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>
37 #include <linux/workqueue.h>
43 #define mod_64(x, y) ((x) - (y) * div64_u64(x, y))
45 #define mod_64(x, y) ((x) % (y))
48 #define RW_STATE_LSB 1
49 #define RW_STATE_MSB 2
50 #define RW_STATE_WORD0 3
51 #define RW_STATE_WORD1 4
53 /* Compute with 96 bit intermediate result: (a*b)/c */
54 static u64
muldiv64(u64 a
, u32 b
, u32 c
)
65 rl
= (u64
)u
.l
.low
* (u64
)b
;
66 rh
= (u64
)u
.l
.high
* (u64
)b
;
68 res
.l
.high
= div64_u64(rh
, c
);
69 res
.l
.low
= div64_u64(((mod_64(rh
, c
) << 32) + (rl
& 0xffffffff)), c
);
73 static void pit_set_gate(struct kvm
*kvm
, int channel
, u32 val
)
75 struct kvm_kpit_channel_state
*c
=
76 &kvm
->arch
.vpit
->pit_state
.channels
[channel
];
78 WARN_ON(!mutex_is_locked(&kvm
->arch
.vpit
->pit_state
.lock
));
84 /* XXX: just disable/enable counting */
90 /* Restart counting on rising edge. */
92 c
->count_load_time
= ktime_get();
99 static int pit_get_gate(struct kvm
*kvm
, int channel
)
101 WARN_ON(!mutex_is_locked(&kvm
->arch
.vpit
->pit_state
.lock
));
103 return kvm
->arch
.vpit
->pit_state
.channels
[channel
].gate
;
106 static s64
__kpit_elapsed(struct kvm
*kvm
)
110 struct kvm_kpit_state
*ps
= &kvm
->arch
.vpit
->pit_state
;
112 if (!ps
->pit_timer
.period
)
116 * The Counter does not stop when it reaches zero. In
117 * Modes 0, 1, 4, and 5 the Counter ``wraps around'' to
118 * the highest count, either FFFF hex for binary counting
119 * or 9999 for BCD counting, and continues counting.
120 * Modes 2 and 3 are periodic; the Counter reloads
121 * itself with the initial count and continues counting
124 remaining
= hrtimer_get_remaining(&ps
->pit_timer
.timer
);
125 elapsed
= ps
->pit_timer
.period
- ktime_to_ns(remaining
);
126 elapsed
= mod_64(elapsed
, ps
->pit_timer
.period
);
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
->pit_timer
.pending
);
244 /* spurious acks can be generated if, for example, the
245 * PIC is being reset. Handle it gracefully here
247 atomic_inc(&ps
->pit_timer
.pending
);
249 /* in this case, we had multiple outstanding pit interrupts
250 * that we needed to inject. Reinject
252 queue_work(ps
->pit
->wq
, &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
.pit_timer
.timer
;
266 if (hrtimer_cancel(timer
))
267 hrtimer_start_expires(timer
, HRTIMER_MODE_ABS
);
270 static void destroy_pit_timer(struct kvm_pit
*pit
)
272 hrtimer_cancel(&pit
->pit_state
.pit_timer
.timer
);
273 cancel_work_sync(&pit
->expired
);
276 static bool kpit_is_periodic(struct kvm_timer
*ktimer
)
278 struct kvm_kpit_state
*ps
= container_of(ktimer
, struct kvm_kpit_state
,
280 return ps
->is_periodic
;
283 static struct kvm_timer_ops kpit_ops
= {
284 .is_periodic
= kpit_is_periodic
,
287 static void pit_do_work(struct work_struct
*work
)
289 struct kvm_pit
*pit
= container_of(work
, struct kvm_pit
, expired
);
290 struct kvm
*kvm
= pit
->kvm
;
291 struct kvm_vcpu
*vcpu
;
293 struct kvm_kpit_state
*ps
= &pit
->pit_state
;
296 /* Try to inject pending interrupts when
297 * last one has been acked.
