				nodes[nodeid].end >> PAGE_SHIFT);

		prevbase = base;

		node_set(nodeid, node_possible_map);
	} 

	if (!found)
		return -1; 

	memnode_shift = compute_hash_shift(nodes, 8);
	if (memnode_shift < 0) { 
		printk(KERN_ERR "No NUMA node hash function found. Contact maintainer\n"); 
		return -1; 
	} 
	printk(KERN_INFO "Using node hash shift of %d\n", memnode_shift); 

	for (i = 0; i < 8; i++) {
		if (nodes[i].start != nodes[i].end) { 
			nodeid = nodeids[i];
			apicid_to_node[nodeid << dualcore] = i;
			apicid_to_node[(nodeid << dualcore) + dualcore] = i;
			setup_node_bootmem(i, nodes[i].start, nodes[i].end); 
		} 
	}

	numa_init_array();
	return 0;
}