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