Merge branch 'fix/intel' of https://git.kernel.org/pub/scm/linux/kernel/git/broonie...
[linux-2.6-microblaze.git] / drivers / ptp / ptp_kvm.c
1 /*
2  * Virtual PTP 1588 clock for use with KVM guests
3  *
4  * Copyright (C) 2017 Red Hat Inc.
5  *
6  *  This program is free software; you can redistribute it and/or modify
7  *  it under the terms of the GNU General Public License as published by
8  *  the Free Software Foundation; either version 2 of the License, or
9  *  (at your option) any later version.
10  *
11  *  This program is distributed in the hope that it will be useful,
12  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
13  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14  *  GNU General Public License for more details.
15  *
16  */
17 #include <linux/device.h>
18 #include <linux/err.h>
19 #include <linux/init.h>
20 #include <linux/kernel.h>
21 #include <linux/module.h>
22 #include <uapi/linux/kvm_para.h>
23 #include <asm/kvm_para.h>
24 #include <asm/pvclock.h>
25 #include <asm/kvmclock.h>
26 #include <uapi/asm/kvm_para.h>
27
28 #include <linux/ptp_clock_kernel.h>
29
30 struct kvm_ptp_clock {
31         struct ptp_clock *ptp_clock;
32         struct ptp_clock_info caps;
33 };
34
35 DEFINE_SPINLOCK(kvm_ptp_lock);
36
37 static struct pvclock_vsyscall_time_info *hv_clock;
38
39 static struct kvm_clock_pairing clock_pair;
40 static phys_addr_t clock_pair_gpa;
41
42 static int ptp_kvm_get_time_fn(ktime_t *device_time,
43                                struct system_counterval_t *system_counter,
44                                void *ctx)
45 {
46         unsigned long ret;
47         struct timespec64 tspec;
48         unsigned version;
49         int cpu;
50         struct pvclock_vcpu_time_info *src;
51
52         spin_lock(&kvm_ptp_lock);
53
54         preempt_disable_notrace();
55         cpu = smp_processor_id();
56         src = &hv_clock[cpu].pvti;
57
58         do {
59                 /*
60                  * We are using a TSC value read in the hosts
61                  * kvm_hc_clock_pairing handling.
62                  * So any changes to tsc_to_system_mul
63                  * and tsc_shift or any other pvclock
64                  * data invalidate that measurement.
65                  */
66                 version = pvclock_read_begin(src);
67
68                 ret = kvm_hypercall2(KVM_HC_CLOCK_PAIRING,
69                                      clock_pair_gpa,
70                                      KVM_CLOCK_PAIRING_WALLCLOCK);
71                 if (ret != 0) {
72                         pr_err_ratelimited("clock pairing hypercall ret %lu\n", ret);
73                         spin_unlock(&kvm_ptp_lock);
74                         preempt_enable_notrace();
75                         return -EOPNOTSUPP;
76                 }
77
78                 tspec.tv_sec = clock_pair.sec;
79                 tspec.tv_nsec = clock_pair.nsec;
80                 ret = __pvclock_read_cycles(src, clock_pair.tsc);
81         } while (pvclock_read_retry(src, version));
82
83         preempt_enable_notrace();
84
85         system_counter->cycles = ret;
86         system_counter->cs = &kvm_clock;
87
88         *device_time = timespec64_to_ktime(tspec);
89
90         spin_unlock(&kvm_ptp_lock);
91
92         return 0;
93 }
94
95 static int ptp_kvm_getcrosststamp(struct ptp_clock_info *ptp,
96                                   struct system_device_crosststamp *xtstamp)
97 {
98         return get_device_system_crosststamp(ptp_kvm_get_time_fn, NULL,
99                                              NULL, xtstamp);
100 }
101
102 /*
103  * PTP clock operations
104  */
105
106 static int ptp_kvm_adjfreq(struct ptp_clock_info *ptp, s32 ppb)
107 {
108         return -EOPNOTSUPP;
109 }
110
111 static int ptp_kvm_adjtime(struct ptp_clock_info *ptp, s64 delta)
112 {
113         return -EOPNOTSUPP;
114 }
115
116 static int ptp_kvm_settime(struct ptp_clock_info *ptp,
117                            const struct timespec64 *ts)
118 {
119         return -EOPNOTSUPP;
120 }
121
122 static int ptp_kvm_gettime(struct ptp_clock_info *ptp, struct timespec64 *ts)
123 {
124         unsigned long ret;
125         struct timespec64 tspec;
126
127         spin_lock(&kvm_ptp_lock);
128
129         ret = kvm_hypercall2(KVM_HC_CLOCK_PAIRING,
130                              clock_pair_gpa,
131                              KVM_CLOCK_PAIRING_WALLCLOCK);
132         if (ret != 0) {
133                 pr_err_ratelimited("clock offset hypercall ret %lu\n", ret);
134                 spin_unlock(&kvm_ptp_lock);
135                 return -EOPNOTSUPP;
136         }
137
138         tspec.tv_sec = clock_pair.sec;
139         tspec.tv_nsec = clock_pair.nsec;
140         spin_unlock(&kvm_ptp_lock);
141
142         memcpy(ts, &tspec, sizeof(struct timespec64));
143
144         return 0;
145 }
146
147 static int ptp_kvm_enable(struct ptp_clock_info *ptp,
148                           struct ptp_clock_request *rq, int on)
149 {
150         return -EOPNOTSUPP;
151 }
152
153 static const struct ptp_clock_info ptp_kvm_caps = {
154         .owner          = THIS_MODULE,
155         .name           = "KVM virtual PTP",
156         .max_adj        = 0,
157         .n_ext_ts       = 0,
158         .n_pins         = 0,
159         .pps            = 0,
160         .adjfreq        = ptp_kvm_adjfreq,
161         .adjtime        = ptp_kvm_adjtime,
162         .gettime64      = ptp_kvm_gettime,
163         .settime64      = ptp_kvm_settime,
164         .enable         = ptp_kvm_enable,
165         .getcrosststamp = ptp_kvm_getcrosststamp,
166 };
167
168 /* module operations */
169
170 static struct kvm_ptp_clock kvm_ptp_clock;
171
172 static void __exit ptp_kvm_exit(void)
173 {
174         ptp_clock_unregister(kvm_ptp_clock.ptp_clock);
175 }
176
177 static int __init ptp_kvm_init(void)
178 {
179         long ret;
180
181         if (!kvm_para_available())
182                 return -ENODEV;
183
184         clock_pair_gpa = slow_virt_to_phys(&clock_pair);
185         hv_clock = pvclock_get_pvti_cpu0_va();
186
187         if (!hv_clock)
188                 return -ENODEV;
189
190         ret = kvm_hypercall2(KVM_HC_CLOCK_PAIRING, clock_pair_gpa,
191                         KVM_CLOCK_PAIRING_WALLCLOCK);
192         if (ret == -KVM_ENOSYS || ret == -KVM_EOPNOTSUPP)
193                 return -ENODEV;
194
195         kvm_ptp_clock.caps = ptp_kvm_caps;
196
197         kvm_ptp_clock.ptp_clock = ptp_clock_register(&kvm_ptp_clock.caps, NULL);
198
199         return PTR_ERR_OR_ZERO(kvm_ptp_clock.ptp_clock);
200 }
201
202 module_init(ptp_kvm_init);
203 module_exit(ptp_kvm_exit);
204
205 MODULE_AUTHOR("Marcelo Tosatti <mtosatti@redhat.com>");
206 MODULE_DESCRIPTION("PTP clock using KVMCLOCK");
207 MODULE_LICENSE("GPL");