2 * Copyright (c) 2009 Adrian Chadd
3 * Copyright (c) 2012 Spectra Logic Corporation
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * \file dev/xen/timer/timer.c
31 * \brief A timer driver for the Xen hypervisor's PV clock.
34 #include <sys/cdefs.h>
35 __FBSDID("$FreeBSD$");
37 #include <sys/param.h>
38 #include <sys/systm.h>
40 #include <sys/kernel.h>
41 #include <sys/module.h>
43 #include <sys/timetc.h>
44 #include <sys/timeet.h>
46 #include <sys/limits.h>
47 #include <sys/clock.h>
50 #include <xen/xen-os.h>
51 #include <xen/features.h>
52 #include <xen/xen_intr.h>
53 #include <xen/hypervisor.h>
54 #include <xen/interface/io/xenbus.h>
55 #include <xen/interface/vcpu.h>
56 #include <xen/error.h>
58 #include <machine/cpu.h>
59 #include <machine/cpufunc.h>
60 #include <machine/clock.h>
61 #include <machine/_inttypes.h>
62 #include <machine/smp.h>
63 #include <machine/pvclock.h>
65 #include <dev/xen/timer/timer.h>
69 static devclass_t xentimer_devclass;
71 #define NSEC_IN_SEC 1000000000ULL
72 #define NSEC_IN_USEC 1000ULL
73 /* 18446744073 = int(2^64 / NSEC_IN_SC) = 1 ns in 64-bit fractions */
74 #define FRAC_IN_NSEC 18446744073LL
76 /* Xen timers may fire up to 100us off */
77 #define XENTIMER_MIN_PERIOD_IN_NSEC 100*NSEC_IN_USEC
80 * The real resolution of the PV clock is 1ns, but the highest
81 * resolution that FreeBSD supports is 1us, so just use that.
83 #define XENCLOCK_RESOLUTION 1
85 #define XENTIMER_QUALITY 950
87 struct xentimer_pcpu_data {
89 uint64_t last_processed;
93 DPCPU_DEFINE(struct xentimer_pcpu_data, xentimer_pcpu);
95 DPCPU_DECLARE(struct vcpu_info *, vcpu_info);
97 struct xentimer_softc {
99 struct timecounter tc;
100 struct eventtimer et;
104 xentimer_identify(driver_t *driver, device_t parent)
109 /* Handle all Xen PV timers in one device instance. */
110 if (devclass_get_device(xentimer_devclass, 0))
113 BUS_ADD_CHILD(parent, 0, "xen_et", 0);
117 xentimer_probe(device_t dev)
119 KASSERT((xen_domain()), ("Trying to use Xen timer on bare metal"));
121 * In order to attach, this driver requires the following:
122 * - Vector callback support by the hypervisor, in order to deliver
123 * timer interrupts to the correct CPU for CPUs other than 0.
124 * - Access to the hypervisor shared info page, in order to look up
125 * each VCPU's timer information and the Xen wallclock time.
126 * - The hypervisor must say its PV clock is "safe" to use.
127 * - The hypervisor must support VCPUOP hypercalls.
128 * - The maximum number of CPUs supported by FreeBSD must not exceed
129 * the number of VCPUs supported by the hypervisor.
131 #define XTREQUIRES(condition, reason...) \
132 if (!(condition)) { \
133 device_printf(dev, ## reason); \
134 device_detach(dev); \
138 if (xen_hvm_domain()) {
139 XTREQUIRES(xen_vector_callback_enabled,
140 "vector callbacks unavailable\n");
141 XTREQUIRES(xen_feature(XENFEAT_hvm_safe_pvclock),
142 "HVM safe pvclock unavailable\n");
144 XTREQUIRES(HYPERVISOR_shared_info != NULL,
145 "shared info page unavailable\n");
146 XTREQUIRES(HYPERVISOR_vcpu_op(VCPUOP_stop_periodic_timer, 0, NULL) == 0,
147 "VCPUOPs interface unavailable\n");
149 device_set_desc(dev, "Xen PV Clock");
150 return (BUS_PROBE_NOWILDCARD);
154 * \brief Get the current time, in nanoseconds, since the hypervisor booted.
