Loading...
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Xen time implementation.
4 *
5 * This is implemented in terms of a clocksource driver which uses
6 * the hypervisor clock as a nanosecond timebase, and a clockevent
7 * driver which uses the hypervisor's timer mechanism.
8 *
9 * Jeremy Fitzhardinge <jeremy@xensource.com>, XenSource Inc, 2007
10 */
11#include <linux/kernel.h>
12#include <linux/interrupt.h>
13#include <linux/clocksource.h>
14#include <linux/clockchips.h>
15#include <linux/gfp.h>
16#include <linux/slab.h>
17#include <linux/pvclock_gtod.h>
18#include <linux/timekeeper_internal.h>
19
20#include <asm/pvclock.h>
21#include <asm/xen/hypervisor.h>
22#include <asm/xen/hypercall.h>
23
24#include <xen/events.h>
25#include <xen/features.h>
26#include <xen/interface/xen.h>
27#include <xen/interface/vcpu.h>
28
29#include "xen-ops.h"
30
31/* Minimum amount of time until next clock event fires */
32#define TIMER_SLOP 100000
33
34static u64 xen_sched_clock_offset __read_mostly;
35
36/* Get the TSC speed from Xen */
37static unsigned long xen_tsc_khz(void)
38{
39 struct pvclock_vcpu_time_info *info =
40 &HYPERVISOR_shared_info->vcpu_info[0].time;
41
42 setup_force_cpu_cap(X86_FEATURE_TSC_KNOWN_FREQ);
43 return pvclock_tsc_khz(info);
44}
45
46static u64 xen_clocksource_read(void)
47{
48 struct pvclock_vcpu_time_info *src;
49 u64 ret;
50
51 preempt_disable_notrace();
52 src = &__this_cpu_read(xen_vcpu)->time;
53 ret = pvclock_clocksource_read(src);
54 preempt_enable_notrace();
55 return ret;
56}
57
58static u64 xen_clocksource_get_cycles(struct clocksource *cs)
59{
60 return xen_clocksource_read();
61}
62
63static u64 xen_sched_clock(void)
64{
65 return xen_clocksource_read() - xen_sched_clock_offset;
66}
67
68static void xen_read_wallclock(struct timespec64 *ts)
69{
70 struct shared_info *s = HYPERVISOR_shared_info;
71 struct pvclock_wall_clock *wall_clock = &(s->wc);
72 struct pvclock_vcpu_time_info *vcpu_time;
73
74 vcpu_time = &get_cpu_var(xen_vcpu)->time;
75 pvclock_read_wallclock(wall_clock, vcpu_time, ts);
76 put_cpu_var(xen_vcpu);
77}
78
79static void xen_get_wallclock(struct timespec64 *now)
80{
81 xen_read_wallclock(now);
82}
83
84static int xen_set_wallclock(const struct timespec64 *now)
85{
86 return -ENODEV;
87}
88
89static int xen_pvclock_gtod_notify(struct notifier_block *nb,
90 unsigned long was_set, void *priv)
91{
92 /* Protected by the calling core code serialization */
93 static struct timespec64 next_sync;
94
95 struct xen_platform_op op;
96 struct timespec64 now;
97 struct timekeeper *tk = priv;
98 static bool settime64_supported = true;
99 int ret;
100
101 now.tv_sec = tk->xtime_sec;
102 now.tv_nsec = (long)(tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift);
103
104 /*
105 * We only take the expensive HV call when the clock was set
106 * or when the 11 minutes RTC synchronization time elapsed.
107 */
108 if (!was_set && timespec64_compare(&now, &next_sync) < 0)
109 return NOTIFY_OK;
110
111again:
112 if (settime64_supported) {
113 op.cmd = XENPF_settime64;
114 op.u.settime64.mbz = 0;
115 op.u.settime64.secs = now.tv_sec;
116 op.u.settime64.nsecs = now.tv_nsec;
117 op.u.settime64.system_time = xen_clocksource_read();
118 } else {
119 op.cmd = XENPF_settime32;
120 op.u.settime32.secs = now.tv_sec;
121 op.u.settime32.nsecs = now.tv_nsec;
122 op.u.settime32.system_time = xen_clocksource_read();
123 }
124
125 ret = HYPERVISOR_platform_op(&op);
126
127 if (ret == -ENOSYS && settime64_supported) {
128 settime64_supported = false;
129 goto again;
130 }
131 if (ret < 0)
132 return NOTIFY_BAD;
133
134 /*
135 * Move the next drift compensation time 11 minutes
136 * ahead. That's emulating the sync_cmos_clock() update for
137 * the hardware RTC.
138 */
139 next_sync = now;
140 next_sync.tv_sec += 11 * 60;
141
142 return NOTIFY_OK;
143}
144
145static struct notifier_block xen_pvclock_gtod_notifier = {
146 .notifier_call = xen_pvclock_gtod_notify,
147};
148
149static int xen_cs_enable(struct clocksource *cs)
150{
151 vclocks_set_used(VDSO_CLOCKMODE_PVCLOCK);
152 return 0;
153}
154
155static struct clocksource xen_clocksource __read_mostly = {
156 .name = "xen",
157 .rating = 400,
158 .read = xen_clocksource_get_cycles,
159 .mask = CLOCKSOURCE_MASK(64),
160 .flags = CLOCK_SOURCE_IS_CONTINUOUS,
161 .enable = xen_cs_enable,
162};
163
164/*
165 Xen clockevent implementation
166
167 Xen has two clockevent implementations:
168
169 The old timer_op one works with all released versions of Xen prior
170 to version 3.0.4. This version of the hypervisor provides a
171 single-shot timer with nanosecond resolution. However, sharing the
172 same event channel is a 100Hz tick which is delivered while the
173 vcpu is running. We don't care about or use this tick, but it will
174 cause the core time code to think the timer fired too soon, and
175 will end up resetting it each time. It could be filtered, but
176 doing so has complications when the ktime clocksource is not yet
177 the xen clocksource (ie, at boot time).
