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/*
* This file is part of the coreboot project.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; version 2 of the License.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#include <console/console.h>
#include <cpu/x86/lapic.h>
#include <cpu/intel/hyperthreading.h>
#include <device/device.h>
#include <pc80/mc146818rtc.h>
#include <smp/spinlock.h>
#include <assert.h>
#if IS_ENABLED(CONFIG_PARALLEL_CPU_INIT)
#error Intel hyper-threading requires serialized CPU init
#endif
static int first_time = 1;
static int disable_siblings = !CONFIG_LOGICAL_CPUS;
/* Return true if running thread does not have the smallest lapic ID
* within a CPU core.
*/
int intel_ht_sibling(void)
{
unsigned int core_ids, apic_ids, threads;
apic_ids = 1;
if (cpuid_eax(0) >= 1)
apic_ids = (cpuid_ebx(1) >> 16) & 0xff;
if (apic_ids < 1)
apic_ids = 1;
core_ids = 1;
if (cpuid_eax(0) >= 4) {
struct cpuid_result result;
result = cpuid_ext(4, 0);
core_ids += (result.eax >> 26) & 0x3f;
}
threads = (apic_ids / core_ids);
return !!(lapicid() & (threads-1));
}
void intel_sibling_init(struct device *cpu)
{
unsigned int i, siblings;
struct cpuid_result result;
/* On the bootstrap processor see if I want sibling cpus enabled */
if (first_time) {
first_time = 0;
get_option(&disable_siblings, "hyper_threading");
}
result = cpuid(1);
/* Is hyperthreading supported */
if (!(result.edx & (1 << 28)))
return;
/* See how many sibling cpus we have */
siblings = (result.ebx >> 16) & 0xff;
if (siblings < 1)
siblings = 1;
printk(BIOS_DEBUG, "CPU: %u %d siblings\n",
cpu->path.apic.apic_id,
siblings);
/* See if I am a sibling cpu */
if (cpu->path.apic.apic_id & (siblings - 1)) {
if (disable_siblings)
cpu->enabled = 0;
return;
}
/* I am the primary CPU start up my siblings */
for (i = 1; i < siblings; i++) {
struct device_path cpu_path;
struct device *new;
/* Build the CPU device path */
cpu_path.type = DEVICE_PATH_APIC;
cpu_path.apic.apic_id = cpu->path.apic.apic_id + i;
/* Allocate new CPU device structure iff sibling CPU
* was not in static device tree.
*/
new = alloc_find_dev(cpu->bus, &cpu_path);
if (!new)
continue;
printk(BIOS_DEBUG, "CPU: %u has sibling %u\n",
cpu->path.apic.apic_id,
new->path.apic.apic_id);
}
}
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