Release 4.18 arch/x86/kernel/cpu/intel_pconfig.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Intel PCONFIG instruction support.
 *
 * Copyright (C) 2017 Intel Corporation
 *
 * Author:
 *      Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
 */

#include <asm/cpufeature.h>
#include <asm/intel_pconfig.h>


#define	PCONFIG_CPUID			0x1b


#define PCONFIG_CPUID_SUBLEAF_MASK	((1 << 12) - 1)

/* Subleaf type (EAX) for PCONFIG CPUID leaf (0x1B) */

enum {
	
PCONFIG_CPUID_SUBLEAF_INVALID	= 0,
	
PCONFIG_CPUID_SUBLEAF_TARGETID	= 1,
};

/* Bitmask of supported targets */

static u64 targets_supported __read_mostly;



int pconfig_target_supported(enum pconfig_target target)
{
	/*
         * We would need to re-think the implementation once we get > 64
         * PCONFIG targets. Spec allows up to 2^32 targets.
         */
	BUILD_BUG_ON(PCONFIG_TARGET_NR >= 64);

	if (WARN_ON_ONCE(target >= 64))
		return 0;
	return targets_supported & (1ULL << target);
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Kirill A. Shutemov
38
100.00%
1
100.00%
Total
38
100.00%
1
100.00%



static int __init intel_pconfig_init(void)
{
	int subleaf;

	if (!boot_cpu_has(X86_FEATURE_PCONFIG))
		return 0;

	/*
         * Scan subleafs of PCONFIG CPUID leaf.
         *
         * Subleafs of the same type need not to be consecutive.
         *
         * Stop on the first invalid subleaf type. All subleafs after the first
         * invalid are invalid too.
         */
	for (subleaf = 0; subleaf < INT_MAX; subleaf++) {
		struct cpuid_regs regs;

		cpuid_count(PCONFIG_CPUID, subleaf,
				&regs.eax, &regs.ebx, &regs.ecx, &regs.edx);

		switch (regs.eax & PCONFIG_CPUID_SUBLEAF_MASK) {
		case PCONFIG_CPUID_SUBLEAF_INVALID:
			/* Stop on the first invalid subleaf */
			goto out;
		case PCONFIG_CPUID_SUBLEAF_TARGETID:
			/* Mark supported PCONFIG targets */
			if (regs.ebx < 64)
				targets_supported |= (1ULL << regs.ebx);
			if (regs.ecx < 64)
				targets_supported |= (1ULL << regs.ecx);
			if (regs.edx < 64)
				targets_supported |= (1ULL << regs.edx);
			break;
		default:
			/* Unknown CPUID.PCONFIG subleaf: ignore */
			break;
		}
	}
out:
	return 0;
}
Contributors
Person
Tokens
Prop
Commits
CommitProp
Kirill A. Shutemov
154
100.00%
1
100.00%
Total
154
100.00%
1
100.00%

arch_initcall(intel_pconfig_init);
Overall Contributors
Person
Tokens
Prop
Commits
CommitProp
Kirill A. Shutemov
231
100.00%
1
100.00%
Total
231
100.00%
1
100.00%
Directory: arch/x86/kernel/cpu

Information contained on this website is for historical information purposes only and does not indicate or represent copyright ownership.