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);
125 elapsed = mod_64(elapsed, ps->period);
130 static s64 kpit_elapsed(struct kvm *kvm, struct kvm_kpit_channel_state *c,
134 return __kpit_elapsed(kvm);
136 return ktime_to_ns(ktime_sub(ktime_get(), c->count_load_time));
139 static int pit_get_count(struct kvm *kvm, int channel)
141 struct kvm_kpit_channel_state *c =
142 &kvm->arch.vpit->pit_state.channels[channel];
146 WARN_ON(!mutex_is_locked(&kvm->arch.vpit->pit_state.lock));
148 t = kpit_elapsed(kvm, c, channel);
149 d = muldiv64(t, KVM_PIT_FREQ, NSEC_PER_SEC);
156 counter = (c->count - d) & 0xffff;
159 /* XXX: may be incorrect for odd counts */
160 counter = c->count - (mod_64((2 * d), c->count));
163 counter = c->count - mod_64(d, c->count);
169 static int pit_get_out(struct kvm *kvm, int channel)
171 struct kvm_kpit_channel_state *c =
172 &kvm->arch.vpit->pit_state.channels[channel];
176 WARN_ON(!mutex_is_locked(&kvm->arch.vpit->pit_state.lock));
178 t = kpit_elapsed(kvm, c, channel);
179 d = muldiv64(t, KVM_PIT_FREQ, NSEC_PER_SEC);
184 out = (d >= c->count);
187 out = (d < c->count);
190 out = ((mod_64(d, c->count) == 0) && (d != 0));
193 out = (mod_64(d, c->count) < ((c->count + 1) >> 1));
197 out = (d == c->count);
204 static void pit_latch_count(struct kvm *kvm, int channel)
206 struct kvm_kpit_channel_state *c =
207 &kvm->arch.vpit->pit_state.channels[channel];
209 WARN_ON(!mutex_is_locked(&kvm->arch.vpit->pit_state.lock));
211 if (!c->count_latched) {
212 c->latched_count = pit_get_count(kvm, channel);
213 c->count_latched = c->rw_mode;
217 static void pit_latch_status(struct kvm *kvm, int channel)
219 struct kvm_kpit_channel_state *c =
220 &kvm->arch.vpit->pit_state.channels[channel];
222 WARN_ON(!mutex_is_locked(&kvm->arch.vpit->pit_state.lock));
224 if (!c->status_latched) {
225 /* TODO: Return NULL COUNT (bit 6). */
226 c->status = ((pit_get_out(kvm, channel) << 7) |
230 c->status_latched = 1;
234 static void kvm_pit_ack_irq(struct kvm_irq_ack_notifier *kian)
236 struct kvm_kpit_state *ps = container_of(kian, struct kvm_kpit_state,
240 spin_lock(&ps->inject_lock);
241 value = atomic_dec_return(&ps->pending);
243 /* spurious acks can be generated if, for example, the
244 * PIC is being reset. Handle it gracefully here
246 atomic_inc(&ps->pending);
248 /* in this case, we had multiple outstanding pit interrupts
249 * that we needed to inject. Reinject
251 queue_kthread_work(&ps->pit->worker, &ps->pit->expired);
253 spin_unlock(&ps->inject_lock);
256 void __kvm_migrate_pit_timer(struct kvm_vcpu *vcpu)
258 struct kvm_pit *pit = vcpu->kvm->arch.vpit;
259 struct hrtimer *timer;
261 if (!kvm_vcpu_is_bsp(vcpu) || !pit)
264 timer = &pit->pit_state.timer;
265 if (hrtimer_cancel(timer))
266 hrtimer_start_expires(timer, HRTIMER_MODE_ABS);
269 static void destroy_pit_timer(struct kvm_pit *pit)
271 hrtimer_cancel(&pit->pit_state.timer);
272 flush_kthread_work(&pit->expired);
275 static void pit_do_work(struct kthread_work *work)
277 struct kvm_pit *pit = container_of(work, struct kvm_pit, expired);
278 struct kvm *kvm = pit->kvm;
279 struct kvm_vcpu *vcpu;
281 struct kvm_kpit_state *ps = &pit->pit_state;
284 /* Try to inject pending interrupts when
285 * last one has been acked.
287 spin_lock(&ps->inject_lock);
292 spin_unlock(&ps->inject_lock);
294 kvm_set_irq(kvm, kvm->arch.vpit->irq_source_id, 0, 1);
295 kvm_set_irq(kvm, kvm->arch.vpit->irq_source_id, 0, 0);
298 * Provides NMI watchdog support via Virtual Wire mode.
299 * The route is: PIT -> PIC -> LVT0 in NMI mode.
