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/* SPDX-License-Identifier: GPL-2.0-only */
#include <cpu/cpu.h>
#include <cpu/intel/common/common.h>
#include <types.h>
bool intel_ht_supported(void)
{
/* Is HyperThreading supported? */
return !!(cpuid_edx(1) & CPUID_FEAURE_HTT);
}
/*
* Return true if running thread does not have the smallest lapic ID
* within a CPU core.
*/
bool intel_ht_sibling(void)
{
struct cpuid_result result;
unsigned int core_ids, apic_ids;
unsigned int max_leaf;
uint32_t initial_lapicid, threads;
if (!intel_ht_supported())
return false;
max_leaf = cpuid_get_max_func();
/* Detect from 32-bit X2APIC ID. */
if (max_leaf >= 0xb) {
result = cpuid_ext(0xb, 0);
threads = 1 << (result.eax & 0x1f);
initial_lapicid = result.edx;
return initial_lapicid % threads > 0;
}
/* Detect from 8-bit XAPIC ID. */
result = cpuid_ext(0x1, 0);
initial_lapicid = result.ebx >> 24;
apic_ids = (result.ebx >> 16) & 0xff;
if (apic_ids == 0)
apic_ids = 1;
core_ids = 1;
if (max_leaf >= 4) {
result = cpuid_ext(4, 0);
core_ids += (result.eax >> 26) & 0x3f;
}
threads = (apic_ids / core_ids);
return initial_lapicid % threads > 0;
}
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