root/arch/x86/include/asm/pvclock.h

INCLUDED FROM

DEFINITIONS

1. pvclock_read_begin
2. pvclock_read_retry
3. pvclock_scale_delta
4. __pvclock_read_cycles
5. pvclock_get_pvti_cpu0_va

   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 
   8 /* some helper functions for xen and kvm pv clock sources */
   9 u64 pvclock_clocksource_read(struct pvclock_vcpu_time_info *src);
  10 u8 pvclock_read_flags(struct pvclock_vcpu_time_info *src);
  11 void pvclock_set_flags(u8 flags);
  12 unsigned long pvclock_tsc_khz(struct pvclock_vcpu_time_info *src);
  13 void pvclock_read_wallclock(struct pvclock_wall_clock *wall,
  14                             struct pvclock_vcpu_time_info *vcpu,
  15                             struct timespec64 *ts);
  16 void pvclock_resume(void);
  17 
  18 void pvclock_touch_watchdogs(void);
  19 
  20 static __always_inline
  21 unsigned 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 
  29 static __always_inline
  30 bool 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  */
  42 static 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 
  81 static __always_inline
  82 u64 __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 
  90 struct 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
  97 void pvclock_set_pvti_cpu0_va(struct pvclock_vsyscall_time_info *pvti);
  98 struct pvclock_vsyscall_time_info *pvclock_get_pvti_cpu0_va(void);
  99 #else
 100 static 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 */