299 spin_lock(&ps
->inject_lock
);
304 spin_unlock(&ps
->inject_lock
);
306 kvm_set_irq(kvm
, kvm
->arch
.vpit
->irq_source_id
, 0, 1);
307 kvm_set_irq(kvm
, kvm
->arch
.vpit
->irq_source_id
, 0, 0);
310 * Provides NMI watchdog support via Virtual Wire mode.
311 * The route is: PIT -> PIC -> LVT0 in NMI mode.
313 * Note: Our Virtual Wire implementation is simplified, only
314 * propagating PIT interrupts to all VCPUs when they have set
315 * LVT0 to NMI delivery. Other PIC interrupts are just sent to
316 * VCPU0, and only if its LVT0 is in EXTINT mode.
318 if (kvm
->arch
.vapics_in_nmi_mode
> 0)
319 kvm_for_each_vcpu(i
, vcpu
, kvm
)
320 kvm_apic_nmi_wd_deliver(vcpu
);
324 static enum hrtimer_restart
pit_timer_fn(struct hrtimer
*data
)
326 struct kvm_timer
*ktimer
= container_of(data
, struct kvm_timer
, timer
);
327 struct kvm_pit
*pt
= ktimer
->kvm
->arch
.vpit
;
329 if (ktimer
->reinject
|| !atomic_read(&ktimer
->pending
)) {
330 atomic_inc(&ktimer
->pending
);
331 queue_work(pt
->wq
, &pt
->expired
);
334 if (ktimer
->t_ops
->is_periodic(ktimer
)) {
335 hrtimer_add_expires_ns(&ktimer
->timer
, ktimer
->period
);
336 return HRTIMER_RESTART
;
338 return HRTIMER_NORESTART
;
341 static void create_pit_timer(struct kvm
*kvm
, u32 val
, int is_period
)
343 struct kvm_kpit_state
*ps
= &kvm
->arch
.vpit
->pit_state
;
344 struct kvm_timer
*pt
= &ps
->pit_timer
;
347 if (!irqchip_in_kernel(kvm
) || ps
->flags
& KVM_PIT_FLAGS_HPET_LEGACY
)
350 interval
= muldiv64(val
, NSEC_PER_SEC
, KVM_PIT_FREQ
);
352 pr_debug("create pit timer, interval is %llu nsec\n", interval
);
354 /* TODO The new value only affected after the retriggered */
355 hrtimer_cancel(&pt
->timer
);
356 cancel_work_sync(&ps
->pit
->expired
);
357 pt
->period
= interval
;
358 ps
->is_periodic
= is_period
;
360 pt
->timer
.function
= pit_timer_fn
;
361 pt
->t_ops
= &kpit_ops
;
362 pt
->kvm
= ps
->pit
->kvm
;
364 atomic_set(&pt
->pending
, 0);
367 hrtimer_start(&pt
->timer
, ktime_add_ns(ktime_get(), interval
),
371 static void pit_load_count(struct kvm
*kvm
, int channel
, u32 val
)
373 struct kvm_kpit_state
*ps
= &kvm
->arch
.vpit
->pit_state
;
375 WARN_ON(!mutex_is_locked(&ps
->lock
));
377 pr_debug("load_count val is %d, channel is %d\n", val
, channel
);
380 * The largest possible initial count is 0; this is equivalent
381 * to 216 for binary counting and 104 for BCD counting.
