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authorAndré Fabian Silva Delgado <emulatorman@parabola.nu>2015-08-05 17:04:01 -0300
committerAndré Fabian Silva Delgado <emulatorman@parabola.nu>2015-08-05 17:04:01 -0300
commit57f0f512b273f60d52568b8c6b77e17f5636edc0 (patch)
tree5e910f0e82173f4ef4f51111366a3f1299037a7b /arch/x86/xen/time.c
Initial import
Diffstat (limited to 'arch/x86/xen/time.c')
-rw-r--r--arch/x86/xen/time.c558
1 files changed, 558 insertions, 0 deletions
diff --git a/arch/x86/xen/time.c b/arch/x86/xen/time.c
new file mode 100644
index 000000000..55da33b1d
--- /dev/null
+++ b/arch/x86/xen/time.c
@@ -0,0 +1,558 @@
+/*
+ * 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 <linux/math64.h>
+#include <linux/gfp.h>
+#include <linux/slab.h>
+#include <linux/pvclock_gtod.h>
+
+#include <asm/pvclock.h>
+#include <asm/xen/hypervisor.h>
+#include <asm/xen/hypercall.h>
+
+#include <xen/events.h>
+#include <xen/features.h>
+#include <xen/interface/xen.h>
+#include <xen/interface/vcpu.h>
+
+#include "xen-ops.h"
+
+/* Xen may fire a timer up to this many ns early */
+#define TIMER_SLOP 100000
+#define NS_PER_TICK (1000000000LL / HZ)
+
+/* runstate info updated by Xen */
+static DEFINE_PER_CPU(struct vcpu_runstate_info, xen_runstate);
+
+/* snapshots of runstate info */
+static DEFINE_PER_CPU(struct vcpu_runstate_info, xen_runstate_snapshot);
+
+/* unused ns of stolen time */
+static DEFINE_PER_CPU(u64, xen_residual_stolen);
+
+/* 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 = this_cpu_ptr(&xen_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);
+}
+
+/* return true when a vcpu could run but has no real cpu to run on */
+bool xen_vcpu_stolen(int vcpu)
+{
+ return per_cpu(xen_runstate, vcpu).state == RUNSTATE_runnable;
+}
+
+void xen_setup_runstate_info(int cpu)
+{
+ struct vcpu_register_runstate_memory_area area;
+
+ area.addr.v = &per_cpu(xen_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 runnable, offline, stolen;
+ cputime_t ticks;
+
+ get_runstate_snapshot(&state);
+
+ WARN_ON(state.state != RUNSTATE_running);
+
+ snap = this_cpu_ptr(&xen_runstate_snapshot);
+
+ /* work out how much time the VCPU has not been runn*ing* */
+ 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. */
+ stolen = runnable + offline + __this_cpu_read(xen_residual_stolen);
+
+ if (stolen < 0)
+ stolen = 0;
+
+ ticks = iter_div_u64_rem(stolen, NS_PER_TICK, &stolen);
+ __this_cpu_write(xen_residual_stolen, stolen);
+ account_steal_ticks(ticks);
+}
+
+/* Get the TSC speed from Xen */
+static unsigned long xen_tsc_khz(void)
+{
+ struct pvclock_vcpu_time_info *info =
+ &HYPERVISOR_shared_info->vcpu_info[0].time;
+
+ return pvclock_tsc_khz(info);
+}
+
+cycle_t xen_clocksource_read(void)
+{
+ struct pvclock_vcpu_time_info *src;
+ cycle_t ret;
+
+ preempt_disable_notrace();
+ src = &__this_cpu_read(xen_vcpu)->time;
+ ret = pvclock_clocksource_read(src);
+ preempt_enable_notrace();
+ return ret;
+}
+
+static cycle_t xen_clocksource_get_cycles(struct clocksource *cs)
+{
+ return xen_clocksource_read();
+}
+
+static void xen_read_wallclock(struct timespec *ts)
+{
+ struct shared_info *s = HYPERVISOR_shared_info;
+ struct pvclock_wall_clock *wall_clock = &(s->wc);
+ struct pvclock_vcpu_time_info *vcpu_time;
+
+ vcpu_time = &get_cpu_var(xen_vcpu)->time;
+ pvclock_read_wallclock(wall_clock, vcpu_time, ts);
+ put_cpu_var(xen_vcpu);
+}
+
+static void xen_get_wallclock(struct timespec *now)
+{
+ xen_read_wallclock(now);
+}
+
+static int xen_set_wallclock(const struct timespec *now)
+{
+ return -1;
+}
+
+static int xen_pvclock_gtod_notify(struct notifier_block *nb,
+ unsigned long was_set, void *priv)
+{
+ /* Protected by the calling core code serialization */
+ static struct timespec next_sync;
+
+ struct xen_platform_op op;
+ struct timespec now;
+
+ now = __current_kernel_time();
+
+ /*
+ * We only take the expensive HV call when the clock was set
+ * or when the 11 minutes RTC synchronization time elapsed.
