diff options
Diffstat (limited to 'arch/x86/kernel/cpu/intel_pconfig.c')
-rw-r--r-- | arch/x86/kernel/cpu/intel_pconfig.c | 82 |
1 files changed, 82 insertions, 0 deletions
diff --git a/arch/x86/kernel/cpu/intel_pconfig.c b/arch/x86/kernel/cpu/intel_pconfig.c new file mode 100644 index 0000000000..0771a905b2 --- /dev/null +++ b/arch/x86/kernel/cpu/intel_pconfig.c @@ -0,0 +1,82 @@ +// 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); +} + +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); |