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
8 #include <linux/device.h>
9 #include <linux/kernel.h>
10 #include <asm/pvclock.h>
11 #include <asm/kvmclock.h>
12 #include <linux/module.h>
13 #include <uapi/asm/kvm_para.h>
14 #include <uapi/linux/kvm_para.h>
15 #include <linux/ptp_clock_kernel.h>
16 #include <linux/ptp_kvm.h>
17
18 static phys_addr_t clock_pair_gpa;
19 static struct kvm_clock_pairing clock_pair;
20
kvm_arch_ptp_init(void)21 int kvm_arch_ptp_init(void)
22 {
23 long ret;
24
25 if (!kvm_para_available())
26 return -ENODEV;
27
28 clock_pair_gpa = slow_virt_to_phys(&clock_pair);
29 if (!pvclock_get_pvti_cpu0_va())
30 return -ENODEV;
31
32 ret = kvm_hypercall2(KVM_HC_CLOCK_PAIRING, clock_pair_gpa,
33 KVM_CLOCK_PAIRING_WALLCLOCK);
34 if (ret == -KVM_ENOSYS)
35 return -ENODEV;
36
37 return ret;
38 }
39
kvm_arch_ptp_get_clock(struct timespec64 * ts)40 int kvm_arch_ptp_get_clock(struct timespec64 *ts)
41 {
42 long ret;
43
44 ret = kvm_hypercall2(KVM_HC_CLOCK_PAIRING,
45 clock_pair_gpa,
46 KVM_CLOCK_PAIRING_WALLCLOCK);
47 if (ret != 0) {
48 pr_err_ratelimited("clock offset hypercall ret %lu\n", ret);
49 return -EOPNOTSUPP;
50 }
51
52 ts->tv_sec = clock_pair.sec;
53 ts->tv_nsec = clock_pair.nsec;
54
55 return 0;
56 }
57
kvm_arch_ptp_get_crosststamp(u64 * cycle,struct timespec64 * tspec,struct clocksource ** cs)58 int kvm_arch_ptp_get_crosststamp(u64 *cycle, struct timespec64 *tspec,
59 struct clocksource **cs)
60 {
61 struct pvclock_vcpu_time_info *src;
62 unsigned int version;
63 long ret;
64
65 src = this_cpu_pvti();
66
67 do {
68 /*
69 * We are using a TSC value read in the hosts
70 * kvm_hc_clock_pairing handling.
71 * So any changes to tsc_to_system_mul
72 * and tsc_shift or any other pvclock
73 * data invalidate that measurement.
74 */
75 version = pvclock_read_begin(src);
76
77 ret = kvm_hypercall2(KVM_HC_CLOCK_PAIRING,
78 clock_pair_gpa,
79 KVM_CLOCK_PAIRING_WALLCLOCK);
80 if (ret != 0) {
81 pr_err_ratelimited("clock pairing hypercall ret %lu\n", ret);
82 return -EOPNOTSUPP;
83 }
84 tspec->tv_sec = clock_pair.sec;
85 tspec->tv_nsec = clock_pair.nsec;
86 *cycle = __pvclock_read_cycles(src, clock_pair.tsc);
87 } while (pvclock_read_retry(src, version));
88
89 *cs = &kvm_clock;
90
91 return 0;
92 }
93