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 __FBSDID("$FreeBSD$"); 38 39 #include <sys/param.h> 40 #include <sys/systm.h> 41 #include <sys/bus.h> 42 #include <sys/kernel.h> 43 #include <sys/module.h> 44 #include <sys/time.h> 45 #include <sys/timetc.h> 46 #include <sys/timeet.h> 47 #include <sys/smp.h> 48 #include <sys/limits.h> 49 #include <sys/clock.h> 50 #include <sys/proc.h> 51 52 #include <xen/xen-os.h> 53 #include <xen/features.h> 54 #include <xen/xen_intr.h> 55 #include <xen/hypervisor.h> 56 #include <contrib/xen/io/xenbus.h> 57 #include <contrib/xen/vcpu.h> 58 #include <xen/error.h> 59 60 #include <machine/cpu.h> 61 #include <machine/cpufunc.h> 62 #include <machine/clock.h> 63 #include <machine/_inttypes.h> 64 #include <machine/smp.h> 65 #include <machine/pvclock.h> 66 67 #include <dev/xen/timer/timer.h> 68 69 #include "clock_if.h" 70 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 75 76 /* Xen timers may fire up to 100us off */ 77 #define XENTIMER_MIN_PERIOD_IN_NSEC 100*NSEC_IN_USEC 78 79 /* 80 * The real resolution of the PV clock is 1ns, but the highest 81 * resolution that FreeBSD supports is 1us, so just use that. 82 */ 83 #define XENCLOCK_RESOLUTION 1 84 85 #define XENTIMER_QUALITY 950 86 87 struct xentimer_pcpu_data { 88 uint64_t timer; 89 uint64_t last_processed; 90 void *irq_handle; 91 }; 92 93 DPCPU_DEFINE(struct xentimer_pcpu_data, xentimer_pcpu); 94 95 DPCPU_DECLARE(struct vcpu_info *, vcpu_info); 96 97 struct xentimer_softc { 98 device_t dev; 99 struct timecounter tc; 100 struct eventtimer et; 101 }; 102 103 static void 104 xentimer_identify(driver_t *driver, device_t parent) 105 { 106 if (!xen_domain()) 107 return; 108 109 /* Handle all Xen PV timers in one device instance. */ 110 if (devclass_get_device(devclass_find(driver->name), 0)) 111 return; 112 113 BUS_ADD_CHILD(parent, 0, driver->name, 0); 114 } 115 116 static int 117 xentimer_probe(device_t dev) 118 { 119 KASSERT((xen_domain()), ("Trying to use Xen timer on bare metal")); 120 /* 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. 130 */ 131 #define XTREQUIRES(condition, reason...) \ 132 if (!(condition)) { \ 133 device_printf(dev, ## reason); \ 134 device_detach(dev); \ 135 return (ENXIO); \ 136 } 137 138 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"); 143 } 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"); 148 #undef XTREQUIRES 149 device_set_desc(dev, "Xen PV Clock"); 150 return (BUS_PROBE_NOWILDCARD); 151 } 152 153 /** 154 * \brief Get the current time, in nanoseconds, since the hypervisor booted. 155 * 156 * \param vcpu vcpu_info structure to fetch the time from. 157 * 158 */ 159 static uint64_t 160 xen_fetch_vcpu_time(struct vcpu_info *vcpu) 161 { 162 struct pvclock_vcpu_time_info *time; 163 164 time = (struct pvclock_vcpu_time_info *) &vcpu->time; 165 166 return (pvclock_get_timecount(time)); 167 } 168 169 static uint32_t 170 xentimer_get_timecount(struct timecounter *tc) 171 { 172 uint64_t vcpu_time; 173 174 /* 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). 180 */ 181 vcpu_time = xen_fetch_vcpu_time(DPCPU_GET(vcpu_info)); 182 183 return (vcpu_time & UINT32_MAX); 184 } 185 186 /** 187 * \brief Fetch the hypervisor boot time, known as the "Xen wallclock". 188 * 189 * \param ts Timespec to store the current stable value. 190 * \param version Pointer to store the corresponding wallclock version. 