arch/x86/include/asm/pvclock.h

   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 #ifdef CONFIG_KVM_GUEST
   9 extern struct pvclock_vsyscall_time_info *pvclock_pvti_cpu0_va(void);
  10 #else
  11 static inline struct pvclock_vsyscall_time_info *pvclock_pvti_cpu0_va(void)
  12 {
  13         return NULL;
  14 }
  15 #endif
  16
  17 /* some helper functions for xen and kvm pv clock sources */
  18 u64 pvclock_clocksource_read(struct pvclock_vcpu_time_info *src);
  19 u8 pvclock_read_flags(struct pvclock_vcpu_time_info *src);
  20 void pvclock_set_flags(u8 flags);
  21 unsigned long pvclock_tsc_khz(struct pvclock_vcpu_time_info *src);
  22 void pvclock_read_wallclock(struct pvclock_wall_clock *wall,
  23                             struct pvclock_vcpu_time_info *vcpu,
  24                             struct timespec *ts);
  25 void pvclock_resume(void);
  26
  27 void pvclock_touch_watchdogs(void);
  28
  29 static __always_inline
  30 unsigned pvclock_read_begin(const struct pvclock_vcpu_time_info *src)
  31 {
  32         unsigned version = src->version & ~1;
  33         /* Make sure that the version is read before the data. */
  34         virt_rmb();
  35         return version;
  36 }
  37
  38 static __always_inline
  39 bool pvclock_read_retry(const struct pvclock_vcpu_time_info *src,
  40                         unsigned version)
  41 {
  42         /* Make sure that the version is re-read after the data. */
  43         virt_rmb();
  44         return unlikely(version != src->version);
  45 }
  46
  47 /*
  48  * Scale a 64-bit delta by scaling and multiplying by a 32-bit fraction,
  49  * yielding a 64-bit result.
  50  */
  51 static inline u64 pvclock_scale_delta(u64 delta, u32 mul_frac, int shift)
  52 {
  53         u64 product;
  54 #ifdef __i386__
  55         u32 tmp1, tmp2;
  56 #else
  57         ulong tmp;
  58 #endif
  59
  60         if (shift < 0)
  61                 delta >>= -shift;
  62         else
  63                 delta <<= shift;
  64
  65 #ifdef __i386__
  66         __asm__ (
  67                 "mul  %5       ; "
  68                 "mov  %4,%%eax ; "
  69                 "mov  %%edx,%4 ; "
  70                 "mul  %5       ; "
  71                 "xor  %5,%5    ; "
  72                 "add  %4,%%eax ; "
  73                 "adc  %5,%%edx ; "
  74                 : "=A" (product), "=r" (tmp1), "=r" (tmp2)
  75                 : "a" ((u32)delta), "1" ((u32)(delta >> 32)), "2" (mul_frac) );
  76 #elif defined(__x86_64__)
  77         __asm__ (
  78                 "mulq %[mul_frac] ; shrd $32, %[hi], %[lo]"
  79                 : [lo]"=a"(product),
  80                   [hi]"=d"(tmp)
  81                 : "0"(delta),
  82                   [mul_frac]"rm"((u64)mul_frac));
  83 #else
  84 #error implement me!
  85 #endif
  86
  87         return product;
  88 }
  89
  90 static __always_inline
  91 u64 __pvclock_read_cycles(const struct pvclock_vcpu_time_info *src, u64 tsc)
  92 {
  93         u64 delta = tsc - src->tsc_timestamp;
  94         u64 offset = pvclock_scale_delta(delta, src->tsc_to_system_mul,
  95                                              src->tsc_shift);
  96         return src->system_time + offset;
  97 }
  98
  99 struct pvclock_vsyscall_time_info {
 100         struct pvclock_vcpu_time_info pvti;
 101 } __attribute__((__aligned__(SMP_CACHE_BYTES)));
 102
 103 #define PVTI_SIZE sizeof(struct pvclock_vsyscall_time_info)
 104
 105 #endif /* _ASM_X86_PVCLOCK_H */