arch/x86/kvm/i8259.c - kernel/mindspeed - Git at Google

 /*
  * 8259 interrupt controller emulation
  *
  * Copyright (c) 2003-2004 Fabrice Bellard
  * Copyright (c) 2007 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:
  *   Yaozu (Eddie) Dong <Eddie.dong@intel.com>
  *   Port from Qemu.
  */
 #include <linux/mm.h>
 #include <linux/slab.h>
 #include <linux/bitops.h>
 #include "irq.h"

 #include <linux/kvm_host.h>
 #include "trace.h"

 #define pr_pic_unimpl(fmt, ...)	\
 	pr_err_ratelimited("kvm: pic: " fmt, ## __VA_ARGS__)

 static void pic_irq_request(struct kvm *kvm, int level);

 static void pic_lock(struct kvm_pic *s)
 	__acquires(&s->lock)
 {
 	spin_lock(&s->lock);
 }

 static void pic_unlock(struct kvm_pic *s)
 	__releases(&s->lock)
 {
 	bool wakeup = s->wakeup_needed;
 	struct kvm_vcpu *vcpu, *found = NULL;
 	int i;

 	s->wakeup_needed = false;

 	spin_unlock(&s->lock);

 	if (wakeup) {
 		kvm_for_each_vcpu(i, vcpu, s->kvm) {
 			if (kvm_apic_accept_pic_intr(vcpu)) {
 				found = vcpu;
 				break;
 			}
 		}

 		if (!found)
 			return;

 		kvm_make_request(KVM_REQ_EVENT, found);
 		kvm_vcpu_kick(found);
 	}
 }

 static void pic_clear_isr(struct kvm_kpic_state *s, int irq)
 {
 	s->isr &= ~(1 << irq);
 	if (s != &s->pics_state->pics[0])
 		irq += 8;
 	/*
 	 * We are dropping lock while calling ack notifiers since ack
 	 * notifier callbacks for assigned devices call into PIC recursively.
 	 * Other interrupt may be delivered to PIC while lock is dropped but
 	 * it should be safe since PIC state is already updated at this stage.
 	 */
 	pic_unlock(s->pics_state);
 	kvm_notify_acked_irq(s->pics_state->kvm, SELECT_PIC(irq), irq);
 	pic_lock(s->pics_state);
 }

 /*
  * set irq level. If an edge is detected, then the IRR is set to 1
  */
 static inline int pic_set_irq1(struct kvm_kpic_state *s, int irq, int level)
 {
 	int mask, ret = 1;
 	mask = 1 << irq;
 	if (s->elcr & mask)	/* level triggered */
 		if (level) {
 			ret = !(s->irr & mask);
 			s->irr |= mask;
 			s->last_irr |= mask;
 		} else {
 			s->irr &= ~mask;
 			s->last_irr &= ~mask;
 		}
 	else	/* edge triggered */
 		if (level) {
 			if ((s->last_irr & mask) == 0) {
 				ret = !(s->irr & mask);
 				s->irr |= mask;
 			}
 			s->last_irr |= mask;
 		} else
 			s->last_irr &= ~mask;

 	return (s->imr & mask) ? -1 : ret;
 }

 /*
  * return the highest priority found in mask (highest = smallest
  * number). Return 8 if no irq
  */
 static inline int get_priority(struct kvm_kpic_state *s, int mask)
 {
 	int priority;
 	if (mask == 0)
 		return 8;
 	priority = 0;
 	while ((mask & (1 << ((priority + s->priority_add) & 7))) == 0)
 		priority++;
 	return priority;
 }

 /*
  * return the pic wanted interrupt. return -1 if none
  */
 static int pic_get_irq(struct kvm_kpic_state *s)
 {
 	int mask, cur_priority, priority;

 	mask = s->irr & ~s->imr;
 	priority = get_priority(s, mask);
 	if (priority == 8)
 		return -1;
 	/*
 	 * compute current priority. If special fully nested mode on the
 	 * master, the IRQ coming from the slave is not taken into account
 	 * for the priority computation.
 	 */
 	mask = s->isr;
 	if (s->special_fully_nested_mode && s == &s->pics_state->pics[0])
 		mask &= ~(1 << 2);
 	cur_priority = get_priority(s, mask);
 	if (priority < cur_priority)
 		/*
 		 * higher priority found: an irq should be generated
 		 */
 		return (priority + s->priority_add) & 7;
 	else
 		return -1;
 }

