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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 | // SPDX-License-Identifier: GPL-2.0 /* * 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/gfp.h> #include <linux/slab.h> #include <linux/pvclock_gtod.h> #include <linux/timekeeper_internal.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" /* Minimum amount of time until next clock event fires */ #define TIMER_SLOP 100000 static u64 xen_sched_clock_offset __read_mostly; /* 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; setup_force_cpu_cap(X86_FEATURE_TSC_KNOWN_FREQ); return pvclock_tsc_khz(info); } static u64 xen_clocksource_read(void) { struct pvclock_vcpu_time_info *src; u64 ret; preempt_disable_notrace(); src = &__this_cpu_read(xen_vcpu)->time; ret = pvclock_clocksource_read(src); preempt_enable_notrace(); return ret; } static u64 xen_clocksource_get_cycles(struct clocksource *cs) { return xen_clocksource_read(); } static u64 xen_sched_clock(void) { return xen_clocksource_read() - xen_sched_clock_offset; } static void xen_read_wallclock(struct timespec64 *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 timespec64 *now) { xen_read_wallclock(now); } static int xen_set_wallclock(const struct timespec64 *now) { return -ENODEV; } 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 timespec64 next_sync; struct xen_platform_op op; struct timespec64 now; struct timekeeper *tk = priv; static bool settime64_supported = true; int ret; now.tv_sec = tk->xtime_sec; now.tv_nsec = (long)(tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift); /* * We only take the expensive HV call when the clock was set * or when the 11 minutes RTC synchronization time elapsed. */ if (!was_set && timespec64_compare(&now, &next_sync) < 0) return NOTIFY_OK; again: if (settime64_supported) { op.cmd = XENPF_settime64; op.u.settime64.mbz = 0; op.u.settime64.secs = now.tv_sec; op.u.settime64.nsecs = now.tv_nsec; op.u.settime64.system_time = xen_clocksource_read(); } else { op.cmd = XENPF_settime32; op.u.settime32.secs = now.tv_sec; op.u.settime32.nsecs = now.tv_nsec; op.u.settime32.system_time = xen_clocksource_read(); } ret = HYPERVISOR_platform_op(&op); if (ret == -ENOSYS && settime64_supported) { settime64_supported = false; goto again; } if (ret < 0) return NOTIFY_BAD; /* * 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 int xen_cs_enable(struct clocksource *cs) { vclocks_set_used(VDSO_CLOCKMODE_PVCLOCK); return 0; } static struct clocksource xen_clocksource __read_mostly = { .name = "xen", .rating = 400, .read = xen_clocksource_get_cycles, .mask = CLOCKSOURCE_MASK(64), .flags = CLOCK_SOURCE_IS_CONTINUOUS, .enable = xen_cs_enable, }; /* 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 int xen_timerop_shutdown(struct clock_event_device *evt) { /* cancel timeout */ HYPERVISOR_set_timer_op(0); return 0; } static int xen_timerop_set_next_event(unsigned long delta, struct clock_event_device *evt) { WARN_ON(!clockevent_state_oneshot(evt)); 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 struct clock_event_device xen_timerop_clockevent __ro_after_init = { .name = "xen", .features = CLOCK_EVT_FEAT_ONESHOT, .max_delta_ns = 0xffffffff, .max_delta_ticks = 0xffffffff, .min_delta_ns = TIMER_SLOP, .min_delta_ticks = TIMER_SLOP, .mult = 1, .shift = 0, .rating = 500, .set_state_shutdown = xen_timerop_shutdown, .set_next_event = xen_timerop_set_next_event, }; static int xen_vcpuop_shutdown(struct clock_event_device *evt) { int cpu = smp_processor_id(); if (HYPERVISOR_vcpu_op(VCPUOP_stop_singleshot_timer, xen_vcpu_nr(cpu), NULL) || HYPERVISOR_vcpu_op(VCPUOP_stop_periodic_timer, xen_vcpu_nr(cpu), NULL)) BUG(); return 0; } static int xen_vcpuop_set_oneshot(struct clock_event_device *evt) { int cpu = smp_processor_id(); if (HYPERVISOR_vcpu_op(VCPUOP_stop_periodic_timer, xen_vcpu_nr(cpu), NULL)) BUG(); return 0; } 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(!clockevent_state_oneshot(evt)); single.timeout_abs_ns = get_abs_timeout(delta); /* Get an event anyway, even if the timeout is already expired */ single.flags = 0; ret = HYPERVISOR_vcpu_op(VCPUOP_set_singleshot_timer, xen_vcpu_nr(cpu), &single); BUG_ON(ret != 0); return ret; } static struct clock_event_device xen_vcpuop_clockevent __ro_after_init = { .name = "xen", .features = CLOCK_EVT_FEAT_ONESHOT, .max_delta_ns = 0xffffffff, .max_delta_ticks = 0xffffffff, .min_delta_ns = TIMER_SLOP, .min_delta_ticks = TIMER_SLOP, .mult = 1, .shift = 0, .rating = 500, .set_state_shutdown = xen_vcpuop_shutdown, .set_state_oneshot = xen_vcpuop_set_oneshot, .