arch/x86/lib/msr.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include <linux/export.h>
   3 #include <linux/percpu.h>
   4 #include <linux/preempt.h>
   5 #include <asm/msr.h>
   6 #define CREATE_TRACE_POINTS
   7 #include <asm/msr-trace.h>
   8
   9 struct msr *msrs_alloc(void)
  10 {
  11         struct msr *msrs = NULL;
  12
  13         msrs = alloc_percpu(struct msr);
  14         if (!msrs) {
  15                 pr_warn("%s: error allocating msrs\n", __func__);
  16                 return NULL;
  17         }
  18
  19         return msrs;
  20 }
  21 EXPORT_SYMBOL(msrs_alloc);
  22
  23 void msrs_free(struct msr *msrs)
  24 {
  25         free_percpu(msrs);
  26 }
  27 EXPORT_SYMBOL(msrs_free);
  28
  29 /**
  30  * Read an MSR with error handling
  31  *
  32  * @msr: MSR to read
  33  * @m: value to read into
  34  *
  35  * It returns read data only on success, otherwise it doesn't change the output
  36  * argument @m.
  37  *
  38  */
  39 int msr_read(u32 msr, struct msr *m)
  40 {
  41         int err;
  42         u64 val;
  43
  44         err = rdmsrl_safe(msr, &val);
  45         if (!err)
  46                 m->q = val;
  47
  48         return err;
  49 }
  50
  51 /**
  52  * Write an MSR with error handling
  53  *
  54  * @msr: MSR to write
  55  * @m: value to write
  56  */
  57 int msr_write(u32 msr, struct msr *m)
  58 {
  59         return wrmsrl_safe(msr, m->q);
  60 }
  61
  62 static inline int __flip_bit(u32 msr, u8 bit, bool set)
  63 {
  64         struct msr m, m1;
  65         int err = -EINVAL;
  66
  67         if (bit > 63)
  68                 return err;
  69
  70         err = msr_read(msr, &m);
  71         if (err)
  72                 return err;
  73
  74         m1 = m;
  75         if (set)
  76                 m1.q |=  BIT_64(bit);
  77         else
  78                 m1.q &= ~BIT_64(bit);
  79
  80         if (m1.q == m.q)
  81                 return 0;
  82
  83         err = msr_write(msr, &m1);
  84         if (err)
  85                 return err;
  86
  87         return 1;
  88 }
  89
  90 /**
  91  * Set @bit in a MSR @msr.
  92  *
  93  * Retval:
  94  * < 0: An error was encountered.
  95  * = 0: Bit was already set.
  96  * > 0: Hardware accepted the MSR write.
  97  */
  98 int msr_set_bit(u32 msr, u8 bit)
  99 {
 100         return __flip_bit(msr, bit, true);
 101 }
 102
 103 /**
 104  * Clear @bit in a MSR @msr.
 105  *
 106  * Retval:
 107  * < 0: An error was encountered.
 108  * = 0: Bit was already cleared.
 109  * > 0: Hardware accepted the MSR write.
 110  */
 111 int msr_clear_bit(u32 msr, u8 bit)
 112 {
 113         return __flip_bit(msr, bit, false);
 114 }
 115
 116 #ifdef CONFIG_TRACEPOINTS
 117 void do_trace_write_msr(unsigned int msr, u64 val, int failed)
 118 {
 119         trace_write_msr(msr, val, failed);
 120 }
 121 EXPORT_SYMBOL(do_trace_write_msr);
 122 EXPORT_TRACEPOINT_SYMBOL(write_msr);
 123
 124 void do_trace_read_msr(unsigned int msr, u64 val, int failed)
 125 {
 126         trace_read_msr(msr, val, failed);
 127 }
 128 EXPORT_SYMBOL(do_trace_read_msr);
 129 EXPORT_TRACEPOINT_SYMBOL(read_msr);
 130
 131 void do_trace_rdpmc(unsigned counter, u64 val, int failed)
 132 {
 133         trace_rdpmc(counter, val, failed);
 134 }
 135 EXPORT_SYMBOL(do_trace_rdpmc);
 136 EXPORT_TRACEPOINT_SYMBOL(rdpmc);
 137
 138 #endif