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
18static phys_addr_t clock_pair_gpa;
19static struct kvm_clock_pairing clock_pair;
20
21int 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
40int 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
58int 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}