178
179 The new vcpu_op-based timer interface allows the tick timer period
180 to be changed or turned off. The tick timer is not useful as a
181 periodic timer because events are only delivered to running vcpus.
182 The one-shot timer can report when a timeout is in the past, so
183 set_next_event is capable of returning -ETIME when appropriate.
184 This interface is used when available.
185*/
186
187
188/*
189 Get a hypervisor absolute time. In theory we could maintain an
190 offset between the kernel's time and the hypervisor's time, and
191 apply that to a kernel's absolute timeout. Unfortunately the
192 hypervisor and kernel times can drift even if the kernel is using
193 the Xen clocksource, because ntp can warp the kernel's clocksource.
194*/
195static s64 get_abs_timeout(unsigned long delta)
196{
197 return xen_clocksource_read() + delta;
198}
199
200static int xen_timerop_shutdown(struct clock_event_device *evt)
201{
202 /* cancel timeout */
203 HYPERVISOR_set_timer_op(0);
204
205 return 0;
206}
207
208static int xen_timerop_set_next_event(unsigned long delta,
209 struct clock_event_device *evt)
210{
211 WARN_ON(!clockevent_state_oneshot(evt));
212
213 if (HYPERVISOR_set_timer_op(get_abs_timeout(delta)) < 0)
214 BUG();
215
216 /* We may have missed the deadline, but there's no real way of
217 knowing for sure. If the event was in the past, then we'll
218 get an immediate interrupt. */
219
220 return 0;
221}
222
223static struct clock_event_device xen_timerop_clockevent __ro_after_init = {
224 .name = "xen",
225 .features = CLOCK_EVT_FEAT_ONESHOT,
226
227 .max_delta_ns = 0xffffffff,
228 .max_delta_ticks = 0xffffffff,
229 .min_delta_ns = TIMER_SLOP,
230 .min_delta_ticks = TIMER_SLOP,
231
232 .mult = 1,
233 .shift = 0,
234 .rating = 500,
235
236 .set_state_shutdown = xen_timerop_shutdown,
237 .set_next_event = xen_timerop_set_next_event,
238};
239
240static int xen_vcpuop_shutdown(struct clock_event_device *evt)
241{
242 int cpu = smp_processor_id();
243
244 if (HYPERVISOR_vcpu_op(VCPUOP_stop_singleshot_timer, xen_vcpu_nr(cpu),
245 NULL) ||
246 HYPERVISOR_vcpu_op(VCPUOP_stop_periodic_timer, xen_vcpu_nr(cpu),
247 NULL))
248 BUG();
249
250 return 0;
251}
252
253static int xen_vcpuop_set_oneshot(struct clock_event_device *evt)
254{
255 int cpu = smp_processor_id();
256
257 if (HYPERVISOR_vcpu_op(VCPUOP_stop_periodic_timer, xen_vcpu_nr(cpu),
258 NULL))
259 BUG();
260
261 return 0;
262}
263
264static int xen_vcpuop_set_next_event(unsigned long delta,
265 struct clock_event_device *evt)
266{
267 int cpu = smp_processor_id();
268 struct vcpu_set_singleshot_timer single;
269 int ret;
270
271 WARN_ON(!clockevent_state_oneshot(evt));
272
273 single.timeout_abs_ns = get_abs_timeout(delta);
274 /* Get an event anyway, even if the timeout is already expired */
275 single.flags = 0;
276
277 ret = HYPERVISOR_vcpu_op(VCPUOP_set_singleshot_timer, xen_vcpu_nr(cpu),
278 &single);
279 BUG_ON(ret != 0);
280
281 return ret;
282}
283
284static struct clock_event_device xen_vcpuop_clockevent __ro_after_init = {
285 .name = "xen",
286 .features = CLOCK_EVT_FEAT_ONESHOT,
287
288 .max_delta_ns = 0xffffffff,
289 .max_delta_ticks = 0xffffffff,
290 .min_delta_ns = TIMER_SLOP,
291 .min_delta_ticks = TIMER_SLOP,
292
293 .mult = 1,
294 .shift = 0,
295 .rating = 500,
296
297 .set_state_shutdown = xen_vcpuop_shutdown,
298 .set_state_oneshot = xen_vcpuop_set_oneshot,
299 .set_next_event = xen_vcpuop_set_next_event,
300};
301
302static const struct clock_event_device *xen_clockevent =
303 &xen_timerop_clockevent;
304
305struct xen_clock_event_device {
306 struct clock_event_device evt;
307 char name[16];
308};
309static DEFINE_PER_CPU(struct xen_clock_event_device, xen_clock_events) = { .evt.irq = -1 };
310
311static irqreturn_t xen_timer_interrupt(int irq, void *dev_id)
312{
313 struct clock_event_device *evt = this_cpu_ptr(&xen_clock_events.evt);
314 irqreturn_t ret;
315
316 ret = IRQ_NONE;
317 if (evt->event_handler) {
318 evt->event_handler(evt);
319 ret = IRQ_HANDLED;
320 }
321
322 return ret;
323}
324
325void xen_teardown_timer(int cpu)
326{
327 struct clock_event_device *evt;
328 evt = &per_cpu(xen_clock_events, cpu).evt;
329
330 if (evt->irq >= 0) {
331 unbind_from_irqhandler(evt->irq, NULL);
332 evt->irq = -1;
333 }
334}
335
336void xen_setup_timer(int cpu)
337{
338 struct xen_clock_event_device *xevt = &per_cpu(xen_clock_events, cpu);
339 struct clock_event_device *evt = &xevt->evt;
340 int irq;
341
342 WARN(evt->irq >= 0, "IRQ%d for CPU%d is already allocated\n", evt->irq, cpu);
343 if (evt->irq >= 0)
344 xen_teardown_timer(cpu);