301 * Note: Our Virtual Wire implementation is simplified, only
302 * propagating PIT interrupts to all VCPUs when they have set
303 * LVT0 to NMI delivery. Other PIC interrupts are just sent to
304 * VCPU0, and only if its LVT0 is in EXTINT mode.
306 if (kvm->arch.vapics_in_nmi_mode > 0)
307 kvm_for_each_vcpu(i, vcpu, kvm)
308 kvm_apic_nmi_wd_deliver(vcpu);
312 static enum hrtimer_restart pit_timer_fn(struct hrtimer *data)
314 struct kvm_kpit_state *ps = container_of(data, struct kvm_kpit_state, timer);
315 struct kvm_pit *pt = ps->kvm->arch.vpit;
317 if (ps->reinject || !atomic_read(&ps->pending)) {
318 atomic_inc(&ps->pending);
319 queue_kthread_work(&pt->worker, &pt->expired);
322 if (ps->is_periodic) {
323 hrtimer_add_expires_ns(&ps->timer, ps->period);
324 return HRTIMER_RESTART;
326 return HRTIMER_NORESTART;
329 static void create_pit_timer(struct kvm *kvm, u32 val, int is_period)
331 struct kvm_kpit_state *ps = &kvm->arch.vpit->pit_state;
334 if (!irqchip_in_kernel(kvm) || ps->flags & KVM_PIT_FLAGS_HPET_LEGACY)
337 interval = muldiv64(val, NSEC_PER_SEC, KVM_PIT_FREQ);
339 pr_debug("create pit timer, interval is %llu nsec\n", interval);
341 /* TODO The new value only affected after the retriggered */
342 hrtimer_cancel(&ps->timer);
343 flush_kthread_work(&ps->pit->expired);
344 ps->period = interval;
345 ps->is_periodic = is_period;
347 ps->timer.function = pit_timer_fn;
348 ps->kvm = ps->pit->kvm;
350 atomic_set(&ps->pending, 0);
353 hrtimer_start(&ps->timer, ktime_add_ns(ktime_get(), interval),
357 static void pit_load_count(struct kvm *kvm, int channel, u32 val)
359 struct kvm_kpit_state *ps = &kvm->arch.vpit->pit_state;
361 WARN_ON(!mutex_is_locked(&ps->lock));
363 pr_debug("load_count val is %d, channel is %d\n", val, channel);
366 * The largest possible initial count is 0; this is equivalent
367 * to 216 for binary counting and 104 for BCD counting.
372 ps->channels[channel].count = val;
375 ps->channels[channel].count_load_time = ktime_get();
379 /* Two types of timer
380 * mode 1 is one shot, mode 2 is period, otherwise del timer */
381 switch (ps->channels[0].mode) {
384 /* FIXME: enhance mode 4 precision */
386 create_pit_timer(kvm, val, 0);
390 create_pit_timer(kvm, val, 1);
393 destroy_pit_timer(kvm->arch.vpit);
397 void kvm_pit_load_count(struct kvm *kvm, int channel, u32 val, int hpet_legacy_start)
400 if (hpet_legacy_start) {
401 /* save existing mode for later reenablement */
402 saved_mode = kvm->arch.vpit->pit_state.channels[0].mode;
403 kvm->arch.vpit->pit_state.channels[0].mode = 0xff; /* disable timer */
404 pit_load_count(kvm, channel, val);
405 kvm->arch.vpit->pit_state.channels[0].mode = saved_mode;
407 pit_load_count(kvm, channel, val);
411 static inline struct kvm_pit *dev_to_pit(struct kvm_io_device *dev)
413 return container_of(dev, struct kvm_pit, dev);
416 static inline struct kvm_pit *speaker_to_pit(struct kvm_io_device *dev)
418 return container_of(dev, struct kvm_pit, speaker_dev);
421 static inline int pit_in_range(gpa_t addr)
423 return ((addr >= KVM_PIT_BASE_ADDRESS) &&
424 (addr < KVM_PIT_BASE_ADDRESS + KVM_PIT_MEM_LENGTH));
427 static int pit_ioport_write(struct kvm_io_device *this,
428 gpa_t addr, int len, const void *data)
430 struct kvm_pit *pit = dev_to_pit(this);
431 struct kvm_kpit_state *pit_state = &pit->pit_state;
432 struct kvm *kvm = pit->kvm;
434 struct kvm_kpit_channel_state *s;
435 u32 val = *(u32 *) data;
436 if (!pit_in_range(addr))