 /*
  * raise irq to CPU if necessary. must be called every time the active
  * irq may change
  */
 static void pic_update_irq(struct kvm_pic *s)
 {
 	int irq2, irq;

 	irq2 = pic_get_irq(&s->pics[1]);
 	if (irq2 >= 0) {
 		/*
 		 * if irq request by slave pic, signal master PIC
 		 */
 		pic_set_irq1(&s->pics[0], 2, 1);
 		pic_set_irq1(&s->pics[0], 2, 0);
 	}
 	irq = pic_get_irq(&s->pics[0]);
 	pic_irq_request(s->kvm, irq >= 0);
 }

 void kvm_pic_update_irq(struct kvm_pic *s)
 {
 	pic_lock(s);
 	pic_update_irq(s);
 	pic_unlock(s);
 }

 int kvm_pic_set_irq(void *opaque, int irq, int level)
 {
 	struct kvm_pic *s = opaque;
 	int ret = -1;

 	pic_lock(s);
 	if (irq >= 0 && irq < PIC_NUM_PINS) {
 		ret = pic_set_irq1(&s->pics[irq >> 3], irq & 7, level);
 		pic_update_irq(s);
 		trace_kvm_pic_set_irq(irq >> 3, irq & 7, s->pics[irq >> 3].elcr,
 				      s->pics[irq >> 3].imr, ret == 0);
 	}
 	pic_unlock(s);

 	return ret;
 }

 /*
  * acknowledge interrupt 'irq'
  */
 static inline void pic_intack(struct kvm_kpic_state *s, int irq)
 {
 	s->isr |= 1 << irq;
 	/*
 	 * We don't clear a level sensitive interrupt here
 	 */
 	if (!(s->elcr & (1 << irq)))
 		s->irr &= ~(1 << irq);

 	if (s->auto_eoi) {
 		if (s->rotate_on_auto_eoi)
 			s->priority_add = (irq + 1) & 7;
 		pic_clear_isr(s, irq);
 	}

 }

 int kvm_pic_read_irq(struct kvm *kvm)
 {
 	int irq, irq2, intno;
 	struct kvm_pic *s = pic_irqchip(kvm);

 	pic_lock(s);
 	irq = pic_get_irq(&s->pics[0]);
 	if (irq >= 0) {
 		pic_intack(&s->pics[0], irq);
 		if (irq == 2) {
 			irq2 = pic_get_irq(&s->pics[1]);
 			if (irq2 >= 0)
 				pic_intack(&s->pics[1], irq2);
 			else
 				/*
 				 * spurious IRQ on slave controller
 				 */
 				irq2 = 7;
 			intno = s->pics[1].irq_base + irq2;
 			irq = irq2 + 8;
 		} else
 			intno = s->pics[0].irq_base + irq;
 	} else {
 		/*
 		 * spurious IRQ on host controller
 		 */
 		irq = 7;
 		intno = s->pics[0].irq_base + irq;
 	}
 	pic_update_irq(s);
 	pic_unlock(s);

 	return intno;
 }

 void kvm_pic_reset(struct kvm_kpic_state *s)
 {
 	int irq;
 	struct kvm_vcpu *vcpu0 = s->pics_state->kvm->bsp_vcpu;
 	u8 irr = s->irr, isr = s->imr;

 	s->last_irr = 0;
 	s->irr = 0;
 	s->imr = 0;
 	s->isr = 0;
 	s->priority_add = 0;
 	s->irq_base = 0;
 	s->read_reg_select = 0;
 	s->poll = 0;
 	s->special_mask = 0;
 	s->init_state = 0;
 	s->auto_eoi = 0;
 	s->rotate_on_auto_eoi = 0;
 	s->special_fully_nested_mode = 0;
 	s->init4 = 0;

 	for (irq = 0; irq < PIC_NUM_PINS/2; irq++) {
 		if (vcpu0 && kvm_apic_accept_pic_intr(vcpu0))
 			if (irr & (1 << irq) || isr & (1 << irq)) {
 				pic_clear_isr(s, irq);
 			}
 	}
 }

 static void pic_ioport_write(void *opaque, u32 addr, u32 val)
 {
 	struct kvm_kpic_state *s = opaque;
 	int priority, cmd, irq;

