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x86: kvm: Make kvm_get_time_and_clockread() nanoseconds based

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Convert the relevant base data right away to nanoseconds instead of
doing the conversion on every readout. Reduces text size by 160 bytes.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Gleb Natapov <gleb@kernel.org>
Cc: kvm@vger.kernel.org
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
This commit is contained in:
Thomas Gleixner 2014-07-16 21:04:54 +00:00 • committed by John Stultz
commit cbcf2dd3b3
1 changed files with 15 additions and 31 deletions
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46
arch/x86/kvm/x86.c
View file

@ -984,9 +984,8 @@ struct pvclock_gtod_data {
u32 shift; u32 shift;
} clock; } clock;
/* open coded 'struct timespec' */ u64 boot_ns;
u64 monotonic_time_snsec; u64 nsec_base;
time_t monotonic_time_sec;
}; };
static struct pvclock_gtod_data pvclock_gtod_data; static struct pvclock_gtod_data pvclock_gtod_data;
@ -994,6 +993,9 @@ static struct pvclock_gtod_data pvclock_gtod_data;
static void update_pvclock_gtod(struct timekeeper *tk) static void update_pvclock_gtod(struct timekeeper *tk)
{ {
struct pvclock_gtod_data *vdata = &pvclock_gtod_data; struct pvclock_gtod_data *vdata = &pvclock_gtod_data;
u64 boot_ns;
boot_ns = ktime_to_ns(ktime_add(tk->base_mono, tk->offs_boot));
write_seqcount_begin(&vdata->seq); write_seqcount_begin(&vdata->seq);
@ -1004,17 +1006,8 @@ static void update_pvclock_gtod(struct timekeeper *tk)
vdata->clock.mult = tk->mult; vdata->clock.mult = tk->mult;
vdata->clock.shift = tk->shift; vdata->clock.shift = tk->shift;
vdata->monotonic_time_sec = tk->xtime_sec vdata->boot_ns = boot_ns;
+ tk->wall_to_monotonic.tv_sec; vdata->nsec_base = tk->xtime_nsec;
vdata->monotonic_time_snsec = tk->xtime_nsec
+ (tk->wall_to_monotonic.tv_nsec
<< tk->shift);
while (vdata->monotonic_time_snsec >=
(((u64)NSEC_PER_SEC) << tk->shift)) {
vdata->monotonic_time_snsec -=
((u64)NSEC_PER_SEC) << tk->shift;
vdata->monotonic_time_sec++;
}
write_seqcount_end(&vdata->seq); write_seqcount_end(&vdata->seq);
} }
@ -1371,23 +1364,22 @@ static inline u64 vgettsc(cycle_t *cycle_now)
return v * gtod->clock.mult; return v * gtod->clock.mult;
} }
static int do_monotonic(struct timespec *ts, cycle_t *cycle_now) static int do_monotonic_boot(s64 *t, cycle_t *cycle_now)
{ {
unsigned long seq;
u64 ns;
int mode;
struct pvclock_gtod_data *gtod = &pvclock_gtod_data; struct pvclock_gtod_data *gtod = &pvclock_gtod_data;
unsigned long seq;
int mode;
u64 ns;
ts->tv_nsec = 0;
do { do {
seq = read_seqcount_begin(&gtod->seq); seq = read_seqcount_begin(&gtod->seq);
mode = gtod->clock.vclock_mode; mode = gtod->clock.vclock_mode;
ts->tv_sec = gtod->monotonic_time_sec; ns = gtod->nsec_base;
ns = gtod->monotonic_time_snsec;
ns += vgettsc(cycle_now); ns += vgettsc(cycle_now);
ns >>= gtod->clock.shift; ns >>= gtod->clock.shift;
ns += gtod->boot_ns;
} while (unlikely(read_seqcount_retry(&gtod->seq, seq))); } while (unlikely(read_seqcount_retry(&gtod->seq, seq)));
timespec_add_ns(ts, ns); *t = ns;
return mode; return mode;
} }
@ -1395,19 +1387,11 @@ static int do_monotonic(struct timespec *ts, cycle_t *cycle_now)
/* returns true if host is using tsc clocksource */ /* returns true if host is using tsc clocksource */
static bool kvm_get_time_and_clockread(s64 *kernel_ns, cycle_t *cycle_now) static bool kvm_get_time_and_clockread(s64 *kernel_ns, cycle_t *cycle_now)
{ {
struct timespec ts;
/* checked again under seqlock below */ /* checked again under seqlock below */
if (pvclock_gtod_data.clock.vclock_mode != VCLOCK_TSC) if (pvclock_gtod_data.clock.vclock_mode != VCLOCK_TSC)
return false; return false;
if (do_monotonic(&ts, cycle_now) != VCLOCK_TSC) return do_monotonic_boot(kernel_ns, cycle_now) == VCLOCK_TSC;
return false;
monotonic_to_bootbased(&ts);
*kernel_ns = timespec_to_ns(&ts);
return true;
} }
#endif #endif