440 addr &= KVM_PIT_CHANNEL_MASK;
442 mutex_lock(&pit_state->lock);
445 pr_debug("write addr is 0x%x, len is %d, val is 0x%x\n",
446 (unsigned int)addr, len, val);
451 /* Read-Back Command. */
452 for (channel = 0; channel < 3; channel++) {
453 s = &pit_state->channels[channel];
454 if (val & (2 << channel)) {
456 pit_latch_count(kvm, channel);
458 pit_latch_status(kvm, channel);
462 /* Select Counter <channel>. */
463 s = &pit_state->channels[channel];
464 access = (val >> 4) & KVM_PIT_CHANNEL_MASK;
466 pit_latch_count(kvm, channel);
469 s->read_state = access;
470 s->write_state = access;
471 s->mode = (val >> 1) & 7;
479 s = &pit_state->channels[addr];
480 switch (s->write_state) {
483 pit_load_count(kvm, addr, val);
486 pit_load_count(kvm, addr, val << 8);
489 s->write_latch = val;
490 s->write_state = RW_STATE_WORD1;
493 pit_load_count(kvm, addr, s->write_latch | (val << 8));
494 s->write_state = RW_STATE_WORD0;
499 mutex_unlock(&pit_state->lock);
503 static int pit_ioport_read(struct kvm_io_device *this,
504 gpa_t addr, int len, void *data)
506 struct kvm_pit *pit = dev_to_pit(this);
507 struct kvm_kpit_state *pit_state = &pit->pit_state;
508 struct kvm *kvm = pit->kvm;
510 struct kvm_kpit_channel_state *s;
511 if (!pit_in_range(addr))
514 addr &= KVM_PIT_CHANNEL_MASK;
518 s = &pit_state->channels[addr];
520 mutex_lock(&pit_state->lock);
522 if (s->status_latched) {
523 s->status_latched = 0;
525 } else if (s->count_latched) {
526 switch (s->count_latched) {
529 ret = s->latched_count & 0xff;
530 s->count_latched = 0;
533 ret = s->latched_count >> 8;
534 s->count_latched = 0;
537 ret = s->latched_count & 0xff;
538 s->count_latched = RW_STATE_MSB;
542 switch (s->read_state) {
545 count = pit_get_count(kvm, addr);
549 count = pit_get_count(kvm, addr);
550 ret = (count >> 8) & 0xff;
553 count = pit_get_count(kvm, addr);
555 s->read_state = RW_STATE_WORD1;
558 count = pit_get_count(kvm, addr);
559 ret = (count >> 8) & 0xff;
560 s->read_state = RW_STATE_WORD0;
565 if (len > sizeof(ret))
567 memcpy(data, (char *)&ret, len);
569 mutex_unlock(&pit_state->lock);
573 static int speaker_ioport_write(struct kvm_io_device *this,
574 gpa_t addr, int len, const void *data)
576 struct kvm_pit *pit = speaker_to_pit(this);
577 struct kvm_kpit_state *pit_state = &pit->pit_state;
578 struct kvm *kvm = pit->kvm;
579 u32 val = *(u32 *) data;
580 if (addr != KVM_SPEAKER_BASE_ADDRESS)
583 mutex_lock(&pit_state->lock);
584 pit_state->speaker_data_on = (val >> 1) & 1;
585 pit_set_gate(kvm, 2, val & 1);
586 mutex_unlock(&pit_state->lock);
590 static int speaker_ioport_read(struct kvm_io_device *this,
591 gpa_t addr, int len, void *data)
593 struct kvm_pit *pit = speaker_to_pit(this);
594 struct kvm_kpit_state *pit_state = &pit->pit_state;
595 struct kvm *kvm = pit->kvm;
596 unsigned int refresh_clock;
598 if (addr != KVM_SPEAKER_BASE_ADDRESS)
601 /* Refresh clock toggles at about 15us. We approximate as 2^14ns. */
602 refresh_clock = ((unsigned int)ktime_to_ns(ktime_get()) >> 14) & 1;
604 mutex_lock(&pit_state->lock);
605 ret = ((pit_state->speaker_data_on << 1) | pit_get_gate(kvm, 2) |
606 (pit_get_out(kvm, 2) << 5) | (refresh_clock << 4));
607 if (len > sizeof(ret))
609 memcpy(data, (char *)&ret, len);
610 mutex_unlock(&pit_state->lock);
614 void kvm_pit_reset(struct kvm_pit *pit)
617 struct kvm_kpit_channel_state *c;
619 mutex_lock(&pit->pit_state.lock);
620 pit->pit_state.flags = 0;