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; } return ret; } void xen_teardown_timer(int cpu) { struct clock_event_device *evt; 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; if (xen_clockevent != &xen_vcpuop_clockevent) return; for_each_online_cpu(cpu) { if (HYPERVISOR_vcpu_op(VCPUOP_stop_periodic_timer, xen_vcpu_nr(cpu), NULL)) BUG(); } } static struct pvclock_vsyscall_time_info *xen_clock __read_mostly; static u64 xen_clock_value_saved; void xen_save_time_memory_area(void) { struct vcpu_register_time_memory_area t; int ret; xen_clock_value_saved = xen_clocksource_read() - xen_sched_clock_offset; if (!xen_clock) return; t.addr.v = NULL; ret = HYPERVISOR_vcpu_op(VCPUOP_register_vcpu_time_memory_area, 0, &t); if (ret != 0) pr_notice("Cannot save secondary vcpu_time_info (err %d)", ret); else clear_page(xen_clock); } void xen_restore_time_memory_area(void) { struct vcpu_register_time_memory_area t; int ret; if (!xen_clock) goto out; t.addr.v = &xen_clock->pvti; ret = HYPERVISOR_vcpu_op(VCPUOP_register_vcpu_time_memory_area, 0, &t); /* * We don't disable VDSO_CLOCKMODE_PVCLOCK entirely if it fails to * register the secondary time info with Xen or if we migrated to a * host without the necessary flags. On both of these cases what * happens is either process seeing a zeroed out pvti or seeing no * PVCLOCK_TSC_STABLE_BIT bit set. Userspace checks the latter and * if 0, it discards the data in pvti and fallbacks to a system * call for a reliable timestamp. */ if (ret != 0) pr_notice("Cannot restore secondary vcpu_time_info (err %d)", ret); out: /* Need pvclock_resume() before using xen_clocksource_read(). */ pvclock_resume(); xen_sched_clock_offset = xen_clocksource_read() - xen_clock_value_saved; } static void xen_setup_vsyscall_time_info(void) { struct vcpu_register_time_memory_area t; struct pvclock_vsyscall_time_info *ti; int ret; ti = (struct pvclock_vsyscall_time_info *)get_zeroed_page(GFP_KERNEL); if (!ti) return; t.addr.v = &ti->pvti; ret = HYPERVISOR_vcpu_op(VCPUOP_register_vcpu_time_memory_area, 0, &t); if (ret) { pr_notice("xen: VDSO_CLOCKMODE_PVCLOCK not supported (err %d)\n", ret); free_page((unsigned long)ti); return; } /* * If primary time info had this bit set, secondary should too since * it's the same data on both just different memory regions. But we * still check it in case hypervisor is buggy. */ if (!(ti->pvti.flags & PVCLOCK_TSC_STABLE_BIT)) { t.addr.v = NULL; ret = HYPERVISOR_vcpu_op(VCPUOP_register_vcpu_time_memory_area, 0, &t); if (!ret) free_page((unsigned long)ti); pr_notice("xen: VDSO_CLOCKMODE_PVCLOCK not supported (tsc unstable)\n"); return; } xen_clock = ti; pvclock_set_pvti_cpu0_va(xen_clock); xen_clocksource.vdso_clock_mode = VDSO_CLOCKMODE_PVCLOCK; } static void __init xen_time_init(void) { struct pvclock_vcpu_time_info *pvti; int cpu = smp_processor_id(); struct timespec64 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, xen_vcpu_nr(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_settimeofday64(&tp); setup_force_cpu_cap(X86_FEATURE_TSC); /* * We check ahead on the primary time info if this * bit is supported hence speeding up Xen clocksource. */ pvti = &__this_cpu_read(xen_vcpu)->time; if (pvti->flags & PVCLOCK_TSC_STABLE_BIT) { pvclock_set_flags(PVCLOCK_TSC_STABLE_BIT); xen_setup_vsyscall_time_info(); } xen_setup_runstate_info(cpu); xen_setup_timer(cpu); xen_setup_cpu_clockevents(); xen_time_setup_guest(); if (xen_initial_domain()) pvclock_gtod_register_notifier(&xen_pvclock_gtod_notifier); } static void __init xen_init_time_common(void) { xen_sched_clock_offset = xen_clocksource_read(); static_call_update(pv_steal_clock, xen_steal_clock); paravirt_set_sched_clock(xen_sched_clock); x86_platform.calibrate_tsc = xen_tsc_khz; x86_platform.get_wallclock = xen_get_wallclock; } void __init xen_init_time_ops(void) { xen_init_time_common(); 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; /* 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) { static bool hvm_time_initialized; if (hvm_time_initialized) return; /* * 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)) { pr_info_once("Xen doesn't support pvclock on HVM, disable pv timer"); return; } /* * Only MAX_VIRT_CPUS 'vcpu_info' are embedded inside 'shared_info'. * The __this_cpu_read(xen_vcpu) is still NULL when Xen HVM guest * boots on vcpu >= MAX_VIRT_CPUS (e.g., kexec), To access * __this_cpu_read(xen_vcpu) via xen_clocksource_read() will panic. * * The xen_hvm_init_time_ops() should be called again later after * __this_cpu_read(xen_vcpu) is available. */ if (!__this_cpu_read(xen_vcpu)) { pr_info("Delay xen_init_time_common() as kernel is running on vcpu=%d\n", xen_vcpu_nr(0)); return; } xen_init_time_common(); x86_init.timers.setup_percpu_clockev = xen_time_init; x86_cpuinit.setup_percpu_clockev = xen_hvm_setup_cpu_clockevents; x86_platform.set_wallclock = xen_set_wallclock; hvm_time_initialized = true; } #endif /* Kernel parameter to specify Xen timer slop */ static int __init parse_xen_timer_slop(char *ptr) { unsigned long slop = memparse(ptr, NULL); xen_timerop_clockevent.min_delta_ns = slop; xen_timerop_clockevent.min_delta_ticks = slop; xen_vcpuop_clockevent.min_delta_ns = slop; xen_vcpuop_clockevent.min_delta_ticks = slop; return 0; } early_param("xen_timer_slop", parse_xen_timer_slop); |