156 * \param vcpu vcpu_info structure to fetch the time from.
160 xen_fetch_vcpu_time(struct vcpu_info *vcpu)
162 struct pvclock_vcpu_time_info *time;
164 time = (struct pvclock_vcpu_time_info *) &vcpu->time;
166 return (pvclock_get_timecount(time));
170 xentimer_get_timecount(struct timecounter *tc)
175 * We don't disable preemption here because the worst that can
176 * happen is reading the vcpu_info area of a different CPU than
177 * the one we are currently running on, but that would also
178 * return a valid tc (and we avoid the overhead of
179 * critical_{enter/exit} calls).
181 vcpu_time = xen_fetch_vcpu_time(DPCPU_GET(vcpu_info));
183 return (vcpu_time & UINT32_MAX);
187 * \brief Fetch the hypervisor boot time, known as the "Xen wallclock".
189 * \param ts Timespec to store the current stable value.
190 * \param version Pointer to store the corresponding wallclock version.
192 * \note This value is updated when Domain-0 shifts its clock to follow
193 * clock drift, e.g. as detected by NTP.
196 xen_fetch_wallclock(struct timespec *ts)
198 shared_info_t *src = HYPERVISOR_shared_info;
199 struct pvclock_wall_clock *wc;
201 wc = (struct pvclock_wall_clock *) &src->wc_version;
203 pvclock_get_wallclock(wc, ts);
207 xen_fetch_uptime(struct timespec *ts)
211 uptime = xen_fetch_vcpu_time(DPCPU_GET(vcpu_info));
213 ts->tv_sec = uptime / NSEC_IN_SEC;
214 ts->tv_nsec = uptime % NSEC_IN_SEC;
218 xentimer_settime(device_t dev __unused, struct timespec *ts)
220 struct xen_platform_op settime;
224 * Don't return EINVAL here; just silently fail if the domain isn't
225 * privileged enough to set the TOD.
227 if (!xen_initial_domain())
230 settime.cmd = XENPF_settime64;
231 settime.u.settime64.mbz = 0;
232 settime.u.settime64.secs = ts->tv_sec;
233 settime.u.settime64.nsecs = ts->tv_nsec;
234 settime.u.settime64.system_time =
235 xen_fetch_vcpu_time(DPCPU_GET(vcpu_info));
237 ret = HYPERVISOR_platform_op(&settime);
238 ret = ret != 0 ? xen_translate_error(ret) : 0;
239 if (ret != 0 && bootverbose)
240 device_printf(dev, "failed to set Xen PV clock: %d\n", ret);
246 * \brief Return current time according to the Xen Hypervisor wallclock.
248 * \param dev Xentimer device.
249 * \param ts Pointer to store the wallclock time.
251 * \note The Xen time structures document the hypervisor start time and the
252 * uptime-since-hypervisor-start (in nsec.) They need to be combined
253 * in order to calculate a TOD clock.
256 xentimer_gettime(device_t dev, struct timespec *ts)
258 struct timespec u_ts;
261 xen_fetch_wallclock(ts);
262 xen_fetch_uptime(&u_ts);
263 timespecadd(ts, &u_ts);
269 * \brief Handle a timer interrupt for the Xen PV timer driver.
271 * \param arg Xen timer driver softc that is expecting the interrupt.
