src/include/cpu/x86/msr_access.h

   1 /* SPDX-License-Identifier: GPL-2.0-only */
   2
   3 #ifndef CPU_X86_MSR_ACCESS_H
   4 #define CPU_X86_MSR_ACCESS_H
   5
   6 #ifndef __ASSEMBLER__
   7 #include <types.h>
   8
   9 typedef union msr_union {
  10         struct {
  11                 unsigned int lo;
  12                 unsigned int hi;
  13         };
  14         uint64_t raw;
  15 } msr_t;
  16 _Static_assert(sizeof(msr_t) == sizeof(uint64_t), "Incorrect size for msr_t");
  17
  18 #if CONFIG(SOC_SETS_MSRS)
  19 msr_t soc_msr_read(unsigned int index);
  20 void soc_msr_write(unsigned int index, msr_t msr);
  21
  22 /* Handle MSR references in the other source code */
  23 static __always_inline msr_t rdmsr(unsigned int index)
  24 {
  25         return soc_msr_read(index);
  26 }
  27
  28 static __always_inline void wrmsr(unsigned int index, msr_t msr)
  29 {
  30         soc_msr_write(index, msr);
  31 }
  32 #else /* CONFIG_SOC_SETS_MSRS */
  33
  34 /* The following functions require the __always_inline due to AMD
  35  * function STOP_CAR_AND_CPU that disables cache as
  36  * RAM, the cache as RAM stack can no longer be used. Called
  37  * functions must be inlined to avoid stack usage. Also, the
  38  * compiler must keep local variables register based and not
  39  * allocated them from the stack. With gcc 4.5.0, some functions
  40  * declared as inline are not being inlined. This patch forces
  41  * these functions to always be inlined by adding the qualifier
  42  * __always_inline to their declaration.
  43  */
  44 static __always_inline msr_t rdmsr(unsigned int index)
  45 {
  46         msr_t result;
  47         __asm__ __volatile__ (
  48                 "rdmsr"
  49                 : "=a" (result.lo), "=d" (result.hi)
  50                 : "c" (index)
  51                 );
  52         return result;
  53 }
  54
  55 static __always_inline void wrmsr(unsigned int index, msr_t msr)
  56 {
  57         __asm__ __volatile__ (
  58                 "wrmsr"
  59                 : /* No outputs */
  60                 : "c" (index), "a" (msr.lo), "d" (msr.hi)
  61                 );
  62 }
  63
  64 #endif /* CONFIG_SOC_SETS_MSRS */
  65 #endif /* __ASSEMBLER__ */
  66 #endif /* CPU_X86_MSR_ACCESS_H */