Line data    Source code

       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           0 : 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           0 :         BUILD_BUG_ON(PCONFIG_TARGET_NR >= 64);
      34             : 
      35           0 :         if (WARN_ON_ONCE(target >= 64))
      36             :                 return 0;
      37           0 :         return targets_supported & (1ULL << target);
      38             : }
      39             : 
      40           1 : static int __init intel_pconfig_init(void)
      41             : {
      42           1 :         int subleaf;
      43             : 
      44           1 :         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           0 :         for (subleaf = 0; subleaf < INT_MAX; subleaf++) {
      56           0 :                 struct cpuid_regs regs;
      57             : 
      58           0 :                 cpuid_count(PCONFIG_CPUID, subleaf,
      59             :                                 &regs.eax, &regs.ebx, &regs.ecx, &regs.edx);
      60             : 
      61           0 :                 switch (regs.eax & PCONFIG_CPUID_SUBLEAF_MASK) {
      62           0 :                 case PCONFIG_CPUID_SUBLEAF_INVALID:
      63             :                         /* Stop on the first invalid subleaf */
      64           0 :                         goto out;
      65           0 :                 case PCONFIG_CPUID_SUBLEAF_TARGETID:
      66             :                         /* Mark supported PCONFIG targets */
      67           0 :                         if (regs.ebx < 64)
      68           0 :                                 targets_supported |= (1ULL << regs.ebx);
      69           0 :                         if (regs.ecx < 64)
      70           0 :                                 targets_supported |= (1ULL << regs.ecx);
      71           0 :                         if (regs.edx < 64)
      72           0 :                                 targets_supported |= (1ULL << regs.edx);
      73             :                         break;
      74             :                 default:
      75             :                         /* Unknown CPUID.PCONFIG subleaf: ignore */
      76             :                         break;
      77             :                 }
      78             :         }
      79           0 : out:
      80             :         return 0;
      81             : }
      82             : arch_initcall(intel_pconfig_init);