linux/arch/x86/kvm/i8254.c
Andy Honig 2febc83913 KVM: x86: Improve thread safety in pit
There's a race condition in the PIT emulation code in KVM.  In
__kvm_migrate_pit_timer the pit_timer object is accessed without
synchronization.  If the race condition occurs at the wrong time this
can crash the host kernel.

This fixes CVE-2014-3611.

Cc: stable@vger.kernel.org
Signed-off-by: Andrew Honig <ahonig@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2014-10-24 13:21:14 +02:00

778 lines
19 KiB
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 "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
/* Compute with 96 bit intermediate result: (a*b)/c */
static u64 muldiv64(u64 a, u32 b, u32 c)
{
union {
u64 ll;
struct {
u32 low, high;
} l;
} u, res;
u64 rl, rh;
u.ll = a;
rl = (u64)u.l.low * (u64)b;
rh = (u64)u.l.high * (u64)b;
rh += (rl >> 32);
res.l.high = div64_u64(rh, c);
res.l.low = div64_u64(((mod_64(rh, c) << 32) + (rl & 0xffffffff)), c);
return res.ll;
}
static void pit_set_gate(struct kvm *kvm, int channel, u32 val)
{
struct kvm_kpit_channel_state *c =
&kvm->arch.vpit->pit_state.channels[channel];
WARN_ON(!mutex_is_locked(&kvm->arch.vpit->pit_state.lock));
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 *kvm, int channel)
{
WARN_ON(!mutex_is_locked(&kvm->arch.vpit->pit_state.lock));
return kvm->arch.vpit->pit_state.channels[channel].gate;
}
static s64 __kpit_elapsed(struct kvm *kvm)
{
s64 elapsed;
ktime_t remaining;
struct kvm_kpit_state *ps = &kvm->arch.vpit->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 *kvm, struct kvm_kpit_channel_state *c,
int channel)
{
if (channel == 0)
return __kpit_elapsed(kvm);
return ktime_to_ns(ktime_sub(ktime_get(), c->count_load_time));
}
static int pit_get_count(struct kvm *kvm, int channel)
{
struct kvm_kpit_channel_state *c =
&kvm->arch.vpit->pit_state.channels[channel];
s64 d, t;
int counter;
WARN_ON(!mutex_is_locked(&kvm->arch.vpit->pit_state.lock));
t = kpit_elapsed(kvm, c, channel);
d = muldiv64(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 *kvm, int channel)
{
struct kvm_kpit_channel_state *c =
&kvm->arch.vpit->pit_state.channels[channel];
s64 d, t;
int out;
WARN_ON(!mutex_is_locked(&kvm->arch.vpit->pit_state.lock));
t = kpit_elapsed(kvm, c, channel);
d = muldiv64(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 *kvm, int channel)
{
struct kvm_kpit_channel_state *c =
&kvm->arch.vpit->pit_state.channels[channel];
WARN_ON(!mutex_is_locked(&kvm->arch.vpit->pit_state.lock));
if (!c->count_latched) {
c->latched_count = pit_get_count(kvm, channel);
c->count_latched = c->rw_mode;
}
}
static void pit_latch_status(struct kvm *kvm, int channel)
{
struct kvm_kpit_channel_state *c =
&kvm->arch.vpit->pit_state.channels[channel];
WARN_ON(!mutex_is_locked(&kvm->arch.vpit->pit_state.lock));
if (!c->status_latched) {
/* TODO: Return NULL COUNT (bit 6). */
c->status = ((pit_get_out(kvm, channel) << 7) |
(c->rw_mode << 4) |
(c->mode << 1) |
c->bcd);
c->status_latched = 1;
}
}
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);
int value;
spin_lock(&ps->inject_lock);
value = atomic_dec_return(&ps->pending);
if (value < 0)
/* spurious acks can be generated if, for example, the
* PIC is being reset. Handle it gracefully here
*/
atomic_inc(&ps->pending);
else if (value > 0)
/* in this case, we had multiple outstanding pit interrupts
* that we needed to inject. Reinject
*/
queue_kthread_work(&ps->pit->worker, &ps->pit->expired);
ps->irq_ack = 1;
spin_unlock(&ps->inject_lock);
}
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);
flush_kthread_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;
int inject = 0;
/* Try to inject pending interrupts when
* last one has been acked.