345
346 printk(KERN_INFO "installing Xen timer for CPU %d\n", cpu);
347
348 snprintf(xevt->name, sizeof(xevt->name), "timer%d", cpu);
349
350 irq = bind_virq_to_irqhandler(VIRQ_TIMER, cpu, xen_timer_interrupt,
351 IRQF_PERCPU|IRQF_NOBALANCING|IRQF_TIMER|
352 IRQF_FORCE_RESUME|IRQF_EARLY_RESUME,
353 xevt->name, NULL);
354 (void)xen_set_irq_priority(irq, XEN_IRQ_PRIORITY_MAX);
355
356 memcpy(evt, xen_clockevent, sizeof(*evt));
357
358 evt->cpumask = cpumask_of(cpu);
359 evt->irq = irq;
360}
361
362
363void xen_setup_cpu_clockevents(void)
364{
365 clockevents_register_device(this_cpu_ptr(&xen_clock_events.evt));
366}
367
368void xen_timer_resume(void)
369{
370 int cpu;
371
372 if (xen_clockevent != &xen_vcpuop_clockevent)
373 return;
374
375 for_each_online_cpu(cpu) {
376 if (HYPERVISOR_vcpu_op(VCPUOP_stop_periodic_timer,
377 xen_vcpu_nr(cpu), NULL))
378 BUG();
379 }
380}
381
382static struct pvclock_vsyscall_time_info *xen_clock __read_mostly;
383static u64 xen_clock_value_saved;
384
385void xen_save_time_memory_area(void)
386{
387 struct vcpu_register_time_memory_area t;
388 int ret;
389
390 xen_clock_value_saved = xen_clocksource_read() - xen_sched_clock_offset;
391
392 if (!xen_clock)
393 return;
394
395 t.addr.v = NULL;
396
397 ret = HYPERVISOR_vcpu_op(VCPUOP_register_vcpu_time_memory_area, 0, &t);
398 if (ret != 0)
399 pr_notice("Cannot save secondary vcpu_time_info (err %d)",
400 ret);
401 else
402 clear_page(xen_clock);
403}
404
405void xen_restore_time_memory_area(void)
406{
407 struct vcpu_register_time_memory_area t;
408 int ret;
409
410 if (!xen_clock)
411 goto out;
412
413 t.addr.v = &xen_clock->pvti;
414
415 ret = HYPERVISOR_vcpu_op(VCPUOP_register_vcpu_time_memory_area, 0, &t);
416
417 /*
418 * We don't disable VDSO_CLOCKMODE_PVCLOCK entirely if it fails to
419 * register the secondary time info with Xen or if we migrated to a
420 * host without the necessary flags. On both of these cases what
421 * happens is either process seeing a zeroed out pvti or seeing no
422 * PVCLOCK_TSC_STABLE_BIT bit set. Userspace checks the latter and
423 * if 0, it discards the data in pvti and fallbacks to a system
424 * call for a reliable timestamp.
425 */
426 if (ret != 0)
427 pr_notice("Cannot restore secondary vcpu_time_info (err %d)",
428 ret);
429
430out:
431 /* Need pvclock_resume() before using xen_clocksource_read(). */
432 pvclock_resume();
433 xen_sched_clock_offset = xen_clocksource_read() - xen_clock_value_saved;
434}
435
436static void xen_setup_vsyscall_time_info(void)
437{
438 struct vcpu_register_time_memory_area t;
439 struct pvclock_vsyscall_time_info *ti;
440 int ret;
441
442 ti = (struct pvclock_vsyscall_time_info *)get_zeroed_page(GFP_KERNEL);
443 if (!ti)
444 return;
445
446 t.addr.v = &ti->pvti;
447
448 ret = HYPERVISOR_vcpu_op(VCPUOP_register_vcpu_time_memory_area, 0, &t);
449 if (ret) {
450 pr_notice("xen: VDSO_CLOCKMODE_PVCLOCK not supported (err %d)\n", ret);
451 free_page((unsigned long)ti);
452 return;
453 }
454
455 /*
456 * If primary time info had this bit set, secondary should too since
457 * it's the same data on both just different memory regions. But we
458 * still check it in case hypervisor is buggy.
459 */
460 if (!(ti->pvti.flags & PVCLOCK_TSC_STABLE_BIT)) {
461 t.addr.v = NULL;
462 ret = HYPERVISOR_vcpu_op(VCPUOP_register_vcpu_time_memory_area,
463 0, &t);
464 if (!ret)
465 free_page((unsigned long)ti);
466
467 pr_notice("xen: VDSO_CLOCKMODE_PVCLOCK not supported (tsc unstable)\n");
468 return;
469 }
470
471 xen_clock = ti;
472 pvclock_set_pvti_cpu0_va(xen_clock);
473
474 xen_clocksource.vdso_clock_mode = VDSO_CLOCKMODE_PVCLOCK;
475}
476
477static void __init xen_time_init(void)
478{
479 struct pvclock_vcpu_time_info *pvti;
480 int cpu = smp_processor_id();
481 struct timespec64 tp;
482
483 /* As Dom0 is never moved, no penalty on using TSC there */
484 if (xen_initial_domain())
485 xen_clocksource.rating = 275;
486
487 clocksource_register_hz(&xen_clocksource, NSEC_PER_SEC);
488
489 if (HYPERVISOR_vcpu_op(VCPUOP_stop_periodic_timer, xen_vcpu_nr(cpu),
490 NULL) == 0) {
491 /* Successfully turned off 100Hz tick, so we have the
492 vcpuop-based timer interface */
493 printk(KERN_DEBUG "Xen: using vcpuop timer interface\n");
494 xen_clockevent = &xen_vcpuop_clockevent;
495 }
496
497 /* Set initial system time with full resolution */
498 xen_read_wallclock(&tp);
499 do_settimeofday64(&tp);
500
501 setup_force_cpu_cap(X86_FEATURE_TSC);
502
503 /*
504 * We check ahead on the primary time info if this
505 * bit is supported hence speeding up Xen clocksource.
