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x86: pvclock: create helper for pvclock data retrieval 

Originally from Jeremy Fitzhardinge.

So code can be reused.

Acked-by: Glauber Costa <glommer@parallels.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
This commit is contained in:
Marcelo Tosatti 2012-11-27 23:28:51 -02:00
parent 42b5637d69
commit dce2db0a35
2 changed files with 30 additions and 14 deletions
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28
arch/x86/include/asm/pvclock.h
View File

@ -56,4 +56,32 @@ static inline u64 pvclock_scale_delta(u64 delta, u32 mul_frac, int shift)
return product;
}
static __always_inline
u64 pvclock_get_nsec_offset(const struct pvclock_vcpu_time_info *src)
{
u64 delta = __native_read_tsc() - src->tsc_timestamp;
return pvclock_scale_delta(delta, src->tsc_to_system_mul,
src->tsc_shift);
}
static __always_inline
unsigned __pvclock_read_cycles(const struct pvclock_vcpu_time_info *src,
cycle_t *cycles, u8 *flags)
{
unsigned version;
cycle_t ret, offset;
u8 ret_flags;
version = src->version;
rdtsc_barrier();
offset = pvclock_get_nsec_offset(src);
ret = src->system_time + offset;
ret_flags = src->flags;
rdtsc_barrier();
*cycles = ret;
*flags = ret_flags;
return version;
}
#endif /* _ASM_X86_PVCLOCK_H */

16
arch/x86/kernel/pvclock.c
View File

@ -26,13 +26,6 @@ void pvclock_set_flags(u8 flags)
valid_flags = flags;
}
static u64 pvclock_get_nsec_offset(const struct pvclock_vcpu_time_info *src)
{
u64 delta = native_read_tsc() - src->tsc_timestamp;
return pvclock_scale_delta(delta, src->tsc_to_system_mul,
src->tsc_shift);
}
unsigned long pvclock_tsc_khz(struct pvclock_vcpu_time_info *src)
{
u64 pv_tsc_khz = 1000000ULL << 32;
@ -55,17 +48,12 @@ void pvclock_resume(void)
cycle_t pvclock_clocksource_read(struct pvclock_vcpu_time_info *src)
{
unsigned version;
cycle_t ret, offset;
cycle_t ret;
u64 last;
u8 flags;
do {
version = src->version;
rdtsc_barrier();
offset = pvclock_get_nsec_offset(src);
ret = src->system_time + offset;
flags = src->flags;
rdtsc_barrier();
version = __pvclock_read_cycles(src, &ret, &flags);
} while ((src->version & 1) || version != src->version);
if ((valid_flags & PVCLOCK_TSC_STABLE_BIT) &&