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 -ENODEV;
30
31	if (cc_platform_has(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((unsigned long)clock_pair, 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(clock_pair);
48	if (!pvclock_get_pvti_cpu0_va()) {
49		ret = -ENODEV;
50		goto err;
51	}
52
53	ret = kvm_hypercall2(KVM_HC_CLOCK_PAIRING, clock_pair_gpa,
54			     KVM_CLOCK_PAIRING_WALLCLOCK);
55	if (ret == -KVM_ENOSYS) {
56		ret = -ENODEV;
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(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			     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				     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, clock_pair->tsc);
124	} while (pvclock_read_retry(src, version));
125
126	*cs_id = CSID_X86_KVM_CLK;
127
128	return 0;
129}
130