506 */
507 pvti = &__this_cpu_read(xen_vcpu)->time;
508 if (pvti->flags & PVCLOCK_TSC_STABLE_BIT) {
509 pvclock_set_flags(PVCLOCK_TSC_STABLE_BIT);
510 xen_setup_vsyscall_time_info();
511 }
512
513 xen_setup_runstate_info(cpu);
514 xen_setup_timer(cpu);
515 xen_setup_cpu_clockevents();
516
517 xen_time_setup_guest();
518
519 if (xen_initial_domain())
520 pvclock_gtod_register_notifier(&xen_pvclock_gtod_notifier);
521}
522
523static void __init xen_init_time_common(void)
524{
525 xen_sched_clock_offset = xen_clocksource_read();
526 static_call_update(pv_steal_clock, xen_steal_clock);
527 paravirt_set_sched_clock(xen_sched_clock);
528
529 x86_platform.calibrate_tsc = xen_tsc_khz;
530 x86_platform.get_wallclock = xen_get_wallclock;
531}
532
533void __init xen_init_time_ops(void)
534{
535 xen_init_time_common();
536
537 x86_init.timers.timer_init = xen_time_init;
538 x86_init.timers.setup_percpu_clockev = x86_init_noop;
539 x86_cpuinit.setup_percpu_clockev = x86_init_noop;
540
541 /* Dom0 uses the native method to set the hardware RTC. */
542 if (!xen_initial_domain())
543 x86_platform.set_wallclock = xen_set_wallclock;
544}
545
546#ifdef CONFIG_XEN_PVHVM
547static void xen_hvm_setup_cpu_clockevents(void)
548{
549 int cpu = smp_processor_id();
550 xen_setup_runstate_info(cpu);
551 /*
552 * xen_setup_timer(cpu) - snprintf is bad in atomic context. Hence
553 * doing it xen_hvm_cpu_notify (which gets called by smp_init during
554 * early bootup and also during CPU hotplug events).
555 */
556 xen_setup_cpu_clockevents();
557}
558
559void __init xen_hvm_init_time_ops(void)
560{
561 static bool hvm_time_initialized;
562
563 if (hvm_time_initialized)
564 return;
565
566 /*
567 * vector callback is needed otherwise we cannot receive interrupts
568 * on cpu > 0 and at this point we don't know how many cpus are
569 * available.
570 */
571 if (!xen_have_vector_callback)
572 return;
573
574 if (!xen_feature(XENFEAT_hvm_safe_pvclock)) {
575 pr_info_once("Xen doesn't support pvclock on HVM, disable pv timer");
576 return;
577 }
578
579 /*
580 * Only MAX_VIRT_CPUS 'vcpu_info' are embedded inside 'shared_info'.
581 * The __this_cpu_read(xen_vcpu) is still NULL when Xen HVM guest
582 * boots on vcpu >= MAX_VIRT_CPUS (e.g., kexec), To access
583 * __this_cpu_read(xen_vcpu) via xen_clocksource_read() will panic.
584 *
585 * The xen_hvm_init_time_ops() should be called again later after
586 * __this_cpu_read(xen_vcpu) is available.
587 */
588 if (!__this_cpu_read(xen_vcpu)) {
589 pr_info("Delay xen_init_time_common() as kernel is running on vcpu=%d\n",
590 xen_vcpu_nr(0));
591 return;
592 }
593
594 xen_init_time_common();
595
596 x86_init.timers.setup_percpu_clockev = xen_time_init;
597 x86_cpuinit.setup_percpu_clockev = xen_hvm_setup_cpu_clockevents;
598
599 x86_platform.set_wallclock = xen_set_wallclock;
600
601 hvm_time_initialized = true;
602}
603#endif
604
605/* Kernel parameter to specify Xen timer slop */
606static int __init parse_xen_timer_slop(char *ptr)
607{
608 unsigned long slop = memparse(ptr, NULL);
609
610 xen_timerop_clockevent.min_delta_ns = slop;
611 xen_timerop_clockevent.min_delta_ticks = slop;
612 xen_vcpuop_clockevent.min_delta_ns = slop;
613 xen_vcpuop_clockevent.min_delta_ticks = slop;
614
615 return 0;
616}
617early_param("xen_timer_slop", parse_xen_timer_slop);
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Xen time implementation.
4 *
5 * This is implemented in terms of a clocksource driver which uses
6 * the hypervisor clock as a nanosecond timebase, and a clockevent
7 * driver which uses the hypervisor's timer mechanism.