 	addr &= 1;
 	if (addr == 0) {
 		if (val & 0x10) {
 			s->init4 = val & 1;
 			s->last_irr = 0;
 			s->imr = 0;
 			s->priority_add = 0;
 			s->special_mask = 0;
 			s->read_reg_select = 0;
 			if (!s->init4) {
 				s->special_fully_nested_mode = 0;
 				s->auto_eoi = 0;
 			}
 			s->init_state = 1;
 			if (val & 0x02)
 				pr_pic_unimpl("single mode not supported");
 			if (val & 0x08)
 				pr_pic_unimpl(
 					"level sensitive irq not supported");
 		} else if (val & 0x08) {
 			if (val & 0x04)
 				s->poll = 1;
 			if (val & 0x02)
 				s->read_reg_select = val & 1;
 			if (val & 0x40)
 				s->special_mask = (val >> 5) & 1;
 		} else {
 			cmd = val >> 5;
 			switch (cmd) {
 			case 0:
 			case 4:
 				s->rotate_on_auto_eoi = cmd >> 2;
 				break;
 			case 1:	/* end of interrupt */
 			case 5:
 				priority = get_priority(s, s->isr);
 				if (priority != 8) {
 					irq = (priority + s->priority_add) & 7;
 					if (cmd == 5)
 						s->priority_add = (irq + 1) & 7;
 					pic_clear_isr(s, irq);
 					pic_update_irq(s->pics_state);
 				}
 				break;
 			case 3:
 				irq = val & 7;
 				pic_clear_isr(s, irq);
 				pic_update_irq(s->pics_state);
 				break;
 			case 6:
 				s->priority_add = (val + 1) & 7;
 				pic_update_irq(s->pics_state);
 				break;
 			case 7:
 				irq = val & 7;
 				s->priority_add = (irq + 1) & 7;
 				pic_clear_isr(s, irq);
 				pic_update_irq(s->pics_state);
 				break;
 			default:
 				break;	/* no operation */
 			}
 		}
 	} else
 		switch (s->init_state) {
 		case 0: { /* normal mode */
 			u8 imr_diff = s->imr ^ val,
 				off = (s == &s->pics_state->pics[0]) ? 0 : 8;
 			s->imr = val;
 			for (irq = 0; irq < PIC_NUM_PINS/2; irq++)
 				if (imr_diff & (1 << irq))
 					kvm_fire_mask_notifiers(
 						s->pics_state->kvm,
 						SELECT_PIC(irq + off),
 						irq + off,
 						!!(s->imr & (1 << irq)));
 			pic_update_irq(s->pics_state);
 			break;
 		}
 		case 1:
 			s->irq_base = val & 0xf8;
 			s->init_state = 2;
 			break;
 		case 2:
 			if (s->init4)
 				s->init_state = 3;
 			else
 				s->init_state = 0;
 			break;
 		case 3:
 			s->special_fully_nested_mode = (val >> 4) & 1;
 			s->auto_eoi = (val >> 1) & 1;
 			s->init_state = 0;
 			break;
 		}
 }

 static u32 pic_poll_read(struct kvm_kpic_state *s, u32 addr1)
 {
 	int ret;

 	ret = pic_get_irq(s);
 	if (ret >= 0) {
 		if (addr1 >> 7) {
 			s->pics_state->pics[0].isr &= ~(1 << 2);
 			s->pics_state->pics[0].irr &= ~(1 << 2);
 		}
 		s->irr &= ~(1 << ret);
 		pic_clear_isr(s, ret);
 		if (addr1 >> 7 || ret != 2)
 			pic_update_irq(s->pics_state);
 	} else {
 		ret = 0x07;
 		pic_update_irq(s->pics_state);
 	}

 	return ret;
 }

 static u32 pic_ioport_read(void *opaque, u32 addr1)
 {
 	struct kvm_kpic_state *s = opaque;
 	unsigned int addr;
 	int ret;

 	addr = addr1;
 	addr &= 1;
 	if (s->poll) {
 		ret = pic_poll_read(s, addr1);
 		s->poll = 0;
 	} else
 		if (addr == 0)
 			if (s->read_reg_select)
 				ret = s->isr;
 			else
 				ret = s->irr;
 		else
 			ret = s->imr;
 	return ret;
 }

 static void elcr_ioport_write(void *opaque, u32 addr, u32 val)
 {
 	struct kvm_kpic_state *s = opaque;
 	s->elcr = val & s->elcr_mask;
 }

 static u32 elcr_ioport_read(void *opaque, u32 addr1)
 {
 	struct kvm_kpic_state *s = opaque;
 	return s->elcr;
 }