274 xentimer_intr(void *arg)
276 struct xentimer_softc *sc = (struct xentimer_softc *)arg;
277 struct xentimer_pcpu_data *pcpu = DPCPU_PTR(xentimer_pcpu);
279 pcpu->last_processed = xen_fetch_vcpu_time(DPCPU_GET(vcpu_info));
280 if (pcpu->timer != 0 && sc->et.et_active)
281 sc->et.et_event_cb(&sc->et, sc->et.et_arg);
283 return (FILTER_HANDLED);
287 xentimer_vcpu_start_timer(int vcpu, uint64_t next_time)
289 struct vcpu_set_singleshot_timer single;
291 single.timeout_abs_ns = next_time;
292 /* Get an event anyway, even if the timeout is already expired */
294 return (HYPERVISOR_vcpu_op(VCPUOP_set_singleshot_timer, vcpu, &single));
298 xentimer_vcpu_stop_timer(int vcpu)
301 return (HYPERVISOR_vcpu_op(VCPUOP_stop_singleshot_timer, vcpu, NULL));
305 * \brief Set the next oneshot time for the current CPU.
307 * \param et Xen timer driver event timer to schedule on.
308 * \param first Delta to the next time to schedule the interrupt for.
309 * \param period Not used.
311 * \note See eventtimers(9) for more information.
317 xentimer_et_start(struct eventtimer *et,
318 sbintime_t first, sbintime_t period)
321 struct xentimer_softc *sc = et->et_priv;
322 int cpu = PCPU_GET(vcpu_id);
323 struct xentimer_pcpu_data *pcpu = DPCPU_PTR(xentimer_pcpu);
324 struct vcpu_info *vcpu = DPCPU_GET(vcpu_info);
325 uint64_t first_in_ns, next_time;
327 struct thread *td = curthread;
330 KASSERT(td->td_critnest != 0,
331 ("xentimer_et_start called without preemption disabled"));
333 /* See sbttots() for this formula. */
334 first_in_ns = (((first >> 32) * NSEC_IN_SEC) +
335 (((uint64_t)NSEC_IN_SEC * (uint32_t)first) >> 32));
337 next_time = xen_fetch_vcpu_time(vcpu) + first_in_ns;
338 error = xentimer_vcpu_start_timer(cpu, next_time);
340 panic("%s: Error %d setting singleshot timer to %"PRIu64"\n",
341 device_get_nameunit(sc->dev), error, next_time);
343 pcpu->timer = next_time;
348 * \brief Cancel the event timer's currently running timer, if any.
351 xentimer_et_stop(struct eventtimer *et)
353 int cpu = PCPU_GET(vcpu_id);
354 struct xentimer_pcpu_data *pcpu = DPCPU_PTR(xentimer_pcpu);
357 return (xentimer_vcpu_stop_timer(cpu));
361 * \brief Attach a Xen PV timer driver instance.
363 * \param dev Bus device object to attach.
369 xentimer_attach(device_t dev)
371 struct xentimer_softc *sc = device_get_softc(dev);
376 /* Bind an event channel to a VIRQ on each VCPU. */
378 struct xentimer_pcpu_data *pcpu;
380 pcpu = DPCPU_ID_PTR(i, xentimer_pcpu);
381 error = HYPERVISOR_vcpu_op(VCPUOP_stop_periodic_timer, i, NULL);
383 device_printf(dev, "Error disabling Xen periodic timer "
388 error = xen_intr_bind_virq(dev, VIRQ_TIMER, i, xentimer_intr,
389 NULL, sc, INTR_TYPE_CLK, &pcpu->irq_handle);
391 device_printf(dev, "Error %d binding VIRQ_TIMER "
392 "to VCPU %d\n", error, i);
395 xen_intr_describe(pcpu->irq_handle, "c%d", i);
398 /* Register the event timer. */
399 sc->et.et_name = "XENTIMER";
400 sc->et.et_quality = XENTIMER_QUALITY;
401 sc->et.et_flags = ET_FLAGS_ONESHOT | ET_FLAGS_PERCPU;
402 sc->et.et_frequency = NSEC_IN_SEC;
403 /* See tstosbt() for this formula */
404 sc->et.et_min_period = (XENTIMER_MIN_PERIOD_IN_NSEC *
405 (((uint64_t)1 << 63) / 500000000) >> 32);
406 sc->et.et_max_period = ((sbintime_t)4 << 32);
407 sc->et.et_start = xentimer_et_start;
408 sc->et.et_stop = xentimer_et_stop;
410 et_register(&sc->et);
412 /* Register the timecounter. */
413 sc->tc.tc_name = "XENTIMER";
414 sc->tc.tc_quality = XENTIMER_QUALITY;
416 * FIXME: due to the lack of ordering during resume, FreeBSD cannot
417 * guarantee that the Xen PV timer is resumed before any other device
418 * attempts to make use of it, so mark it as not safe for suspension
419 * (ie: remove the TC_FLAGS_SUSPEND_SAFE flag).
