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)
  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] __read_mostly = { [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 extern struct genapic apic_physflat;
  35
  36 struct genapic *genapic = &apic_flat;
  37
  38
  39 /*
  40  * Check the APIC IDs in bios_cpu_apicid and choose the APIC mode.
  41  */
  42 void __init clustered_apic_check(void)
  43 {
  44         long i;
  45         u8 clusters, max_cluster;
  46         u8 id;
  47         u8 cluster_cnt[NUM_APIC_CLUSTERS];
  48         int max_apic = 0;
  49
  50 #if defined(CONFIG_ACPI)
  51         /*
  52          * Some x86_64 machines use physical APIC mode regardless of how many
  53          * procs/clusters are present (x86_64 ES7000 is an example).
  54          */
  55         if (acpi_fadt.revision > FADT2_REVISION_ID)
  56                 if (acpi_fadt.force_apic_physical_destination_mode) {
  57                         genapic = &apic_cluster;
  58                         goto print;
  59                 }
  60 #endif
  61
  62         memset(cluster_cnt, 0, sizeof(cluster_cnt));
  63         for (i = 0; i < NR_CPUS; i++) {
  64                 id = bios_cpu_apicid[i];
  65                 if (id == BAD_APICID)
  66                         continue;
  67                 if (id > max_apic)
  68                         max_apic = id;
  69                 cluster_cnt[APIC_CLUSTERID(id)]++;
  70         }
  71
  72         /* Don't use clustered mode on AMD platforms. */
  73         if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD) {
  74                 genapic = &apic_physflat;
  75 #ifndef CONFIG_HOTPLUG_CPU
  76                 /* In the CPU hotplug case we cannot use broadcast mode
  77                    because that opens a race when a CPU is removed.
  78                    Stay at physflat mode in this case.
  79                    It is bad to do this unconditionally though. Once
  80                    we have ACPI platform support for CPU hotplug
  81                    we should detect hotplug capablity from ACPI tables and
  82                    only do this when really needed. -AK */
  83                 if (max_apic <= 8)
  84                         genapic = &apic_flat;
  85 #endif
  86                 goto print;
  87         }
  88
  89         clusters = 0;
  90         max_cluster = 0;
  91
  92         for (i = 0; i < NUM_APIC_CLUSTERS; i++) {
  93                 if (cluster_cnt[i] > 0) {
  94                         ++clusters;
  95                         if (cluster_cnt[i] > max_cluster)
  96                                 max_cluster = cluster_cnt[i];
  97                 }
  98         }
  99
 100         /*
 101          * If we have clusters <= 1 and CPUs <= 8 in cluster 0, then flat mode,
 102          * else if max_cluster <= 4 and cluster_cnt[15] == 0, clustered logical
 103          * else physical mode.
 104          * (We don't use lowest priority delivery + HW APIC IRQ steering, so
 105          * can ignore the clustered logical case and go straight to physical.)
 106          */
 107         if (clusters <= 1 && max_cluster <= 8 && cluster_cnt[0] == max_cluster) {
 108 #ifdef CONFIG_HOTPLUG_CPU
 109                 /* Don't use APIC shortcuts in CPU hotplug to avoid races */
 110                 genapic = &apic_physflat;
 111 #else
 112                 genapic = &apic_flat;
 113 #endif
 114         } else
 115                 genapic = &apic_cluster;
 116
 117 print:
 118         printk(KERN_INFO "Setting APIC routing to %s\n", genapic->name);
 119 }
 120
 121 /* Same for both flat and clustered. */
 122
 123 void send_IPI_self(int vector)
 124 {
 125         __send_IPI_shortcut(APIC_DEST_SELF, vector, APIC_DEST_PHYSICAL);
 126 }