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>
42 #define mod_64(x, y) ((x) - (y) * div64_u64(x, y))
44 #define mod_64(x, y) ((x) % (y))
47 #define RW_STATE_LSB 1
48 #define RW_STATE_MSB 2
49 #define RW_STATE_WORD0 3
50 #define RW_STATE_WORD1 4
52 /* Compute with 96 bit intermediate result: (a*b)/c */
53 static u64 muldiv64(u64 a, u32 b, u32 c)
64 rl = (u64)u.l.low * (u64)b;
65 rh = (u64)u.l.high * (u64)b;
67 res.l.high = div64_u64(rh, c);
68 res.l.low = div64_u64(((mod_64(rh, c) << 32) + (rl & 0xffffffff)), c);
72 static void pit_set_gate(struct kvm *kvm, int channel, u32 val)
74 struct kvm_kpit_channel_state *c =
75 &kvm->arch.vpit->pit_state.channels[channel];
77 WARN_ON(!mutex_is_locked(&kvm->arch.vpit->pit_state.lock));
83 /* XXX: just disable/enable counting */
89 /* Restart counting on rising edge. */
91 c->count_load_time = ktime_get();
98 static int pit_get_gate(struct kvm *kvm, int channel)
100 WARN_ON(!mutex_is_locked(&kvm->arch.vpit->pit_state.lock));
102 return kvm->arch.vpit->pit_state.channels[channel].gate;
105 static s64 __kpit_elapsed(struct kvm *kvm)
109 struct kvm_kpit_state *ps = &kvm->arch.vpit->pit_state;
115 * The Counter does not stop when it reaches zero. In
116 * Modes 0, 1, 4, and 5 the Counter ``wraps around'' to
117 * the highest count, either FFFF hex for binary counting
118 * or 9999 for BCD counting, and continues counting.
119 * Modes 2 and 3 are periodic; the Counter reloads
120 * itself with the initial count and continues counting
123 remaining = hrtimer_get_remaining(&ps->timer);
124 elapsed = ps->period - ktime_to_ns(remaining);
129 static s64 kpit_elapsed(struct kvm *kvm, struct kvm_kpit_channel_state *c,
133 return __kpit_elapsed(kvm);
135 return ktime_to_ns(ktime_sub(ktime_get(), c->count_load_time));
138 static int pit_get_count(struct kvm *kvm, int channel)
140 struct kvm_kpit_channel_state *c =
141 &kvm->arch.vpit->pit_state.channels[channel];
145 WARN_ON(!mutex_is_locked(&kvm->arch.vpit->pit_state.lock));
147 t = kpit_elapsed(kvm, c, channel);
148 d = muldiv64(t, KVM_PIT_FREQ, NSEC_PER_SEC);
155 counter = (c->count - d) & 0xffff;
158 /* XXX: may be incorrect for odd counts */
159 counter = c->count - (mod_64((2 * d), c->count));
162 counter = c->count - mod_64(d, c->count);
168 static int pit_get_out(struct kvm *kvm, int channel)
170 struct kvm_kpit_channel_state *c =
171 &kvm->arch.vpit->pit_state.channels[channel];
175 WARN_ON(!mutex_is_locked(&kvm->arch.vpit->pit_state.lock));
177 t = kpit_elapsed(kvm, c, channel);
178 d = muldiv64(t, KVM_PIT_FREQ, NSEC_PER_SEC);
183 out = (d >= c->count);
186 out = (d < c->count);
189 out = ((mod_64(d, c->count) == 0) && (d != 0));
192 out = (mod_64(d, c->count) < ((c->count + 1) >> 1));
196 out = (d == c->count);
203 static void pit_latch_count(struct kvm *kvm, int channel)
205 struct kvm_kpit_channel_state *c =
206 &kvm->arch.vpit->pit_state.channels[channel];
208 WARN_ON(!mutex_is_locked(&kvm->arch.vpit->pit_state.lock));
210 if (!c->count_latched) {
211 c->latched_count = pit_get_count(kvm, channel);
212 c->count_latched = c->rw_mode;
216 static void pit_latch_status(struct kvm *kvm, int channel)
218 struct kvm_kpit_channel_state *c =
219 &kvm->arch.vpit->pit_state.channels[channel];
221 WARN_ON(!mutex_is_locked(&kvm->arch.vpit->pit_state.lock));
223 if (!c->status_latched) {
224 /* TODO: Return NULL COUNT (bit 6). */
225 c->status = ((pit_get_out(kvm, channel) << 7) |
229 c->status_latched = 1;
