https://github.com/torvalds/linux
Tip revision: c79f46a282390e0f5b306007bf7b11a46d529538 authored by Linus Torvalds on 05 January 2020, 22:23:27 UTC
Linux 5.5-rc5
Linux 5.5-rc5
Tip revision: c79f46a
i8254.c
/*
* 8253/8254 interval timer emulation
*
* Copyright (c) 2003-2004 Fabrice Bellard
* Copyright (c) 2006 Intel Corporation
* Copyright (c) 2007 Keir Fraser, XenSource Inc
* Copyright (c) 2008 Intel Corporation
* Copyright 2009 Red Hat, Inc. and/or its affiliates.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*
* Authors:
* Sheng Yang <sheng.yang@intel.com>
* Based on QEMU and Xen.
*/
#define pr_fmt(fmt) "pit: " fmt
#include <linux/kvm_host.h>
#include <linux/slab.h>
#include "ioapic.h"
#include "irq.h"
#include "i8254.h"
#include "x86.h"
#ifndef CONFIG_X86_64
#define mod_64(x, y) ((x) - (y) * div64_u64(x, y))
#else
#define mod_64(x, y) ((x) % (y))
#endif
#define RW_STATE_LSB 1
#define RW_STATE_MSB 2
#define RW_STATE_WORD0 3
#define RW_STATE_WORD1 4
static void pit_set_gate(struct kvm_pit *pit, int channel, u32 val)
{
struct kvm_kpit_channel_state *c = &pit->pit_state.channels[channel];
switch (c->mode) {
default:
case 0:
case 4:
/* XXX: just disable/enable counting */
break;
case 1:
case 2:
case 3:
case 5:
/* Restart counting on rising edge. */
if (c->gate < val)
c->count_load_time = ktime_get();
break;
}
c->gate = val;
}
static int pit_get_gate(struct kvm_pit *pit, int channel)
{
return pit->pit_state.channels[channel].gate;
}
static s64 __kpit_elapsed(struct kvm_pit *pit)
{
s64 elapsed;
ktime_t remaining;
struct kvm_kpit_state *ps = &pit->pit_state;
if (!ps->period)
return 0;
/*
* The Counter does not stop when it reaches zero. In
* Modes 0, 1, 4, and 5 the Counter ``wraps around'' to
* the highest count, either FFFF hex for binary counting
* or 9999 for BCD counting, and continues counting.
* Modes 2 and 3 are periodic; the Counter reloads
* itself with the initial count and continues counting
* from there.
*/
remaining = hrtimer_get_remaining(&ps->timer);
elapsed = ps->period - ktime_to_ns(remaining);
return elapsed;
}
static s64 kpit_elapsed(struct kvm_pit *pit, struct kvm_kpit_channel_state *c,
int channel)
{
if (channel == 0)
return __kpit_elapsed(pit);
return ktime_to_ns(ktime_sub(ktime_get(), c->count_load_time));
}
static int pit_get_count(struct kvm_pit *pit, int channel)
{
struct kvm_kpit_channel_state *c = &pit->pit_state.channels[channel];
s64 d, t;
int counter;
t = kpit_elapsed(pit, c, channel);
d = mul_u64_u32_div(t, KVM_PIT_FREQ, NSEC_PER_SEC);
switch (c->mode) {
case 0:
case 1:
case 4:
case 5:
counter = (c->count - d) & 0xffff;
break;
case 3:
/* XXX: may be incorrect for odd counts */
counter = c->count - (mod_64((2 * d), c->count));
break;
default:
counter = c->count - mod_64(d, c->count);
break;
}
return counter;
}
static int pit_get_out(struct kvm_pit *pit, int channel)
{
struct kvm_kpit_channel_state *c = &pit->pit_state.channels[channel];
s64 d, t;
int out;
t = kpit_elapsed(pit, c, channel);
d = mul_u64_u32_div(t, KVM_PIT_FREQ, NSEC_PER_SEC);
switch (c->mode) {
default:
case 0:
out = (d >= c->count);
break;
case 1:
out = (d < c->count);
break;
case 2:
out = ((mod_64(d, c->count) == 0) && (d != 0));
break;
case 3:
out = (mod_64(d, c->count) < ((c->count + 1) >> 1));
break;
case 4:
case 5:
out = (d == c->count);
break;
}
return out;
}
static void pit_latch_count(struct kvm_pit *pit, int channel)
{
struct kvm_kpit_channel_state *c = &pit->pit_state.channels[channel];
if (!c->count_latched) {
c->latched_count = pit_get_count(pit, channel);
c->count_latched = c->rw_mode;
}
}
static void pit_latch_status(struct kvm_pit *pit, int channel)
{
struct kvm_kpit_channel_state *c = &pit->pit_state.channels[channel];
if (!c->status_latched) {
/* TODO: Return NULL COUNT (bit 6). */
c->status = ((pit_get_out(pit, channel) << 7) |
(c->rw_mode << 4) |
(c->mode << 1) |
c->bcd);
c->status_latched = 1;
}
}
static inline struct kvm_pit *pit_state_to_pit(struct kvm_kpit_state *ps)
{
return container_of(ps, struct kvm_pit, pit_state);
}
static void kvm_pit_ack_irq(struct kvm_irq_ack_notifier *kian)
{
struct kvm_kpit_state *ps = container_of(kian, struct kvm_kpit_state,
irq_ack_notifier);
struct kvm_pit *pit = pit_state_to_pit(ps);
atomic_set(&ps->irq_ack, 1);
/* irq_ack should be set before pending is read. Order accesses with
* inc(pending) in pit_timer_fn and xchg(irq_ack, 0) in pit_do_work.