8 *
9 * Jeremy Fitzhardinge <jeremy@xensource.com>, XenSource Inc, 2007
10 */
11#include <linux/kernel.h>
12#include <linux/interrupt.h>
13#include <linux/clocksource.h>
14#include <linux/clockchips.h>
15#include <linux/gfp.h>
16#include <linux/slab.h>
17#include <linux/pvclock_gtod.h>
18#include <linux/timekeeper_internal.h>
19
20#include <asm/pvclock.h>
21#include <asm/xen/hypervisor.h>
22#include <asm/xen/hypercall.h>
23#include <asm/xen/cpuid.h>
24
25#include <xen/events.h>
26#include <xen/features.h>
27#include <xen/interface/xen.h>
28#include <xen/interface/vcpu.h>
29
30#include "xen-ops.h"
31
32/* Minimum amount of time until next clock event fires */
33#define TIMER_SLOP 100000
34
35static u64 xen_sched_clock_offset __read_mostly;
36
37/* Get the TSC speed from Xen */
38static unsigned long xen_tsc_khz(void)
39{
40 struct pvclock_vcpu_time_info *info =
41 &HYPERVISOR_shared_info->vcpu_info[0].time;
42
43 setup_force_cpu_cap(X86_FEATURE_TSC_KNOWN_FREQ);
44 return pvclock_tsc_khz(info);
45}
46
47static u64 xen_clocksource_read(void)
48{
49 struct pvclock_vcpu_time_info *src;
50 u64 ret;
51
52 preempt_disable_notrace();
53 src = &__this_cpu_read(xen_vcpu)->time;
54 ret = pvclock_clocksource_read(src);
55 preempt_enable_notrace();
56 return ret;
57}
58
59static u64 xen_clocksource_get_cycles(struct clocksource *cs)
60{
61 return xen_clocksource_read();
62}
63
64static noinstr u64 xen_sched_clock(void)
65{
66 struct pvclock_vcpu_time_info *src;
67 u64 ret;
68
69 src = &__this_cpu_read(xen_vcpu)->time;
70 ret = pvclock_clocksource_read_nowd(src);
71 ret -= xen_sched_clock_offset;
72
73 return ret;
74}
75
76static void xen_read_wallclock(struct timespec64 *ts)
77{
78 struct shared_info *s = HYPERVISOR_shared_info;
79 struct pvclock_wall_clock *wall_clock = &(s->wc);
80 struct pvclock_vcpu_time_info *vcpu_time;
81
82 vcpu_time = &get_cpu_var(xen_vcpu)->time;
83 pvclock_read_wallclock(wall_clock, vcpu_time, ts);
84 put_cpu_var(xen_vcpu);
85}
86
87static void xen_get_wallclock(struct timespec64 *now)
88{
89 xen_read_wallclock(now);
90}
91
92static int xen_set_wallclock(const struct timespec64 *now)
93{
94 return -ENODEV;
95}
96
97static int xen_pvclock_gtod_notify(struct notifier_block *nb,
98 unsigned long was_set, void *priv)
99{
100 /* Protected by the calling core code serialization */
101 static struct timespec64 next_sync;
102
103 struct xen_platform_op op;
104 struct timespec64 now;
105 struct timekeeper *tk = priv;
106 static bool settime64_supported = true;
107 int ret;
108
109 now.tv_sec = tk->xtime_sec;
110 now.tv_nsec = (long)(tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift);
111
112 /*
113 * We only take the expensive HV call when the clock was set
114 * or when the 11 minutes RTC synchronization time elapsed.
115 */
116 if (!was_set && timespec64_compare(&now, &next_sync) < 0)
117 return NOTIFY_OK;
118
119again:
120 if (settime64_supported) {
121 op.cmd = XENPF_settime64;
122 op.u.settime64.mbz = 0;
123 op.u.settime64.secs = now.tv_sec;
124 op.u.settime64.nsecs = now.tv_nsec;
125 op.u.settime64.system_time = xen_clocksource_read();
126 } else {
127 op.cmd = XENPF_settime32;
128 op.u.settime32.secs = now.tv_sec;
129 op.u.settime32.nsecs = now.tv_nsec;
130 op.u.settime32.system_time = xen_clocksource_read();
131 }
132
133 ret = HYPERVISOR_platform_op(&op);
134
135 if (ret == -ENOSYS && settime64_supported) {
136 settime64_supported = false;
137 goto again;
138 }
139 if (ret < 0)
140 return NOTIFY_BAD;
141
142 /*
143 * Move the next drift compensation time 11 minutes
144 * ahead. That's emulating the sync_cmos_clock() update for
145 * the hardware RTC.
146 */
147 next_sync = now;
148 next_sync.tv_sec += 11 * 60;
149
150 return NOTIFY_OK;
151}
152
153static struct notifier_block xen_pvclock_gtod_notifier = {
154 .notifier_call = xen_pvclock_gtod_notify,
155};
156
157static int xen_cs_enable(struct clocksource *cs)
158{
159 vclocks_set_used(VDSO_CLOCKMODE_PVCLOCK);
160 return 0;
161}
162
163static struct clocksource xen_clocksource __read_mostly = {
164 .name = "xen",
165 .rating = 400,
166 .read = xen_clocksource_get_cycles,
167 .mask = CLOCKSOURCE_MASK(64),
168 .flags = CLOCK_SOURCE_IS_CONTINUOUS,
169 .enable = xen_cs_enable,
170};
171
172/*
173 Xen clockevent implementation
174
175 Xen has two clockevent implementations:
176
177 The old timer_op one works with all released versions of Xen prior
178 to version 3.0.4. This version of the hypervisor provides a
179 single-shot timer with nanosecond resolution. However, sharing the
180 same event channel is a 100Hz tick which is delivered while the
181 vcpu is running. We don't care about or use this tick, but it will
182 cause the core time code to think the timer fired too soon, and
183 will end up resetting it each time. It could be filtered, but
184 doing so has complications when the ktime clocksource is not yet
185 the xen clocksource (ie, at boot time).
186
187 The new vcpu_op-based timer interface allows the tick timer period
188 to be changed or turned off. The tick timer is not useful as a
189 periodic timer because events are only delivered to running vcpus.