191 * 192 * \note This value is updated when Domain-0 shifts its clock to follow 193 * clock drift, e.g. as detected by NTP. 194 */ 195 static void 196 xen_fetch_wallclock(struct timespec *ts) 197 { 198 shared_info_t *src = HYPERVISOR_shared_info; 199 struct pvclock_wall_clock *wc; 200 201 wc = (struct pvclock_wall_clock *) &src->wc_version; 202 203 pvclock_get_wallclock(wc, ts); 204 } 205 206 static void 207 xen_fetch_uptime(struct timespec *ts) 208 { 209 uint64_t uptime; 210 211 uptime = xen_fetch_vcpu_time(DPCPU_GET(vcpu_info)); 212 213 ts->tv_sec = uptime / NSEC_IN_SEC; 214 ts->tv_nsec = uptime % NSEC_IN_SEC; 215 } 216 217 static int 218 xentimer_settime(device_t dev __unused, struct timespec *ts) 219 { 220 struct xen_platform_op settime; 221 int ret; 222 223 /* 224 * Don't return EINVAL here; just silently fail if the domain isn't 225 * privileged enough to set the TOD. 226 */ 227 if (!xen_initial_domain()) 228 return (0); 229 230 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)); 236 237 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); 241 242 return (ret); 243 } 244 245 /** 246 * \brief Return current time according to the Xen Hypervisor wallclock. 247 * 248 * \param dev Xentimer device. 249 * \param ts Pointer to store the wallclock time. 250 * 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. 254 */ 255 static int 256 xentimer_gettime(device_t dev, struct timespec *ts) 257 { 258 struct timespec u_ts; 259 260 timespecclear(ts); 261 xen_fetch_wallclock(ts); 262 xen_fetch_uptime(&u_ts); 263 timespecadd(ts, &u_ts, ts); 264 265 return (0); 266 } 267 268 /** 269 * \brief Handle a timer interrupt for the Xen PV timer driver. 270 * 271 * \param arg Xen timer driver softc that is expecting the interrupt. 272 */ 273 static int 274 xentimer_intr(void *arg) 275 { 276 struct xentimer_softc *sc = (struct xentimer_softc *)arg; 277 struct xentimer_pcpu_data *pcpu = DPCPU_PTR(xentimer_pcpu); 278 279 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); 282 283 return (FILTER_HANDLED); 284 } 285 286 static int 287 xentimer_vcpu_start_timer(int vcpu, uint64_t next_time) 288 { 289 struct vcpu_set_singleshot_timer single; 290 291 single.timeout_abs_ns = next_time; 292 /* Get an event anyway, even if the timeout is already expired */ 293 single.flags = 0; 294 return (HYPERVISOR_vcpu_op(VCPUOP_set_singleshot_timer, vcpu, &single)); 295 } 296 297 static int 298 xentimer_vcpu_stop_timer(int vcpu) 299 { 300 301 return (HYPERVISOR_vcpu_op(VCPUOP_stop_singleshot_timer, vcpu, NULL)); 302 } 303 304 /** 305 * \brief Set the next oneshot time for the current CPU. 306 * 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. 310 * 311 * \note See eventtimers(9) for more information. 312 * \note 313 * 314 * \returns 0 315 */ 316 static int 317 xentimer_et_start(struct eventtimer *et, 318 sbintime_t first, sbintime_t period) 319 { 320 int error; 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; 326 #ifdef INVARIANTS 327 struct thread *td = curthread; 328 #endif 329 330 KASSERT(td->td_critnest != 0, 331 ("xentimer_et_start called without preemption disabled")); 332 333 /* See sbttots() for this formula. */ 334 first_in_ns = (((first >> 32) * NSEC_IN_SEC) + 335 (((uint64_t)NSEC_IN_SEC * (uint32_t)first) >> 32)); 336 337 next_time = xen_fetch_vcpu_time(vcpu) + first_in_ns; 338 error = xentimer_vcpu_start_timer(cpu, next_time); 339 if (error) 340 panic("%s: Error %d setting singleshot timer to %"PRIu64"\n", 341 device_get_nameunit(sc->dev), error, next_time); 342 343 pcpu->timer = next_time; 344 return (error); 345 } 346 347 /** 348 * \brief Cancel the event timer's currently running timer, if any. 349 */ 350 static int 351 xentimer_et_stop(struct eventtimer *et) 352 { 353 int cpu = PCPU_GET(vcpu_id); 354 struct xentimer_pcpu_data *pcpu = DPCPU_PTR(xentimer_pcpu); 355 356 pcpu->timer = 0; 357 return (xentimer_vcpu_stop_timer(cpu)); 358 } 359 360 /** 361 * \brief Attach a Xen PV timer driver instance. 362 * 363 * \param dev Bus device object to attach. 