*/
smp_mb();
if (atomic_dec_if_positive(&ps->pending) > 0)
kthread_queue_work(pit->worker, &pit->expired);
}
void __kvm_migrate_pit_timer(struct kvm_vcpu *vcpu)
{
struct kvm_pit *pit = vcpu->kvm->arch.vpit;
struct hrtimer *timer;
if (!kvm_vcpu_is_bsp(vcpu) || !pit)
return;
timer = &pit->pit_state.timer;
mutex_lock(&pit->pit_state.lock);
if (hrtimer_cancel(timer))
hrtimer_start_expires(timer, HRTIMER_MODE_ABS);
mutex_unlock(&pit->pit_state.lock);
}
static void destroy_pit_timer(struct kvm_pit *pit)
{
hrtimer_cancel(&pit->pit_state.timer);
kthread_flush_work(&pit->expired);
}
static void pit_do_work(struct kthread_work *work)
{
struct kvm_pit *pit = container_of(work, struct kvm_pit, expired);
struct kvm *kvm = pit->kvm;
struct kvm_vcpu *vcpu;
int i;
struct kvm_kpit_state *ps = &pit->pit_state;
if (atomic_read(&ps->reinject) && !atomic_xchg(&ps->irq_ack, 0))
return;
kvm_set_irq(kvm, pit->irq_source_id, 0, 1, false);
kvm_set_irq(kvm, pit->irq_source_id, 0, 0, false);
/*
* Provides NMI watchdog support via Virtual Wire mode.
* The route is: PIT -> LVT0 in NMI mode.
*
* Note: Our Virtual Wire implementation does not follow
* the MP specification. We propagate a PIT interrupt to all
* VCPUs and only when LVT0 is in NMI mode. The interrupt can
* also be simultaneously delivered through PIC and IOAPIC.
*/
if (atomic_read(&kvm->arch.vapics_in_nmi_mode) > 0)
kvm_for_each_vcpu(i, vcpu, kvm)
kvm_apic_nmi_wd_deliver(vcpu);
}
static enum hrtimer_restart pit_timer_fn(struct hrtimer *data)
{
struct kvm_kpit_state *ps = container_of(data, struct kvm_kpit_state, timer);
struct kvm_pit *pt = pit_state_to_pit(ps);
if (atomic_read(&ps->reinject))
atomic_inc(&ps->pending);
kthread_queue_work(pt->worker, &pt->expired);
if (ps->is_periodic) {
hrtimer_add_expires_ns(&ps->timer, ps->period);
return HRTIMER_RESTART;
} else
return HRTIMER_NORESTART;
}
static inline void kvm_pit_reset_reinject(struct kvm_pit *pit)
{
atomic_set(&pit->pit_state.pending, 0);
atomic_set(&pit->pit_state.irq_ack, 1);
}
void kvm_pit_set_reinject(struct kvm_pit *pit, bool reinject)
{
struct kvm_kpit_state *ps = &pit->pit_state;
struct kvm *kvm = pit->kvm;
if (atomic_read(&ps->reinject) == reinject)
return;
if (reinject) {
/* The initial state is preserved while ps->reinject == 0. */
kvm_pit_reset_reinject(pit);
kvm_register_irq_ack_notifier(kvm, &ps->irq_ack_notifier);
kvm_register_irq_mask_notifier(kvm, 0, &pit->mask_notifier);
} else {
kvm_unregister_irq_ack_notifier(kvm, &ps->irq_ack_notifier);
kvm_unregister_irq_mask_notifier(kvm, 0, &pit->mask_notifier);
}
atomic_set(&ps->reinject, reinject);
}
static void create_pit_timer(struct kvm_pit *pit, u32 val, int is_period)
{
struct kvm_kpit_state *ps = &pit->pit_state;
struct kvm *kvm = pit->kvm;
s64 interval;
if (!ioapic_in_kernel(kvm) ||
ps->flags & KVM_PIT_FLAGS_HPET_LEGACY)
return;
interval = mul_u64_u32_div(val, NSEC_PER_SEC, KVM_PIT_FREQ);
pr_debug("create pit timer, interval is %llu nsec\n", interval);
/* TODO The new value only affected after the retriggered */
hrtimer_cancel(&ps->timer);
kthread_flush_work(&pit->expired);
ps->period = interval;
ps->is_periodic = is_period;
kvm_pit_reset_reinject(pit);
/*
* Do not allow the guest to program periodic timers with small
* interval, since the hrtimers are not throttled by the host
* scheduler.
