Release 4.14 arch/x86/kernel/cpu/topology.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Check for extended topology enumeration cpuid leaf 0xb and if it
 * exists, use it for populating initial_apicid and cpu topology
 * detection.
 */

#include <linux/cpu.h>
#include <asm/apic.h>
#include <asm/pat.h>
#include <asm/processor.h>

/* leaf 0xb SMT level */

#define SMT_LEVEL	0

/* leaf 0xb sub-leaf types */

#define INVALID_TYPE	0

#define SMT_TYPE	1

#define CORE_TYPE	2


#define LEAFB_SUBTYPE(ecx)		(((ecx) >> 8) & 0xff)

#define BITS_SHIFT_NEXT_LEVEL(eax)	((eax) & 0x1f)

#define LEVEL_MAX_SIBLINGS(ebx)		((ebx) & 0xffff)

/*
 * Check for extended topology enumeration cpuid leaf 0xb and if it
 * exists, use it for populating initial_apicid and cpu topology
 * detection.
 */


void detect_extended_topology(struct cpuinfo_x86 *c)
{
#ifdef CONFIG_SMP
	unsigned int eax, ebx, ecx, edx, sub_index;
	unsigned int ht_mask_width, core_plus_mask_width;
	unsigned int core_select_mask, core_level_siblings;
	static bool printed;

	if (c->cpuid_level < 0xb)
		return;

	cpuid_count(0xb, SMT_LEVEL, &eax, &ebx, &ecx, &edx);

	/*
         * check if the cpuid leaf 0xb is actually implemented.
         */
	if (ebx == 0 || (LEAFB_SUBTYPE(ecx) != SMT_TYPE))
		return;

	set_cpu_cap(c, X86_FEATURE_XTOPOLOGY);

	/*
         * initial apic id, which also represents 32-bit extended x2apic id.
         */
	c->initial_apicid = edx;

	/*
         * Populate HT related information from sub-leaf level 0.
         */
	core_level_siblings = smp_num_siblings = LEVEL_MAX_SIBLINGS(ebx);
	core_plus_mask_width = ht_mask_width = BITS_SHIFT_NEXT_LEVEL(eax);

	sub_index = 1;
	do {
		cpuid_count(0xb, sub_index, &eax, &ebx, &ecx, &edx);

		/*
                 * Check for the Core type in the implemented sub leaves.
                 */
		if (LEAFB_SUBTYPE(ecx) == CORE_TYPE) {
			core_level_siblings = LEVEL_MAX_SIBLINGS(ebx);
			core_plus_mask_width = BITS_SHIFT_NEXT_LEVEL(eax);
			break;
		}

		sub_index++;
	} while (LEAFB_SUBTYPE(ecx) != INVALID_TYPE);

	core_select_mask = (~(-1 << core_plus_mask_width)) >> ht_mask_width;

	c->cpu_core_id = apic->phys_pkg_id(c->initial_apicid, ht_mask_width)
						 & core_select_mask;
	c->phys_proc_id = apic->phys_pkg_id(c->initial_apicid, core_plus_mask_width);
	/*
         * Reinit the apicid, now that we have extended initial_apicid.
         */
	c->apicid = apic->phys_pkg_id(c->initial_apicid, 0);

	c->x86_max_cores = (core_level_siblings / smp_num_siblings);

	if (!printed) {
		pr_info("CPU: Physical Processor ID: %d\n",
		       c->phys_proc_id);
		if (c->x86_max_cores > 1)
			pr_info("CPU: Processor Core ID: %d\n",
			       c->cpu_core_id);
		printed = 1;
	}
	return;
#endif
}
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Suresh B. Siddha
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Mike Travis
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1
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Ingo Molnar
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Total
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315
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4.27%
1
9.09%
Ingo Molnar
7
1.99%
2
18.18%
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5
1.42%
1
9.09%
H. Peter Anvin
4
1.14%
1
9.09%
Thomas Gleixner
2
0.57%
1
9.09%
Chen Yucong
2
0.57%
1
9.09%
Greg Kroah-Hartman
1
0.28%
1
9.09%
Total
351
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Directory: arch/x86/kernel/cpu

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