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 __wrmsr_on_cpu(void *info)
  20 {
  21         struct msr_info *rv = info;
  22
  23         wrmsr(rv->msr_no, rv->l, rv->h);
  24 }
  25
  26 int rdmsr_on_cpu(unsigned int cpu, u32 msr_no, u32 *l, u32 *h)
  27 {
  28         int err;
  29         struct msr_info rv;
  30
  31         rv.msr_no = msr_no;
  32         err = smp_call_function_single(cpu, __rdmsr_on_cpu, &rv, 1);
  33         *l = rv.l;
  34         *h = rv.h;
  35
  36         return err;
  37 }
  38
  39 int wrmsr_on_cpu(unsigned int cpu, u32 msr_no, u32 l, u32 h)
  40 {
  41         int err;
  42         struct msr_info rv;
  43
  44         rv.msr_no = msr_no;
  45         rv.l = l;
  46         rv.h = h;
  47         err = smp_call_function_single(cpu, __wrmsr_on_cpu, &rv, 1);
  48
  49         return err;
  50 }
  51
  52 /* These "safe" variants are slower and should be used when the target MSR
  53    may not actually exist. */
  54 static void __rdmsr_safe_on_cpu(void *info)
  55 {
  56         struct msr_info *rv = info;
  57
  58         rv->err = rdmsr_safe(rv->msr_no, &rv->l, &rv->h);
  59 }
  60
  61 static void __wrmsr_safe_on_cpu(void *info)
  62 {
  63         struct msr_info *rv = info;
  64
  65         rv->err = wrmsr_safe(rv->msr_no, rv->l, rv->h);
  66 }
  67
  68 int rdmsr_safe_on_cpu(unsigned int cpu, u32 msr_no, u32 *l, u32 *h)
  69 {
  70         int err;
  71         struct msr_info rv;
  72
  73         rv.msr_no = msr_no;
  74         err = smp_call_function_single(cpu, __rdmsr_safe_on_cpu, &rv, 1);
  75         *l = rv.l;
  76         *h = rv.h;
  77
  78         return err ? err : rv.err;
  79 }
  80
  81 int wrmsr_safe_on_cpu(unsigned int cpu, u32 msr_no, u32 l, u32 h)
  82 {
  83         int err;
  84         struct msr_info rv;
  85
  86         rv.msr_no = msr_no;
  87         rv.l = l;
  88         rv.h = h;
  89         err = smp_call_function_single(cpu, __wrmsr_safe_on_cpu, &rv, 1);
  90
  91         return err ? err : rv.err;
  92 }
  93
  94 EXPORT_SYMBOL(rdmsr_on_cpu);
  95 EXPORT_SYMBOL(wrmsr_on_cpu);
  96 EXPORT_SYMBOL(rdmsr_safe_on_cpu);
  97 EXPORT_SYMBOL(wrmsr_safe_on_cpu);