386 ps
->channels
[channel
].count
= val
;
389 ps
->channels
[channel
].count_load_time
= ktime_get();
393 /* Two types of timer
394 * mode 1 is one shot, mode 2 is period, otherwise del timer */
395 switch (ps
->channels
[0].mode
) {
398 /* FIXME: enhance mode 4 precision */
400 create_pit_timer(kvm
, val
, 0);
404 create_pit_timer(kvm
, val
, 1);
407 destroy_pit_timer(kvm
->arch
.vpit
);
411 void kvm_pit_load_count(struct kvm
*kvm
, int channel
, u32 val
, int hpet_legacy_start
)
414 if (hpet_legacy_start
) {
415 /* save existing mode for later reenablement */
416 saved_mode
= kvm
->arch
.vpit
->pit_state
.channels
[0].mode
;
417 kvm
->arch
.vpit
->pit_state
.channels
[0].mode
= 0xff; /* disable timer */
418 pit_load_count(kvm
, channel
, val
);
419 kvm
->arch
.vpit
->pit_state
.channels
[0].mode
= saved_mode
;
421 pit_load_count(kvm
, channel
, val
);
425 static inline struct kvm_pit
*dev_to_pit(struct kvm_io_device
*dev
)
427 return container_of(dev
, struct kvm_pit
, dev
);
430 static inline struct kvm_pit
*speaker_to_pit(struct kvm_io_device
*dev
)
432 return container_of(dev
, struct kvm_pit
, speaker_dev
);
435 static inline int pit_in_range(gpa_t addr
)
437 return ((addr
>= KVM_PIT_BASE_ADDRESS
) &&
438 (addr
< KVM_PIT_BASE_ADDRESS
+ KVM_PIT_MEM_LENGTH
));
441 static int pit_ioport_write(struct kvm_io_device
*this,
442 gpa_t addr
, int len
, const void *data
)
444 struct kvm_pit
*pit
= dev_to_pit(this);
445 struct kvm_kpit_state
*pit_state
= &pit
->pit_state
;
446 struct kvm
*kvm
= pit
->kvm
;
448 struct kvm_kpit_channel_state
*s
;
449 u32 val
= *(u32
*) data
;
450 if (!pit_in_range(addr
))
454 addr
&= KVM_PIT_CHANNEL_MASK
;
456 mutex_lock(&pit_state
->lock
);
459 pr_debug("write addr is 0x%x, len is %d, val is 0x%x\n",
460 (unsigned int)addr
, len
, val
);
465 /* Read-Back Command. */
466 for (channel
= 0; channel
< 3; channel
++) {
467 s
= &pit_state
->channels
[channel
];
468 if (val
& (2 << channel
)) {
470 pit_latch_count(kvm
, channel
);
472 pit_latch_status(kvm
, channel
);
476 /* Select Counter <channel>. */
477 s
= &pit_state
->channels
[channel
];
478 access
= (val
>> 4) & KVM_PIT_CHANNEL_MASK
;
480 pit_latch_count(kvm
, channel
);
483 s
->read_state
= access
;
484 s
->write_state
= access
;
485 s
->mode
= (val
>> 1) & 7;
493 s
= &pit_state
->channels
[addr
];
494 switch (s
->write_state
) {
497 pit_load_count(kvm
, addr
, val
);
500 pit_load_count(kvm
, addr
, val
<< 8);
503 s
->write_latch
= val
;
504 s
->write_state
= RW_STATE_WORD1
;
507 pit_load_count(kvm
, addr
, s
->write_latch
| (val
<< 8));
508 s
->write_state
= RW_STATE_WORD0
;
513 mutex_unlock(&pit_state
->lock
);
517 static int pit_ioport_read(struct kvm_io_device
*this,
518 gpa_t addr
, int len
, void *data
)
520 struct kvm_pit
*pit
= dev_to_pit(this);
521 struct kvm_kpit_state
*pit_state
= &pit
->pit_state
;
522 struct kvm
*kvm
= pit
->kvm
;
