LXR linux/arch/x86/lib/msr.c

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