2 * 8253/8254 interval timer emulation
4 * Copyright (c) 2003-2004 Fabrice Bellard
5 * Copyright (c) 2006 Intel Corporation
6 * Copyright (c) 2007 Keir Fraser, XenSource Inc
7 * Copyright (c) 2008 Intel Corporation
8 * Copyright 2009 Red Hat, Inc. and/or its affiliates.
10 * Permission is hereby granted, free of charge, to any person obtaining a copy
11 * of this software and associated documentation files (the "Software"), to deal
12 * in the Software without restriction, including without limitation the rights
13 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
14 * copies of the Software, and to permit persons to whom the Software is
15 * furnished to do so, subject to the following conditions:
17 * The above copyright notice and this permission notice shall be included in
18 * all copies or substantial portions of the Software.
20 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
21 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
22 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
23 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
24 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
25 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
29 * Sheng Yang <sheng.yang@intel.com>
30 * Based on QEMU and Xen.
33 #define pr_fmt(fmt) "pit: " fmt
35 #include <linux/kvm_host.h>
36 #include <linux/slab.h>
44 #define mod_64(x, y) ((x) - (y) * div64_u64(x, y))
46 #define mod_64(x, y) ((x) % (y))
49 #define RW_STATE_LSB 1
50 #define RW_STATE_MSB 2
51 #define RW_STATE_WORD0 3
52 #define RW_STATE_WORD1 4
54 /* Compute with 96 bit intermediate result: (a*b)/c */
55 static u64 muldiv64(u64 a, u32 b, u32 c)
66 rl = (u64)u.l.low * (u64)b;
67 rh = (u64)u.l.high * (u64)b;
69 res.l.high = div64_u64(rh, c);
70 res.l.low = div64_u64(((mod_64(rh, c) << 32) + (rl & 0xffffffff)), c);
74 static void pit_set_gate(struct kvm *kvm, int channel, u32 val)
76 struct kvm_kpit_channel_state *c =
77 &kvm->arch.vpit->pit_state.channels[channel];
79 WARN_ON(!mutex_is_locked(&kvm->arch.vpit->pit_state.lock));
85 /* XXX: just disable/enable counting */
91 /* Restart counting on rising edge. */
93 c->count_load_time = ktime_get();
100 static int pit_get_gate(struct kvm *kvm, int channel)
102 WARN_ON(!mutex_is_locked(&kvm->arch.vpit->pit_state.lock));
104 return kvm->arch.vpit->pit_state.channels[channel].gate;
107 static s64 __kpit_elapsed(struct kvm *kvm)
111 struct kvm_kpit_state *ps = &kvm->arch.vpit->pit_state;
117 * The Counter does not stop when it reaches zero. In
118 * Modes 0, 1, 4, and 5 the Counter ``wraps around'' to
119 * the highest count, either FFFF hex for binary counting
120 * or 9999 for BCD counting, and continues counting.
121 * Modes 2 and 3 are periodic; the Counter reloads
122 * itself with the initial count and continues counting
125 remaining = hrtimer_get_remaining(&ps->timer);
126 elapsed = ps->period - ktime_to_ns(remaining);
131 static s64 kpit_elapsed(struct kvm *kvm, struct kvm_kpit_channel_state *c,
135 return __kpit_elapsed(kvm);
137 return ktime_to_ns(ktime_sub(ktime_get(), c->count_load_time));
140 static int pit_get_count(struct kvm *kvm, int channel)
142 struct kvm_kpit_channel_state *c =
143 &kvm->arch.vpit->pit_state.channels[channel];
147 WARN_ON(!mutex_is_locked(&kvm->arch.vpit->pit_state.lock));
149 t = kpit_elapsed(kvm, c, channel);
