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         preempt_disable();
  30         if (smp_processor_id() == cpu)
  31                 if (safe)
  32                         err = rdmsr_safe(msr_no, l, h);
  33                 else
  34                         rdmsr(msr_no, *l, *h);
  35         else {
  36                 struct msr_info rv;
  37
  38                 rv.msr_no = msr_no;
  39                 if (safe) {
  40                         smp_call_function_single(cpu, __rdmsr_safe_on_cpu,
  41                                                  &rv, 0, 1);
  42                         err = rv.err;
  43                 } else {
  44                         smp_call_function_single(cpu, __rdmsr_on_cpu, &rv, 0, 1);
  45                 }
  46                 *l = rv.l;
  47                 *h = rv.h;
  48         }
  49         preempt_enable();
  50         return err;
  51 }
  52
  53 static void __wrmsr_on_cpu(void *info)
  54 {
  55         struct msr_info *rv = info;
  56
  57         wrmsr(rv->msr_no, rv->l, rv->h);
  58 }
  59
  60 static void __wrmsr_safe_on_cpu(void *info)
  61 {
  62         struct msr_info *rv = info;
  63
  64         rv->err = wrmsr_safe(rv->msr_no, rv->l, rv->h);
  65 }
  66
  67 static int _wrmsr_on_cpu(unsigned int cpu, u32 msr_no, u32 l, u32 h, int safe)
  68 {
  69         int err = 0;
  70         preempt_disable();
  71         if (smp_processor_id() == cpu)
  72                 if (safe)
  73                         err = wrmsr_safe(msr_no, l, h);
  74                 else
  75                         wrmsr(msr_no, l, h);
  76         else {
  77                 struct msr_info rv;
  78
  79                 rv.msr_no = msr_no;
  80                 rv.l = l;
  81                 rv.h = h;
  82                 if (safe) {
  83                         smp_call_function_single(cpu, __wrmsr_safe_on_cpu,
  84                                                  &rv, 0, 1);
  85                         err = rv.err;
  86                 } else {
  87                         smp_call_function_single(cpu, __wrmsr_on_cpu, &rv, 0, 1);
  88                 }
  89         }
  90         preempt_enable();
  91         return err;
  92 }
  93
  94 void wrmsr_on_cpu(unsigned int cpu, u32 msr_no, u32 l, u32 h)
  95 {
  96         _wrmsr_on_cpu(cpu, msr_no, l, h, 0);
  97 }
  98
  99 void rdmsr_on_cpu(unsigned int cpu, u32 msr_no, u32 *l, u32 *h)
 100 {
 101         _rdmsr_on_cpu(cpu, msr_no, l, h, 0);
 102 }
 103
 104 /* These "safe" variants are slower and should be used when the target MSR
 105    may not actually exist. */
 106 int wrmsr_safe_on_cpu(unsigned int cpu, u32 msr_no, u32 l, u32 h)
 107 {
 108         return _wrmsr_on_cpu(cpu, msr_no, l, h, 1);
 109 }
 110
 111 int rdmsr_safe_on_cpu(unsigned int cpu, u32 msr_no, u32 *l, u32 *h)
 112 {
 113         return _rdmsr_on_cpu(cpu, msr_no, l, h, 1);
 114 }
 115
 116 EXPORT_SYMBOL(rdmsr_on_cpu);
 117 EXPORT_SYMBOL(wrmsr_on_cpu);
 118 EXPORT_SYMBOL(rdmsr_safe_on_cpu);
 119 EXPORT_SYMBOL(wrmsr_safe_on_cpu);