diff options
Diffstat (limited to 'arch/i386/xen/time.c')
| -rw-r--r-- | arch/i386/xen/time.c | 593 |
1 files changed, 0 insertions, 593 deletions
diff --git a/arch/i386/xen/time.c b/arch/i386/xen/time.c deleted file mode 100644 index dfd6db69ead..00000000000 --- a/arch/i386/xen/time.c +++ /dev/null @@ -1,593 +0,0 @@ -/* - * Xen time implementation. - * - * This is implemented in terms of a clocksource driver which uses - * the hypervisor clock as a nanosecond timebase, and a clockevent - * driver which uses the hypervisor's timer mechanism. - * - * Jeremy Fitzhardinge <jeremy@xensource.com>, XenSource Inc, 2007 - */ -#include <linux/kernel.h> -#include <linux/interrupt.h> -#include <linux/clocksource.h> -#include <linux/clockchips.h> -#include <linux/kernel_stat.h> - -#include <asm/xen/hypervisor.h> -#include <asm/xen/hypercall.h> - -#include <xen/events.h> -#include <xen/interface/xen.h> -#include <xen/interface/vcpu.h> - -#include "xen-ops.h" - -#define XEN_SHIFT 22 - -/* Xen may fire a timer up to this many ns early */ -#define TIMER_SLOP 100000 -#define NS_PER_TICK (1000000000LL / HZ) - -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); - -/* snapshots of runstate info */ -static DEFINE_PER_CPU(struct vcpu_runstate_info, runstate_snapshot); - -/* unused ns of stolen and blocked time */ -static DEFINE_PER_CPU(u64, residual_stolen); -static DEFINE_PER_CPU(u64, residual_blocked); - -/* return an consistent snapshot of 64-bit time/counter value */ -static u64 get64(const u64 *p) -{ - u64 ret; - - if (BITS_PER_LONG < 64) { - u32 *p32 = (u32 *)p; - u32 h, l; - - /* - * Read high then low, and then make sure high is - * still the same; this will only loop if low wraps - * and carries into high. - * XXX some clean way to make this endian-proof? - */ - do { - h = p32[1]; - barrier(); - l = p32[0]; - barrier(); - } while (p32[1] != h); - - ret = (((u64)h) << 32) | l; - } else - ret = *p; - - return ret; -} - -/* - * Runstate accounting - */ -static void get_runstate_snapshot(struct vcpu_runstate_info *res) -{ - u64 state_time; - struct vcpu_runstate_info *state; - - BUG_ON(preemptible()); - - state = &__get_cpu_var(runstate); - - /* - * The runstate info is always updated by the hypervisor on - * the current CPU, so there's no need to use anything - * stronger than a compiler barrier when fetching it. - */ - do { - state_time = get64(&state->state_entry_time); - barrier(); - *res = *state; - barrier(); - } while (get64(&state->state_entry_time) != state_time); -} - -static void setup_runstate_info(int cpu) -{ - struct vcpu_register_runstate_memory_area area; - - area.addr.v = &per_cpu(runstate, cpu); - - if (HYPERVISOR_vcpu_op(VCPUOP_register_runstate_memory_area, - cpu, &area)) - BUG(); -} - -static void do_stolen_accounting(void) -{ - struct vcpu_runstate_info state; - struct vcpu_runstate_info *snap; - s64 blocked, runnable, offline, stolen; - cputime_t ticks; - - get_runstate_snapshot(&state); - - WARN_ON(state.state != RUNSTATE_running); - - snap = &__get_cpu_var(runstate_snapshot); - - /* work out how much time the VCPU has not been runn*ing* */ - blocked = state.time[RUNSTATE_blocked] - snap->time[RUNSTATE_blocked]; - runnable = state.time[RUNSTATE_runnable] - snap->time[RUNSTATE_runnable]; - offline = state.time[RUNSTATE_offline] - snap->time[RUNSTATE_offline]; - - *snap = state; - - /* Add the appropriate number of ticks of stolen time, - including any left-overs from last time. Passing NULL to - account_steal_time accounts the time as stolen. */ - stolen = runnable + offline + __get_cpu_var(residual_stolen); - - if (stolen < 0) - stolen = 0; - - ticks = 0; - while (stolen >= NS_PER_TICK) { - ticks++; - stolen -= NS_PER_TICK; - } - __get_cpu_var(residual_stolen) = stolen; - account_steal_time(NULL, ticks); - - /* Add the appropriate number of ticks of blocked time, - including any left-overs from last time. Passing idle to - account_steal_time