*/
if (ps->is_periodic) {
s64 min_period = min_timer_period_us * 1000LL;
if (ps->period < min_period) {
pr_info_ratelimited(
"kvm: requested %lld ns "
"i8254 timer period limited to %lld ns\n",
ps->period, min_period);
ps->period = min_period;
}
}
hrtimer_start(&ps->timer, ktime_add_ns(ktime_get(), interval),
HRTIMER_MODE_ABS);
}
static void pit_load_count(struct kvm_pit *pit, int channel, u32 val)
{
struct kvm_kpit_state *ps = &pit->pit_state;
pr_debug("load_count val is %d, channel is %d\n", val, channel);
/*
* The largest possible initial count is 0; this is equivalent
* to 216 for binary counting and 104 for BCD counting.
*/
if (val == 0)
val = 0x10000;
ps->channels[channel].count = val;
if (channel != 0) {
ps->channels[channel].count_load_time = ktime_get();
return;
}
/* Two types of timer
* mode 1 is one shot, mode 2 is period, otherwise del timer */
switch (ps->channels[0].mode) {
case 0:
case 1:
/* FIXME: enhance mode 4 precision */
case 4:
create_pit_timer(pit, val, 0);
break;
case 2:
case 3:
create_pit_timer(pit, val, 1);
break;
default:
destroy_pit_timer(pit);
}
}
void kvm_pit_load_count(struct kvm_pit *pit, int channel, u32 val,
int hpet_legacy_start)
{
u8 saved_mode;
WARN_ON_ONCE(!mutex_is_locked(&pit->pit_state.lock));
if (hpet_legacy_start) {
/* save existing mode for later reenablement */
WARN_ON(channel != 0);
saved_mode = pit->pit_state.channels[0].mode;
pit->pit_state.channels[0].mode = 0xff; /* disable timer */
pit_load_count(pit, channel, val);
pit->pit_state.channels[0].mode = saved_mode;
} else {
pit_load_count(pit, channel, val);
}
}
static inline struct kvm_pit *dev_to_pit(struct kvm_io_device *dev)
{
return container_of(dev, struct kvm_pit, dev);
}
static inline struct kvm_pit *speaker_to_pit(struct kvm_io_device *dev)
{
return container_of(dev, struct kvm_pit, speaker_dev);
}
static inline int pit_in_range(gpa_t addr)
{
return ((addr >= KVM_PIT_BASE_ADDRESS) &&
(addr < KVM_PIT_BASE_ADDRESS + KVM_PIT_MEM_LENGTH));
}
static int pit_ioport_write(struct kvm_vcpu *vcpu,
struct kvm_io_device *this,
gpa_t addr, int len, const void *data)
{
struct kvm_pit *pit = dev_to_pit(this);
struct kvm_kpit_state *pit_state = &pit->pit_state;
int channel, access;
struct kvm_kpit_channel_state *s;
u32 val = *(u32 *) data;
if (!pit_in_range(addr))
return -EOPNOTSUPP;
val &= 0xff;
addr &= KVM_PIT_CHANNEL_MASK;
mutex_lock(&pit_state->lock);
if (val != 0)
pr_debug("write addr is 0x%x, len is %d, val is 0x%x\n",
(unsigned int)addr, len, val);
if (addr == 3) {
channel = val >> 6;
if (channel == 3) {
/* Read-Back Command. */
for (channel = 0; channel < 3; channel++) {
s = &pit_state->channels[channel];
if (val & (2 << channel)) {
if (!(val & 0x20))
pit_latch_count(pit, channel);
if (!(val & 0x10))
pit_latch_status(pit, channel);
}
}
} else {
/* Select Counter <channel>. */
s = &pit_state->channels[channel];
access = (val >> 4) & KVM_PIT_CHANNEL_MASK;
if (access == 0) {
pit_latch_count(pit, channel);
} else {
s->rw_mode = access;
s->read_state = access;
