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#include <linux/set_memory.h>
18
19static phys_addr_t clock_pair_gpa;
20static struct kvm_clock_pairing clock_pair_glbl;
21static struct kvm_clock_pairing *clock_pair;
22
23int kvm_arch_ptp_init(void)
24{
25 struct page *p;
26 long ret;
27
28 if (!kvm_para_available())
29 return -EOPNOTSUPP;
30
31 if (cc_platform_has(attr: CC_ATTR_GUEST_MEM_ENCRYPT)) {
32 p = alloc_page(GFP_KERNEL | __GFP_ZERO);
33 if (!p)
34 return -ENOMEM;
35
36 clock_pair = page_address(p);
37 ret = set_memory_decrypted(addr: (unsigned long)clock_pair, numpages: 1);
38 if (ret) {
39 __free_page(p);
40 clock_pair = NULL;
41 goto nofree;
42 }
43 } else {
44 clock_pair = &clock_pair_glbl;
45 }
46
47 clock_pair_gpa = slow_virt_to_phys(address: clock_pair);
48 if (!pvclock_get_pvti_cpu0_va()) {
49 ret = -EOPNOTSUPP;
50 goto err;
51 }
52
53 ret = kvm_hypercall2(KVM_HC_CLOCK_PAIRING, p1: clock_pair_gpa,
54 KVM_CLOCK_PAIRING_WALLCLOCK);
55 if (ret == -KVM_ENOSYS) {
56 ret = -EOPNOTSUPP;
57 goto err;
58 }
59
60 return ret;
61
62err:
63 kvm_arch_ptp_exit();
64nofree:
65 return ret;
66}
67
68void kvm_arch_ptp_exit(void)
69{
70 if (cc_platform_has(attr: CC_ATTR_GUEST_MEM_ENCRYPT)) {
71 WARN_ON(set_memory_encrypted((unsigned long)clock_pair, 1));
72 free_page((unsigned long)clock_pair);
73 clock_pair = NULL;
74 }
75}
76
77int kvm_arch_ptp_get_clock(struct timespec64 *ts)
78{
79 long ret;
80
81 ret = kvm_hypercall2(KVM_HC_CLOCK_PAIRING,
82 p1: clock_pair_gpa,
83 KVM_CLOCK_PAIRING_WALLCLOCK);
84 if (ret != 0) {
85 pr_err_ratelimited("clock offset hypercall ret %lu\n", ret);
86 return -EOPNOTSUPP;
87 }
88
89 ts->tv_sec = clock_pair->sec;
90 ts->tv_nsec = clock_pair->nsec;
91
92 return 0;
93}
94
95int kvm_arch_ptp_get_crosststamp(u64 *cycle, struct timespec64 *tspec,
96 enum clocksource_ids *cs_id)
97{
98 struct pvclock_vcpu_time_info *src;
99 unsigned int version;
100 long ret;
101
102 src = this_cpu_pvti();
103
104 do {
105 /*
106 * We are using a TSC value read in the hosts
107 * kvm_hc_clock_pairing handling.
108 * So any changes to tsc_to_system_mul
109 * and tsc_shift or any other pvclock
110 * data invalidate that measurement.
111 */
112 version = pvclock_read_begin(src);
113
114 ret = kvm_hypercall2(KVM_HC_CLOCK_PAIRING,
115 p1: clock_pair_gpa,
116 KVM_CLOCK_PAIRING_WALLCLOCK);
117 if (ret != 0) {
118 pr_err_ratelimited("clock pairing hypercall ret %lu\n", ret);
119 return -EOPNOTSUPP;
120 }
121 tspec->tv_sec = clock_pair->sec;
122 tspec->tv_nsec = clock_pair->nsec;
123 *cycle = __pvclock_read_cycles(src, tsc: clock_pair->tsc);
124 } while (pvclock_read_retry(src, version));
125
126 *cs_id = CSID_X86_KVM_CLK;
127
128 return 0;
129}
130