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 static void pit_set_gate(struct kvm_pit *pit, int channel, u32 val)
56 struct kvm_kpit_channel_state *c = &pit->pit_state.channels[channel];
62 /* XXX: just disable/enable counting */
68 /* Restart counting on rising edge. */
70 c->count_load_time = ktime_get();
77 static int pit_get_gate(struct kvm_pit *pit, int channel)
79 return pit->pit_state.channels[channel].gate;
82 static s64 __kpit_elapsed(struct kvm_pit *pit)
86 struct kvm_kpit_state *ps = &pit->pit_state;
92 * The Counter does not stop when it reaches zero. In
93 * Modes 0, 1, 4, and 5 the Counter ``wraps around'' to
94 * the highest count, either FFFF hex for binary counting
95 * or 9999 for BCD counting, and continues counting.
96 * Modes 2 and 3 are periodic; the Counter reloads
97 * itself with the initial count and continues counting
100 remaining = hrtimer_get_remaining(&ps->timer);
101 elapsed = ps->period - ktime_to_ns(remaining);
106 static s64 kpit_elapsed(struct kvm_pit *pit, struct kvm_kpit_channel_state *c,
110 return __kpit_elapsed(pit);
112 return ktime_to_ns(ktime_sub(ktime_get(), c->count_load_time));
115 static int pit_get_count(struct kvm_pit *pit, int channel)
117 struct kvm_kpit_channel_state *c = &pit->pit_state.channels[channel];
121 t = kpit_elapsed(pit, c, channel);
122 d = mul_u64_u32_div(t, KVM_PIT_FREQ, NSEC_PER_SEC);
129 counter = (c->count - d) & 0xffff;
132 /* XXX: may be incorrect for odd counts */
133 counter = c->count - (mod_64((2 * d), c->count));
136 counter = c->count - mod_64(d, c->count);
142 static int pit_get_out(struct kvm_pit *pit, int channel)
144 struct kvm_kpit_channel_state *c = &pit->pit_state.channels[channel];
148 t = kpit_elapsed(pit, c, channel);
149 d = mul_u64_u32_div(t, KVM_PIT_FREQ, NSEC_PER_SEC);
154 out = (d >= c->count);
157 out = (d < c->count);
160 out = ((mod_64(d, c->count) == 0) && (d != 0));
163 out = (mod_64(d, c->count) < ((c->count + 1) >> 1));
167 out = (d == c->count);
174 static void pit_latch_count(struct kvm_pit *pit, int channel)
176 struct kvm_kpit_channel_state *c = &pit->pit_state.channels[channel];
178 if (!c->count_latched) {
179 c->latched_count = pit_get_count(pit, channel);
180 c->count_latched = c->rw_mode;
184 static void pit_latch_status(struct kvm_pit *pit, int channel)
186 struct kvm_kpit_channel_state *c = &pit->pit_state.channels[channel];
188 if (!c->status_latched) {
189 /* TODO: Return NULL COUNT (bit 6). */
190 c->status = ((pit_get_out(pit, channel) << 7) |
194 c->status_latched = 1;
198 static inline struct kvm_pit *pit_state_to_pit(struct kvm_kpit_state *ps)
200 return container_of(ps, struct kvm_pit, pit_state);
203 static void kvm_pit_ack_irq(struct kvm_irq_ack_notifier *kian)
205 struct kvm_kpit_state *ps = container_of(kian, struct kvm_kpit_state,
207 struct kvm_pit *pit = pit_state_to_pit(ps);
209 atomic_set(&ps->irq_ack, 1);
210 /* irq_ack should be set before pending is read. Order accesses with
211 * inc(pending) in pit_timer_fn and xchg(irq_ack, 0) in pit_do_work.