s->write_state = access;
s->mode = (val >> 1) & 7;
if (s->mode > 5)
s->mode -= 4;
s->bcd = val & 1;
}
}
} else {
/* Write Count. */
s = &pit_state->channels[addr];
switch (s->write_state) {
default:
case RW_STATE_LSB:
pit_load_count(pit, addr, val);
break;
case RW_STATE_MSB:
pit_load_count(pit, addr, val << 8);
break;
case RW_STATE_WORD0:
s->write_latch = val;
s->write_state = RW_STATE_WORD1;
break;
case RW_STATE_WORD1:
pit_load_count(pit, addr, s->write_latch | (val << 8));
s->write_state = RW_STATE_WORD0;
break;
}
}
mutex_unlock(&pit_state->lock);
return 0;
}
static int pit_ioport_read(struct kvm_vcpu *vcpu,
struct kvm_io_device *this,
gpa_t addr, int len, void *data)
{
struct kvm_pit *pit = dev_to_pit(this);
struct kvm_kpit_state *pit_state = &pit->pit_state;
int ret, count;
struct kvm_kpit_channel_state *s;
if (!pit_in_range(addr))
return -EOPNOTSUPP;
addr &= KVM_PIT_CHANNEL_MASK;
if (addr == 3)
return 0;
s = &pit_state->channels[addr];
mutex_lock(&pit_state->lock);
if (s->status_latched) {
s->status_latched = 0;
ret = s->status;
} else if (s->count_latched) {
switch (s->count_latched) {
default:
case RW_STATE_LSB:
ret = s->latched_count & 0xff;
s->count_latched = 0;
break;
case RW_STATE_MSB:
ret = s->latched_count >> 8;
s->count_latched = 0;
break;
case RW_STATE_WORD0:
ret = s->latched_count & 0xff;
s->count_latched = RW_STATE_MSB;
break;
}
} else {
switch (s->read_state) {
default:
case RW_STATE_LSB:
count = pit_get_count(pit, addr);
ret = count & 0xff;
break;
case RW_STATE_MSB:
count = pit_get_count(pit, addr);
ret = (count >> 8) & 0xff;
break;
case RW_STATE_WORD0:
count = pit_get_count(pit, addr);
ret = count & 0xff;
s->read_state = RW_STATE_WORD1;
break;
case RW_STATE_WORD1:
count = pit_get_count(pit, addr);
ret = (count >> 8) & 0xff;
s->read_state = RW_STATE_WORD0;
break;
}
}
if (len > sizeof(ret))
len = sizeof(ret);
memcpy(data, (char *)&ret, len);
mutex_unlock(&pit_state->lock);
return 0;
}
static int speaker_ioport_write(struct kvm_vcpu *vcpu,
struct kvm_io_device *this,
gpa_t addr, int len, const void *data)
{
struct kvm_pit *pit = speaker_to_pit(this);
struct kvm_kpit_state *pit_state = &pit->pit_state;
u32 val = *(u32 *) data;
if (addr != KVM_SPEAKER_BASE_ADDRESS)
return -EOPNOTSUPP;
mutex_lock(&pit_state->lock);
pit_state->speaker_data_on = (val >> 1) & 1;
pit_set_gate(pit, 2, val & 1);
mutex_unlock(&pit_state->lock);
return 0;
}
static int speaker_ioport_read(struct kvm_vcpu *vcpu,
struct kvm_io_device *this,
gpa_t addr, int len, void *data)
{
struct kvm_pit *pit = speaker_to_pit(this);
struct kvm_kpit_state *pit_state = &pit->pit_state;
unsigned int refresh_clock;
int ret;
if (addr != KVM_SPEAKER_BASE_ADDRESS)
return -EOPNOTSUPP;
/* Refresh clock toggles at about 15us. We approximate as 2^14ns. */
refresh_clock = ((unsigned int)ktime_to_ns(ktime_get()) >> 14) & 1;
mutex_lock(&pit_state->lock);
ret = ((pit_state->speaker_data_on << 1) | pit_get_gate(pit, 2) |
(pit_get_out(pit, 2) << 5) | (refresh_clock << 4));
