1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef _ASM_X86_PVCLOCK_H
3#define _ASM_X86_PVCLOCK_H
4
5#include <linux/clocksource.h>
6#include <asm/pvclock-abi.h>
7
8/* some helper functions for xen and kvm pv clock sources */
9u64 pvclock_clocksource_read(struct pvclock_vcpu_time_info *src);
10u8 pvclock_read_flags(struct pvclock_vcpu_time_info *src);
11void pvclock_set_flags(u8 flags);
12unsigned long pvclock_tsc_khz(struct pvclock_vcpu_time_info *src);
13void pvclock_read_wallclock(struct pvclock_wall_clock *wall,
14 struct pvclock_vcpu_time_info *vcpu,
15 struct timespec64 *ts);
16void pvclock_resume(void);
17
18void pvclock_touch_watchdogs(void);
19
20static __always_inline
21unsigned pvclock_read_begin(const struct pvclock_vcpu_time_info *src)
22{
23 unsigned version = src->version & ~1;
24 /* Make sure that the version is read before the data. */
25 virt_rmb();
26 return version;
27}
28
29static __always_inline
30bool pvclock_read_retry(const struct pvclock_vcpu_time_info *src,
31 unsigned version)
32{
33 /* Make sure that the version is re-read after the data. */
34 virt_rmb();
35 return unlikely(version != src->version);
36}
37
38/*
39 * Scale a 64-bit delta by scaling and multiplying by a 32-bit fraction,
40 * yielding a 64-bit result.
41 */
42static inline u64 pvclock_scale_delta(u64 delta, u32 mul_frac, int shift)
43{
44 u64 product;
45#ifdef __i386__
46 u32 tmp1, tmp2;
47#else
48 ulong tmp;
49#endif
50
51 if (shift < 0)
52 delta >>= -shift;
53 else
54 delta <<= shift;
55
56#ifdef __i386__
57 __asm__ (
58 "mul %5 ; "
59 "mov %4,%%eax ; "
60 "mov %%edx,%4 ; "
61 "mul %5 ; "
62 "xor %5,%5 ; "
63 "add %4,%%eax ; "
64 "adc %5,%%edx ; "
65 : "=A" (product), "=r" (tmp1), "=r" (tmp2)
66 : "a" ((u32)delta), "1" ((u32)(delta >> 32)), "2" (mul_frac) );
67#elif defined(__x86_64__)
68 __asm__ (
69 "mulq %[mul_frac] ; shrd $32, %[hi], %[lo]"
70 : [lo]"=a"(product),
71 [hi]"=d"(tmp)
72 : "0"(delta),
73 [mul_frac]"rm"((u64)mul_frac));
74#else
75#error implement me!
76#endif
77
78 return product;
79}
80
81static __always_inline
82u64 __pvclock_read_cycles(const struct pvclock_vcpu_time_info *src, u64 tsc)
83{
84 u64 delta = tsc - src->tsc_timestamp;
85 u64 offset = pvclock_scale_delta(delta, src->tsc_to_system_mul,
86 src->tsc_shift);
87 return src->system_time + offset;
88}
89
90struct pvclock_vsyscall_time_info {
91 struct pvclock_vcpu_time_info pvti;
92} __attribute__((__aligned__(SMP_CACHE_BYTES)));
93
94#define PVTI_SIZE sizeof(struct pvclock_vsyscall_time_info)
95
96#ifdef CONFIG_PARAVIRT_CLOCK
97void pvclock_set_pvti_cpu0_va(struct pvclock_vsyscall_time_info *pvti);
98struct pvclock_vsyscall_time_info *pvclock_get_pvti_cpu0_va(void);
99#else
100static inline struct pvclock_vsyscall_time_info *pvclock_get_pvti_cpu0_va(void)
101{
102 return NULL;
103}
104#endif
105
106#endif /* _ASM_X86_PVCLOCK_H */
107