150 d = muldiv64(t, KVM_PIT_FREQ, NSEC_PER_SEC);
157 counter = (c->count - d) & 0xffff;
160 /* XXX: may be incorrect for odd counts */
161 counter = c->count - (mod_64((2 * d), c->count));
164 counter = c->count - mod_64(d, c->count);
170 static int pit_get_out(struct kvm *kvm, int channel)
172 struct kvm_kpit_channel_state *c =
173 &kvm->arch.vpit->pit_state.channels[channel];
177 WARN_ON(!mutex_is_locked(&kvm->arch.vpit->pit_state.lock));
179 t = kpit_elapsed(kvm, c, channel);
180 d = muldiv64(t, KVM_PIT_FREQ, NSEC_PER_SEC);
185 out = (d >= c->count);
188 out = (d < c->count);
191 out = ((mod_64(d, c->count) == 0) && (d != 0));
194 out = (mod_64(d, c->count) < ((c->count + 1) >> 1));
198 out = (d == c->count);
205 static void pit_latch_count(struct kvm *kvm, int channel)
207 struct kvm_kpit_channel_state *c =
208 &kvm->arch.vpit->pit_state.channels[channel];
210 WARN_ON(!mutex_is_locked(&kvm->arch.vpit->pit_state.lock));
212 if (!c->count_latched) {
213 c->latched_count = pit_get_count(kvm, channel);
214 c->count_latched = c->rw_mode;
218 static void pit_latch_status(struct kvm *kvm, int channel)
220 struct kvm_kpit_channel_state *c =
221 &kvm->arch.vpit->pit_state.channels[channel];
223 WARN_ON(!mutex_is_locked(&kvm->arch.vpit->pit_state.lock));
225 if (!c->status_latched) {
226 /* TODO: Return NULL COUNT (bit 6). */
227 c->status = ((pit_get_out(kvm, channel) << 7) |
231 c->status_latched = 1;
235 static void kvm_pit_ack_irq(struct kvm_irq_ack_notifier *kian)
237 struct kvm_kpit_state *ps = container_of(kian, struct kvm_kpit_state,
241 spin_lock(&ps->inject_lock);
242 value = atomic_dec_return(&ps->pending);
244 /* spurious acks can be generated if, for example, the
245 * PIC is being reset. Handle it gracefully here
247 atomic_inc(&ps->pending);
249 /* in this case, we had multiple outstanding pit interrupts
250 * that we needed to inject. Reinject
252 queue_kthread_work(&ps->pit->worker, &ps->pit->expired);
254 spin_unlock(&ps->inject_lock);
257 void __kvm_migrate_pit_timer(struct kvm_vcpu *vcpu)
259 struct kvm_pit *pit = vcpu->kvm->arch.vpit;
260 struct hrtimer *timer;
262 if (!kvm_vcpu_is_bsp(vcpu) || !pit)
265 timer = &pit->pit_state.timer;
266 mutex_lock(&pit->pit_state.lock);
267 if (hrtimer_cancel(timer))
268 hrtimer_start_expires(timer, HRTIMER_MODE_ABS);
269 mutex_unlock(&pit->pit_state.lock);
272 static void destroy_pit_timer(struct kvm_pit *pit)
274 hrtimer_cancel(&pit->pit_state.timer);
275 flush_kthread_work(&pit->expired);
278 static void pit_do_work(struct kthread_work *work)
280 struct kvm_pit *pit = container_of(work, struct kvm_pit, expired);
281 struct kvm *kvm = pit->kvm;
282 struct kvm_vcpu *vcpu;
284 struct kvm_kpit_state *ps = &pit->pit_state;
287 /* Try to inject pending interrupts when
288 * last one has been acked.
290 spin_lock(&ps->inject_lock);
295 spin_unlock(&ps->inject_lock);
297 kvm_set_irq(kvm, kvm->arch.vpit->irq_source_id, 0, 1, false);
298 kvm_set_irq(kvm, kvm->arch.vpit->irq_source_id, 0, 0, false);
301 * Provides NMI watchdog support via Virtual Wire mode.
302 * The route is: PIT -> PIC -> LVT0 in NMI mode.
304 * Note: Our Virtual Wire implementation is simplified, only
305 * propagating PIT interrupts to all VCPUs when they have set
306 * LVT0 to NMI delivery. Other PIC interrupts are just sent to
307 * VCPU0, and only if its LVT0 is in EXTINT mode.
