arch/x86/kernel/cpu/addon_cpuid_features.c

   1
   2 /*
   3  *      Routines to indentify additional cpu features that are scattered in
   4  *      cpuid space.
   5  */
   6
   7 #include <linux/cpu.h>
   8
   9 #include <asm/processor.h>
  10
  11 struct cpuid_bit {
  12         u16 feature;
  13         u8 reg;
  14         u8 bit;
  15         u32 level;
  16 };
  17
  18 enum cpuid_regs {
  19         CR_EAX = 0,
  20         CR_ECX,
  21         CR_EDX,
  22         CR_EBX
  23 };
  24
  25 void __cpuinit init_scattered_cpuid_features(struct cpuinfo_x86 *c)
  26 {
  27         u32 max_level;
  28         u32 regs[4];
  29         const struct cpuid_bit *cb;
  30
  31         static const struct cpuid_bit cpuid_bits[] = {
  32                 { X86_FEATURE_IDA, CR_EAX, 1, 0x00000006 },
  33                 { 0, 0, 0, 0 }
  34         };
  35
  36         for (cb = cpuid_bits; cb->feature; cb++) {
  37
  38                 /* Verify that the level is valid */
  39                 max_level = cpuid_eax(cb->level & 0xffff0000);
  40                 if (max_level < cb->level ||
  41                     max_level > (cb->level | 0xffff))
  42                         continue;
  43
  44                 cpuid(cb->level, &regs[CR_EAX], &regs[CR_EBX],
  45                         &regs[CR_ECX], &regs[CR_EDX]);
  46
  47                 if (regs[cb->reg] & (1 << cb->bit))
  48                         set_cpu_cap(c, cb->feature);
  49         }
  50 }