214 if (atomic_dec_if_positive(&ps->pending) > 0)
215 kthread_queue_work(pit->worker, &pit->expired);
218 void __kvm_migrate_pit_timer(struct kvm_vcpu *vcpu)
220 struct kvm_pit *pit = vcpu->kvm->arch.vpit;
221 struct hrtimer *timer;
223 if (!kvm_vcpu_is_bsp(vcpu) || !pit)
226 timer = &pit->pit_state.timer;
227 mutex_lock(&pit->pit_state.lock);
228 if (hrtimer_cancel(timer))
229 hrtimer_start_expires(timer, HRTIMER_MODE_ABS);
230 mutex_unlock(&pit->pit_state.lock);
233 static void destroy_pit_timer(struct kvm_pit *pit)
235 hrtimer_cancel(&pit->pit_state.timer);
236 kthread_flush_work(&pit->expired);
239 static void pit_do_work(struct kthread_work *work)
241 struct kvm_pit *pit = container_of(work, struct kvm_pit, expired);
242 struct kvm *kvm = pit->kvm;
243 struct kvm_vcpu *vcpu;
245 struct kvm_kpit_state *ps = &pit->pit_state;
247 if (atomic_read(&ps->reinject) && !atomic_xchg(&ps->irq_ack, 0))
250 kvm_set_irq(kvm, pit->irq_source_id, 0, 1, false);
251 kvm_set_irq(kvm, pit->irq_source_id, 0, 0, false);
254 * Provides NMI watchdog support via Virtual Wire mode.
255 * The route is: PIT -> LVT0 in NMI mode.
257 * Note: Our Virtual Wire implementation does not follow
258 * the MP specification. We propagate a PIT interrupt to all
259 * VCPUs and only when LVT0 is in NMI mode. The interrupt can
260 * also be simultaneously delivered through PIC and IOAPIC.
262 if (atomic_read(&kvm->arch.vapics_in_nmi_mode) > 0)
263 kvm_for_each_vcpu(i, vcpu, kvm)
264 kvm_apic_nmi_wd_deliver(vcpu);
267 static enum hrtimer_restart pit_timer_fn(struct hrtimer *data)
269 struct kvm_kpit_state *ps = container_of(data, struct kvm_kpit_state, timer);
270 struct kvm_pit *pt = pit_state_to_pit(ps);
272 if (atomic_read(&ps->reinject))
273 atomic_inc(&ps->pending);
275 kthread_queue_work(pt->worker, &pt->expired);
277 if (ps->is_periodic) {
278 hrtimer_add_expires_ns(&ps->timer, ps->period);
279 return HRTIMER_RESTART;
281 return HRTIMER_NORESTART;
284 static inline void kvm_pit_reset_reinject(struct kvm_pit *pit)
286 atomic_set(&pit->pit_state.pending, 0);
287 atomic_set(&pit->pit_state.irq_ack, 1);
290 void kvm_pit_set_reinject(struct kvm_pit *pit, bool reinject)
292 struct kvm_kpit_state *ps = &pit->pit_state;
293 struct kvm *kvm = pit->kvm;
295 if (atomic_read(&ps->reinject) == reinject)
299 /* The initial state is preserved while ps->reinject == 0. */
300 kvm_pit_reset_reinject(pit);
301 kvm_register_irq_ack_notifier(kvm, &ps->irq_ack_notifier);
302 kvm_register_irq_mask_notifier(kvm, 0, &pit->mask_notifier);
304 kvm_unregister_irq_ack_notifier(kvm, &ps->irq_ack_notifier);
305 kvm_unregister_irq_mask_notifier(kvm, 0, &pit->mask_notifier);
308 atomic_set(&ps->reinject, reinject);
311 static void create_pit_timer(struct kvm_pit *pit, u32 val, int is_period)
313 struct kvm_kpit_state *ps = &pit->pit_state;
314 struct kvm *kvm = pit->kvm;
317 if (!ioapic_in_kernel(kvm) ||
318 ps->flags & KVM_PIT_FLAGS_HPET_LEGACY)
321 interval = mul_u64_u32_div(val, NSEC_PER_SEC, KVM_PIT_FREQ);
323 pr_debug("create pit timer, interval is %llu nsec\n", interval);
325 /* TODO The new value only affected after the retriggered */
326 hrtimer_cancel(&ps->timer);
327 kthread_flush_work(&pit->expired);
328 ps->period = interval;
329 ps->is_periodic = is_period;
331 kvm_pit_reset_reinject(pit);
334 * Do not allow the guest to program periodic timers with small
335 * interval, since the hrtimers are not throttled by the host
338 if (ps->is_periodic) {
339 s64 min_period = min_timer_period_us * 1000LL;
341 if (ps->period < min_period) {
343 "kvm: requested %lld ns "
344 "i8254 timer period limited to %lld ns\n",
345 ps->period, min_period);
346 ps->period = min_period;
350 hrtimer_start(&ps->timer, ktime_add_ns(ktime_get(), interval),
354 static void pit_load_count(struct kvm_pit *pit, int channel, u32 val)
356 struct kvm_kpit_state *ps = &pit->pit_state;
358 pr_debug("load_count val is %d, channel is %d\n", val, channel);
361 * The largest possible initial count is 0; this is equivalent
362 * to 216 for binary counting and 104 for BCD counting.
