From cbcf2dd3b3d4d990610259e8d878fc8dc1f17d80 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Wed, 16 Jul 2014 21:04:54 +0000 Subject: [PATCH] x86: kvm: Make kvm_get_time_and_clockread() nanoseconds based 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 Cc: Gleb Natapov Cc: kvm@vger.kernel.org Acked-by: Paolo Bonzini Signed-off-by: John Stultz --- arch/x86/kvm/x86.c | 44 ++++++++++++++------------------------------ 1 file changed, 14 insertions(+), 30 deletions(-) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 65c430512132..63832f5110b6 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -984,9 +984,8 @@ struct pvclock_gtod_data { u32 shift; } clock; - /* open coded 'struct timespec' */ - u64 monotonic_time_snsec; - time_t monotonic_time_sec; + u64 boot_ns; + u64 nsec_base; }; 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) { 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); @@ -1004,17 +1006,8 @@ static void update_pvclock_gtod(struct timekeeper *tk) vdata->clock.mult = tk->mult; vdata->clock.shift = tk->shift; - vdata->monotonic_time_sec = tk->xtime_sec - + tk->wall_to_monotonic.tv_sec; - 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++; - } + vdata->boot_ns = boot_ns; + vdata->nsec_base = tk->xtime_nsec; write_seqcount_end(&vdata->seq); } @@ -1371,23 +1364,22 @@ static inline u64 vgettsc(cycle_t *cycle_now) 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) { + struct pvclock_gtod_data *gtod = &pvclock_gtod_data; unsigned long seq; - u64 ns; int mode; - struct pvclock_gtod_data *gtod = &pvclock_gtod_data; + u64 ns; - ts->tv_nsec = 0; do { seq = read_seqcount_begin(>od->seq); mode = gtod->clock.vclock_mode; - ts->tv_sec = gtod->monotonic_time_sec; - ns = gtod->monotonic_time_snsec; + ns = gtod->nsec_base; ns += vgettsc(cycle_now); ns >>= gtod->clock.shift; + ns += gtod->boot_ns; } while (unlikely(read_seqcount_retry(>od->seq, seq))); - timespec_add_ns(ts, ns); + *t = ns; 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 */ static bool kvm_get_time_and_clockread(s64 *kernel_ns, cycle_t *cycle_now) { - struct timespec ts; - /* checked again under seqlock below */ if (pvclock_gtod_data.clock.vclock_mode != VCLOCK_TSC) return false; - if (do_monotonic(&ts, cycle_now) != VCLOCK_TSC) - return false; - - monotonic_to_bootbased(&ts); - *kernel_ns = timespec_to_ns(&ts); - - return true; + return do_monotonic_boot(kernel_ns, cycle_now) == VCLOCK_TSC; } #endif -- 2.20.1