233 static void kvm_pit_ack_irq(struct kvm_irq_ack_notifier *kian)
235 struct kvm_kpit_state *ps = container_of(kian, struct kvm_kpit_state,
239 spin_lock(&ps->inject_lock);
240 value = atomic_dec_return(&ps->pending);
242 /* spurious acks can be generated if, for example, the
243 * PIC is being reset. Handle it gracefully here
245 atomic_inc(&ps->pending);
247 /* in this case, we had multiple outstanding pit interrupts
248 * that we needed to inject. Reinject
250 queue_kthread_work(&ps->pit->worker, &ps->pit->expired);
252 spin_unlock(&ps->inject_lock);
255 void __kvm_migrate_pit_timer(struct kvm_vcpu *vcpu)
257 struct kvm_pit *pit = vcpu->kvm->arch.vpit;
258 struct hrtimer *timer;
260 if (!kvm_vcpu_is_bsp(vcpu) || !pit)
263 timer = &pit->pit_state.timer;
264 if (hrtimer_cancel(timer))
265 hrtimer_start_expires(timer, HRTIMER_MODE_ABS);
268 static void destroy_pit_timer(struct kvm_pit *pit)
270 hrtimer_cancel(&pit->pit_state.timer);
271 flush_kthread_work(&pit->expired);
274 static void pit_do_work(struct kthread_work *work)
276 struct kvm_pit *pit = container_of(work, struct kvm_pit, expired);
277 struct kvm *kvm = pit->kvm;
278 struct kvm_vcpu *vcpu;
280 struct kvm_kpit_state *ps = &pit->pit_state;
283 /* Try to inject pending interrupts when
284 * last one has been acked.
286 spin_lock(&ps->inject_lock);
291 spin_unlock(&ps->inject_lock);
293 kvm_set_irq(kvm, kvm->arch.vpit->irq_source_id, 0, 1);
294 kvm_set_irq(kvm, kvm->arch.vpit->irq_source_id, 0, 0);
297 * Provides NMI watchdog support via Virtual Wire mode.
298 * The route is: PIT -> PIC -> LVT0 in NMI mode.
300 * Note: Our Virtual Wire implementation is simplified, only
301 * propagating PIT interrupts to all VCPUs when they have set
302 * LVT0 to NMI delivery. Other PIC interrupts are just sent to
303 * VCPU0, and only if its LVT0 is in EXTINT mode.
305 if (kvm->arch.vapics_in_nmi_mode > 0)
306 kvm_for_each_vcpu(i, vcpu, kvm)
307 kvm_apic_nmi_wd_deliver(vcpu);
311 static enum hrtimer_restart pit_timer_fn(struct hrtimer *data)
313 struct kvm_kpit_state *ps = container_of(data, struct kvm_kpit_state, timer);
314 struct kvm_pit *pt = ps->kvm->arch.vpit;
316 if (ps->reinject || !atomic_read(&ps->pending)) {
317 atomic_inc(&ps->pending);
318 queue_kthread_work(&pt->worker, &pt->expired);
321 if (ps->is_periodic) {
322 hrtimer_add_expires_ns(&ps->timer, ps->period);
323 return HRTIMER_RESTART;
325 return HRTIMER_NORESTART;
328 static void create_pit_timer(struct kvm *kvm, u32 val, int is_period)
330 struct kvm_kpit_state *ps = &kvm->arch.vpit->pit_state;
333 if (!irqchip_in_kernel(kvm) || ps->flags & KVM_PIT_FLAGS_HPET_LEGACY)
336 interval = muldiv64(val, NSEC_PER_SEC, KVM_PIT_FREQ);
338 pr_debug("create pit timer, interval is %llu nsec\n", interval);
340 /* TODO The new value only affected after the retriggered */
341 hrtimer_cancel(&ps->timer);
342 flush_kthread_work(&ps->pit->expired);
343 ps->period = interval;
344 ps->is_periodic = is_period;
346 ps->timer.function = pit_timer_fn;
347 ps->kvm = ps->pit->kvm;
349 atomic_set(&ps->pending, 0);
352 hrtimer_start(&ps->timer, ktime_add_ns(ktime_get(), interval),
356 static void pit_load_count(struct kvm *kvm, int channel, u32 val)
358 struct kvm_kpit_state *ps = &kvm->arch.vpit->pit_state;
360 WARN_ON(!mutex_is_locked(&ps->lock));
362 pr_debug("load_count val is %d, channel is %d\n", val, channel);
365 * The largest possible initial count is 0; this is equivalent
366 * to 216 for binary counting and 104 for BCD counting.