*/
spin_lock(&ps->inject_lock);
if (ps->irq_ack) {
ps->irq_ack = 0;
inject = 1;
}
spin_unlock(&ps->inject_lock);
if (inject) {
kvm_set_irq(kvm, kvm->arch.vpit->irq_source_id, 0, 1, false);
kvm_set_irq(kvm, kvm->arch.vpit->irq_source_id, 0, 0, false);
/*
* Provides NMI watchdog support via Virtual Wire mode.
* The route is: PIT -> PIC -> LVT0 in NMI mode.
*
* Note: Our Virtual Wire implementation is simplified, only
* propagating PIT interrupts to all VCPUs when they have set
* LVT0 to NMI delivery. Other PIC interrupts are just sent to
* VCPU0, and only if its LVT0 is in EXTINT mode.
*/
if (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 = ps->kvm->arch.vpit;
if (ps->reinject || !atomic_read(&ps->pending)) {
atomic_inc(&ps->pending);
queue_kthread_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 void create_pit_timer(struct kvm *kvm, u32 val, int is_period)
{
struct kvm_kpit_state *ps = &kvm->arch.vpit->pit_state;
s64 interval;
if (!irqchip_in_kernel(kvm) || ps->flags & KVM_PIT_FLAGS_HPET_LEGACY)
return;
interval = muldiv64(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);
flush_kthread_work(&ps->pit->expired);
ps->period = interval;
ps->is_periodic = is_period;
ps->timer.function = pit_timer_fn;
ps->kvm = ps->pit->kvm;
atomic_set(&ps->pending, 0);
ps->irq_ack = 1;
/*
* 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 *kvm, int channel, u32 val)
{
struct kvm_kpit_state *ps = &kvm->arch.vpit->pit_state;
WARN_ON(!mutex_is_locked(&ps->lock));
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(kvm, val, 0);
break;
case 2:
case 3:
create_pit_timer(kvm, val, 1);
break;
default:
destroy_pit_timer(kvm->arch.vpit);
}
}
void kvm_pit_load_count(struct kvm *kvm, int channel, u32 val, int hpet_legacy_start)
{
u8 saved_mode;
if (hpet_legacy_start) {
/* save existing mode for later reenablement */
saved_mode = kvm->arch.vpit->pit_state.channels[0].mode;
kvm->arch.vpit->pit_state.channels[0].mode = 0xff; /* disable timer */
pit_load_count(kvm, channel, val);
kvm->arch.vpit->pit_state.channels[0].mode = saved_mode;
} else {
pit_load_count(kvm, 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_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;
struct kvm *kvm = pit->kvm;
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(kvm, channel);
if (!(val & 0x10))
pit_latch_status(kvm, channel);
}
}
} else {
/* Select Counter <channel>. */
s = &pit_state->channels[channel];
access = (val >> 4) & KVM_PIT_CHANNEL_MASK;
if (access == 0) {
pit_latch_count(kvm, 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(kvm, addr, val);
break;
case RW_STATE_MSB:
pit_load_count(kvm, 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(kvm, 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_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;
struct kvm *kvm = pit->kvm;
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(kvm, addr);
ret = count & 0xff;
break;
case RW_STATE_MSB:
count = pit_get_count(kvm, addr);
ret = (count >> 8) & 0xff;
break;
case RW_STATE_WORD0:
count = pit_get_count(kvm, addr);
ret = count & 0xff;
s->read_state = RW_STATE_WORD1;
break;
case RW_STATE_WORD1:
count = pit_get_count(kvm, 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_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;
struct kvm *kvm = pit->kvm;