309 if (atomic_read(&kvm->arch.vapics_in_nmi_mode) > 0)
310 kvm_for_each_vcpu(i, vcpu, kvm)
311 kvm_apic_nmi_wd_deliver(vcpu);
315 static enum hrtimer_restart pit_timer_fn(struct hrtimer *data)
317 struct kvm_kpit_state *ps = container_of(data, struct kvm_kpit_state, timer);
318 struct kvm_pit *pt = ps->kvm->arch.vpit;
320 if (ps->reinject || !atomic_read(&ps->pending)) {
321 atomic_inc(&ps->pending);
322 queue_kthread_work(&pt->worker, &pt->expired);
325 if (ps->is_periodic) {
326 hrtimer_add_expires_ns(&ps->timer, ps->period);
327 return HRTIMER_RESTART;
329 return HRTIMER_NORESTART;
332 static void create_pit_timer(struct kvm *kvm, u32 val, int is_period)
334 struct kvm_kpit_state *ps = &kvm->arch.vpit->pit_state;
337 if (!ioapic_in_kernel(kvm) ||
338 ps->flags & KVM_PIT_FLAGS_HPET_LEGACY)
341 interval = muldiv64(val, NSEC_PER_SEC, KVM_PIT_FREQ);
343 pr_debug("create pit timer, interval is %llu nsec\n", interval);
345 /* TODO The new value only affected after the retriggered */
346 hrtimer_cancel(&ps->timer);
347 flush_kthread_work(&ps->pit->expired);
348 ps->period = interval;
349 ps->is_periodic = is_period;
351 ps->timer.function = pit_timer_fn;
352 ps->kvm = ps->pit->kvm;
354 atomic_set(&ps->pending, 0);
358 * Do not allow the guest to program periodic timers with small
359 * interval, since the hrtimers are not throttled by the host
362 if (ps->is_periodic) {
363 s64 min_period = min_timer_period_us * 1000LL;
365 if (ps->period < min_period) {
367 "kvm: requested %lld ns "
368 "i8254 timer period limited to %lld ns\n",
369 ps->period, min_period);
370 ps->period = min_period;
374 hrtimer_start(&ps->timer, ktime_add_ns(ktime_get(), interval),
378 static void pit_load_count(struct kvm *kvm, int channel, u32 val)
380 struct kvm_kpit_state *ps = &kvm->arch.vpit->pit_state;
382 WARN_ON(!mutex_is_locked(&ps->lock));
384 pr_debug("load_count val is %d, channel is %d\n", val, channel);
387 * The largest possible initial count is 0; this is equivalent
388 * to 216 for binary counting and 104 for BCD counting.
393 ps->channels[channel].count = val;
396 ps->channels[channel].count_load_time = ktime_get();
400 /* Two types of timer
401 * mode 1 is one shot, mode 2 is period, otherwise del timer */
402 switch (ps->channels[0].mode) {
405 /* FIXME: enhance mode 4 precision */
407 create_pit_timer(kvm, val, 0);
411 create_pit_timer(kvm, val, 1);
414 destroy_pit_timer(kvm->arch.vpit);
418 void kvm_pit_load_count(struct kvm *kvm, int channel, u32 val, int hpet_legacy_start)
421 if (hpet_legacy_start) {
422 /* save existing mode for later reenablement */
423 saved_mode = kvm->arch.vpit->pit_state.channels[0].mode;
424 kvm->arch.vpit->pit_state.channels[0].mode = 0xff; /* disable timer */
425 pit_load_count(kvm, channel, val);
426 kvm->arch.vpit->pit_state.channels[0].mode = saved_mode;
428 pit_load_count(kvm, channel, val);
432 static inline struct kvm_pit *dev_to_pit(struct kvm_io_device *dev)
434 return container_of(dev, struct kvm_pit, dev);
437 static inline struct kvm_pit *speaker_to_pit(struct kvm_io_device *dev)
439 return container_of(dev, struct kvm_pit, speaker_dev);
442 static inline int pit_in_range(gpa_t addr)
444 return ((addr >= KVM_PIT_BASE_ADDRESS) &&
445 (addr < KVM_PIT_BASE_ADDRESS + KVM_PIT_MEM_LENGTH));
448 static int pit_ioport_write(struct kvm_vcpu *vcpu,
449 struct kvm_io_device *this,
450 gpa_t addr, int len, const void *data)
452 struct kvm_pit *pit = dev_to_pit(this);
453 struct kvm_kpit_state *pit_state = &pit->pit_state;
454 struct kvm *kvm = pit->kvm;