 static int picdev_in_range(gpa_t addr)
 {
 	switch (addr) {
 	case 0x20:
 	case 0x21:
 	case 0xa0:
 	case 0xa1:
 	case 0x4d0:
 	case 0x4d1:
 		return 1;
 	default:
 		return 0;
 	}
 }

 static int picdev_write(struct kvm_pic *s,
 			 gpa_t addr, int len, const void *val)
 {
 	unsigned char data = *(unsigned char *)val;
 	if (!picdev_in_range(addr))
 		return -EOPNOTSUPP;

 	if (len != 1) {
 		pr_pic_unimpl("non byte write\n");
 		return 0;
 	}
 	pic_lock(s);
 	switch (addr) {
 	case 0x20:
 	case 0x21:
 	case 0xa0:
 	case 0xa1:
 		pic_ioport_write(&s->pics[addr >> 7], addr, data);
 		break;
 	case 0x4d0:
 	case 0x4d1:
 		elcr_ioport_write(&s->pics[addr & 1], addr, data);
 		break;
 	}
 	pic_unlock(s);
 	return 0;
 }

 static int picdev_read(struct kvm_pic *s,
 		       gpa_t addr, int len, void *val)
 {
 	unsigned char data = 0;
 	if (!picdev_in_range(addr))
 		return -EOPNOTSUPP;

 	if (len != 1) {
 		pr_pic_unimpl("non byte read\n");
 		return 0;
 	}
 	pic_lock(s);
 	switch (addr) {
 	case 0x20:
 	case 0x21:
 	case 0xa0:
 	case 0xa1:
 		data = pic_ioport_read(&s->pics[addr >> 7], addr);
 		break;
 	case 0x4d0:
 	case 0x4d1:
 		data = elcr_ioport_read(&s->pics[addr & 1], addr);
 		break;
 	}
 	*(unsigned char *)val = data;
 	pic_unlock(s);
 	return 0;
 }

 static int picdev_master_write(struct kvm_io_device *dev,
 			       gpa_t addr, int len, const void *val)
 {
 	return picdev_write(container_of(dev, struct kvm_pic, dev_master),
 			    addr, len, val);
 }

 static int picdev_master_read(struct kvm_io_device *dev,
 			      gpa_t addr, int len, void *val)
 {
 	return picdev_read(container_of(dev, struct kvm_pic, dev_master),
 			    addr, len, val);
 }

 static int picdev_slave_write(struct kvm_io_device *dev,
 			      gpa_t addr, int len, const void *val)
 {
 	return picdev_write(container_of(dev, struct kvm_pic, dev_slave),
 			    addr, len, val);
 }

 static int picdev_slave_read(struct kvm_io_device *dev,
 			     gpa_t addr, int len, void *val)
 {
 	return picdev_read(container_of(dev, struct kvm_pic, dev_slave),
 			    addr, len, val);
 }

 static int picdev_eclr_write(struct kvm_io_device *dev,
 			     gpa_t addr, int len, const void *val)
 {
 	return picdev_write(container_of(dev, struct kvm_pic, dev_eclr),
 			    addr, len, val);
 }

 static int picdev_eclr_read(struct kvm_io_device *dev,
 			    gpa_t addr, int len, void *val)
 {
 	return picdev_read(container_of(dev, struct kvm_pic, dev_eclr),
 			    addr, len, val);
 }

 /*
  * callback when PIC0 irq status changed
  */
 static void pic_irq_request(struct kvm *kvm, int level)
 {
 	struct kvm_pic *s = pic_irqchip(kvm);

 	if (!s->output)
 		s->wakeup_needed = true;
 	s->output = level;
 }

 static const struct kvm_io_device_ops picdev_master_ops = {
 	.read     = picdev_master_read,
 	.write    = picdev_master_write,
 };

 static const struct kvm_io_device_ops picdev_slave_ops = {
 	.read     = picdev_slave_read,
 	.write    = picdev_slave_write,
 };

 static const struct kvm_io_device_ops picdev_eclr_ops = {
 	.read     = picdev_eclr_read,
 	.write    = picdev_eclr_write,
 };

 struct kvm_pic *kvm_create_pic(struct kvm *kvm)
 {
 	struct kvm_pic *s;
 	int ret;

 	s = kzalloc(sizeof(struct kvm_pic), GFP_KERNEL);
 	if (!s)
 		return NULL;
 	spin_lock_init(&s->lock);
 	s->kvm = kvm;
 	s->pics[0].elcr_mask = 0xf8;
 	s->pics[1].elcr_mask = 0xde;
 	s->pics[0].pics_state = s;
 	s->pics[1].pics_state = s;