367 ps->channels[channel].count = val;
370 ps->channels[channel].count_load_time = ktime_get();
374 /* Two types of timer
375 * mode 1 is one shot, mode 2 is period, otherwise del timer */
376 switch (ps->channels[0].mode) {
379 /* FIXME: enhance mode 4 precision */
381 create_pit_timer(pit, val, 0);
385 create_pit_timer(pit, val, 1);
388 destroy_pit_timer(pit);
392 void kvm_pit_load_count(struct kvm_pit *pit, int channel, u32 val,
393 int hpet_legacy_start)
397 WARN_ON_ONCE(!mutex_is_locked(&pit->pit_state.lock));
399 if (hpet_legacy_start) {
400 /* save existing mode for later reenablement */
401 WARN_ON(channel != 0);
402 saved_mode = pit->pit_state.channels[0].mode;
403 pit->pit_state.channels[0].mode = 0xff; /* disable timer */
404 pit_load_count(pit, channel, val);
405 pit->pit_state.channels[0].mode = saved_mode;
407 pit_load_count(pit, 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_vcpu *vcpu,
428 struct kvm_io_device *this,
429 gpa_t addr, int len, const void *data)
431 struct kvm_pit *pit = dev_to_pit(this);
432 struct kvm_kpit_state *pit_state = &pit->pit_state;
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(pit, channel);
458 pit_latch_status(pit, channel);
462 /* Select Counter <channel>. */
463 s = &pit_state->channels[channel];
464 access = (val >> 4) & KVM_PIT_CHANNEL_MASK;
466 pit_latch_count(pit, 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(pit, addr, val);
486 pit_load_count(pit, addr, val << 8);
489 s->write_latch = val;
490 s->write_state = RW_STATE_WORD1;
493 pit_load_count(pit, 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_vcpu *vcpu,
504 struct kvm_io_device *this,
505 gpa_t addr, int len, void *data)
507 struct kvm_pit *pit = dev_to_pit(this);
508 struct kvm_kpit_state *pit_state = &pit->pit_state;
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(pit, addr);
549 count = pit_get_count(pit, addr);
550 ret = (count >> 8) & 0xff;
553 count = pit_get_count(pit, addr);
555 s->read_state = RW_STATE_WORD1;
558 count = pit_get_count(pit, 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_vcpu *vcpu,
574 struct kvm_io_device *this,
575 gpa_t addr, int len, const void *data)
577 struct kvm_pit *pit = speaker_to_pit(this);
578 struct kvm_kpit_state *pit_state = &pit->pit_state;
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(pit, 2, val & 1);
586 mutex_unlock(&pit_state->lock);
590 static int speaker_ioport_read(struct kvm_vcpu *vcpu,
591 struct kvm_io_device *this,
592 gpa_t addr, int len, void *data)
594 struct kvm_pit *pit = speaker_to_pit(this);
595 struct kvm_kpit_state *pit_state = &pit->pit_state;
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(pit, 2) |
606 (pit_get_out(pit, 2) << 5) | (refresh_clock << 4));
607 if (len > sizeof(ret))
