1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause
3 *
4 * Copyright (c) 2009 Adrian Chadd
5 * Copyright (c) 2012 Spectra Logic Corporation
6 * All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 *
29 */
30
31 /**
32 * \file dev/xen/timer/xen_timer.c
33 * \brief A timer driver for the Xen hypervisor's PV clock.
34 */
35
36 #include <sys/cdefs.h>
37 #include <sys/param.h>
38 #include <sys/systm.h>
39 #include <sys/bus.h>
40 #include <sys/kernel.h>
41 #include <sys/module.h>
42 #include <sys/time.h>
43 #include <sys/timetc.h>
44 #include <sys/timeet.h>
45 #include <sys/smp.h>
46 #include <sys/limits.h>
47 #include <sys/clock.h>
48 #include <sys/proc.h>
49
50 #include <xen/xen-os.h>
51 #include <xen/features.h>
52 #include <xen/xen_intr.h>
53 #include <xen/hypervisor.h>
54 #include <contrib/xen/io/xenbus.h>
55 #include <contrib/xen/vcpu.h>
56 #include <xen/error.h>
57
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>
64
65 #include <dev/xen/timer/timer.h>
66
67 #include "clock_if.h"
68
69 #define NSEC_IN_SEC 1000000000ULL
70 #define NSEC_IN_USEC 1000ULL
71 /* 18446744073 = int(2^64 / NSEC_IN_SC) = 1 ns in 64-bit fractions */
72 #define FRAC_IN_NSEC 18446744073LL
73
74 /* Xen timers may fire up to 100us off */
75 #define XENTIMER_MIN_PERIOD_IN_NSEC 100*NSEC_IN_USEC
76
77 /*
78 * The real resolution of the PV clock is 1ns, but the highest
79 * resolution that FreeBSD supports is 1us, so just use that.
80 */
81 #define XENCLOCK_RESOLUTION 1
82
83 #define XENTIMER_QUALITY 950
84
85 struct xentimer_pcpu_data {
86 uint64_t timer;
87 uint64_t last_processed;
88 void *irq_handle;
89 };
90
91 DPCPU_DEFINE(struct xentimer_pcpu_data, xentimer_pcpu);
92
93 DPCPU_DECLARE(struct vcpu_info *, vcpu_info);
94
95 struct xentimer_softc {
96 device_t dev;
97 struct timecounter tc;
98 struct eventtimer et;
99 };
100
101 static void
xentimer_identify(driver_t * driver,device_t parent)102 xentimer_identify(driver_t *driver, device_t parent)
103 {
104 if (!xen_domain())
105 return;
106
107 /* Handle all Xen PV timers in one device instance. */
108 if (devclass_get_device(devclass_find(driver->name), 0))
109 return;
110
111 BUS_ADD_CHILD(parent, 0, driver->name, 0);
112 }
113
114 static int
xentimer_probe(device_t dev)115 xentimer_probe(device_t dev)
116 {
117 KASSERT((xen_domain()), ("Trying to use Xen timer on bare metal"));
118 /*
119 * In order to attach, this driver requires the following:
120 * - Vector callback support by the hypervisor, in order to deliver
121 * timer interrupts to the correct CPU for CPUs other than 0.
122 * - Access to the hypervisor shared info page, in order to look up
123 * each VCPU's timer information and the Xen wallclock time.
124 * - The hypervisor must say its PV clock is "safe" to use.
125 * - The hypervisor must support VCPUOP hypercalls.
126 * - The maximum number of CPUs supported by FreeBSD must not exceed
127 * the number of VCPUs supported by the hypervisor.