accounts the time as idle/wait. */ - blocked += __get_cpu_var(residual_blocked); - - if (blocked < 0) - blocked = 0; - - ticks = 0; - while (blocked >= NS_PER_TICK) { - ticks++; - blocked -= NS_PER_TICK; - } - __get_cpu_var(residual_blocked) = blocked; - account_steal_time(idle_task(smp_processor_id()), ticks); -} - -/* - * Xen sched_clock implementation. Returns the number of unstolen - * nanoseconds, which is nanoseconds the VCPU spent in RUNNING+BLOCKED - * states. - */ -unsigned long long xen_sched_clock(void) -{ - struct vcpu_runstate_info state; - cycle_t now; - u64 ret; - s64 offset; - - /* - * Ideally sched_clock should be called on a per-cpu basis - * anyway, so preempt should already be disabled, but that's - * not current practice at the moment. - */ - preempt_disable(); - - now = xen_clocksource_read(); - - get_runstate_snapshot(&state); - - WARN_ON(state.state != RUNSTATE_running); - - offset = now - state.state_entry_time; - if (offset < 0) - offset = 0; - - ret = state.time[RUNSTATE_blocked] + - state.time[RUNSTATE_running] + - offset; - - preempt_enable(); - - return ret; -} - - -/* Get the CPU speed from Xen */ -unsigned long xen_cpu_khz(void) -{ - u64 cpu_khz = 1000000ULL << 32; - const struct vcpu_time_info *info = - &HYPERVISOR_shared_info->vcpu_info[0].time; - - do_div(cpu_khz, info->tsc_to_system_mul); - if (info->tsc_shift < 0) - cpu_khz <<= -info->tsc_shift; - else - cpu_khz >>= info->tsc_shift; - - return cpu_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); - 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); - - 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)); - - 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); -} - -unsigned long xen_get_wallclock(void) -{ - struct timespec ts; - - xen_read_wallclock(&ts); - - return ts.tv_sec; -} - -int xen_set_wallclock(unsigned long now) -{ - /* do nothing for domU */ - return -1; -} - -static struct clocksource xen_clocksource __read_mostly = { - .name = "xen", - .rating = 400, - .read = xen_clocksource_read, - .mask = ~0, - .mult = 1<<XEN_SHIFT, /* time directly in nanoseconds */ - .shift = XEN_SHIFT, - .flags = CLOCK_SOURCE_IS_CONTINUOUS, -}; - -/* - Xen clockevent implementation - - Xen has two clockevent implementations: - - The old timer_op one works with all released versions of Xen prior - to version 3.0.4. This version of the hypervisor provides a - single-shot timer with nanosecond resolution. However, sharing the - same event channel is a 100Hz tick which is delivered while the - vcpu is running. We don't care about or use this tick, but it will - cause the core time code to think the timer fired too soon, and - will end up resetting it each time. It could be filtered, but - doing so has complications when the ktime clocksource is not yet - the xen clocksource (ie, at boot time). - - The new vcpu_op-based timer interface allows the tick timer period - to be changed or turned off. The tick timer is not useful as a - periodic timer because events are only delivered to running vcpus. - The one-shot timer can report when a timeout is in the past, so - set_next_event is capable of returning -ETIME when appropriate. - This interface is used when available. -*/ - - -/* - Get a hypervisor absolute time. In theory we could maintain an - offset between the kernel's time and the hypervisor's time, and - apply that to a kernel's absolute timeout. Unfortunately the - hypervisor and kernel times can drift even if the kernel is using - the Xen clocksource, because ntp can warp the kernel's clocksource. -*/ -static s64 get_abs_timeout(unsigned long delta) -{ - return xen_clocksource_read() + delta; -} - -static void xen_timerop_set_mode(enum clock_event_mode mode, - struct clock_event_device *evt) -{ - switch (mode) { - case CLOCK_EVT_MODE_PERIODIC: - /* unsupported */ - WARN_ON(1); - break; - - case CLOCK_EVT_MODE_ONESHOT: - case CLOCK_EVT_MODE_RESUME: - break; - - case CLOCK_EVT_MODE_UNUSED: - case CLOCK_EVT_MODE_SHUTDOWN: - HYPERVISOR_set_timer_op(0); /* cancel timeout */ - break; - } -} - -static int xen_timerop_set_next_event(unsigned long delta, - struct clock_event_device *evt) -{ - WARN_ON(evt->mode != CLOCK_EVT_MODE_ONESHOT); - - if (HYPERVISOR_set_timer_op(get_abs_timeout(delta)) < 0) - BUG(); - - /* We may have missed the deadline, but there's no real way of - knowing for sure. If the event was in the past, then we'll - get an immediate interrupt. */ - - return 0; -} - -static const struct clock_event_device xen_timerop_clockevent = { - .name = "xen", - .features = CLOCK_EVT_FEAT_ONESHOT, - - .max_delta_ns = 0xffffffff, - .min_delta_ns = TIMER_SLOP, - - .mult = 1, - .shift = 0, - .rating = 500, - - .set_mode = xen_timerop_set_mode, - .set_next_event = xen_timerop_set_next_event, -}; - - - -static void xen_vcpuop_set_mode(enum clock_event_mode mode, - struct clock_event_device *evt) -{ - int cpu = smp_processor_id(); - - switch (mode) { - case CLOCK_EVT_MODE_PERIODIC: - WARN_ON(1); /* unsupported */ - break; - - case CLOCK_EVT_MODE_ONESHOT: - if (HYPERVISOR_vcpu_op(VCPUOP_stop_periodic_timer, cpu, NULL)) - BUG(); - break; - - case CLOCK_EVT_MODE_UNUSED: - case CLOCK_EVT_MODE_SHUTDOWN: - if (HYPERVISOR_vcpu_op(VCPUOP_stop_singleshot_timer, cpu, NULL) || - HYPERVISOR_vcpu_op(VCPUOP_stop_periodic_timer, cpu, NULL)) - BUG(); - break; - case CLOCK_EVT_MODE_RESUME: - break; - } -} - -static int xen_vcpuop_set_next_event(unsigned long delta, - struct clock_event_device *evt) -{ - int cpu = smp_processor_id(); - struct vcpu_set_singleshot_timer single; - int ret; - - WARN_ON(evt->mode != CLOCK_EVT_MODE_ONESHOT); - - single.timeout_abs_ns = get_abs_timeout(delta); - single.flags = VCPU_SSHOTTMR_future; - - ret = HYPERVISOR_vcpu_op(VCPUOP_set_singleshot_timer, cpu, &single); - - BUG_ON(ret != 0 && ret != -ETIME); - - return ret; -} - -static const struct clock_event_device xen_vcpuop_clockevent = { - .name = "xen", - .features = CLOCK_EVT_FEAT_ONESHOT, - - .max_delta_ns = 0xffffffff, - .min_delta_ns = TIMER_SLOP, - - .mult = 1, - .shift = 0, - .rating = 500, - - .set_mode = xen_vcpuop_set_mode, - .set_next_event = xen_vcpuop_set_next_event, -}; - -static const struct clock_event_device *xen_clockevent = - &xen_timerop_clockevent; -static DEFINE_PER_CPU(struct clock_event_device, xen_clock_events); - -static irqreturn_t xen_timer_interrupt(int irq, void *dev_id) -{ - struct clock_event_device *evt = &__get_cpu_var(xen_clock_events); - irqreturn_t ret; - - ret = IRQ_NONE; - if (evt->event_handler) { - evt->event_handler(evt); - ret = IRQ_HANDLED; - } - - do_stolen_accounting(); - - return ret; -} - -void xen_setup_timer(int cpu) -{ - const char *name; - struct clock_event_device *evt; - int irq; - - printk(KERN_INFO "installing Xen timer for CPU %d\n", cpu); - - name = kasprintf(GFP_KERNEL, "timer%d", cpu); - if (!name) - name = "<timer kasprintf failed>"; - - irq = bind_virq_to_irqhandler(VIRQ_TIMER, cpu, xen_timer_interrupt, - IRQF_DISABLED|IRQF_PERCPU|IRQF_NOBALANCING, - name, NULL); - - evt = &per_cpu(xen_clock_events, cpu); - memcpy(evt, xen_clockevent, sizeof(*evt)); - - evt->cpumask = cpumask_of_cpu(cpu); - evt->irq = irq; - - setup_runstate_info(cpu); -} - -void xen_setup_cpu_clockevents(void) -{ - BUG_ON(preemptible()); - - clockevents_register_device(&__get_cpu_var(xen_clock_events)); -} - -__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) { - /* Successfully turned off 100Hz tick, so we have the - vcpuop-based timer interface */ - printk(KERN_DEBUG "Xen: using vcpuop timer interface\n"); - xen_clockevent = &xen_vcpuop_clockevent; - } - - /* Set initial system time with full resolution */ - xen_read_wallclock(&xtime); - set_normalized_timespec(&wall_to_monotonic, - -xtime.tv_sec, -xtime.tv_nsec); - - tsc_disable = 0; - - xen_setup_timer(cpu); - xen_setup_cpu_clockevents(); -} |