 	/*
 	 * Initialize PIO device
 	 */
 	kvm_iodevice_init(&s->dev_master, &picdev_master_ops);
 	kvm_iodevice_init(&s->dev_slave, &picdev_slave_ops);
 	kvm_iodevice_init(&s->dev_eclr, &picdev_eclr_ops);
 	mutex_lock(&kvm->slots_lock);
 	ret = kvm_io_bus_register_dev(kvm, KVM_PIO_BUS, 0x20, 2,
 				      &s->dev_master);
 	if (ret < 0)
 		goto fail_unlock;

 	ret = kvm_io_bus_register_dev(kvm, KVM_PIO_BUS, 0xa0, 2, &s->dev_slave);
 	if (ret < 0)
 		goto fail_unreg_2;

 	ret = kvm_io_bus_register_dev(kvm, KVM_PIO_BUS, 0x4d0, 2, &s->dev_eclr);
 	if (ret < 0)
 		goto fail_unreg_1;

 	mutex_unlock(&kvm->slots_lock);

 	return s;

 fail_unreg_1:
 	kvm_io_bus_unregister_dev(kvm, KVM_PIO_BUS, &s->dev_slave);

 fail_unreg_2:
 	kvm_io_bus_unregister_dev(kvm, KVM_PIO_BUS, &s->dev_master);

 fail_unlock:
 	mutex_unlock(&kvm->slots_lock);

 	kfree(s);

 	return NULL;
 }

 void kvm_destroy_pic(struct kvm *kvm)
 {
 	struct kvm_pic *vpic = kvm->arch.vpic;

 	if (vpic) {
 		kvm_io_bus_unregister_dev(kvm, KVM_PIO_BUS, &vpic->dev_master);
 		kvm_io_bus_unregister_dev(kvm, KVM_PIO_BUS, &vpic->dev_slave);
 		kvm_io_bus_unregister_dev(kvm, KVM_PIO_BUS, &vpic->dev_eclr);
 		kvm->arch.vpic = NULL;
 		kfree(vpic);
 	}
 }
	/*
	* 8259 interrupt controller emulation
	*
	* Copyright (c) 2003-2004 Fabrice Bellard
	* Copyright (c) 2007 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:
	* Yaozu (Eddie) Dong <Eddie.dong@intel.com>
	* Port from Qemu.
	*/
	#include <linux/mm.h>
	#include <linux/slab.h>
	#include <linux/bitops.h>
	#include "irq.h"

	#include <linux/kvm_host.h>
	#include "trace.h"

	#define pr_pic_unimpl(fmt, ...) \
	pr_err_ratelimited("kvm: pic: " fmt, ## __VA_ARGS__)

	static void pic_irq_request(struct kvm *kvm, int level);

	static void pic_lock(struct kvm_pic *s)
	__acquires(&s->lock)
	{
	spin_lock(&s->lock);
	}

	static void pic_unlock(struct kvm_pic *s)
	__releases(&s->lock)
	{
	bool wakeup = s->wakeup_needed;
	struct kvm_vcpu vcpu, found = NULL;
	int i;

	s->wakeup_needed = false;

	spin_unlock(&s->lock);

	if (wakeup) {
	kvm_for_each_vcpu(i, vcpu, s->kvm) {
	if (kvm_apic_accept_pic_intr(vcpu)) {
	found = vcpu;
	break;
	}
	}

	if (!found)
	return;

	kvm_make_request(KVM_REQ_EVENT, found);
	kvm_vcpu_kick(found);
	}
	}

	static void pic_clear_isr(struct kvm_kpic_state *s, int irq)
	{
	s->isr &= ~(1 << irq);
	if (s != &s->pics_state->pics[0])
	irq += 8;
	/*
	* We are dropping lock while calling ack notifiers since ack
	* notifier callbacks for assigned devices call into PIC recursively.
	* Other interrupt may be delivered to PIC while lock is dropped but
	* it should be safe since PIC state is already updated at this stage.
	*/
	pic_unlock(s->pics_state);
	kvm_notify_acked_irq(s->pics_state->kvm, SELECT_PIC(irq), irq);
	pic_lock(s->pics_state);
	}