190 The one-shot timer can report when a timeout is in the past, so
191 set_next_event is capable of returning -ETIME when appropriate.
192 This interface is used when available.
193*/
194
195
196/*
197 Get a hypervisor absolute time. In theory we could maintain an
198 offset between the kernel's time and the hypervisor's time, and
199 apply that to a kernel's absolute timeout. Unfortunately the
200 hypervisor and kernel times can drift even if the kernel is using
201 the Xen clocksource, because ntp can warp the kernel's clocksource.
202*/
203static s64 get_abs_timeout(unsigned long delta)
204{
205 return xen_clocksource_read() + delta;
206}
207
208static int xen_timerop_shutdown(struct clock_event_device *evt)
209{
210 /* cancel timeout */
211 HYPERVISOR_set_timer_op(0);
212
213 return 0;
214}
215
216static int xen_timerop_set_next_event(unsigned long delta,
217 struct clock_event_device *evt)
218{
219 WARN_ON(!clockevent_state_oneshot(evt));
220
221 if (HYPERVISOR_set_timer_op(get_abs_timeout(delta)) < 0)
222 BUG();
223
224 /* We may have missed the deadline, but there's no real way of
225 knowing for sure. If the event was in the past, then we'll
226 get an immediate interrupt. */
227
228 return 0;
229}
230
231static struct clock_event_device xen_timerop_clockevent __ro_after_init = {
232 .name = "xen",
233 .features = CLOCK_EVT_FEAT_ONESHOT,
234
235 .max_delta_ns = 0xffffffff,
236 .max_delta_ticks = 0xffffffff,
237 .min_delta_ns = TIMER_SLOP,
238 .min_delta_ticks = TIMER_SLOP,
239
240 .mult = 1,
241 .shift = 0,
242 .rating = 500,
243
244 .set_state_shutdown = xen_timerop_shutdown,
245 .set_next_event = xen_timerop_set_next_event,
246};
247
248static int xen_vcpuop_shutdown(struct clock_event_device *evt)
249{
250 int cpu = smp_processor_id();
251
252 if (HYPERVISOR_vcpu_op(VCPUOP_stop_singleshot_timer, xen_vcpu_nr(cpu),
253 NULL) ||
254 HYPERVISOR_vcpu_op(VCPUOP_stop_periodic_timer, xen_vcpu_nr(cpu),
255 NULL))
256 BUG();
257
258 return 0;
259}
260
261static int xen_vcpuop_set_oneshot(struct clock_event_device *evt)
262{
263 int cpu = smp_processor_id();
264
265 if (HYPERVISOR_vcpu_op(VCPUOP_stop_periodic_timer, xen_vcpu_nr(cpu),
266 NULL))
267 BUG();
268
269 return 0;
270}
271
272static int xen_vcpuop_set_next_event(unsigned long delta,
273 struct clock_event_device *evt)
274{
275 int cpu = smp_processor_id();
276 struct vcpu_set_singleshot_timer single;
277 int ret;
278
279 WARN_ON(!clockevent_state_oneshot(evt));
280
281 single.timeout_abs_ns = get_abs_timeout(delta);
282 /* Get an event anyway, even if the timeout is already expired */
283 single.flags = 0;
284
285 ret = HYPERVISOR_vcpu_op(VCPUOP_set_singleshot_timer, xen_vcpu_nr(cpu),
286 &single);
287 BUG_ON(ret != 0);
288
289 return ret;
290}
291
292static struct clock_event_device xen_vcpuop_clockevent __ro_after_init = {
293 .name = "xen",
294 .features = CLOCK_EVT_FEAT_ONESHOT,
295
296 .max_delta_ns = 0xffffffff,
297 .max_delta_ticks = 0xffffffff,
298 .min_delta_ns = TIMER_SLOP,
299 .min_delta_ticks = TIMER_SLOP,
300
301 .mult = 1,
302 .shift = 0,
303 .rating = 500,
304
305 .set_state_shutdown = xen_vcpuop_shutdown,
306 .set_state_oneshot = xen_vcpuop_set_oneshot,
307 .set_next_event = xen_vcpuop_set_next_event,
308};
309
310static const struct clock_event_device *xen_clockevent =
311 &xen_timerop_clockevent;
312
313struct xen_clock_event_device {
314 struct clock_event_device evt;
315 char name[16];
316};
317static DEFINE_PER_CPU(struct xen_clock_event_device, xen_clock_events) = { .evt.irq = -1 };
318
319static irqreturn_t xen_timer_interrupt(int irq, void *dev_id)
320{
321 struct clock_event_device *evt = this_cpu_ptr(&xen_clock_events.evt);
322 irqreturn_t ret;
323
324 ret = IRQ_NONE;
325 if (evt->event_handler) {
326 evt->event_handler(evt);
327 ret = IRQ_HANDLED;
328 }
329
330 return ret;
331}
332
333void xen_teardown_timer(int cpu)
334{
335 struct clock_event_device *evt;
336 evt = &per_cpu(xen_clock_events, cpu).evt;
337
338 if (evt->irq >= 0) {
339 unbind_from_irqhandler(evt->irq, NULL);
340 evt->irq = -1;
341 }
342}
343
344void xen_setup_timer(int cpu)
345{
346 struct xen_clock_event_device *xevt = &per_cpu(xen_clock_events, cpu);
347 struct clock_event_device *evt = &xevt->evt;
348 int irq;
349
350 WARN(evt->irq >= 0, "IRQ%d for CPU%d is already allocated\n", evt->irq, cpu);
351 if (evt->irq >= 0)
352 xen_teardown_timer(cpu);
353
354 printk(KERN_INFO "installing Xen timer for CPU %d\n", cpu);
355
