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
9struct 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}
21EXPORT_SYMBOL(msrs_alloc);
22
23void msrs_free(struct msr *msrs)
24{
25 free_percpu(pdata: msrs);
26}
27EXPORT_SYMBOL(msrs_free);
28
29/**
30 * msr_read - Read an MSR with error handling
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 * Return: %0 for success, otherwise an error code
38 */
39static int msr_read(u32 msr, struct msr *m)
40{
41 int err;
42 u64 val;
43
44 err = rdmsrl_safe(msr, p: &val);
45 if (!err)
46 m->q = val;
47
48 return err;
49}
50
51/**
52 * msr_write - Write an MSR with error handling
53 *
54 * @msr: MSR to write
55 * @m: value to write
56 *
57 * Return: %0 for success, otherwise an error code
58 */
59static int msr_write(u32 msr, struct msr *m)
60{
61 return wrmsrl_safe(msr, val: m->q);
62}
63
64static inline int __flip_bit(u32 msr, u8 bit, bool set)
65{
66 struct msr m, m1;
67 int err = -EINVAL;
68
69 if (bit > 63)
70 return err;
71
72 err = msr_read(msr, m: &m);
73 if (err)
74 return err;
75
76 m1 = m;
77 if (set)
78 m1.q |= BIT_64(bit);
79 else
80 m1.q &= ~BIT_64(bit);
81
82 if (m1.q == m.q)
83 return 0;
84
85 err = msr_write(msr, m: &m1);
86 if (err)
87 return err;
88
89 return 1;
90}
91
92/**
93 * msr_set_bit - Set @bit in a MSR @msr.
94 * @msr: MSR to write
95 * @bit: bit number to set
96 *
97 * Return:
98 * * < 0: An error was encountered.
99 * * = 0: Bit was already set.
100 * * > 0: Hardware accepted the MSR write.
101 */
102int msr_set_bit(u32 msr, u8 bit)
103{
104 return __flip_bit(msr, bit, set: true);
105}
106
107/**
108 * msr_clear_bit - Clear @bit in a MSR @msr.
109 * @msr: MSR to write
110 * @bit: bit number to clear
111 *
112 * Return:
113 * * < 0: An error was encountered.
114 * * = 0: Bit was already cleared.
115 * * > 0: Hardware accepted the MSR write.
116 */
117int msr_clear_bit(u32 msr, u8 bit)
118{
119 return __flip_bit(msr, bit, set: false);
120}
121
122#ifdef CONFIG_TRACEPOINTS
123void do_trace_write_msr(unsigned int msr, u64 val, int failed)
124{
125 trace_write_msr(msr, val, failed);
126}
127EXPORT_SYMBOL(do_trace_write_msr);
128EXPORT_TRACEPOINT_SYMBOL(write_msr);
129
130void do_trace_read_msr(unsigned int msr, u64 val, int failed)
131{
132 trace_read_msr(msr, val, failed);
133}
134EXPORT_SYMBOL(do_trace_read_msr);
135EXPORT_TRACEPOINT_SYMBOL(read_msr);
136
137void do_trace_rdpmc(unsigned counter, u64 val, int failed)
138{
139 trace_rdpmc(msr: counter, val, failed);
140}
141EXPORT_SYMBOL(do_trace_rdpmc);
142EXPORT_TRACEPOINT_SYMBOL(rdpmc);
143
144#endif
145

source code of linux/arch/x86/lib/msr.c