	/*
	* set irq level. If an edge is detected, then the IRR is set to 1
	*/
	static inline int pic_set_irq1(struct kvm_kpic_state *s, int irq, int level)
	{
	int mask, ret = 1;
	mask = 1 << irq;
	if (s->elcr & mask) /* level triggered */
	if (level) {
	ret = !(s->irr & mask);
	s->irr \|= mask;
	s->last_irr \|= mask;
	} else {
	s->irr &= ~mask;
	s->last_irr &= ~mask;
	}
	else /* edge triggered */
	if (level) {
	if ((s->last_irr & mask) == 0) {
	ret = !(s->irr & mask);
	s->irr \|= mask;
	}
	s->last_irr \|= mask;
	} else
	s->last_irr &= ~mask;

	return (s->imr & mask) ? -1 : ret;
	}

	/*
	* return the highest priority found in mask (highest = smallest
	* number). Return 8 if no irq
	*/
	static inline int get_priority(struct kvm_kpic_state *s, int mask)
	{
	int priority;
	if (mask == 0)
	return 8;
	priority = 0;
	while ((mask & (1 << ((priority + s->priority_add) & 7))) == 0)
	priority++;
	return priority;
	}

	/*
	* return the pic wanted interrupt. return -1 if none
	*/
	static int pic_get_irq(struct kvm_kpic_state *s)
	{
	int mask, cur_priority, priority;

	mask = s->irr & ~s->imr;
	priority = get_priority(s, mask);
	if (priority == 8)
	return -1;
	/*
	* compute current priority. If special fully nested mode on the
	* master, the IRQ coming from the slave is not taken into account
	* for the priority computation.
	*/
	mask = s->isr;
	if (s->special_fully_nested_mode && s == &s->pics_state->pics[0])
	mask &= ~(1 << 2);
	cur_priority = get_priority(s, mask);
	if (priority < cur_priority)
	/*
	* higher priority found: an irq should be generated
	*/
	return (priority + s->priority_add) & 7;
	else
	return -1;
	}

	/*
	* raise irq to CPU if necessary. must be called every time the active
	* irq may change
	*/
	static void pic_update_irq(struct kvm_pic *s)
	{
	int irq2, irq;

	irq2 = pic_get_irq(&s->pics[1]);
	if (irq2 >= 0) {
	/*
	* if irq request by slave pic, signal master PIC
	*/
	pic_set_irq1(&s->pics[0], 2, 1);
	pic_set_irq1(&s->pics[0], 2, 0);
	}
	irq = pic_get_irq(&s->pics[0]);
	pic_irq_request(s->kvm, irq >= 0);
	}

	void kvm_pic_update_irq(struct kvm_pic *s)
	{
	pic_lock(s);
	pic_update_irq(s);
	pic_unlock(s);
	}

	int kvm_pic_set_irq(void *opaque, int irq, int level)
	{
	struct kvm_pic *s = opaque;
	int ret = -1;

	pic_lock(s);
	if (irq >= 0 && irq < PIC_NUM_PINS) {
	ret = pic_set_irq1(&s->pics[irq >> 3], irq & 7, level);
	pic_update_irq(s);
	trace_kvm_pic_set_irq(irq >> 3, irq & 7, s->pics[irq >> 3].elcr,
	s->pics[irq >> 3].imr, ret == 0);
	}
	pic_unlock(s);

	return ret;
	}

	/*
	* acknowledge interrupt 'irq'
	*/
	static inline void pic_intack(struct kvm_kpic_state *s, int irq)
	{
	s->isr \|= 1 << irq;
	/*
	* We don't clear a level sensitive interrupt here
	*/
	if (!(s->elcr & (1 << irq)))
	s->irr &= ~(1 << irq);

	if (s->auto_eoi) {
	if (s->rotate_on_auto_eoi)
	s->priority_add = (irq + 1) & 7;
	pic_clear_isr(s, irq);
	}

