tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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
20struct kvm_ptp_clock {
21 struct ptp_clock *ptp_clock;
22 struct ptp_clock_info caps;
23};
24
25static DEFINE_SPINLOCK(kvm_ptp_lock);
26
27static struct pvclock_vsyscall_time_info *hv_clock;
28
29static struct kvm_clock_pairing clock_pair;
30static phys_addr_t clock_pair_gpa;
31
32static 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
85static 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
96static int ptp_kvm_adjfreq(struct ptp_clock_info *ptp, s32 ppb)
97{
98 return -EOPNOTSUPP;
99}
100
101static int ptp_kvm_adjtime(struct ptp_clock_info *ptp, s64 delta)
102{
103 return -EOPNOTSUPP;
104}
105
106static int ptp_kvm_settime(struct ptp_clock_info *ptp,
107 const struct timespec64 *ts)
108{
109 return -EOPNOTSUPP;
110}
111
112static 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
137static int ptp_kvm_enable(struct ptp_clock_info *ptp,
138 struct ptp_clock_request *rq, int on)
139{
140 return -EOPNOTSUPP;
141}
142
143static 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
160static struct kvm_ptp_clock kvm_ptp_clock;
161
162static void __exit ptp_kvm_exit(void)
163{
164 ptp_clock_unregister(kvm_ptp_clock.ptp_clock);
165}
166
167static 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
192module_init(ptp_kvm_init);
193module_exit(ptp_kvm_exit);
194
195MODULE_AUTHOR("Marcelo Tosatti <mtosatti@redhat.com>");
196MODULE_DESCRIPTION("PTP clock using KVMCLOCK");
197MODULE_LICENSE("GPL");