128 */
129 #define XTREQUIRES(condition, reason...) \
130 if (!(condition)) { \
131 device_printf(dev, ## reason); \
132 device_detach(dev); \
133 return (ENXIO); \
134 }
135
136 if (xen_hvm_domain()) {
137 XTREQUIRES(xen_vector_callback_enabled,
138 "vector callbacks unavailable\n");
139 XTREQUIRES(xen_feature(XENFEAT_hvm_safe_pvclock),
140 "HVM safe pvclock unavailable\n");
141 }
142 XTREQUIRES(HYPERVISOR_shared_info != NULL,
143 "shared info page unavailable\n");
144 XTREQUIRES(HYPERVISOR_vcpu_op(VCPUOP_stop_periodic_timer, 0, NULL) == 0,
145 "VCPUOPs interface unavailable\n");
146 #undef XTREQUIRES
147 device_set_desc(dev, "Xen PV Clock");
148 return (BUS_PROBE_NOWILDCARD);
149 }
150
151 /**
152 * \brief Get the current time, in nanoseconds, since the hypervisor booted.
153 *
154 * \param vcpu vcpu_info structure to fetch the time from.
155 *
156 */
157 static uint64_t
xen_fetch_vcpu_time(struct vcpu_info * vcpu)158 xen_fetch_vcpu_time(struct vcpu_info *vcpu)
159 {
160 struct pvclock_vcpu_time_info *time;
161
162 time = (struct pvclock_vcpu_time_info *) &vcpu->time;
163
164 return (pvclock_get_timecount(time));
165 }
166
167 static uint32_t
xentimer_get_timecount(struct timecounter * tc)168 xentimer_get_timecount(struct timecounter *tc)
169 {
170 uint64_t vcpu_time;
171
172 /*
173 * We don't disable preemption here because the worst that can
174 * happen is reading the vcpu_info area of a different CPU than
175 * the one we are currently running on, but that would also
176 * return a valid tc (and we avoid the overhead of
177 * critical_{enter/exit} calls).
178 */
179 vcpu_time = xen_fetch_vcpu_time(DPCPU_GET(vcpu_info));
180
181 return (vcpu_time & UINT32_MAX);
182 }
183
184 /**
185 * \brief Fetch the hypervisor boot time, known as the "Xen wallclock".
186 *
187 * \param ts Timespec to store the current stable value.
188 * \param version Pointer to store the corresponding wallclock version.
189 *
190 * \note This value is updated when Domain-0 shifts its clock to follow
191 * clock drift, e.g. as detected by NTP.
192 */
193 static void
xen_fetch_wallclock(struct timespec * ts)194 xen_fetch_wallclock(struct timespec *ts)
195 {
196 shared_info_t *src = HYPERVISOR_shared_info;
197 struct pvclock_wall_clock *wc;
198
199 wc = (struct pvclock_wall_clock *) &src->wc_version;
200
201 pvclock_get_wallclock(wc, ts);
202 }
203
204 static void
xen_fetch_uptime(struct timespec * ts)205 xen_fetch_uptime(struct timespec *ts)
206 {
207 uint64_t uptime;
208
209 uptime = xen_fetch_vcpu_time(DPCPU_GET(vcpu_info));
210
211 ts->tv_sec = uptime / NSEC_IN_SEC;
212 ts->tv_nsec = uptime % NSEC_IN_SEC;
213 }
214
215 static int
xentimer_settime(device_t dev __unused,struct timespec * ts)216 xentimer_settime(device_t dev __unused, struct timespec *ts)
217 {
218 struct xen_platform_op settime;
219 int ret;
220
221 /*
222 * Don't return EINVAL here; just silently fail if the domain isn't
223 * privileged enough to set the TOD.
224 */
225 if (!xen_initial_domain())
226 return (0);
227
228 settime.cmd = XENPF_settime64;
229 settime.u.settime64.mbz = 0;
230 settime.u.settime64.secs = ts->tv_sec;
231 settime.u.settime64.nsecs = ts->tv_nsec;
232 settime.u.settime64.system_time =
233 xen_fetch_vcpu_time(DPCPU_GET(vcpu_info));
234
235 ret = HYPERVISOR_platform_op(&settime);
236 ret = ret != 0 ? xen_translate_error(ret) : 0;
237 if (ret != 0 && bootverbose)
238 device_printf(dev, "failed to set Xen PV clock: %d\n", ret);
239
240 return (ret);
241 }
242
243 /**
244 * \brief Return current time according to the Xen Hypervisor wallclock.
