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
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
18struct pvclock_vsyscall_time_info *hv_clock;
19
20static phys_addr_t clock_pair_gpa;
21static struct kvm_clock_pairing clock_pair;
22
23int kvm_arch_ptp_init(void)
24{
25 long ret;
26
27 if (!kvm_para_available())
28 return -ENODEV;
29
30 clock_pair_gpa = slow_virt_to_phys(&clock_pair);
31 hv_clock = pvclock_get_pvti_cpu0_va();
32 if (!hv_clock)
33 return -ENODEV;
34
35 ret = kvm_hypercall2(KVM_HC_CLOCK_PAIRING, clock_pair_gpa,
36 KVM_CLOCK_PAIRING_WALLCLOCK);
37 if (ret == -KVM_ENOSYS || ret == -KVM_EOPNOTSUPP)
38 return -ENODEV;
39
40 return 0;
41}
42
43int kvm_arch_ptp_get_clock(struct timespec64 *ts)
44{
45 long ret;
46
47 ret = kvm_hypercall2(KVM_HC_CLOCK_PAIRING,
48 clock_pair_gpa,
49 KVM_CLOCK_PAIRING_WALLCLOCK);
50 if (ret != 0) {
51 pr_err_ratelimited("clock offset hypercall ret %lu\n", ret);
52 return -EOPNOTSUPP;
53 }
54
55 ts->tv_sec = clock_pair.sec;
56 ts->tv_nsec = clock_pair.nsec;
57
58 return 0;
59}
60
61int kvm_arch_ptp_get_crosststamp(u64 *cycle, struct timespec64 *tspec,
62 struct clocksource **cs)
63{
64 struct pvclock_vcpu_time_info *src;
65 unsigned int version;
66 long ret;
67 int cpu;
68
69 cpu = smp_processor_id();
70 src = &hv_clock[cpu].pvti;
71
72 do {
73 /*
74 * We are using a TSC value read in the hosts
75 * kvm_hc_clock_pairing handling.
76 * So any changes to tsc_to_system_mul
77 * and tsc_shift or any other pvclock
78 * data invalidate that measurement.
79 */
80 version = pvclock_read_begin(src);
81
82 ret = kvm_hypercall2(KVM_HC_CLOCK_PAIRING,
83 clock_pair_gpa,
84 KVM_CLOCK_PAIRING_WALLCLOCK);
85 if (ret != 0) {
86 pr_err_ratelimited("clock pairing hypercall ret %lu\n", ret);
87 return -EOPNOTSUPP;
88 }
89 tspec->tv_sec = clock_pair.sec;
90 tspec->tv_nsec = clock_pair.nsec;
91 *cycle = __pvclock_read_cycles(src, clock_pair.tsc);
92 } while (pvclock_read_retry(src, version));
93
94 *cs = &kvm_clock;
95
96 return 0;
97}