621 for (i = 0; i < 3; i++) {
622 c = &pit->pit_state.channels[i];
625 pit_load_count(pit->kvm, i, 0);
627 mutex_unlock(&pit->pit_state.lock);
629 atomic_set(&pit->pit_state.pending, 0);
630 pit->pit_state.irq_ack = 1;
633 static void pit_mask_notifer(struct kvm_irq_mask_notifier *kimn, bool mask)
635 struct kvm_pit *pit = container_of(kimn, struct kvm_pit, mask_notifier);
638 atomic_set(&pit->pit_state.pending, 0);
639 pit->pit_state.irq_ack = 1;
643 static const struct kvm_io_device_ops pit_dev_ops = {
644 .read = pit_ioport_read,
645 .write = pit_ioport_write,
648 static const struct kvm_io_device_ops speaker_dev_ops = {
649 .read = speaker_ioport_read,
650 .write = speaker_ioport_write,
653 /* Caller must hold slots_lock */
654 struct kvm_pit *kvm_create_pit(struct kvm *kvm, u32 flags)
657 struct kvm_kpit_state *pit_state;
662 pit = kzalloc(sizeof(struct kvm_pit), GFP_KERNEL);
666 pit->irq_source_id = kvm_request_irq_source_id(kvm);
667 if (pit->irq_source_id < 0) {
672 mutex_init(&pit->pit_state.lock);
673 mutex_lock(&pit->pit_state.lock);
674 spin_lock_init(&pit->pit_state.inject_lock);
676 pid = get_pid(task_tgid(current));
677 pid_nr = pid_vnr(pid);
680 init_kthread_worker(&pit->worker);
681 pit->worker_task = kthread_run(kthread_worker_fn, &pit->worker,
682 "kvm-pit/%d", pid_nr);
683 if (IS_ERR(pit->worker_task)) {
684 mutex_unlock(&pit->pit_state.lock);
685 kvm_free_irq_source_id(kvm, pit->irq_source_id);
689 init_kthread_work(&pit->expired, pit_do_work);
691 kvm->arch.vpit = pit;
694 pit_state = &pit->pit_state;
695 pit_state->pit = pit;
696 hrtimer_init(&pit_state->timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
697 pit_state->irq_ack_notifier.gsi = 0;
698 pit_state->irq_ack_notifier.irq_acked = kvm_pit_ack_irq;
699 kvm_register_irq_ack_notifier(kvm, &pit_state->irq_ack_notifier);
700 pit_state->reinject = true;
701 mutex_unlock(&pit->pit_state.lock);
705 pit->mask_notifier.func = pit_mask_notifer;
706 kvm_register_irq_mask_notifier(kvm, 0, &pit->mask_notifier);
708 kvm_iodevice_init(&pit->dev, &pit_dev_ops);
709 ret = kvm_io_bus_register_dev(kvm, KVM_PIO_BUS, KVM_PIT_BASE_ADDRESS,
710 KVM_PIT_MEM_LENGTH, &pit->dev);
714 if (flags & KVM_PIT_SPEAKER_DUMMY) {
715 kvm_iodevice_init(&pit->speaker_dev, &speaker_dev_ops);
716 ret = kvm_io_bus_register_dev(kvm, KVM_PIO_BUS,
717 KVM_SPEAKER_BASE_ADDRESS, 4,
720 goto fail_unregister;
726 kvm_io_bus_unregister_dev(kvm, KVM_PIO_BUS, &pit->dev);
729 kvm_unregister_irq_mask_notifier(kvm, 0, &pit->mask_notifier);
730 kvm_unregister_irq_ack_notifier(kvm, &pit_state->irq_ack_notifier);
731 kvm_free_irq_source_id(kvm, pit->irq_source_id);
732 kthread_stop(pit->worker_task);
737 void kvm_free_pit(struct kvm *kvm)
739 struct hrtimer *timer;
741 if (kvm->arch.vpit) {
742 kvm_io_bus_unregister_dev(kvm, KVM_PIO_BUS, &kvm->arch.vpit->dev);
743 kvm_io_bus_unregister_dev(kvm, KVM_PIO_BUS,
744 &kvm->arch.vpit->speaker_dev);
745 kvm_unregister_irq_mask_notifier(kvm, 0,
746 &kvm->arch.vpit->mask_notifier);
747 kvm_unregister_irq_ack_notifier(kvm,
748 &kvm->arch.vpit->pit_state.irq_ack_notifier);
749 mutex_lock(&kvm->arch.vpit->pit_state.lock);
750 timer = &kvm->arch.vpit->pit_state.timer;
751 hrtimer_cancel(timer);
752 flush_kthread_work(&kvm->arch.vpit->expired);
753 kthread_stop(kvm->arch.vpit->worker_task);
754 kvm_free_irq_source_id(kvm, kvm->arch.vpit->irq_source_id);
755 mutex_unlock(&kvm->arch.vpit->pit_state.lock);
756 kfree(kvm->arch.vpit);