364 * 365 * \note 366 * \returns EINVAL 367 */ 368 static int 369 xentimer_attach(device_t dev) 370 { 371 struct xentimer_softc *sc = device_get_softc(dev); 372 int error, i; 373 374 sc->dev = dev; 375 376 /* Bind an event channel to a VIRQ on each VCPU. */ 377 CPU_FOREACH(i) { 378 struct xentimer_pcpu_data *pcpu; 379 380 pcpu = DPCPU_ID_PTR(i, xentimer_pcpu); 381 error = HYPERVISOR_vcpu_op(VCPUOP_stop_periodic_timer, i, NULL); 382 if (error) { 383 device_printf(dev, "Error disabling Xen periodic timer " 384 "on CPU %d\n", i); 385 return (error); 386 } 387 388 error = xen_intr_bind_virq(dev, VIRQ_TIMER, i, xentimer_intr, 389 NULL, sc, INTR_TYPE_CLK, &pcpu->irq_handle); 390 if (error) { 391 device_printf(dev, "Error %d binding VIRQ_TIMER " 392 "to VCPU %d\n", error, i); 393 return (error); 394 } 395 xen_intr_describe(pcpu->irq_handle, "c%d", i); 396 } 397 398 /* 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; 409 sc->et.et_priv = sc; 410 et_register(&sc->et); 411 412 /* Register the timecounter. */ 413 sc->tc.tc_name = "XENTIMER"; 414 sc->tc.tc_quality = XENTIMER_QUALITY; 415 /* 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). 420 * 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 424 * later. 425 * 426 * sc->tc.tc_flags = TC_FLAGS_SUSPEND_SAFE; 427 */ 428 /* 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. 432 */ 433 sc->tc.tc_frequency = NSEC_IN_SEC; 434 sc->tc.tc_counter_mask = ~0u; 435 sc->tc.tc_get_timecount = xentimer_get_timecount; 436 sc->tc.tc_priv = sc; 437 tc_init(&sc->tc); 438 439 /* Register the Hypervisor wall clock */ 440 clock_register(dev, XENCLOCK_RESOLUTION); 441 442 return (0); 443 } 444 445 static int 446 xentimer_detach(device_t dev) 447 { 448 449 /* Implement Xen PV clock teardown - XXX see hpet_detach ? */ 450 /* If possible: 451 * 1. need to deregister timecounter 452 * 2. need to deregister event timer 453 * 3. need to deregister virtual IRQ event channels 454 */ 455 return (EBUSY); 456 } 457 458 static void 459 xentimer_percpu_resume(void *arg) 460 { 461 device_t dev = (device_t) arg; 462 struct xentimer_softc *sc = device_get_softc(dev); 463 464 xentimer_et_start(&sc->et, sc->et.et_min_period, 0); 465 } 466 467 static int 468 xentimer_resume(device_t dev) 469 { 470 int error; 471 int i; 472 473 /* Disable the periodic timer */ 474 CPU_FOREACH(i) { 475 error = HYPERVISOR_vcpu_op(VCPUOP_stop_periodic_timer, i, NULL); 476 if (error != 0) { 477 device_printf(dev, 478 "Error disabling Xen periodic timer on CPU %d\n", 479 i); 480 return (error); 481 } 482 } 483 484 /* Reset the last uptime value */ 485 pvclock_resume(); 486 487 /* Reset the RTC clock */ 488 inittodr(time_second); 489 490 /* Kick the timers on all CPUs */ 491 smp_rendezvous(NULL, xentimer_percpu_resume, NULL, dev); 492 493 if (bootverbose) 494 device_printf(dev, "resumed operation after suspension\n"); 495 496 return (0); 497 } 498 499 static int 500 xentimer_suspend(device_t dev) 501 { 502 return (0); 503 } 504 505 /* 506 * Xen early clock init 507 */ 508 void 509 xen_clock_init(void) 510 { 511 } 512 513 /* 514 * Xen PV DELAY function 515 * 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. 519 */ 520 void 521 xen_delay(int n) 522 { 523 struct vcpu_info *vcpu = &HYPERVISOR_shared_info->vcpu_info[0]; 524 uint64_t end_ns; 525 uint64_t current; 526 527 end_ns = xen_fetch_vcpu_time(vcpu); 528 end_ns += n * NSEC_IN_USEC; 529 530 for (;;) { 531 current = xen_fetch_vcpu_time(vcpu); 532 if (current >= end_ns) 533 break; 534 } 535 } 536 537 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), 547 DEVMETHOD_END 548 }; 549 550 static driver_t xentimer_driver = { 551 "xen_et", 552 xentimer_methods, 553 sizeof(struct xentimer_softc), 554 }; 555 556 DRIVER_MODULE(xentimer, xenpv, xentimer_driver, 0, 0); 557 MODULE_DEPEND(xentimer, xenpv, 1, 1, 1); 558