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 
msrs_alloc(void)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 
msrs_free(struct msr * msrs)23 void msrs_free(struct msr *msrs)
24 {
25 	free_percpu(msrs);
26 }
27 EXPORT_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  */
msr_read(u32 msr,struct msr * m)39 static 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  * 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  */
msr_write(u32 msr,struct msr * m)59 static int msr_write(u32 msr, struct msr *m)
60 {
61 	return wrmsrl_safe(msr, m->q);
62 }
63 
__flip_bit(u32 msr,u8 bit,bool set)64 static 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);
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, &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  */
msr_set_bit(u32 msr,u8 bit)102 int msr_set_bit(u32 msr, u8 bit)
103 {
104 	return __flip_bit(msr, bit, 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  */
msr_clear_bit(u32 msr,u8 bit)117 int msr_clear_bit(u32 msr, u8 bit)
118 {
119 	return __flip_bit(msr, bit, false);
120 }
121 
122 #ifdef CONFIG_TRACEPOINTS
do_trace_write_msr(unsigned int msr,u64 val,int failed)123 void do_trace_write_msr(unsigned int msr, u64 val, int failed)
124 {
125 	trace_write_msr(msr, val, failed);
126 }
127 EXPORT_SYMBOL(do_trace_write_msr);
128 EXPORT_TRACEPOINT_SYMBOL(write_msr);
129 
do_trace_read_msr(unsigned int msr,u64 val,int failed)130 void do_trace_read_msr(unsigned int msr, u64 val, int failed)
131 {
132 	trace_read_msr(msr, val, failed);
133 }
134 EXPORT_SYMBOL(do_trace_read_msr);
135 EXPORT_TRACEPOINT_SYMBOL(read_msr);
136 
do_trace_rdpmc(unsigned counter,u64 val,int failed)137 void do_trace_rdpmc(unsigned counter, u64 val, int failed)
138 {
139 	trace_rdpmc(counter, val, failed);
140 }
141 EXPORT_SYMBOL(do_trace_rdpmc);
142 EXPORT_TRACEPOINT_SYMBOL(rdpmc);
143 
144 #endif
145