421 * NB: This was not a problem in previous FreeBSD versions because the
422 * timer was directly attached to the nexus, but it is an issue now
423 * that the timer is attached to the xenpv bus, and thus resumed
426 * sc->tc.tc_flags = TC_FLAGS_SUSPEND_SAFE;
429 * The underlying resolution is in nanoseconds, since the timer info
430 * scales TSC frequencies using a fraction that represents time in
431 * terms of nanoseconds.
433 sc->tc.tc_frequency = NSEC_IN_SEC;
434 sc->tc.tc_counter_mask = ~0u;
435 sc->tc.tc_get_timecount = xentimer_get_timecount;
439 /* Register the Hypervisor wall clock */
440 clock_register(dev, XENCLOCK_RESOLUTION);
446 xentimer_detach(device_t dev)
449 /* Implement Xen PV clock teardown - XXX see hpet_detach ? */
451 * 1. need to deregister timecounter
452 * 2. need to deregister event timer
453 * 3. need to deregister virtual IRQ event channels
459 xentimer_percpu_resume(void *arg)
461 device_t dev = (device_t) arg;
462 struct xentimer_softc *sc = device_get_softc(dev);
464 xentimer_et_start(&sc->et, sc->et.et_min_period, 0);
468 xentimer_resume(device_t dev)
473 /* Disable the periodic timer */
475 error = HYPERVISOR_vcpu_op(VCPUOP_stop_periodic_timer, i, NULL);
478 "Error disabling Xen periodic timer on CPU %d\n",
484 /* Reset the last uptime value */
487 /* Reset the RTC clock */
488 inittodr(time_second);
490 /* Kick the timers on all CPUs */
491 smp_rendezvous(NULL, xentimer_percpu_resume, NULL, dev);
494 device_printf(dev, "resumed operation after suspension\n");
500 xentimer_suspend(device_t dev)
506 * Xen early clock init
514 * Xen PV DELAY function
516 * When running on PVH mode we don't have an emulated i8524, so
517 * make use of the Xen time info in order to code a simple DELAY
518 * function that can be used during early boot.
523 struct vcpu_info *vcpu = &HYPERVISOR_shared_info->vcpu_info[0];
527 end_ns = xen_fetch_vcpu_time(vcpu);
528 end_ns += n * NSEC_IN_USEC;
531 current = xen_fetch_vcpu_time(vcpu);
532 if (current >= end_ns)
537 static device_method_t xentimer_methods[] = {
538 DEVMETHOD(device_identify, xentimer_identify),
539 DEVMETHOD(device_probe, xentimer_probe),
540 DEVMETHOD(device_attach, xentimer_attach),
541 DEVMETHOD(device_detach, xentimer_detach),
542 DEVMETHOD(device_suspend, xentimer_suspend),
543 DEVMETHOD(device_resume, xentimer_resume),
544 /* clock interface */
545 DEVMETHOD(clock_gettime, xentimer_gettime),
546 DEVMETHOD(clock_settime, xentimer_settime),
550 static driver_t xentimer_driver = {
553 sizeof(struct xentimer_softc),
556 DRIVER_MODULE(xentimer, xenpv, xentimer_driver, xentimer_devclass, 0, 0);
557 MODULE_DEPEND(xentimer, xenpv, 1, 1, 1);