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 #if defined(CONFIG_ACPI_BUS)
  24 #include <acpi/acpi_bus.h>
  25 #endif
  26
  27 /* which logical CPU number maps to which CPU (physical APIC ID) */
  28 u8 x86_cpu_to_apicid[NR_CPUS] = { [0 ... NR_CPUS-1] = BAD_APICID };
  29 EXPORT_SYMBOL(x86_cpu_to_apicid);
  30 u8 x86_cpu_to_log_apicid[NR_CPUS] = { [0 ... NR_CPUS-1] = BAD_APICID };
  31
  32 extern struct genapic apic_cluster;
  33 extern struct genapic apic_flat;
  34
  35 struct genapic *genapic = &apic_flat;
  36
  37
  38 /*
  39  * Check the APIC IDs in bios_cpu_apicid and choose the APIC mode.
  40  */
  41 void __init clustered_apic_check(void)
  42 {
  43         long i;
  44         u8 clusters, max_cluster;
  45         u8 id;
  46         u8 cluster_cnt[NUM_APIC_CLUSTERS];
  47
  48         if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD) {
  49                 /* AMD always uses flat mode right now */
  50                 genapic = &apic_flat;
  51                 goto print;
  52         }
  53
  54 #if defined(CONFIG_ACPI_BUS)
  55         /*
  56          * Some x86_64 machines use physical APIC mode regardless of how many
  57          * procs/clusters are present (x86_64 ES7000 is an example).
  58          */
  59         if (acpi_fadt.revision > FADT2_REVISION_ID)
  60                 if (acpi_fadt.force_apic_physical_destination_mode) {
  61                         genapic = &apic_cluster;
  62                         goto print;
  63                 }
  64 #endif
  65
  66         memset(cluster_cnt, 0, sizeof(cluster_cnt));
  67
  68         for (i = 0; i < NR_CPUS; i++) {
  69                 id = bios_cpu_apicid[i];
  70                 if (id != BAD_APICID)
  71                         cluster_cnt[APIC_CLUSTERID(id)]++;
  72         }
  73
  74         clusters = 0;
  75         max_cluster = 0;
  76         for (i = 0; i < NUM_APIC_CLUSTERS; i++) {
  77                 if (cluster_cnt[i] > 0) {
  78                         ++clusters;
  79                         if (cluster_cnt[i] > max_cluster)
  80                                 max_cluster = cluster_cnt[i];
  81                 }
  82         }
  83
  84         /*
  85          * If we have clusters <= 1 and CPUs <= 8 in cluster 0, then flat mode,
  86          * else if max_cluster <= 4 and cluster_cnt[15] == 0, clustered logical
  87          * else physical mode.
  88          * (We don't use lowest priority delivery + HW APIC IRQ steering, so
  89          * can ignore the clustered logical case and go straight to physical.)
  90          */
  91         if (clusters <= 1 && max_cluster <= 8 && cluster_cnt[0] == max_cluster)
  92                 genapic = &apic_flat;
  93         else
  94                 genapic = &apic_cluster;
  95
  96 print:
  97         printk(KERN_INFO "Setting APIC routing to %s\n", genapic->name);
  98 }
  99
 100 /* Same for both flat and clustered. */
 101
 102 void send_IPI_self(int vector)
 103 {
 104         __send_IPI_shortcut(APIC_DEST_SELF, vector, APIC_DEST_PHYSICAL);
 105 }