245 *
246 * \param dev Xentimer device.
247 * \param ts Pointer to store the wallclock time.
248 *
249 * \note The Xen time structures document the hypervisor start time and the
250 * uptime-since-hypervisor-start (in nsec.) They need to be combined
251 * in order to calculate a TOD clock.
252 */
253 static int
xentimer_gettime(device_t dev,struct timespec * ts)254 xentimer_gettime(device_t dev, struct timespec *ts)
255 {
256 struct timespec u_ts;
257
258 timespecclear(ts);
259 xen_fetch_wallclock(ts);
260 xen_fetch_uptime(&u_ts);
261 timespecadd(ts, &u_ts, ts);
262
263 return (0);
264 }
265
266 /**
267 * \brief Handle a timer interrupt for the Xen PV timer driver.
268 *
269 * \param arg Xen timer driver softc that is expecting the interrupt.
270 */
271 static int
xentimer_intr(void * arg)272 xentimer_intr(void *arg)
273 {
274 struct xentimer_softc *sc = (struct xentimer_softc *)arg;
275 struct xentimer_pcpu_data *pcpu = DPCPU_PTR(xentimer_pcpu);
276
277 pcpu->last_processed = xen_fetch_vcpu_time(DPCPU_GET(vcpu_info));
278 if (pcpu->timer != 0 && sc->et.et_active)
279 sc->et.et_event_cb(&sc->et, sc->et.et_arg);
280
281 return (FILTER_HANDLED);
282 }
283
284 static int
xentimer_vcpu_start_timer(int vcpu,uint64_t next_time)285 xentimer_vcpu_start_timer(int vcpu, uint64_t next_time)
286 {
287 struct vcpu_set_singleshot_timer single;
288
289 single.timeout_abs_ns = next_time;
290 /* Get an event anyway, even if the timeout is already expired */
291 single.flags = 0;
292 return (HYPERVISOR_vcpu_op(VCPUOP_set_singleshot_timer, vcpu, &single));
293 }
294
295 static int
xentimer_vcpu_stop_timer(int vcpu)296 xentimer_vcpu_stop_timer(int vcpu)
297 {
298
299 return (HYPERVISOR_vcpu_op(VCPUOP_stop_singleshot_timer, vcpu, NULL));
300 }
301
302 /**
303 * \brief Set the next oneshot time for the current CPU.
304 *
305 * \param et Xen timer driver event timer to schedule on.
306 * \param first Delta to the next time to schedule the interrupt for.
307 * \param period Not used.
308 *
309 * \note See eventtimers(9) for more information.
310 * \note
311 *
312 * \returns 0
313 */
314 static int
xentimer_et_start(struct eventtimer * et,sbintime_t first,sbintime_t period)315 xentimer_et_start(struct eventtimer *et,
316 sbintime_t first, sbintime_t period)
317 {
318 int error;
319 struct xentimer_softc *sc = et->et_priv;
320 int cpu = PCPU_GET(vcpu_id);
321 struct xentimer_pcpu_data *pcpu = DPCPU_PTR(xentimer_pcpu);
322 struct vcpu_info *vcpu = DPCPU_GET(vcpu_info);
323 uint64_t first_in_ns, next_time;
324 #ifdef INVARIANTS
325 struct thread *td = curthread;
326 #endif
327
328 KASSERT(td->td_critnest != 0,
329 ("xentimer_et_start called without preemption disabled"));
330
331 /* See sbttots() for this formula. */
332 first_in_ns = (((first >> 32) * NSEC_IN_SEC) +
333 (((uint64_t)NSEC_IN_SEC * (uint32_t)first) >> 32));
334
335 next_time = xen_fetch_vcpu_time(vcpu) + first_in_ns;
336 error = xentimer_vcpu_start_timer(cpu, next_time);
337 if (error)
338 panic("%s: Error %d setting singleshot timer to %"PRIu64"\n",
339 device_get_nameunit(sc->dev), error, next_time);
340
341 pcpu->timer = next_time;
342 return (error);
343 }
344
345 /**
346 * \brief Cancel the event timer's currently running timer, if any.
