arch/x86/kernel/cpu/scattered.c

   1 /*
   2  *      Routines to identify additional cpu features that are scattered in
   3  *      cpuid space.
   4  */
   5 #include <linux/cpu.h>
   6
   7 #include <asm/pat.h>
   8 #include <asm/processor.h>
   9
  10 #include <asm/apic.h>
  11
  12 struct cpuid_bit {
  13         u16 feature;
  14         u8 reg;
  15         u8 bit;
  16         u32 level;
  17         u32 sub_leaf;
  18 };
  19
  20 enum cpuid_regs {
  21         CR_EAX = 0,
  22         CR_ECX,
  23         CR_EDX,
  24         CR_EBX
  25 };
  26
  27 void init_scattered_cpuid_features(struct cpuinfo_x86 *c)
  28 {
  29         u32 max_level;
  30         u32 regs[4];
  31         const struct cpuid_bit *cb;
  32
  33         static const struct cpuid_bit cpuid_bits[] = {
  34                 { X86_FEATURE_INTEL_PT,         CR_EBX,25, 0x00000007, 0 },
  35                 { X86_FEATURE_APERFMPERF,       CR_ECX, 0, 0x00000006, 0 },
  36                 { X86_FEATURE_EPB,              CR_ECX, 3, 0x00000006, 0 },
  37                 { X86_FEATURE_HW_PSTATE,        CR_EDX, 7, 0x80000007, 0 },
  38                 { X86_FEATURE_CPB,              CR_EDX, 9, 0x80000007, 0 },
  39                 { X86_FEATURE_PROC_FEEDBACK,    CR_EDX,11, 0x80000007, 0 },
  40                 { 0, 0, 0, 0, 0 }
  41         };
  42
  43         for (cb = cpuid_bits; cb->feature; cb++) {
  44
  45                 /* Verify that the level is valid */
  46                 max_level = cpuid_eax(cb->level & 0xffff0000);
  47                 if (max_level < cb->level ||
  48                     max_level > (cb->level | 0xffff))
  49                         continue;
  50
  51                 cpuid_count(cb->level, cb->sub_leaf, &regs[CR_EAX],
  52                             &regs[CR_EBX], &regs[CR_ECX], &regs[CR_EDX]);
  53
  54                 if (regs[cb->reg] & (1 << cb->bit))
  55                         set_cpu_cap(c, cb->feature);
  56         }
  57 }