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