	}

	int kvm_pic_read_irq(struct kvm *kvm)
	{
	int irq, irq2, intno;
	struct kvm_pic *s = pic_irqchip(kvm);

	pic_lock(s);
	irq = pic_get_irq(&s->pics[0]);
	if (irq >= 0) {
	pic_intack(&s->pics[0], irq);
	if (irq == 2) {
	irq2 = pic_get_irq(&s->pics[1]);
	if (irq2 >= 0)
	pic_intack(&s->pics[1], irq2);
	else
	/*
	* spurious IRQ on slave controller
	*/
	irq2 = 7;
	intno = s->pics[1].irq_base + irq2;
	irq = irq2 + 8;
	} else
	intno = s->pics[0].irq_base + irq;
	} else {
	/*
	* spurious IRQ on host controller
	*/
	irq = 7;
	intno = s->pics[0].irq_base + irq;
	}
	pic_update_irq(s);
	pic_unlock(s);

	return intno;
	}

	void kvm_pic_reset(struct kvm_kpic_state *s)
	{
	int irq;
	struct kvm_vcpu *vcpu0 = s->pics_state->kvm->bsp_vcpu;
	u8 irr = s->irr, isr = s->imr;

	s->last_irr = 0;
	s->irr = 0;
	s->imr = 0;
	s->isr = 0;
	s->priority_add = 0;
	s->irq_base = 0;
	s->read_reg_select = 0;
	s->poll = 0;
	s->special_mask = 0;
	s->init_state = 0;
	s->auto_eoi = 0;
	s->rotate_on_auto_eoi = 0;
	s->special_fully_nested_mode = 0;
	s->init4 = 0;

	for (irq = 0; irq < PIC_NUM_PINS/2; irq++) {
	if (vcpu0 && kvm_apic_accept_pic_intr(vcpu0))
	if (irr & (1 << irq) \|\| isr & (1 << irq)) {
	pic_clear_isr(s, irq);
	}
	}
	}

	static void pic_ioport_write(void *opaque, u32 addr, u32 val)
	{
	struct kvm_kpic_state *s = opaque;
	int priority, cmd, irq;

	addr &= 1;
	if (addr == 0) {
	if (val & 0x10) {
	s->init4 = val & 1;
	s->last_irr = 0;
	s->imr = 0;
	s->priority_add = 0;
	s->special_mask = 0;
	s->read_reg_select = 0;
	if (!s->init4) {
	s->special_fully_nested_mode = 0;
	s->auto_eoi = 0;
	}
	s->init_state = 1;
	if (val & 0x02)
	pr_pic_unimpl("single mode not supported");
	if (val & 0x08)
	pr_pic_unimpl(
	"level sensitive irq not supported");
	} else if (val & 0x08) {
	if (val & 0x04)
	s->poll = 1;
	if (val & 0x02)
	s->read_reg_select = val & 1;
	if (val & 0x40)
	s->special_mask = (val >> 5) & 1;
	} else {
	cmd = val >> 5;
	switch (cmd) {
	case 0:
	case 4:
	s->rotate_on_auto_eoi = cmd >> 2;
	break;
	case 1: /* end of interrupt */
	case 5:
	priority = get_priority(s, s->isr);
	if (priority != 8) {
	irq = (priority + s->priority_add) & 7;
	if (cmd == 5)
	s->priority_add = (irq + 1) & 7;
	pic_clear_isr(s, irq);
	pic_update_irq(s->pics_state);
	}
	break;
	case 3:
	irq = val & 7;
	pic_clear_isr(s, irq);
	pic_update_irq(s->pics_state);
	break;
	case 6:
	s->priority_add = (val + 1) & 7;
	pic_update_irq(s->pics_state);
	break;
	case 7:
	irq = val & 7;
	s->priority_add = (irq + 1) & 7;
	pic_clear_isr(s, irq);
	pic_update_irq(s->pics_state);
	break;
	default:
	break; /* no operation */
	}
	}
	} else
	switch (s->init_state) {
	case 0: { /* normal mode */
	u8 imr_diff = s->imr ^ val,
	off = (s == &s->pics_state->pics[0]) ? 0 : 8;
	s->imr = val;
	for (irq = 0; irq < PIC_NUM_PINS/2; irq++)
	if (imr_diff & (1 << irq))
	kvm_fire_mask_notifiers(
	s->pics_state->kvm,
	SELECT_PIC(irq + off),
	irq + off,
	!!(s->imr & (1 << irq)));
	pic_update_irq(s->pics_state);
	break;
	}
	case 1:
	s->irq_base = val & 0xf8;
	s->init_state = 2;
	break;
	case 2:
	if (s->init4)
	s->init_state = 3;
	else
	s->init_state = 0;
	break;
	case 3:
	s->special_fully_nested_mode = (val >> 4) & 1;
	s->auto_eoi = (val >> 1) & 1;
	s->init_state = 0;
	break;
	}
	}

	static u32 pic_poll_read(struct kvm_kpic_state *s, u32 addr1)
	{
	int ret;