+ */
+ if (!was_set && timespec_compare(&now, &next_sync) < 0)
+ return NOTIFY_OK;
+
+ op.cmd = XENPF_settime;
+ op.u.settime.secs = now.tv_sec;
+ op.u.settime.nsecs = now.tv_nsec;
+ op.u.settime.system_time = xen_clocksource_read();
+
+ (void)HYPERVISOR_dom0_op(&op);
+
+ /*
+ * Move the next drift compensation time 11 minutes
+ * ahead. That's emulating the sync_cmos_clock() update for
+ * the hardware RTC.
+ */
+ next_sync = now;
+ next_sync.tv_sec += 11 * 60;
+
+ return NOTIFY_OK;
+}
+
+static struct notifier_block xen_pvclock_gtod_notifier = {
+ .notifier_call = xen_pvclock_gtod_notify,
+};
+
+static struct clocksource xen_clocksource __read_mostly = {
+ .name = "xen",
+ .rating = 400,
+ .read = xen_clocksource_get_cycles,
+ .mask = ~0,
+ .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;
+
+struct xen_clock_event_device {
+ struct clock_event_device evt;
+ char name[16];
+};
+static DEFINE_PER_CPU(struct xen_clock_event_device, xen_clock_events) = { .evt.irq = -1 };
+
+static irqreturn_t xen_timer_interrupt(int irq, void *dev_id)
+{
+ struct clock_event_device *evt = this_cpu_ptr(&xen_clock_events.evt);
+ irqreturn_t ret;
+
+ ret = IRQ_NONE;
+ if (evt->event_handler) {
+ evt->event_handler(evt);
+ ret = IRQ_HANDLED;
+ }
+
+ do_stolen_accounting();
+
+ return ret;
+}
+
+void xen_teardown_timer(int cpu)
+{
+ struct clock_event_device *evt;
+ BUG_ON(cpu == 0);
+ evt = &per_cpu(xen_clock_events, cpu).evt;
+
+ if (evt->irq >= 0) {
+ unbind_from_irqhandler(evt->irq, NULL);
+ evt->irq = -1;
+ }
+}
+
+void xen_setup_timer(int cpu)
+{
+ struct xen_clock_event_device *xevt = &per_cpu(xen_clock_events, cpu);
+ struct clock_event_device *evt = &xevt->evt;
+ int irq;
+
+ WARN(evt->irq >= 0, "IRQ%d for CPU%d is already allocated\n", evt->irq, cpu);
+ if (evt->irq >= 0)
+ xen_teardown_timer(cpu);
+
+ printk(KERN_INFO "installing Xen timer for CPU %d\n", cpu);
+
+ snprintf(xevt->name, sizeof(xevt->name), "timer%d", cpu);
+
+ irq = bind_virq_to_irqhandler(VIRQ_TIMER, cpu, xen_timer_interrupt,
+ IRQF_PERCPU|IRQF_NOBALANCING|IRQF_TIMER|
+ IRQF_FORCE_RESUME|IRQF_EARLY_RESUME,
+ xevt->name, NULL);
+ (void)xen_set_irq_priority(irq, XEN_IRQ_PRIORITY_MAX);
+
+ memcpy(evt, xen_clockevent, sizeof(*evt));
+
+ evt->cpumask = cpumask_of(cpu);
+ evt->irq = irq;
+}
+
+
+void xen_setup_cpu_clockevents(void)
+{
+ clockevents_register_device(this_cpu_ptr(&xen_clock_events.evt));
+}
+
+void xen_timer_resume(void)
+{
+ int cpu;