609 memcpy(data, (char *)&ret, len);
610 mutex_unlock(&pit_state->lock);
614 static void kvm_pit_reset(struct kvm_pit *pit)
617 struct kvm_kpit_channel_state *c;
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, i, 0);
627 kvm_pit_reset_reinject(pit);
630 static void pit_mask_notifer(struct kvm_irq_mask_notifier *kimn, bool mask)
632 struct kvm_pit *pit = container_of(kimn, struct kvm_pit, mask_notifier);
635 kvm_pit_reset_reinject(pit);
638 static const struct kvm_io_device_ops pit_dev_ops = {
639 .read = pit_ioport_read,
640 .write = pit_ioport_write,
643 static const struct kvm_io_device_ops speaker_dev_ops = {
644 .read = speaker_ioport_read,
645 .write = speaker_ioport_write,
648 struct kvm_pit *kvm_create_pit(struct kvm *kvm, u32 flags)
651 struct kvm_kpit_state *pit_state;
656 pit = kzalloc(sizeof(struct kvm_pit), GFP_KERNEL_ACCOUNT);
660 pit->irq_source_id = kvm_request_irq_source_id(kvm);
661 if (pit->irq_source_id < 0)
664 mutex_init(&pit->pit_state.lock);
666 pid = get_pid(task_tgid(current));
667 pid_nr = pid_vnr(pid);
670 pit->worker = kthread_create_worker(0, "kvm-pit/%d", pid_nr);
671 if (IS_ERR(pit->worker))
674 kthread_init_work(&pit->expired, pit_do_work);
678 pit_state = &pit->pit_state;
679 hrtimer_init(&pit_state->timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
680 pit_state->timer.function = pit_timer_fn;
682 pit_state->irq_ack_notifier.gsi = 0;
683 pit_state->irq_ack_notifier.irq_acked = kvm_pit_ack_irq;
684 pit->mask_notifier.func = pit_mask_notifer;
688 kvm_pit_set_reinject(pit, true);
690 mutex_lock(&kvm->slots_lock);
691 kvm_iodevice_init(&pit->dev, &pit_dev_ops);
692 ret = kvm_io_bus_register_dev(kvm, KVM_PIO_BUS, KVM_PIT_BASE_ADDRESS,
693 KVM_PIT_MEM_LENGTH, &pit->dev);
695 goto fail_register_pit;
697 if (flags & KVM_PIT_SPEAKER_DUMMY) {
698 kvm_iodevice_init(&pit->speaker_dev, &speaker_dev_ops);
699 ret = kvm_io_bus_register_dev(kvm, KVM_PIO_BUS,
700 KVM_SPEAKER_BASE_ADDRESS, 4,
703 goto fail_register_speaker;
705 mutex_unlock(&kvm->slots_lock);
709 fail_register_speaker:
710 kvm_io_bus_unregister_dev(kvm, KVM_PIO_BUS, &pit->dev);
712 mutex_unlock(&kvm->slots_lock);
713 kvm_pit_set_reinject(pit, false);
714 kthread_destroy_worker(pit->worker);
716 kvm_free_irq_source_id(kvm, pit->irq_source_id);
722 void kvm_free_pit(struct kvm *kvm)
724 struct kvm_pit *pit = kvm->arch.vpit;
727 mutex_lock(&kvm->slots_lock);
728 kvm_io_bus_unregister_dev(kvm, KVM_PIO_BUS, &pit->dev);
729 kvm_io_bus_unregister_dev(kvm, KVM_PIO_BUS, &pit->speaker_dev);
730 mutex_unlock(&kvm->slots_lock);
731 kvm_pit_set_reinject(pit, false);
732 hrtimer_cancel(&pit->pit_state.timer);
733 kthread_destroy_worker(pit->worker);
734 kvm_free_irq_source_id(kvm, pit->irq_source_id);