356 snprintf(xevt->name, sizeof(xevt->name), "timer%d", cpu);
357
358 irq = bind_virq_to_irqhandler(VIRQ_TIMER, cpu, xen_timer_interrupt,
359 IRQF_PERCPU|IRQF_NOBALANCING|IRQF_TIMER|
360 IRQF_FORCE_RESUME|IRQF_EARLY_RESUME,
361 xevt->name, NULL);
362 (void)xen_set_irq_priority(irq, XEN_IRQ_PRIORITY_MAX);
363
364 memcpy(evt, xen_clockevent, sizeof(*evt));
365
366 evt->cpumask = cpumask_of(cpu);
367 evt->irq = irq;
368}
369
370
371void xen_setup_cpu_clockevents(void)
372{
373 clockevents_register_device(this_cpu_ptr(&xen_clock_events.evt));
374}
375
376void xen_timer_resume(void)
377{
378 int cpu;
379
380 if (xen_clockevent != &xen_vcpuop_clockevent)
381 return;
382
383 for_each_online_cpu(cpu) {
384 if (HYPERVISOR_vcpu_op(VCPUOP_stop_periodic_timer,
385 xen_vcpu_nr(cpu), NULL))
386 BUG();
387 }
388}
389
390static struct pvclock_vsyscall_time_info *xen_clock __read_mostly;
391static u64 xen_clock_value_saved;
392
393void xen_save_time_memory_area(void)
394{
395 struct vcpu_register_time_memory_area t;
396 int ret;
397
398 xen_clock_value_saved = xen_clocksource_read() - xen_sched_clock_offset;
399
400 if (!xen_clock)
401 return;
402
403 t.addr.v = NULL;
404
405 ret = HYPERVISOR_vcpu_op(VCPUOP_register_vcpu_time_memory_area, 0, &t);
406 if (ret != 0)
407 pr_notice("Cannot save secondary vcpu_time_info (err %d)",
408 ret);
409 else
410 clear_page(xen_clock);
411}
412
413void xen_restore_time_memory_area(void)
414{
415 struct vcpu_register_time_memory_area t;
416 int ret;
417
418 if (!xen_clock)
419 goto out;
420
421 t.addr.v = &xen_clock->pvti;
422
423 ret = HYPERVISOR_vcpu_op(VCPUOP_register_vcpu_time_memory_area, 0, &t);
424
425 /*
426 * We don't disable VDSO_CLOCKMODE_PVCLOCK entirely if it fails to
427 * register the secondary time info with Xen or if we migrated to a
428 * host without the necessary flags. On both of these cases what
429 * happens is either process seeing a zeroed out pvti or seeing no
430 * PVCLOCK_TSC_STABLE_BIT bit set. Userspace checks the latter and
431 * if 0, it discards the data in pvti and fallbacks to a system
432 * call for a reliable timestamp.
433 */
434 if (ret != 0)
435 pr_notice("Cannot restore secondary vcpu_time_info (err %d)",
436 ret);
437
438out:
439 /* Need pvclock_resume() before using xen_clocksource_read(). */
440 pvclock_resume();
441 xen_sched_clock_offset = xen_clocksource_read() - xen_clock_value_saved;
442}
443
444static void xen_setup_vsyscall_time_info(void)
445{
446 struct vcpu_register_time_memory_area t;
447 struct pvclock_vsyscall_time_info *ti;
448 int ret;
449
450 ti = (struct pvclock_vsyscall_time_info *)get_zeroed_page(GFP_KERNEL);
451 if (!ti)
452 return;
453
454 t.addr.v = &ti->pvti;
455
456 ret = HYPERVISOR_vcpu_op(VCPUOP_register_vcpu_time_memory_area, 0, &t);
457 if (ret) {
458 pr_notice("xen: VDSO_CLOCKMODE_PVCLOCK not supported (err %d)\n", ret);
459 free_page((unsigned long)ti);
460 return;
461 }
462
463 /*
464 * If primary time info had this bit set, secondary should too since
465 * it's the same data on both just different memory regions. But we
466 * still check it in case hypervisor is buggy.
467 */
468 if (!(ti->pvti.flags & PVCLOCK_TSC_STABLE_BIT)) {
469 t.addr.v = NULL;
470 ret = HYPERVISOR_vcpu_op(VCPUOP_register_vcpu_time_memory_area,
471 0, &t);
472 if (!ret)
473 free_page((unsigned long)ti);
474
475 pr_notice("xen: VDSO_CLOCKMODE_PVCLOCK not supported (tsc unstable)\n");
476 return;
477 }
478
479 xen_clock = ti;
480 pvclock_set_pvti_cpu0_va(xen_clock);
481
482 xen_clocksource.vdso_clock_mode = VDSO_CLOCKMODE_PVCLOCK;
483}
484
485/*
486 * Check if it is possible to safely use the tsc as a clocksource. This is
487 * only true if the hypervisor notifies the guest that its tsc is invariant,
488 * the tsc is stable, and the tsc instruction will never be emulated.
489 */
490static int __init xen_tsc_safe_clocksource(void)
491{
492 u32 eax, ebx, ecx, edx;
493
494 if (!(boot_cpu_has(X86_FEATURE_CONSTANT_TSC)))
495 return 0;
496
497 if (!(boot_cpu_has(X86_FEATURE_NONSTOP_TSC)))
498 return 0;
499
500 if (check_tsc_unstable())
501 return 0;
502
503 /* Leaf 4, sub-leaf 0 (0x40000x03) */
504 cpuid_count(xen_cpuid_base() + 3, 0, &eax, &ebx, &ecx, &edx);
505
506 return ebx == XEN_CPUID_TSC_MODE_NEVER_EMULATE;
507}
508
509static void __init xen_time_init(void)
510{
511 struct pvclock_vcpu_time_info *pvti;
512 int cpu = smp_processor_id();
513 struct timespec64 tp;
514
515 /*
516 * As Dom0 is never moved, no penalty on using TSC there.