371 ps->channels[channel].count = val;
374 ps->channels[channel].count_load_time = ktime_get();
378 /* Two types of timer
379 * mode 1 is one shot, mode 2 is period, otherwise del timer */
380 switch (ps->channels[0].mode) {
383 /* FIXME: enhance mode 4 precision */
385 create_pit_timer(kvm, val, 0);
389 create_pit_timer(kvm, val, 1);
392 destroy_pit_timer(kvm->arch.vpit);
396 void kvm_pit_load_count(struct kvm *kvm, int channel, u32 val, int hpet_legacy_start)
399 if (hpet_legacy_start) {
400 /* save existing mode for later reenablement */
401 saved_mode = kvm->arch.vpit->pit_state.channels[0].mode;
402 kvm->arch.vpit->pit_state.channels[0].mode = 0xff; /* disable timer */
403 pit_load_count(kvm, channel, val);
404 kvm->arch.vpit->pit_state.channels[0].mode = saved_mode;
406 pit_load_count(kvm, channel, val);
410 static inline struct kvm_pit *dev_to_pit(struct kvm_io_device *dev)
412 return container_of(dev, struct kvm_pit, dev);
415 static inline struct kvm_pit *speaker_to_pit(struct kvm_io_device *dev)
417 return container_of(dev, struct kvm_pit, speaker_dev);
420 static inline int pit_in_range(gpa_t addr)
422 return ((addr >= KVM_PIT_BASE_ADDRESS) &&
423 (addr < KVM_PIT_BASE_ADDRESS + KVM_PIT_MEM_LENGTH));
426 static int pit_ioport_write(struct kvm_io_device *this,
427 gpa_t addr, int len, const void *data)
429 struct kvm_pit *pit = dev_to_pit(this);
430 struct kvm_kpit_state *pit_state = &pit->pit_state;
431 struct kvm *kvm = pit->kvm;
433 struct kvm_kpit_channel_state *s;
434 u32 val = *(u32 *) data;
435 if (!pit_in_range(addr))
439 addr &= KVM_PIT_CHANNEL_MASK;
441 mutex_lock(&pit_state->lock);
444 pr_debug("write addr is 0x%x, len is %d, val is 0x%x\n",
445 (unsigned int)addr, len, val);
450 /* Read-Back Command. */
451 for (channel = 0; channel < 3; channel++) {
452 s = &pit_state->channels[channel];
453 if (val & (2 << channel)) {
455 pit_latch_count(kvm, channel);
457 pit_latch_status(kvm, channel);
461 /* Select Counter <channel>. */
462 s = &pit_state->channels[channel];
463 access = (val >> 4) & KVM_PIT_CHANNEL_MASK;
465 pit_latch_count(kvm, channel);
468 s->read_state = access;
469 s->write_state = access;
470 s->mode = (val >> 1) & 7;
478 s = &pit_state->channels[addr];
479 switch (s->write_state) {
482 pit_load_count(kvm, addr, val);
485 pit_load_count(kvm, addr, val << 8);
488 s->write_latch = val;
489 s->write_state = RW_STATE_WORD1;
492 pit_load_count(kvm, addr, s->write_latch | (val << 8));
493 s->write_state = RW_STATE_WORD0;
498 mutex_unlock(&pit_state->lock);
502 static int pit_ioport_read(struct kvm_io_device *this,
503 gpa_t addr, int len, void *data)
505 struct kvm_pit *pit = dev_to_pit(this);
506 struct kvm_kpit_state *pit_state = &pit->pit_state;
507 struct kvm *kvm = pit->kvm;
509 struct kvm_kpit_channel_state *s;
510 if (!pit_in_range(addr))