347 */
348 static int
xentimer_et_stop(struct eventtimer * et)349 xentimer_et_stop(struct eventtimer *et)
350 {
351 int cpu = PCPU_GET(vcpu_id);
352 struct xentimer_pcpu_data *pcpu = DPCPU_PTR(xentimer_pcpu);
353
354 pcpu->timer = 0;
355 return (xentimer_vcpu_stop_timer(cpu));
356 }
357
358 /**
359 * \brief Attach a Xen PV timer driver instance.
360 *
361 * \param dev Bus device object to attach.
362 *
363 * \note
364 * \returns EINVAL
365 */
366 static int
xentimer_attach(device_t dev)367 xentimer_attach(device_t dev)
368 {
369 struct xentimer_softc *sc = device_get_softc(dev);
370 int error, i;
371
372 sc->dev = dev;
373
374 /* Bind an event channel to a VIRQ on each VCPU. */
375 CPU_FOREACH(i) {
376 struct xentimer_pcpu_data *pcpu;
377
378 pcpu = DPCPU_ID_PTR(i, xentimer_pcpu);
379 error = HYPERVISOR_vcpu_op(VCPUOP_stop_periodic_timer, i, NULL);
380 if (error) {
381 device_printf(dev, "Error disabling Xen periodic timer "
382 "on CPU %d\n", i);
383 return (error);
384 }
385
386 error = xen_intr_bind_virq(dev, VIRQ_TIMER, i, xentimer_intr,
387 NULL, sc, INTR_TYPE_CLK, &pcpu->irq_handle);
388 if (error) {
389 device_printf(dev, "Error %d binding VIRQ_TIMER "
390 "to VCPU %d\n", error, i);
391 return (error);
392 }
393 xen_intr_describe(pcpu->irq_handle, "c%d", i);
394 }
395
396 /* Register the event timer. */
397 sc->et.et_name = "XENTIMER";
398 sc->et.et_quality = XENTIMER_QUALITY;
399 sc->et.et_flags = ET_FLAGS_ONESHOT | ET_FLAGS_PERCPU;
400 sc->et.et_frequency = NSEC_IN_SEC;
401 /* See tstosbt() for this formula */
402 sc->et.et_min_period = (XENTIMER_MIN_PERIOD_IN_NSEC *
403 (((uint64_t)1 << 63) / 500000000) >> 32);
404 sc->et.et_max_period = ((sbintime_t)4 << 32);
405 sc->et.et_start = xentimer_et_start;
406 sc->et.et_stop = xentimer_et_stop;
407 sc->et.et_priv = sc;
408 et_register(&sc->et);
409
410 /* Register the timecounter. */
411 sc->tc.tc_name = "XENTIMER";
412 sc->tc.tc_quality = XENTIMER_QUALITY;
413 /*
414 * FIXME: due to the lack of ordering during resume, FreeBSD cannot
415 * guarantee that the Xen PV timer is resumed before any other device
416 * attempts to make use of it, so mark it as not safe for suspension
417 * (ie: remove the TC_FLAGS_SUSPEND_SAFE flag).
418 *
419 * NB: This was not a problem in previous FreeBSD versions because the
420 * timer was directly attached to the nexus, but it is an issue now
421 * that the timer is attached to the xenpv bus, and thus resumed
422 * later.
423 *
424 * sc->tc.tc_flags = TC_FLAGS_SUSPEND_SAFE;
425 */
426 /*
427 * The underlying resolution is in nanoseconds, since the timer info
428 * scales TSC frequencies using a fraction that represents time in
429 * terms of nanoseconds.