517 *
518 * If it is possible for the guest to determine that the tsc is a safe
519 * clocksource, then set xen_clocksource rating below that of the tsc
520 * so that the system prefers tsc instead.
521 */
522 if (xen_initial_domain())
523 xen_clocksource.rating = 275;
524 else if (xen_tsc_safe_clocksource())
525 xen_clocksource.rating = 299;
526
527 clocksource_register_hz(&xen_clocksource, NSEC_PER_SEC);
528
529 if (HYPERVISOR_vcpu_op(VCPUOP_stop_periodic_timer, xen_vcpu_nr(cpu),
530 NULL) == 0) {
531 /* Successfully turned off 100Hz tick, so we have the
532 vcpuop-based timer interface */
533 printk(KERN_DEBUG "Xen: using vcpuop timer interface\n");
534 xen_clockevent = &xen_vcpuop_clockevent;
535 }
536
537 /* Set initial system time with full resolution */
538 xen_read_wallclock(&tp);
539 do_settimeofday64(&tp);
540
541 setup_force_cpu_cap(X86_FEATURE_TSC);
542
543 /*
544 * We check ahead on the primary time info if this
545 * bit is supported hence speeding up Xen clocksource.
546 */
547 pvti = &__this_cpu_read(xen_vcpu)->time;
548 if (pvti->flags & PVCLOCK_TSC_STABLE_BIT) {
549 pvclock_set_flags(PVCLOCK_TSC_STABLE_BIT);
550 xen_setup_vsyscall_time_info();
551 }
552
553 xen_setup_runstate_info(cpu);
554 xen_setup_timer(cpu);
555 xen_setup_cpu_clockevents();
556
557 xen_time_setup_guest();
558
559 if (xen_initial_domain())
560 pvclock_gtod_register_notifier(&xen_pvclock_gtod_notifier);
561}
562
563static void __init xen_init_time_common(void)
564{
565 xen_sched_clock_offset = xen_clocksource_read();
566 static_call_update(pv_steal_clock, xen_steal_clock);
567 paravirt_set_sched_clock(xen_sched_clock);
568
569 x86_platform.calibrate_tsc = xen_tsc_khz;
570 x86_platform.get_wallclock = xen_get_wallclock;
571}
572
573void __init xen_init_time_ops(void)
574{
575 xen_init_time_common();
576
577 x86_init.timers.timer_init = xen_time_init;
578 x86_init.timers.setup_percpu_clockev = x86_init_noop;
579 x86_cpuinit.setup_percpu_clockev = x86_init_noop;
580
581 /* Dom0 uses the native method to set the hardware RTC. */
582 if (!xen_initial_domain())
583 x86_platform.set_wallclock = xen_set_wallclock;
584}
585
586#ifdef CONFIG_XEN_PVHVM
587static void xen_hvm_setup_cpu_clockevents(void)
588{
589 int cpu = smp_processor_id();
590 xen_setup_runstate_info(cpu);
591 /*
592 * xen_setup_timer(cpu) - snprintf is bad in atomic context. Hence
593 * doing it xen_hvm_cpu_notify (which gets called by smp_init during
594 * early bootup and also during CPU hotplug events).
595 */
596 xen_setup_cpu_clockevents();
597}
598
599void __init xen_hvm_init_time_ops(void)
600{
601 static bool hvm_time_initialized;
602
603 if (hvm_time_initialized)
604 return;
605
606 /*
607 * vector callback is needed otherwise we cannot receive interrupts
608 * on cpu > 0 and at this point we don't know how many cpus are
609 * available.
610 */
611 if (!xen_have_vector_callback)
612 return;
613
614 if (!xen_feature(XENFEAT_hvm_safe_pvclock)) {
615 pr_info_once("Xen doesn't support pvclock on HVM, disable pv timer");
616 return;
617 }
618
619 /*
620 * Only MAX_VIRT_CPUS 'vcpu_info' are embedded inside 'shared_info'.
621 * The __this_cpu_read(xen_vcpu) is still NULL when Xen HVM guest
622 * boots on vcpu >= MAX_VIRT_CPUS (e.g., kexec), To access
623 * __this_cpu_read(xen_vcpu) via xen_clocksource_read() will panic.
624 *
625 * The xen_hvm_init_time_ops() should be called again later after
626 * __this_cpu_read(xen_vcpu) is available.
627 */
628 if (!__this_cpu_read(xen_vcpu)) {
629 pr_info("Delay xen_init_time_common() as kernel is running on vcpu=%d\n",
630 xen_vcpu_nr(0));
631 return;
632 }
633
634 xen_init_time_common();
635
636 x86_init.timers.setup_percpu_clockev = xen_time_init;
637 x86_cpuinit.setup_percpu_clockev = xen_hvm_setup_cpu_clockevents;
638
639 x86_platform.set_wallclock = xen_set_wallclock;
640
641 hvm_time_initialized = true;
642}
643#endif
644
645/* Kernel parameter to specify Xen timer slop */
646static int __init parse_xen_timer_slop(char *ptr)
647{
648 unsigned long slop = memparse(ptr, NULL);
649
650 xen_timerop_clockevent.min_delta_ns = slop;
651 xen_timerop_clockevent.min_delta_ticks = slop;
652 xen_vcpuop_clockevent.min_delta_ns = slop;
653 xen_vcpuop_clockevent.min_delta_ticks = slop;
654
655 return 0;
656}
657early_param("xen_timer_slop", parse_xen_timer_slop);