treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 157
[sfrench/cifs-2.6.git] / drivers / ptp / ptp_kvm.c
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * Virtual PTP 1588 clock for use with KVM guests
4  *
5  * Copyright (C) 2017 Red Hat Inc.
6  */
7 #include <linux/device.h>
8 #include <linux/err.h>
9 #include <linux/init.h>
10 #include <linux/kernel.h>
11 #include <linux/module.h>
12 #include <uapi/linux/kvm_para.h>
13 #include <asm/kvm_para.h>
14 #include <asm/pvclock.h>
15 #include <asm/kvmclock.h>
16 #include <uapi/asm/kvm_para.h>
17
18 #include <linux/ptp_clock_kernel.h>
19
20 struct kvm_ptp_clock {
21         struct ptp_clock *ptp_clock;
22         struct ptp_clock_info caps;
23 };
24
25 DEFINE_SPINLOCK(kvm_ptp_lock);
26
27 static struct pvclock_vsyscall_time_info *hv_clock;
28
29 static struct kvm_clock_pairing clock_pair;
30 static phys_addr_t clock_pair_gpa;
31
32 static int ptp_kvm_get_time_fn(ktime_t *device_time,
33                                struct system_counterval_t *system_counter,
34                                void *ctx)
35 {
36         unsigned long ret;
37         struct timespec64 tspec;
38         unsigned version;
39         int cpu;
40         struct pvclock_vcpu_time_info *src;
41
42         spin_lock(&kvm_ptp_lock);
43
44         preempt_disable_notrace();
45         cpu = smp_processor_id();
46         src = &hv_clock[cpu].pvti;
47
48         do {
49                 /*
50                  * We are using a TSC value read in the hosts
51                  * kvm_hc_clock_pairing handling.
52                  * So any changes to tsc_to_system_mul
53                  * and tsc_shift or any other pvclock
54                  * data invalidate that measurement.
55                  */
56                 version = pvclock_read_begin(src);
57
58                 ret = kvm_hypercall2(KVM_HC_CLOCK_PAIRING,
59                                      clock_pair_gpa,
60                                      KVM_CLOCK_PAIRING_WALLCLOCK);
61                 if (ret != 0) {
62                         pr_err_ratelimited("clock pairing hypercall ret %lu\n", ret);
63                         spin_unlock(&kvm_ptp_lock);
64                         preempt_enable_notrace();
65                         return -EOPNOTSUPP;
66                 }
67
68                 tspec.tv_sec = clock_pair.sec;
69                 tspec.tv_nsec = clock_pair.nsec;
70                 ret = __pvclock_read_cycles(src, clock_pair.tsc);
71         } while (pvclock_read_retry(src, version));
72
73         preempt_enable_notrace();
74
75         system_counter->cycles = ret;
76         system_counter->cs = &kvm_clock;
77
78         *device_time = timespec64_to_ktime(tspec);
79
80         spin_unlock(&kvm_ptp_lock);
81
82         return 0;
83 }
84
85 static int ptp_kvm_getcrosststamp(struct ptp_clock_info *ptp,
86                                   struct system_device_crosststamp *xtstamp)
87 {
88         return get_device_system_crosststamp(ptp_kvm_get_time_fn, NULL,
89                                              NULL, xtstamp);
90 }
91
92 /*
93  * PTP clock operations
94  */
95
96 static int ptp_kvm_adjfreq(struct ptp_clock_info *ptp, s32 ppb)
97 {
98         return -EOPNOTSUPP;
99 }
100
101 static int ptp_kvm_adjtime(struct ptp_clock_info *ptp, s64 delta)
102 {
103         return -EOPNOTSUPP;
104 }
105
106 static int ptp_kvm_settime(struct ptp_clock_info *ptp,
107                            const struct timespec64 *ts)
108 {
109         return -EOPNOTSUPP;
110 }
111
112 static int ptp_kvm_gettime(struct ptp_clock_info *ptp, struct timespec64 *ts)
113 {
114         unsigned long ret;
115         struct timespec64 tspec;
116
117         spin_lock(&kvm_ptp_lock);
118
119         ret = kvm_hypercall2(KVM_HC_CLOCK_PAIRING,
120                              clock_pair_gpa,
121                              KVM_CLOCK_PAIRING_WALLCLOCK);
122         if (ret != 0) {
123                 pr_err_ratelimited("clock offset hypercall ret %lu\n", ret);
124                 spin_unlock(&kvm_ptp_lock);
125                 return -EOPNOTSUPP;
126         }
127
128         tspec.tv_sec = clock_pair.sec;
129         tspec.tv_nsec = clock_pair.nsec;
130         spin_unlock(&kvm_ptp_lock);
131
132         memcpy(ts, &tspec, sizeof(struct timespec64));
133
134         return 0;
135 }
136
137 static int ptp_kvm_enable(struct ptp_clock_info *ptp,
138                           struct ptp_clock_request *rq, int on)
139 {
140         return -EOPNOTSUPP;
141 }
142
143 static const struct ptp_clock_info ptp_kvm_caps = {
144         .owner          = THIS_MODULE,
145         .name           = "KVM virtual PTP",
146         .max_adj        = 0,
147         .n_ext_ts       = 0,
148         .n_pins         = 0,
149         .pps            = 0,
150         .adjfreq        = ptp_kvm_adjfreq,
151         .adjtime        = ptp_kvm_adjtime,
152         .gettime64      = ptp_kvm_gettime,
153         .settime64      = ptp_kvm_settime,
154         .enable         = ptp_kvm_enable,
155         .getcrosststamp = ptp_kvm_getcrosststamp,
156 };
157
158 /* module operations */
159
160 static struct kvm_ptp_clock kvm_ptp_clock;
161
162 static void __exit ptp_kvm_exit(void)
163 {
164         ptp_clock_unregister(kvm_ptp_clock.ptp_clock);
165 }
166
167 static int __init ptp_kvm_init(void)
168 {
169         long ret;
170
171         if (!kvm_para_available())
172                 return -ENODEV;
173
174         clock_pair_gpa = slow_virt_to_phys(&clock_pair);
175         hv_clock = pvclock_get_pvti_cpu0_va();
176
177         if (!hv_clock)
178                 return -ENODEV;
179
180         ret = kvm_hypercall2(KVM_HC_CLOCK_PAIRING, clock_pair_gpa,
181                         KVM_CLOCK_PAIRING_WALLCLOCK);
182         if (ret == -KVM_ENOSYS || ret == -KVM_EOPNOTSUPP)
183                 return -ENODEV;
184
185         kvm_ptp_clock.caps = ptp_kvm_caps;
186
187         kvm_ptp_clock.ptp_clock = ptp_clock_register(&kvm_ptp_clock.caps, NULL);
188
189         return PTR_ERR_OR_ZERO(kvm_ptp_clock.ptp_clock);
190 }
191
192 module_init(ptp_kvm_init);
193 module_exit(ptp_kvm_exit);
194
195 MODULE_AUTHOR("Marcelo Tosatti <mtosatti@redhat.com>");
196 MODULE_DESCRIPTION("PTP clock using KVMCLOCK");
197 MODULE_LICENSE("GPL");