arch/x86/lib/msr-on-cpu.c

   1 #include <linux/module.h>
   2 #include <linux/preempt.h>
   3 #include <linux/smp.h>
   4 #include <asm/msr.h>
   5
   6 struct msr_info {
   7         u32 msr_no;
   8         u32 l, h;
   9         int err;
  10 };
  11
  12 static void __rdmsr_on_cpu(void *info)
  13 {
  14         struct msr_info *rv = info;
  15
  16         rdmsr(rv->msr_no, rv->l, rv->h);
  17 }
  18
  19 static void __rdmsr_safe_on_cpu(void *info)
  20 {
  21         struct msr_info *rv = info;
  22
  23         rv->err = rdmsr_safe(rv->msr_no, &rv->l, &rv->h);
  24 }
  25
  26 static int _rdmsr_on_cpu(unsigned int cpu, u32 msr_no, u32 *l, u32 *h, int safe)
  27 {
  28         int err = 0;
  29         struct msr_info rv;
  30
  31         rv.msr_no = msr_no;
  32         if (safe) {
  33                 smp_call_function_single(cpu, __rdmsr_safe_on_cpu, &rv, 0, 1);
  34                 err = rv.err;
  35         } else {
  36                 smp_call_function_single(cpu, __rdmsr_on_cpu, &rv, 0, 1);
  37         }
  38         *l = rv.l;
  39         *h = rv.h;
  40
  41         return err;
  42 }
  43
  44 static void __wrmsr_on_cpu(void *info)
  45 {
  46         struct msr_info *rv = info;
  47
  48         wrmsr(rv->msr_no, rv->l, rv->h);
  49 }
  50
  51 static void __wrmsr_safe_on_cpu(void *info)
  52 {
  53         struct msr_info *rv = info;
  54
  55         rv->err = wrmsr_safe(rv->msr_no, rv->l, rv->h);
  56 }
  57
  58 static int _wrmsr_on_cpu(unsigned int cpu, u32 msr_no, u32 l, u32 h, int safe)
  59 {
  60         int err = 0;
  61         struct msr_info rv;
  62
  63         rv.msr_no = msr_no;
  64         rv.l = l;
  65         rv.h = h;
  66         if (safe) {
  67                 smp_call_function_single(cpu, __wrmsr_safe_on_cpu, &rv, 0, 1);
  68                 err = rv.err;
  69         } else {
  70                 smp_call_function_single(cpu, __wrmsr_on_cpu, &rv, 0, 1);
  71         }
  72
  73         return err;
  74 }
  75
  76 void wrmsr_on_cpu(unsigned int cpu, u32 msr_no, u32 l, u32 h)
  77 {
  78         _wrmsr_on_cpu(cpu, msr_no, l, h, 0);
  79 }
  80
  81 void rdmsr_on_cpu(unsigned int cpu, u32 msr_no, u32 *l, u32 *h)
  82 {
  83         _rdmsr_on_cpu(cpu, msr_no, l, h, 0);
  84 }
  85
  86 /* These "safe" variants are slower and should be used when the target MSR
  87    may not actually exist. */
  88 int wrmsr_safe_on_cpu(unsigned int cpu, u32 msr_no, u32 l, u32 h)
  89 {
  90         return _wrmsr_on_cpu(cpu, msr_no, l, h, 1);
  91 }
  92
  93 int rdmsr_safe_on_cpu(unsigned int cpu, u32 msr_no, u32 *l, u32 *h)
  94 {
  95         return _rdmsr_on_cpu(cpu, msr_no, l, h, 1);
  96 }
  97
  98 EXPORT_SYMBOL(rdmsr_on_cpu);
  99 EXPORT_SYMBOL(wrmsr_on_cpu);
 100 EXPORT_SYMBOL(rdmsr_safe_on_cpu);
 101 EXPORT_SYMBOL(wrmsr_safe_on_cpu);