513 addr &= KVM_PIT_CHANNEL_MASK;
517 s = &pit_state->channels[addr];
519 mutex_lock(&pit_state->lock);
521 if (s->status_latched) {
522 s->status_latched = 0;
524 } else if (s->count_latched) {
525 switch (s->count_latched) {
528 ret = s->latched_count & 0xff;
529 s->count_latched = 0;
532 ret = s->latched_count >> 8;
533 s->count_latched = 0;
536 ret = s->latched_count & 0xff;
537 s->count_latched = RW_STATE_MSB;
541 switch (s->read_state) {
544 count = pit_get_count(kvm, addr);
548 count = pit_get_count(kvm, addr);
549 ret = (count >> 8) & 0xff;
552 count = pit_get_count(kvm, addr);
554 s->read_state = RW_STATE_WORD1;
557 count = pit_get_count(kvm, addr);
558 ret = (count >> 8) & 0xff;
559 s->read_state = RW_STATE_WORD0;
564 if (len > sizeof(ret))
566 memcpy(data, (char *)&ret, len);
568 mutex_unlock(&pit_state->lock);
572 static int speaker_ioport_write(struct kvm_io_device *this,
573 gpa_t addr, int len, const void *data)
575 struct kvm_pit *pit = speaker_to_pit(this);
576 struct kvm_kpit_state *pit_state = &pit->pit_state;
577 struct kvm *kvm = pit->kvm;
578 u32 val = *(u32 *) data;
579 if (addr != KVM_SPEAKER_BASE_ADDRESS)
582 mutex_lock(&pit_state->lock);
583 pit_state->speaker_data_on = (val >> 1) & 1;
584 pit_set_gate(kvm, 2, val & 1);
585 mutex_unlock(&pit_state->lock);
589 static int speaker_ioport_read(struct kvm_io_device *this,
590 gpa_t addr, int len, void *data)
592 struct kvm_pit *pit = speaker_to_pit(this);
593 struct kvm_kpit_state *pit_state = &pit->pit_state;
594 struct kvm *kvm = pit->kvm;
595 unsigned int refresh_clock;
597 if (addr != KVM_SPEAKER_BASE_ADDRESS)
600 /* Refresh clock toggles at about 15us. We approximate as 2^14ns. */
601 refresh_clock = ((unsigned int)ktime_to_ns(ktime_get()) >> 14) & 1;
603 mutex_lock(&pit_state->lock);
604 ret = ((pit_state->speaker_data_on << 1) | pit_get_gate(kvm, 2) |
605 (pit_get_out(kvm, 2) << 5) | (refresh_clock << 4));
606 if (len > sizeof(ret))
608 memcpy(data, (char *)&ret, len);
609 mutex_unlock(&pit_state->lock);
613 void kvm_pit_reset(struct kvm_pit *pit)
616 struct kvm_kpit_channel_state *c;
618 mutex_lock(&pit->pit_state.lock);
619 pit->pit_state.flags = 0;
620 for (i = 0; i < 3; i++) {
621 c = &pit->pit_state.channels[i];
624 pit_load_count(pit->kvm, i, 0);
626 mutex_unlock(&pit->pit_state.lock);
628 atomic_set(&pit->pit_state.pending, 0);
629 pit->pit_state.irq_ack = 1;
632 static void pit_mask_notifer(struct kvm_irq_mask_notifier *kimn, bool mask)
634 struct kvm_pit *pit = container_of(kimn, struct kvm_pit, mask_notifier);
637 atomic_set(&pit->pit_state.pending, 0);
638 pit->pit_state.irq_ack = 1;
642 static const struct kvm_io_device_ops pit_dev_ops = {
643 .read = pit_ioport_read,
644 .write = pit_ioport_write,
647 static const struct kvm_io_device_ops speaker_dev_ops = {
