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