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

 1#include <linux/module.h>
 2#include <linux/preempt.h>
 3#include <asm/msr.h>
 4
 5struct msr *msrs_alloc(void)
 6{
 7	struct msr *msrs = NULL;
 8
 9	msrs = alloc_percpu(struct msr);
10	if (!msrs) {
11		pr_warning("%s: error allocating msrs\n", __func__);
12		return NULL;
13	}
14
15	return msrs;
16}
17EXPORT_SYMBOL(msrs_alloc);
18
19void msrs_free(struct msr *msrs)
20{
21	free_percpu(msrs);
22}
23EXPORT_SYMBOL(msrs_free);