pvclock.h

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