430 */
431 sc->tc.tc_frequency = NSEC_IN_SEC;
432 sc->tc.tc_counter_mask = ~0u;
433 sc->tc.tc_get_timecount = xentimer_get_timecount;
434 sc->tc.tc_priv = sc;
435 tc_init(&sc->tc);
436
437 /* Register the Hypervisor wall clock */
438 clock_register(dev, XENCLOCK_RESOLUTION);
439
440 return (0);
441 }
442
443 static int
xentimer_detach(device_t dev)444 xentimer_detach(device_t dev)
445 {
446
447 /* Implement Xen PV clock teardown - XXX see hpet_detach ? */
448 /* If possible:
449 * 1. need to deregister timecounter
450 * 2. need to deregister event timer
451 * 3. need to deregister virtual IRQ event channels
452 */
453 return (EBUSY);
454 }
455
456 static void
xentimer_percpu_resume(void * arg)457 xentimer_percpu_resume(void *arg)
458 {
459 device_t dev = (device_t) arg;
460 struct xentimer_softc *sc = device_get_softc(dev);
461
462 xentimer_et_start(&sc->et, sc->et.et_min_period, 0);
463 }
464
465 static int
xentimer_resume(device_t dev)466 xentimer_resume(device_t dev)
467 {
468 int error;
469 int i;
470
471 /* Disable the periodic timer */
472 CPU_FOREACH(i) {
473 error = HYPERVISOR_vcpu_op(VCPUOP_stop_periodic_timer, i, NULL);
474 if (error != 0) {
475 device_printf(dev,
476 "Error disabling Xen periodic timer on CPU %d\n",
477 i);
478 return (error);
479 }
480 }
481
482 /* Reset the last uptime value */
483 pvclock_resume();
484
485 /* Reset the RTC clock */
486 inittodr(time_second);
487
488 /* Kick the timers on all CPUs */
489 smp_rendezvous(NULL, xentimer_percpu_resume, NULL, dev);
490
491 if (bootverbose)
492 device_printf(dev, "resumed operation after suspension\n");
493
494 return (0);
495 }
496
497 static int
xentimer_suspend(device_t dev)498 xentimer_suspend(device_t dev)
499 {
500 return (0);
501 }
502
503 /*
504 * Xen early clock init
505 */
506 void
xen_clock_init(void)507 xen_clock_init(void)
508 {
509 }
510
511 /*
512 * Xen PV DELAY function
513 *
514 * When running on PVH mode we don't have an emulated i8524, so
515 * make use of the Xen time info in order to code a simple DELAY
516 * function that can be used during early boot.
517 */
518 void
xen_delay(int n)519 xen_delay(int n)
520 {
521 struct vcpu_info *vcpu = &HYPERVISOR_shared_info->vcpu_info[0];
522 uint64_t end_ns;
523 uint64_t current;
524
525 end_ns = xen_fetch_vcpu_time(vcpu);
526 end_ns += n * NSEC_IN_USEC;
527
528 for (;;) {
529 current = xen_fetch_vcpu_time(vcpu);
530 if (current >= end_ns)
531 break;
532 }
533 }
534
535 static device_method_t xentimer_methods[] = {
536 DEVMETHOD(device_identify, xentimer_identify),
537 DEVMETHOD(device_probe, xentimer_probe),
538 DEVMETHOD(device_attach, xentimer_attach),
539 DEVMETHOD(device_detach, xentimer_detach),
540 DEVMETHOD(device_suspend, xentimer_suspend),
541 DEVMETHOD(device_resume, xentimer_resume),
542 /* clock interface */
543 DEVMETHOD(clock_gettime, xentimer_gettime),
544 DEVMETHOD(clock_settime, xentimer_settime),
545 DEVMETHOD_END
546 };
547
548 static driver_t xentimer_driver = {
549 "xen_et",
550 xentimer_methods,
551 sizeof(struct xentimer_softc),
552 };
553
554 DRIVER_MODULE(xentimer, xenpv, xentimer_driver, 0, 0);
555 MODULE_DEPEND(xentimer, xenpv, 1, 1, 1);
556