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(kvm, 2, val & 1);
mutex_unlock(&pit_state->lock);
return 0;
}
static int speaker_ioport_read(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;
struct kvm *kvm = pit->kvm;
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(kvm, 2) |
(pit_get_out(kvm, 2) << 5) | (refresh_clock << 4));
if (len > sizeof(ret))
len = sizeof(ret);
memcpy(data, (char *)&ret, len);
mutex_unlock(&pit_state->lock);
return 0;
}
void kvm_pit_reset(struct kvm_pit *pit)
{
int i;
struct kvm_kpit_channel_state *c;
mutex_lock(&pit->pit_state.lock);
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->kvm, i, 0);
}
mutex_unlock(&pit->pit_state.lock);
atomic_set(&pit->pit_state.pending, 0);
pit->pit_state.irq_ack = 1;
}
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) {
atomic_set(&pit->pit_state.pending, 0);
pit->pit_state.irq_ack = 1;
}
}
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,
};
/* Caller must hold slots_lock */
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);
if (!pit)
return NULL;
pit->irq_source_id = kvm_request_irq_source_id(kvm);
if (pit->irq_source_id < 0) {
kfree(pit);
return NULL;
}
mutex_init(&pit->pit_state.lock);
mutex_lock(&pit->pit_state.lock);
spin_lock_init(&pit->pit_state.inject_lock);
pid = get_pid(task_tgid(current));
pid_nr = pid_vnr(pid);
put_pid(pid);
init_kthread_worker(&pit->worker);
pit->worker_task = kthread_run(kthread_worker_fn, &pit->worker,
"kvm-pit/%d", pid_nr);
if (IS_ERR(pit->worker_task)) {
mutex_unlock(&pit->pit_state.lock);
kvm_free_irq_source_id(kvm, pit->irq_source_id);
kfree(pit);
return NULL;
}
init_kthread_work(&pit->expired, pit_do_work);
kvm->arch.vpit = pit;
pit->kvm = kvm;
pit_state = &pit->pit_state;
pit_state->pit = pit;
hrtimer_init(&pit_state->timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
pit_state->irq_ack_notifier.gsi = 0;
pit_state->irq_ack_notifier.irq_acked = kvm_pit_ack_irq;
kvm_register_irq_ack_notifier(kvm, &pit_state->irq_ack_notifier);
pit_state->reinject = true;
mutex_unlock(&pit->pit_state.lock);
kvm_pit_reset(pit);
pit->mask_notifier.func = pit_mask_notifer;
kvm_register_irq_mask_notifier(kvm, 0, &pit->mask_notifier);
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;
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_unregister;
}
return pit;
fail_unregister:
kvm_io_bus_unregister_dev(kvm, KVM_PIO_BUS, &pit->dev);
fail:
kvm_unregister_irq_mask_notifier(kvm, 0, &pit->mask_notifier);
kvm_unregister_irq_ack_notifier(kvm, &pit_state->irq_ack_notifier);
kvm_free_irq_source_id(kvm, pit->irq_source_id);
kthread_stop(pit->worker_task);
kfree(pit);
return NULL;
}
void kvm_free_pit(struct kvm *kvm)
{
struct hrtimer *timer;
if (kvm->arch.vpit) {
kvm_io_bus_unregister_dev(kvm, KVM_PIO_BUS, &kvm->arch.vpit->dev);
kvm_io_bus_unregister_dev(kvm, KVM_PIO_BUS,
&kvm->arch.vpit->speaker_dev);
kvm_unregister_irq_mask_notifier(kvm, 0,
&kvm->arch.vpit->mask_notifier);
kvm_unregister_irq_ack_notifier(kvm,
&kvm->arch.vpit->pit_state.irq_ack_notifier);
mutex_lock(&kvm->arch.vpit->pit_state.lock);
timer = &kvm->arch.vpit->pit_state.timer;
hrtimer_cancel(timer);
flush_kthread_work(&kvm->arch.vpit->expired);
kthread_stop(kvm->arch.vpit->worker_task);
kvm_free_irq_source_id(kvm, kvm->arch.vpit->irq_source_id);
mutex_unlock(&kvm->arch.vpit->pit_state.lock);
kfree(kvm->arch.vpit);
}
}