456 struct kvm_kpit_channel_state *s;
457 u32 val = *(u32 *) data;
458 if (!pit_in_range(addr))
462 addr &= KVM_PIT_CHANNEL_MASK;
464 mutex_lock(&pit_state->lock);
467 pr_debug("write addr is 0x%x, len is %d, val is 0x%x\n",
468 (unsigned int)addr, len, val);
473 /* Read-Back Command. */
474 for (channel = 0; channel < 3; channel++) {
475 s = &pit_state->channels[channel];
476 if (val & (2 << channel)) {
478 pit_latch_count(kvm, channel);
480 pit_latch_status(kvm, channel);
484 /* Select Counter <channel>. */
485 s = &pit_state->channels[channel];
486 access = (val >> 4) & KVM_PIT_CHANNEL_MASK;
488 pit_latch_count(kvm, channel);
491 s->read_state = access;
492 s->write_state = access;
493 s->mode = (val >> 1) & 7;
501 s = &pit_state->channels[addr];
502 switch (s->write_state) {
505 pit_load_count(kvm, addr, val);
508 pit_load_count(kvm, addr, val << 8);
511 s->write_latch = val;
512 s->write_state = RW_STATE_WORD1;
515 pit_load_count(kvm, addr, s->write_latch | (val << 8));
516 s->write_state = RW_STATE_WORD0;
521 mutex_unlock(&pit_state->lock);
525 static int pit_ioport_read(struct kvm_vcpu *vcpu,
526 struct kvm_io_device *this,
527 gpa_t addr, int len, void *data)
529 struct kvm_pit *pit = dev_to_pit(this);
530 struct kvm_kpit_state *pit_state = &pit->pit_state;
531 struct kvm *kvm = pit->kvm;
533 struct kvm_kpit_channel_state *s;
534 if (!pit_in_range(addr))
537 addr &= KVM_PIT_CHANNEL_MASK;
541 s = &pit_state->channels[addr];
543 mutex_lock(&pit_state->lock);
545 if (s->status_latched) {
546 s->status_latched = 0;
548 } else if (s->count_latched) {
549 switch (s->count_latched) {
552 ret = s->latched_count & 0xff;
553 s->count_latched = 0;
556 ret = s->latched_count >> 8;
557 s->count_latched = 0;
560 ret = s->latched_count & 0xff;
561 s->count_latched = RW_STATE_MSB;
565 switch (s->read_state) {
568 count = pit_get_count(kvm, addr);
572 count = pit_get_count(kvm, addr);
573 ret = (count >> 8) & 0xff;
576 count = pit_get_count(kvm, addr);
578 s->read_state = RW_STATE_WORD1;
581 count = pit_get_count(kvm, addr);
582 ret = (count >> 8) & 0xff;
583 s->read_state = RW_STATE_WORD0;
588 if (len > sizeof(ret))
590 memcpy(data, (char *)&ret, len);
592 mutex_unlock(&pit_state->lock);
596 static int speaker_ioport_write(struct kvm_vcpu *vcpu,
597 struct kvm_io_device *this,
598 gpa_t addr, int len, const void *data)
600 struct kvm_pit *pit = speaker_to_pit(this);
601 struct kvm_kpit_state *pit_state = &pit->pit_state;
602 struct kvm *kvm = pit->kvm;
603 u32 val = *(u32 *) data;
604 if (addr != KVM_SPEAKER_BASE_ADDRESS)
607 mutex_lock(&pit_state->lock);
608 pit_state->speaker_data_on = (val >> 1) & 1;
609 pit_set_gate(kvm, 2, val & 1);
610 mutex_unlock(&pit_state->lock);
614 static int speaker_ioport_read(struct kvm_vcpu *vcpu,
615 struct kvm_io_device *this,
616 gpa_t addr, int len, void *data)
618 struct kvm_pit *pit = speaker_to_pit(this);
619 struct kvm_kpit_state *pit_state = &pit->pit_state;
620 struct kvm *kvm = pit->kvm;
621 unsigned int refresh_clock;
623 if (addr != KVM_SPEAKER_BASE_ADDRESS)
626 /* Refresh clock toggles at about 15us. We approximate as 2^14ns. */
627 refresh_clock = ((unsigned int)ktime_to_ns(ktime_get()) >> 14) & 1;
629 mutex_lock(&pit_state->lock);
630 ret = ((pit_state->speaker_data_on << 1) | pit_get_gate(kvm, 2) |
631 (pit_get_out(kvm, 2) << 5) | (refresh_clock << 4));
632 if (len > sizeof(ret))
634 memcpy(data, (char *)&ret, len);
635 mutex_unlock(&pit_state->lock);
639 void kvm_pit_reset(struct kvm_pit *pit)
642 struct kvm_kpit_channel_state *c;
