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// 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 <linux/bug.h>
#include <linux/limits.h>
#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);
}
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,
®s.eax, ®s.ebx, ®s.ecx, ®s.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;
}
arch_initcall(intel_pconfig_init);
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