if (len > sizeof(ret))
len = sizeof(ret);
memcpy(data, (char *)&ret, len);
mutex_unlock(&pit_state->lock);
return 0;
}
static void kvm_pit_reset(struct kvm_pit *pit)
{
int i;
struct kvm_kpit_channel_state *c;
pit->pit_state.flags = 0;
for (i = 0; i < 3; i++) {
c = &pit->pit_state.channels[i];
c->mode = 0xff;
c->gate = (i != 2);
pit_load_count(pit, i, 0);
}
kvm_pit_reset_reinject(pit);
}
static void pit_mask_notifer(struct kvm_irq_mask_notifier *kimn, bool mask)
{
struct kvm_pit *pit = container_of(kimn, struct kvm_pit, mask_notifier);
if (!mask)
kvm_pit_reset_reinject(pit);
}
static const struct kvm_io_device_ops pit_dev_ops = {
.read = pit_ioport_read,
.write = pit_ioport_write,
};
static const struct kvm_io_device_ops speaker_dev_ops = {
.read = speaker_ioport_read,
.write = speaker_ioport_write,
};
struct kvm_pit *kvm_create_pit(struct kvm *kvm, u32 flags)
{
struct kvm_pit *pit;
struct kvm_kpit_state *pit_state;
struct pid *pid;
pid_t pid_nr;
int ret;
pit = kzalloc(sizeof(struct kvm_pit), GFP_KERNEL_ACCOUNT);
if (!pit)
return NULL;
pit->irq_source_id = kvm_request_irq_source_id(kvm);
if (pit->irq_source_id < 0)
goto fail_request;
mutex_init(&pit->pit_state.lock);
pid = get_pid(task_tgid(current));
pid_nr = pid_vnr(pid);
put_pid(pid);
pit->worker = kthread_create_worker(0, "kvm-pit/%d", pid_nr);
if (IS_ERR(pit->worker))
goto fail_kthread;
kthread_init_work(&pit->expired, pit_do_work);
pit->kvm = kvm;
pit_state = &pit->pit_state;
hrtimer_init(&pit_state->timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
pit_state->timer.function = pit_timer_fn;
pit_state->irq_ack_notifier.gsi = 0;
pit_state->irq_ack_notifier.irq_acked = kvm_pit_ack_irq;
pit->mask_notifier.func = pit_mask_notifer;
kvm_pit_reset(pit);
kvm_pit_set_reinject(pit, true);
mutex_lock(&kvm->slots_lock);
kvm_iodevice_init(&pit->dev, &pit_dev_ops);
ret = kvm_io_bus_register_dev(kvm, KVM_PIO_BUS, KVM_PIT_BASE_ADDRESS,
KVM_PIT_MEM_LENGTH, &pit->dev);
if (ret < 0)
goto fail_register_pit;
if (flags & KVM_PIT_SPEAKER_DUMMY) {
kvm_iodevice_init(&pit->speaker_dev, &speaker_dev_ops);
ret = kvm_io_bus_register_dev(kvm, KVM_PIO_BUS,
KVM_SPEAKER_BASE_ADDRESS, 4,
&pit->speaker_dev);
if (ret < 0)
goto fail_register_speaker;
}
mutex_unlock(&kvm->slots_lock);
return pit;
fail_register_speaker:
kvm_io_bus_unregister_dev(kvm, KVM_PIO_BUS, &pit->dev);
fail_register_pit:
mutex_unlock(&kvm->slots_lock);
kvm_pit_set_reinject(pit, false);
kthread_destroy_worker(pit->worker);
fail_kthread:
kvm_free_irq_source_id(kvm, pit->irq_source_id);
fail_request:
kfree(pit);
return NULL;
}
void kvm_free_pit(struct kvm *kvm)
{
struct kvm_pit *pit = kvm->arch.vpit;
if (pit) {
mutex_lock(&kvm->slots_lock);
kvm_io_bus_unregister_dev(kvm, KVM_PIO_BUS, &pit->dev);
kvm_io_bus_unregister_dev(kvm, KVM_PIO_BUS, &pit->speaker_dev);
mutex_unlock(&kvm->slots_lock);
kvm_pit_set_reinject(pit, false);
hrtimer_cancel(&pit->pit_state.timer);
kthread_destroy_worker(pit->worker);
kvm_free_irq_source_id(kvm, pit->irq_source_id);
kfree(pit);
}
}