1// SPDX-License-Identifier: GPL-2.0 2/* 3 * Intel PCONFIG instruction support. 4 * 5 * Copyright (C) 2017 Intel Corporation 6 * 7 * Author: 8 * Kirill A. Shutemov <kirill.shutemov@linux.intel.com> 9 */ 10#include <linux/bug.h> 11#include <linux/limits.h> 12 13#include <asm/cpufeature.h> 14#include <asm/intel_pconfig.h> 15 16#define PCONFIG_CPUID 0x1b 17 18#define PCONFIG_CPUID_SUBLEAF_MASK ((1 << 12) - 1) 19 20/* Subleaf type (EAX) for PCONFIG CPUID leaf (0x1B) */ 21enum { 22 PCONFIG_CPUID_SUBLEAF_INVALID = 0, 23 PCONFIG_CPUID_SUBLEAF_TARGETID = 1, 24}; 25 26/* Bitmask of supported targets */ 27static u64 targets_supported __read_mostly; 28 29int pconfig_target_supported(enum pconfig_target target) 30{ 31 /* 32 * We would need to re-think the implementation once we get > 64 33 * PCONFIG targets. Spec allows up to 2^32 targets. 34 */ 35 BUILD_BUG_ON(PCONFIG_TARGET_NR >= 64); 36 37 if (WARN_ON_ONCE(target >= 64)) 38 return 0; 39 return targets_supported & (1ULL << target); 40} 41 42static int __init intel_pconfig_init(void) 43{ 44 int subleaf; 45 46 if (!boot_cpu_has(X86_FEATURE_PCONFIG)) 47 return 0; 48 49 /* 50 * Scan subleafs of PCONFIG CPUID leaf. 51 * 52 * Subleafs of the same type need not to be consecutive. 53 * 54 * Stop on the first invalid subleaf type. All subleafs after the first 55 * invalid are invalid too. 56 */ 57 for (subleaf = 0; subleaf < INT_MAX; subleaf++) { 58 struct cpuid_regs regs; 59 60 cpuid_count(PCONFIG_CPUID, subleaf, 61 ®s.eax, ®s.ebx, ®s.ecx, ®s.edx); 62 63 switch (regs.eax & PCONFIG_CPUID_SUBLEAF_MASK) { 64 case PCONFIG_CPUID_SUBLEAF_INVALID: 65 /* Stop on the first invalid subleaf */ 66 goto out; 67 case PCONFIG_CPUID_SUBLEAF_TARGETID: 68 /* Mark supported PCONFIG targets */ 69 if (regs.ebx < 64) 70 targets_supported |= (1ULL << regs.ebx); 71 if (regs.ecx < 64) 72 targets_supported |= (1ULL << regs.ecx); 73 if (regs.edx < 64) 74 targets_supported |= (1ULL << regs.edx); 75 break; 76 default: 77 /* Unknown CPUID.PCONFIG subleaf: ignore */ 78 break; 79 } 80 } 81out: 82 return 0; 83} 84arch_initcall(intel_pconfig_init); 85