644 mutex_lock(&pit->pit_state.lock);
645 pit->pit_state.flags = 0;
646 for (i = 0; i < 3; i++) {
647 c = &pit->pit_state.channels[i];
650 pit_load_count(pit->kvm, i, 0);
652 mutex_unlock(&pit->pit_state.lock);
654 atomic_set(&pit->pit_state.pending, 0);
655 pit->pit_state.irq_ack = 1;
658 static void pit_mask_notifer(struct kvm_irq_mask_notifier *kimn, bool mask)
660 struct kvm_pit *pit = container_of(kimn, struct kvm_pit, mask_notifier);
663 atomic_set(&pit->pit_state.pending, 0);
664 pit->pit_state.irq_ack = 1;
668 static const struct kvm_io_device_ops pit_dev_ops = {
669 .read = pit_ioport_read,
670 .write = pit_ioport_write,
673 static const struct kvm_io_device_ops speaker_dev_ops = {
674 .read = speaker_ioport_read,
675 .write = speaker_ioport_write,
678 /* Caller must hold slots_lock */
679 struct kvm_pit *kvm_create_pit(struct kvm *kvm, u32 flags)
682 struct kvm_kpit_state *pit_state;
687 pit = kzalloc(sizeof(struct kvm_pit), GFP_KERNEL);
691 pit->irq_source_id = kvm_request_irq_source_id(kvm);
692 if (pit->irq_source_id < 0) {
697 mutex_init(&pit->pit_state.lock);
698 mutex_lock(&pit->pit_state.lock);
699 spin_lock_init(&pit->pit_state.inject_lock);
701 pid = get_pid(task_tgid(current));
702 pid_nr = pid_vnr(pid);
705 init_kthread_worker(&pit->worker);
706 pit->worker_task = kthread_run(kthread_worker_fn, &pit->worker,
707 "kvm-pit/%d", pid_nr);
708 if (IS_ERR(pit->worker_task)) {
709 mutex_unlock(&pit->pit_state.lock);
710 kvm_free_irq_source_id(kvm, pit->irq_source_id);
714 init_kthread_work(&pit->expired, pit_do_work);
716 kvm->arch.vpit = pit;
719 pit_state = &pit->pit_state;
720 pit_state->pit = pit;
721 hrtimer_init(&pit_state->timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
722 pit_state->irq_ack_notifier.gsi = 0;
723 pit_state->irq_ack_notifier.irq_acked = kvm_pit_ack_irq;
724 kvm_register_irq_ack_notifier(kvm, &pit_state->irq_ack_notifier);
725 pit_state->reinject = true;
726 mutex_unlock(&pit->pit_state.lock);
730 pit->mask_notifier.func = pit_mask_notifer;
731 kvm_register_irq_mask_notifier(kvm, 0, &pit->mask_notifier);
733 kvm_iodevice_init(&pit->dev, &pit_dev_ops);
734 ret = kvm_io_bus_register_dev(kvm, KVM_PIO_BUS, KVM_PIT_BASE_ADDRESS,
735 KVM_PIT_MEM_LENGTH, &pit->dev);
739 if (flags & KVM_PIT_SPEAKER_DUMMY) {
740 kvm_iodevice_init(&pit->speaker_dev, &speaker_dev_ops);
741 ret = kvm_io_bus_register_dev(kvm, KVM_PIO_BUS,
742 KVM_SPEAKER_BASE_ADDRESS, 4,
745 goto fail_unregister;
751 kvm_io_bus_unregister_dev(kvm, KVM_PIO_BUS, &pit->dev);
754 kvm_unregister_irq_mask_notifier(kvm, 0, &pit->mask_notifier);
755 kvm_unregister_irq_ack_notifier(kvm, &pit_state->irq_ack_notifier);
756 kvm_free_irq_source_id(kvm, pit->irq_source_id);
757 kthread_stop(pit->worker_task);
762 void kvm_free_pit(struct kvm *kvm)
764 struct hrtimer *timer;
766 if (kvm->arch.vpit) {
767 kvm_io_bus_unregister_dev(kvm, KVM_PIO_BUS, &kvm->arch.vpit->dev);
768 kvm_io_bus_unregister_dev(kvm, KVM_PIO_BUS,
769 &kvm->arch.vpit->speaker_dev);
770 kvm_unregister_irq_mask_notifier(kvm, 0,
771 &kvm->arch.vpit->mask_notifier);
772 kvm_unregister_irq_ack_notifier(kvm,
773 &kvm->arch.vpit->pit_state.irq_ack_notifier);
774 mutex_lock(&kvm->arch.vpit->pit_state.lock);
775 timer = &kvm->arch.vpit->pit_state.timer;
776 hrtimer_cancel(timer);
777 flush_kthread_work(&kvm->arch.vpit->expired);
778 kthread_stop(kvm->arch.vpit->worker_task);
779 kvm_free_irq_source_id(kvm, kvm->arch.vpit->irq_source_id);
780 mutex_unlock(&kvm->arch.vpit->pit_state.lock);
781 kfree(kvm->arch.vpit);