arch/x86_64/kernel/genapic.c

   1 /*
   2  * Copyright 2004 James Cleverdon, IBM.
   3  * Subject to the GNU Public License, v.2
   4  *
   5  * Generic APIC sub-arch probe layer.
   6  *
   7  * Hacked for x86-64 by James Cleverdon from i386 architecture code by
   8  * Martin Bligh, Andi Kleen, James Bottomley, John Stultz, and
   9  * James Cleverdon.
  10  */
  11 #include <linux/config.h>
  12 #include <linux/threads.h>
  13 #include <linux/cpumask.h>
  14 #include <linux/string.h>
  15 #include <linux/kernel.h>
  16 #include <linux/ctype.h>
  17 #include <linux/init.h>
  18 #include <linux/module.h>
  19
  20 #include <asm/smp.h>
  21 #include <asm/ipi.h>
  22
  23 /* which logical CPU number maps to which CPU (physical APIC ID) */
  24 u8 x86_cpu_to_apicid[NR_CPUS] = { [0 ... NR_CPUS-1] = BAD_APICID };
  25 EXPORT_SYMBOL(x86_cpu_to_apicid);
  26 u8 x86_cpu_to_log_apicid[NR_CPUS] = { [0 ... NR_CPUS-1] = BAD_APICID };
  27
  28 extern struct genapic apic_cluster;
  29 extern struct genapic apic_flat;
  30
  31 struct genapic *genapic = &apic_flat;
  32
  33
  34 /*
  35  * Check the APIC IDs in bios_cpu_apicid and choose the APIC mode.
  36  */
  37 void __init clustered_apic_check(void)
  38 {
  39         long i;
  40         u8 clusters, max_cluster;
  41         u8 id;
  42         u8 cluster_cnt[NUM_APIC_CLUSTERS];
  43
  44         if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD) {
  45                 /* AMD always uses flat mode right now */
  46                 genapic = &apic_flat;
  47                 goto print;
  48         }
  49
  50         memset(cluster_cnt, 0, sizeof(cluster_cnt));
  51
  52         for (i = 0; i < NR_CPUS; i++) {
  53                 id = bios_cpu_apicid[i];
  54                 if (id != BAD_APICID)
  55                         cluster_cnt[APIC_CLUSTERID(id)]++;
  56         }
  57
  58         clusters = 0;
  59         max_cluster = 0;
  60         for (i = 0; i < NUM_APIC_CLUSTERS; i++) {
  61                 if (cluster_cnt[i] > 0) {
  62                         ++clusters;
  63                         if (cluster_cnt[i] > max_cluster)
  64                                 max_cluster = cluster_cnt[i];
  65                 }
  66         }
  67
  68         /*
  69          * If we have clusters <= 1 and CPUs <= 8 in cluster 0, then flat mode,
  70          * else if max_cluster <= 4 and cluster_cnt[15] == 0, clustered logical
  71          * else physical mode.
  72          * (We don't use lowest priority delivery + HW APIC IRQ steering, so
  73          * can ignore the clustered logical case and go straight to physical.)
  74          */
  75         if (clusters <= 1 && max_cluster <= 8 && cluster_cnt[0] == max_cluster)
  76                 genapic = &apic_flat;
  77         else
  78                 genapic = &apic_cluster;
  79
  80 print:
  81         printk(KERN_INFO "Setting APIC routing to %s\n", genapic->name);
  82 }
  83
  84 /* Same for both flat and clustered. */
  85
  86 void send_IPI_self(int vector)
  87 {
  88         __send_IPI_shortcut(APIC_DEST_SELF, vector, APIC_DEST_PHYSICAL);
  89 }