524 struct kvm_kpit_channel_state
*s
;
525 if (!pit_in_range(addr
))
528 addr
&= KVM_PIT_CHANNEL_MASK
;
532 s
= &pit_state
->channels
[addr
];
534 mutex_lock(&pit_state
->lock
);
536 if (s
->status_latched
) {
537 s
->status_latched
= 0;
539 } else if (s
->count_latched
) {
540 switch (s
->count_latched
) {
543 ret
= s
->latched_count
& 0xff;
544 s
->count_latched
= 0;
547 ret
= s
->latched_count
>> 8;
548 s
->count_latched
= 0;
551 ret
= s
->latched_count
& 0xff;
552 s
->count_latched
= RW_STATE_MSB
;
556 switch (s
->read_state
) {
559 count
= pit_get_count(kvm
, addr
);
563 count
= pit_get_count(kvm
, addr
);
564 ret
= (count
>> 8) & 0xff;
567 count
= pit_get_count(kvm
, addr
);
569 s
->read_state
= RW_STATE_WORD1
;
572 count
= pit_get_count(kvm
, addr
);
573 ret
= (count
>> 8) & 0xff;
574 s
->read_state
= RW_STATE_WORD0
;
579 if (len
> sizeof(ret
))
581 memcpy(data
, (char *)&ret
, len
);
583 mutex_unlock(&pit_state
->lock
);
587 static int speaker_ioport_write(struct kvm_io_device
*this,
588 gpa_t addr
, int len
, const void *data
)
590 struct kvm_pit
*pit
= speaker_to_pit(this);
591 struct kvm_kpit_state
*pit_state
= &pit
->pit_state
;
592 struct kvm
*kvm
= pit
->kvm
;
593 u32 val
= *(u32
*) data
;
594 if (addr
!= KVM_SPEAKER_BASE_ADDRESS
)
597 mutex_lock(&pit_state
->lock
);
598 pit_state
->speaker_data_on
= (val
>> 1) & 1;
599 pit_set_gate(kvm
, 2, val
& 1);
600 mutex_unlock(&pit_state
->lock
);
604 static int speaker_ioport_read(struct kvm_io_device
*this,
605 gpa_t addr
, int len
, void *data
)
607 struct kvm_pit
*pit
= speaker_to_pit(this);
608 struct kvm_kpit_state
*pit_state
= &pit
->pit_state
;
609 struct kvm
*kvm
= pit
->kvm
;
610 unsigned int refresh_clock
;
612 if (addr
!= KVM_SPEAKER_BASE_ADDRESS
)
615 /* Refresh clock toggles at about 15us. We approximate as 2^14ns. */
616 refresh_clock
= ((unsigned int)ktime_to_ns(ktime_get()) >> 14) & 1;
618 mutex_lock(&pit_state
->lock
);
619 ret
= ((pit_state
->speaker_data_on
<< 1) | pit_get_gate(kvm
, 2) |
620 (pit_get_out(kvm
, 2) << 5) | (refresh_clock
<< 4));
621 if (len
> sizeof(ret
))
623 memcpy(data
, (char *)&ret
, len
);
624 mutex_unlock(&pit_state
->lock
);
628 void kvm_pit_reset(struct kvm_pit
*pit
)
631 struct kvm_kpit_channel_state
*c
;
633 mutex_lock(&pit
->pit_state
.lock
);
634 pit
->pit_state
.flags
= 0;
635 for (i
= 0; i
< 3; i
++) {
636 c
= &pit
->pit_state
.channels
[i
];
639 pit_load_count(pit
->kvm
, i
, 0);
641 mutex_unlock(&pit
->pit_state
.lock
);
643 atomic_set(&pit
->pit_state
.pit_timer
.pending
, 0);
644 pit
->pit_state
.irq_ack
= 1;
647 static void pit_mask_notifer(struct kvm_irq_mask_notifier
*kimn
, bool mask
)
649 struct kvm_pit
*pit
= container_of(kimn
, struct kvm_pit
, mask_notifier
);
652 atomic_set(&pit
->pit_state
.pit_timer
.pending
, 0);
653 pit
->pit_state
.irq_ack
= 1;
657 static const struct kvm_io_device_ops pit_dev_ops
= {
658 .read
= pit_ioport_read
,
