arch/x86/include/asm/pvclock.h

   1 #ifndef _ASM_X86_PVCLOCK_H
   2 #define _ASM_X86_PVCLOCK_H
   3
   4 #include <linux/clocksource.h>
   5 #include <asm/pvclock-abi.h>
   6
   7 /* some helper functions for xen and kvm pv clock sources */
   8 cycle_t pvclock_clocksource_read(struct pvclock_vcpu_time_info *src);
   9 u8 pvclock_read_flags(struct pvclock_vcpu_time_info *src);
  10 void pvclock_set_flags(u8 flags);
  11 unsigned long pvclock_tsc_khz(struct pvclock_vcpu_time_info *src);
  12 void pvclock_read_wallclock(struct pvclock_wall_clock *wall,
  13                             struct pvclock_vcpu_time_info *vcpu,
  14                             struct timespec *ts);
  15 void pvclock_resume(void);
  16
  17 /*
  18  * Scale a 64-bit delta by scaling and multiplying by a 32-bit fraction,
  19  * yielding a 64-bit result.
  20  */
  21 static inline u64 pvclock_scale_delta(u64 delta, u32 mul_frac, int shift)
  22 {
  23         u64 product;
  24 #ifdef __i386__
  25         u32 tmp1, tmp2;
  26 #else
  27         ulong tmp;
  28 #endif
  29
  30         if (shift < 0)
  31                 delta >>= -shift;
  32         else
  33                 delta <<= shift;
  34
  35 #ifdef __i386__
  36         __asm__ (
  37                 "mul  %5       ; "
  38                 "mov  %4,%%eax ; "
  39                 "mov  %%edx,%4 ; "
  40                 "mul  %5       ; "
  41                 "xor  %5,%5    ; "
  42                 "add  %4,%%eax ; "
  43                 "adc  %5,%%edx ; "
  44                 : "=A" (product), "=r" (tmp1), "=r" (tmp2)
  45                 : "a" ((u32)delta), "1" ((u32)(delta >> 32)), "2" (mul_frac) );
  46 #elif defined(__x86_64__)
  47         __asm__ (
  48                 "mulq %[mul_frac] ; shrd $32, %[hi], %[lo]"
  49                 : [lo]"=a"(product),
  50                   [hi]"=d"(tmp)
  51                 : "0"(delta),
  52                   [mul_frac]"rm"((u64)mul_frac));
  53 #else
  54 #error implement me!
  55 #endif
  56
  57         return product;
  58 }
  59
  60 static __always_inline
  61 u64 pvclock_get_nsec_offset(const struct pvclock_vcpu_time_info *src)
  62 {
  63         u64 delta = __native_read_tsc() - src->tsc_timestamp;
  64         return pvclock_scale_delta(delta, src->tsc_to_system_mul,
  65                                    src->tsc_shift);
  66 }
  67
  68 static __always_inline
  69 unsigned __pvclock_read_cycles(const struct pvclock_vcpu_time_info *src,
  70                                cycle_t *cycles, u8 *flags)
  71 {
  72         unsigned version;
  73         cycle_t ret, offset;
  74         u8 ret_flags;
  75
  76         version = src->version;
  77         /* Note: emulated platforms which do not advertise SSE2 support
  78          * result in kvmclock not using the necessary RDTSC barriers.
  79          * Without barriers, it is possible that RDTSC instruction reads from
  80          * the time stamp counter outside rdtsc_barrier protected section
  81          * below, resulting in violation of monotonicity.
  82          */
  83         rdtsc_barrier();
  84         offset = pvclock_get_nsec_offset(src);
  85         ret = src->system_time + offset;
  86         ret_flags = src->flags;
  87         rdtsc_barrier();
  88
  89         *cycles = ret;
  90         *flags = ret_flags;
  91         return version;
  92 }
  93
  94 struct pvclock_vsyscall_time_info {
  95         struct pvclock_vcpu_time_info pvti;
  96         u32 migrate_count;
  97 } __attribute__((__aligned__(SMP_CACHE_BYTES)));
  98
  99 #define PVTI_SIZE sizeof(struct pvclock_vsyscall_time_info)
 100 #define PVCLOCK_VSYSCALL_NR_PAGES (((NR_CPUS-1)/(PAGE_SIZE/PVTI_SIZE))+1)
 101
 102 int __init pvclock_init_vsyscall(struct pvclock_vsyscall_time_info *i,
 103                                  int size);
 104 struct pvclock_vcpu_time_info *pvclock_get_vsyscall_time_info(int cpu);
 105
 106 #endif /* _ASM_X86_PVCLOCK_H */