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x86: vdso: use __pvclock_read_cycles 

The new simplified __pvclock_read_cycles does the same computation
as vread_pvclock, except that (because it takes the pvclock_vcpu_time_info
pointer) it has to be moved inside the loop.  Since the loop is expected to
never roll, this makes no difference.

Acked-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Paolo Bonzini 2016-06-09 20:12:34 +02:00
parent 3aed64f6d3
commit abe9efa79b
1 changed files with 3 additions and 13 deletions
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16
arch/x86/entry/vdso/vclock_gettime.c
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@ -96,9 +96,8 @@ static notrace cycle_t vread_pvclock(int *mode)
{
const struct pvclock_vcpu_time_info *pvti = &get_pvti0()->pvti;
cycle_t ret;
u64 tsc, pvti_tsc;
u64 last, delta, pvti_system_time;
u32 version, pvti_tsc_to_system_mul, pvti_tsc_shift;
u64 last;
u32 version;
/*
* Note: The kernel and hypervisor must guarantee that cpu ID
@ -130,18 +129,9 @@ static notrace cycle_t vread_pvclock(int *mode)
return 0;
}
tsc = rdtsc_ordered();
pvti_tsc_to_system_mul = pvti->tsc_to_system_mul;
pvti_tsc_shift = pvti->tsc_shift;
pvti_system_time = pvti->system_time;
pvti_tsc = pvti->tsc_timestamp;
ret = __pvclock_read_cycles(pvti);
} while (pvclock_read_retry(pvti, version));
delta = tsc - pvti_tsc;
ret = pvti_system_time +
pvclock_scale_delta(delta, pvti_tsc_to_system_mul,
pvti_tsc_shift);
/* refer to vread_tsc() comment for rationale */
last = gtod->cycle_last;