+
+ pvclock_resume();
+
+ if (xen_clockevent != &xen_vcpuop_clockevent)
+ return;
+
+ for_each_online_cpu(cpu) {
+ if (HYPERVISOR_vcpu_op(VCPUOP_stop_periodic_timer, cpu, NULL))
+ BUG();
+ }
+}
+
+static const struct pv_time_ops xen_time_ops __initconst = {
+ .sched_clock = xen_clocksource_read,
+};
+
+static void __init xen_time_init(void)
+{
+ int cpu = smp_processor_id();
+ struct timespec tp;
+
+ /* As Dom0 is never moved, no penalty on using TSC there */
+ if (xen_initial_domain())
+ xen_clocksource.rating = 275;
+
+ clocksource_register_hz(&xen_clocksource, NSEC_PER_SEC);
+
+ 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(&tp);
+ do_settimeofday(&tp);
+
+ setup_force_cpu_cap(X86_FEATURE_TSC);
+
+ xen_setup_runstate_info(cpu);
+ xen_setup_timer(cpu);
+ xen_setup_cpu_clockevents();
+
+ if (xen_initial_domain())
+ pvclock_gtod_register_notifier(&xen_pvclock_gtod_notifier);
+}
+
+void __init xen_init_time_ops(void)
+{
+ pv_time_ops = xen_time_ops;
+
+ x86_init.timers.timer_init = xen_time_init;
+ x86_init.timers.setup_percpu_clockev = x86_init_noop;
+ x86_cpuinit.setup_percpu_clockev = x86_init_noop;
+
+ x86_platform.calibrate_tsc = xen_tsc_khz;
+ x86_platform.get_wallclock = xen_get_wallclock;
+ /* Dom0 uses the native method to set the hardware RTC. */
+ if (!xen_initial_domain())
+ x86_platform.set_wallclock = xen_set_wallclock;
+}
+
+#ifdef CONFIG_XEN_PVHVM
+static void xen_hvm_setup_cpu_clockevents(void)
+{
+ int cpu = smp_processor_id();
+ xen_setup_runstate_info(cpu);
+ /*
+ * xen_setup_timer(cpu) - snprintf is bad in atomic context. Hence
+ * doing it xen_hvm_cpu_notify (which gets called by smp_init during
+ * early bootup and also during CPU hotplug events).
+ */
+ xen_setup_cpu_clockevents();
+}
+
+void __init xen_hvm_init_time_ops(void)
+{
+ /* vector callback is needed otherwise we cannot receive interrupts
+ * on cpu > 0 and at this point we don't know how many cpus are
+ * available */
+ if (!xen_have_vector_callback)
+ return;
+ if (!xen_feature(XENFEAT_hvm_safe_pvclock)) {
+ printk(KERN_INFO "Xen doesn't support pvclock on HVM,"
+ "disable pv timer\n");
+ return;
+ }
+
+ pv_time_ops = xen_time_ops;
+ x86_init.timers.setup_percpu_clockev = xen_time_init;
+ x86_cpuinit.setup_percpu_clockev = xen_hvm_setup_cpu_clockevents;
+
+ x86_platform.calibrate_tsc = xen_tsc_khz;
+ x86_platform.get_wallclock = xen_get_wallclock;
+ x86_platform.set_wallclock = xen_set_wallclock;
+}
+#endif