diff options
Diffstat (limited to 'arch/x86/xen/time.c')
| -rw-r--r-- | arch/x86/xen/time.c | 145 |
1 files changed, 15 insertions, 130 deletions
diff --git a/arch/x86/xen/time.c b/arch/x86/xen/time.c index c39e1a5aa241..41e217503c96 100644 --- a/arch/x86/xen/time.c +++ b/arch/x86/xen/time.c @@ -12,7 +12,9 @@ #include <linux/clocksource.h> #include <linux/clockchips.h> #include <linux/kernel_stat.h> +#include <linux/math64.h> +#include <asm/pvclock.h> #include <asm/xen/hypervisor.h> #include <asm/xen/hypercall.h> @@ -30,17 +32,6 @@ static cycle_t xen_clocksource_read(void); -/* These are perodically updated in shared_info, and then copied here. */ -struct shadow_time_info { - u64 tsc_timestamp; /* TSC at last update of time vals. */ - u64 system_timestamp; /* Time, in nanosecs, since boot. */ - u32 tsc_to_nsec_mul; - int tsc_shift; - u32 version; -}; - -static DEFINE_PER_CPU(struct shadow_time_info, shadow_time); - /* runstate info updated by Xen */ static DEFINE_PER_CPU(struct vcpu_runstate_info, runstate); @@ -150,11 +141,7 @@ static void do_stolen_accounting(void) if (stolen < 0) stolen = 0; - ticks = 0; - while (stolen >= NS_PER_TICK) { - ticks++; - stolen -= NS_PER_TICK; - } + ticks = iter_div_u64_rem(stolen, NS_PER_TICK, &stolen); __get_cpu_var(residual_stolen) = stolen; account_steal_time(NULL, ticks); @@ -166,11 +153,7 @@ static void do_stolen_accounting(void) if (blocked < 0) blocked = 0; - ticks = 0; - while (blocked >= NS_PER_TICK) { - ticks++; - blocked -= NS_PER_TICK; - } + ticks = iter_div_u64_rem(blocked, NS_PER_TICK, &blocked); __get_cpu_var(residual_blocked) = blocked; account_steal_time(idle_task(smp_processor_id()), ticks); } @@ -218,7 +201,7 @@ unsigned long long xen_sched_clock(void) unsigned long xen_cpu_khz(void) { u64 xen_khz = 1000000ULL << 32; - const struct vcpu_time_info *info = + const struct pvclock_vcpu_time_info *info = &HYPERVISOR_shared_info->vcpu_info[0].time; do_div(xen_khz, info->tsc_to_system_mul); @@ -230,121 +213,26 @@ unsigned long xen_cpu_khz(void) return xen_khz; } -/* - * Reads a consistent set of time-base values from Xen, into a shadow data - * area. - */ -static unsigned get_time_values_from_xen(void) -{ - struct vcpu_time_info *src; - struct shadow_time_info *dst; - - /* src is shared memory with the hypervisor, so we need to - make sure we get a consistent snapshot, even in the face of - being preempted. */ - src = &__get_cpu_var(xen_vcpu)->time; - dst = &__get_cpu_var(shadow_time); - - do { - dst->version = src->version; - rmb(); /* fetch version before data */ - dst->tsc_timestamp = src->tsc_timestamp; - dst->system_timestamp = src->system_time; - dst->tsc_to_nsec_mul = src->tsc_to_system_mul; - dst->tsc_shift = src->tsc_shift; - rmb(); /* test version after fetching data */ - } while ((src->version & 1) | (dst->version ^ src->version)); - - return dst->version; -} - -/* - * Scale a 64-bit delta by scaling and multiplying by a 32-bit fraction, - * yielding a 64-bit result. - */ -static inline u64 scale_delta(u64 delta, u32 mul_frac, int shift) -{ - u64 product; -#ifdef __i386__ - u32 tmp1, tmp2; -#endif - - if (shift < 0) - delta >>= -shift; - else - delta <<= shift; - -#ifdef __i386__ - __asm__ ( - "mul %5 ; " - "mov %4,%%eax ; " - "mov %%edx,%4 ; " - "mul %5 ; " - "xor %5,%5 ; " - "add %4,%%eax ; " - "adc %5,%%edx ; " - : "=A" (product), "=r" (tmp1), "=r" (tmp2) - : "a" ((u32)delta), "1" ((u32)(delta >> 32)), "2" (mul_frac) ); -#elif __x86_64__ - __asm__ ( - "mul %%rdx ; shrd $32,%%rdx,%%rax" - : "=a" (product) : "0" (delta), "d" ((u64)mul_frac) ); -#else -#error implement me! -#endif - - return product; -} - -static u64 get_nsec_offset(struct shadow_time_info *shadow) -{ - u64 now, delta; - now = native_read_tsc(); - delta = now - shadow->tsc_timestamp; - return scale_delta(delta, shadow->tsc_to_nsec_mul, shadow->tsc_shift); -} - static cycle_t xen_clocksource_read(void) { - struct shadow_time_info *shadow = &get_cpu_var(shadow_time); + struct pvclock_vcpu_time_info *src; cycle_t ret; - unsigned version; - - do { - version = get_time_values_from_xen(); - barrier(); - ret = shadow->system_timestamp + get_nsec_offset(shadow); - barrier(); - } while (version != __get_cpu_var(xen_vcpu)->time.version); - - put_cpu_var(shadow_time); + src = &get_cpu_var(xen_vcpu)->time; + ret = pvclock_clocksource_read(src); + put_cpu_var(xen_vcpu); return ret; } static void xen_read_wallclock(struct timespec *ts) { - const struct shared_info *s = HYPERVISOR_shared_info; - u32 version; - u64 delta; - struct timespec now; - - /* get wallclock at system boot */ - do { - version = s->wc_version; - rmb(); /* fetch version before time */ - now.tv_sec = s->wc_sec; - now.tv_nsec = s->wc_nsec; - rmb(); /* fetch time before checking version */ - } while ((s->wc_version & 1) | (version ^ s->wc_version)); + struct shared_info *s = HYPERVISOR_shared_info; + struct pvclock_wall_clock *wall_clock = &(s->wc); + struct pvclock_vcpu_time_info *vcpu_time; - delta = xen_clocksource_read(); /* time since system boot */ - delta += now.tv_sec * (u64)NSEC_PER_SEC + now.tv_nsec; - - now.tv_nsec = do_div(delta, NSEC_PER_SEC); - now.tv_sec = delta; - - set_normalized_timespec(ts, now.tv_sec, now.tv_nsec); + vcpu_time = &get_cpu_var(xen_vcpu)->time; + pvclock_read_wallclock(wall_clock, vcpu_time, ts); + put_cpu_var(xen_vcpu); } unsigned long xen_get_wallclock(void) @@ -352,7 +240,6 @@ unsigned long xen_get_wallclock(void) struct timespec ts; xen_read_wallclock(&ts); - return ts.tv_sec; } @@ -576,8 +463,6 @@ __init void xen_time_init(void) { int cpu = smp_processor_id(); - get_time_values_from_xen(); - clocksource_register(&xen_clocksource); if (HYPERVISOR_vcpu_op(VCPUOP_stop_periodic_timer, cpu, NULL) == 0) { |