src/cpu/intel/hyperthreading/intel_sibling.c

   1 #include <console/console.h>
   2 #include <cpu/cpu.h>
   3 #include <cpu/x86/lapic.h>
   4 #include <cpu/intel/hyperthreading.h>
   5 #include <device/device.h>
   6 #include <pc80/mc146818rtc.h>
   7 #include <smp/spinlock.h>
   8
   9 static int first_time = 1;
  10 static int disable_siblings = !CONFIG_LOGICAL_CPUS;
  11
  12 void intel_sibling_init(device_t cpu)
  13 {
  14         unsigned i, siblings;
  15         struct cpuid_result result;
  16
  17         /* On the bootstrap processor see if I want sibling cpus enabled */
  18         if (first_time) {
  19                 first_time = 0;
  20                 get_option(&disable_siblings, "hyper_threading");
  21         }
  22         result = cpuid(1);
  23         /* Is hyperthreading supported */
  24         if (!(result.edx & (1 << 28))) {
  25                 return;
  26         }
  27         /* See how many sibling cpus we have */
  28         siblings = (result.ebx >> 16) & 0xff;
  29         if (siblings < 1) {
  30                 siblings = 1;
  31         }
  32
  33 #if 1
  34         printk(BIOS_DEBUG, "CPU: %u %d siblings\n",
  35                 cpu->path.apic.apic_id,
  36                 siblings);
  37 #endif
  38
  39         /* See if I am a sibling cpu */
  40         if (cpu->path.apic.apic_id & (siblings -1)) {
  41                 if (disable_siblings) {
  42                         cpu->enabled = 0;
  43                 }
  44                 return;
  45         }
  46
  47         /* I am the primary cpu start up my siblings */
  48         for(i = 1; i < siblings; i++) {
  49                 struct device_path cpu_path;
  50                 device_t new;
  51                 /* Build the cpu device path */
  52                 cpu_path.type = DEVICE_PATH_APIC;
  53                 cpu_path.apic.apic_id = cpu->path.apic.apic_id + i;
  54
  55
  56                 /* Allocate the new cpu device structure */
  57                 new = alloc_dev(cpu->bus, &cpu_path);
  58
  59                 if (!new) {
  60                         continue;
  61                 }
  62
  63 #if 1
  64                 printk(BIOS_DEBUG, "CPU: %u has sibling %u\n",
  65                         cpu->path.apic.apic_id,
  66                         new->path.apic.apic_id);
  67 #endif
  68                 /* Start the new cpu */
  69                 if (!start_cpu(new)) {
  70                         /* Record the error in cpu? */
  71                         printk(BIOS_ERR, "CPU %u would not start!\n",
  72                                 new->path.apic.apic_id);
  73                 }
  74         }
  75
  76 }
  77