Initial import

1 files changed, 781 insertions, 0 deletions

diff --git a/arch/x86/kvm/i8254.c b/arch/x86/kvm/i8254.c
new file mode 100644
index 000000000..f90952f64
--- /dev/null
+++ b/arch/x86/kvm/i8254.c
@@ -0,0 +1,781 @@
+/*
+ * 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 (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 = 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_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;
+	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_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;
+	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_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;
+	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_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;
+	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);
+	}
+}