659 .write
= pit_ioport_write
,
662 static const struct kvm_io_device_ops speaker_dev_ops
= {
663 .read
= speaker_ioport_read
,
664 .write
= speaker_ioport_write
,
667 /* Caller must hold slots_lock */
668 struct kvm_pit
*kvm_create_pit(struct kvm
*kvm
, u32 flags
)
671 struct kvm_kpit_state
*pit_state
;
674 pit
= kzalloc(sizeof(struct kvm_pit
), GFP_KERNEL
);
678 pit
->irq_source_id
= kvm_request_irq_source_id(kvm
);
679 if (pit
->irq_source_id
< 0) {
684 mutex_init(&pit
->pit_state
.lock
);
685 mutex_lock(&pit
->pit_state
.lock
);
686 spin_lock_init(&pit
->pit_state
.inject_lock
);
688 pit
->wq
= create_singlethread_workqueue("kvm-pit-wq");
690 mutex_unlock(&pit
->pit_state
.lock
);
691 kvm_free_irq_source_id(kvm
, pit
->irq_source_id
);
695 INIT_WORK(&pit
->expired
, pit_do_work
);
697 kvm
->arch
.vpit
= pit
;
700 pit_state
= &pit
->pit_state
;
701 pit_state
->pit
= pit
;
702 hrtimer_init(&pit_state
->pit_timer
.timer
,
703 CLOCK_MONOTONIC
, HRTIMER_MODE_ABS
);
704 pit_state
->irq_ack_notifier
.gsi
= 0;
705 pit_state
->irq_ack_notifier
.irq_acked
= kvm_pit_ack_irq
;
706 kvm_register_irq_ack_notifier(kvm
, &pit_state
->irq_ack_notifier
);
707 pit_state
->pit_timer
.reinject
= true;
708 mutex_unlock(&pit
->pit_state
.lock
);
712 pit
->mask_notifier
.func
= pit_mask_notifer
;
713 kvm_register_irq_mask_notifier(kvm
, 0, &pit
->mask_notifier
);
715 kvm_iodevice_init(&pit
->dev
, &pit_dev_ops
);
716 ret
= kvm_io_bus_register_dev(kvm
, KVM_PIO_BUS
, KVM_PIT_BASE_ADDRESS
,
717 KVM_PIT_MEM_LENGTH
, &pit
->dev
);
721 if (flags
& KVM_PIT_SPEAKER_DUMMY
) {
722 kvm_iodevice_init(&pit
->speaker_dev
, &speaker_dev_ops
);
723 ret
= kvm_io_bus_register_dev(kvm
, KVM_PIO_BUS
,
724 KVM_SPEAKER_BASE_ADDRESS
, 4,
727 goto fail_unregister
;
733 kvm_io_bus_unregister_dev(kvm
, KVM_PIO_BUS
, &pit
->dev
);
736 kvm_unregister_irq_mask_notifier(kvm
, 0, &pit
->mask_notifier
);
737 kvm_unregister_irq_ack_notifier(kvm
, &pit_state
->irq_ack_notifier
);
738 kvm_free_irq_source_id(kvm
, pit
->irq_source_id
);
739 destroy_workqueue(pit
->wq
);
744 void kvm_free_pit(struct kvm
*kvm
)
746 struct hrtimer
*timer
;
748 if (kvm
->arch
.vpit
) {
749 kvm_io_bus_unregister_dev(kvm
, KVM_PIO_BUS
, &kvm
->arch
.vpit
->dev
);
750 kvm_io_bus_unregister_dev(kvm
, KVM_PIO_BUS
,
751 &kvm
->arch
.vpit
->speaker_dev
);
752 kvm_unregister_irq_mask_notifier(kvm
, 0,
753 &kvm
->arch
.vpit
->mask_notifier
);
754 kvm_unregister_irq_ack_notifier(kvm
,
755 &kvm
->arch
.vpit
->pit_state
.irq_ack_notifier
);
756 mutex_lock(&kvm
->arch
.vpit
->pit_state
.lock
);
757 timer
= &kvm
->arch
.vpit
->pit_state
.pit_timer
.timer
;
758 hrtimer_cancel(timer
);
759 cancel_work_sync(&kvm
->arch
.vpit
->expired
);
760 kvm_free_irq_source_id(kvm
, kvm
->arch
.vpit
->irq_source_id
);
761 mutex_unlock(&kvm
->arch
.vpit
->pit_state
.lock
);
762 destroy_workqueue(kvm
->arch
.vpit
->wq
);
763 kfree(kvm
->arch
.vpit
);