648 .read = speaker_ioport_read,
649 .write = speaker_ioport_write,
652 /* Caller must hold slots_lock */
653 struct kvm_pit *kvm_create_pit(struct kvm *kvm, u32 flags)
656 struct kvm_kpit_state *pit_state;
661 pit = kzalloc(sizeof(struct kvm_pit), GFP_KERNEL);
665 pit->irq_source_id = kvm_request_irq_source_id(kvm);
666 if (pit->irq_source_id < 0) {
671 mutex_init(&pit->pit_state.lock);
672 mutex_lock(&pit->pit_state.lock);
673 spin_lock_init(&pit->pit_state.inject_lock);
675 pid = get_pid(task_tgid(current));
676 pid_nr = pid_vnr(pid);
679 init_kthread_worker(&pit->worker);
680 pit->worker_task = kthread_run(kthread_worker_fn, &pit->worker,
681 "kvm-pit/%d", pid_nr);
682 if (IS_ERR(pit->worker_task)) {
683 mutex_unlock(&pit->pit_state.lock);
684 kvm_free_irq_source_id(kvm, pit->irq_source_id);
688 init_kthread_work(&pit->expired, pit_do_work);
690 kvm->arch.vpit = pit;
693 pit_state = &pit->pit_state;
694 pit_state->pit = pit;
695 hrtimer_init(&pit_state->timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
696 pit_state->irq_ack_notifier.gsi = 0;
697 pit_state->irq_ack_notifier.irq_acked = kvm_pit_ack_irq;
698 kvm_register_irq_ack_notifier(kvm, &pit_state->irq_ack_notifier);
699 pit_state->reinject = true;
700 mutex_unlock(&pit->pit_state.lock);
704 pit->mask_notifier.func = pit_mask_notifer;
705 kvm_register_irq_mask_notifier(kvm, 0, &pit->mask_notifier);
707 kvm_iodevice_init(&pit->dev, &pit_dev_ops);
708 ret = kvm_io_bus_register_dev(kvm, KVM_PIO_BUS, KVM_PIT_BASE_ADDRESS,
709 KVM_PIT_MEM_LENGTH, &pit->dev);
713 if (flags & KVM_PIT_SPEAKER_DUMMY) {
714 kvm_iodevice_init(&pit->speaker_dev, &speaker_dev_ops);
715 ret = kvm_io_bus_register_dev(kvm, KVM_PIO_BUS,
716 KVM_SPEAKER_BASE_ADDRESS, 4,
719 goto fail_unregister;
725 kvm_io_bus_unregister_dev(kvm, KVM_PIO_BUS, &pit->dev);
728 kvm_unregister_irq_mask_notifier(kvm, 0, &pit->mask_notifier);
729 kvm_unregister_irq_ack_notifier(kvm, &pit_state->irq_ack_notifier);
730 kvm_free_irq_source_id(kvm, pit->irq_source_id);
731 kthread_stop(pit->worker_task);
736 void kvm_free_pit(struct kvm *kvm)
738 struct hrtimer *timer;
740 if (kvm->arch.vpit) {
741 kvm_io_bus_unregister_dev(kvm, KVM_PIO_BUS, &kvm->arch.vpit->dev);
742 kvm_io_bus_unregister_dev(kvm, KVM_PIO_BUS,
743 &kvm->arch.vpit->speaker_dev);
744 kvm_unregister_irq_mask_notifier(kvm, 0,
745 &kvm->arch.vpit->mask_notifier);
746 kvm_unregister_irq_ack_notifier(kvm,
747 &kvm->arch.vpit->pit_state.irq_ack_notifier);
748 mutex_lock(&kvm->arch.vpit->pit_state.lock);
749 timer = &kvm->arch.vpit->pit_state.timer;
750 hrtimer_cancel(timer);
751 flush_kthread_work(&kvm->arch.vpit->expired);
752 kthread_stop(kvm->arch.vpit->worker_task);
753 kvm_free_irq_source_id(kvm, kvm->arch.vpit->irq_source_id);
754 mutex_unlock(&kvm->arch.vpit->pit_state.lock);
755 kfree(kvm->arch.vpit);