	ret = pic_get_irq(s);
	if (ret >= 0) {
	if (addr1 >> 7) {
	s->pics_state->pics[0].isr &= ~(1 << 2);
	s->pics_state->pics[0].irr &= ~(1 << 2);
	}
	s->irr &= ~(1 << ret);
	pic_clear_isr(s, ret);
	if (addr1 >> 7 \|\| ret != 2)
	pic_update_irq(s->pics_state);
	} else {
	ret = 0x07;
	pic_update_irq(s->pics_state);
	}

	return ret;
	}

	static u32 pic_ioport_read(void *opaque, u32 addr1)
	{
	struct kvm_kpic_state *s = opaque;
	unsigned int addr;
	int ret;

	addr = addr1;
	addr &= 1;
	if (s->poll) {
	ret = pic_poll_read(s, addr1);
	s->poll = 0;
	} else
	if (addr == 0)
	if (s->read_reg_select)
	ret = s->isr;
	else
	ret = s->irr;
	else
	ret = s->imr;
	return ret;
	}

	static void elcr_ioport_write(void *opaque, u32 addr, u32 val)
	{
	struct kvm_kpic_state *s = opaque;
	s->elcr = val & s->elcr_mask;
	}

	static u32 elcr_ioport_read(void *opaque, u32 addr1)
	{
	struct kvm_kpic_state *s = opaque;
	return s->elcr;
	}

	static int picdev_in_range(gpa_t addr)
	{
	switch (addr) {
	case 0x20:
	case 0x21:
	case 0xa0:
	case 0xa1:
	case 0x4d0:
	case 0x4d1:
	return 1;
	default:
	return 0;
	}
	}

	static int picdev_write(struct kvm_pic *s,
	gpa_t addr, int len, const void *val)
	{
	unsigned char data = (unsigned char )val;
	if (!picdev_in_range(addr))
	return -EOPNOTSUPP;

	if (len != 1) {
	pr_pic_unimpl("non byte write\n");
	return 0;
	}
	pic_lock(s);
	switch (addr) {
	case 0x20:
	case 0x21:
	case 0xa0:
	case 0xa1:
	pic_ioport_write(&s->pics[addr >> 7], addr, data);
	break;
	case 0x4d0:
	case 0x4d1:
	elcr_ioport_write(&s->pics[addr & 1], addr, data);
	break;
	}
	pic_unlock(s);
	return 0;
	}

	static int picdev_read(struct kvm_pic *s,
	gpa_t addr, int len, void *val)
	{
	unsigned char data = 0;
	if (!picdev_in_range(addr))
	return -EOPNOTSUPP;

	if (len != 1) {
	pr_pic_unimpl("non byte read\n");
	return 0;
	}
	pic_lock(s);
	switch (addr) {
	case 0x20:
	case 0x21:
	case 0xa0:
	case 0xa1:
	data = pic_ioport_read(&s->pics[addr >> 7], addr);
	break;
	case 0x4d0:
	case 0x4d1:
	data = elcr_ioport_read(&s->pics[addr & 1], addr);
	break;
	}
	(unsigned char )val = data;
	pic_unlock(s);
	return 0;
	}

	static int picdev_master_write(struct kvm_io_device *dev,
	gpa_t addr, int len, const void *val)
	{
	return picdev_write(container_of(dev, struct kvm_pic, dev_master),
	addr, len, val);
	}

	static int picdev_master_read(struct kvm_io_device *dev,
	gpa_t addr, int len, void *val)
	{
	return picdev_read(container_of(dev, struct kvm_pic, dev_master),
	addr, len, val);
	}

	static int picdev_slave_write(struct kvm_io_device *dev,
	gpa_t addr, int len, const void *val)
	{
	return picdev_write(container_of(dev, struct kvm_pic, dev_slave),
	addr, len, val);
	}

	static int picdev_slave_read(struct kvm_io_device *dev,
	gpa_t addr, int len, void *val)
	{
	return picdev_read(container_of(dev, struct kvm_pic, dev_slave),
	addr, len, val);
	}

	static int picdev_eclr_write(struct kvm_io_device *dev,
	gpa_t addr, int len, const void *val)
	{
	return picdev_write(container_of(dev, struct kvm_pic, dev_eclr),
	addr, len, val);
	}

	static int picdev_eclr_read(struct kvm_io_device *dev,
	gpa_t addr, int len, void *val)
	{
	return picdev_read(container_of(dev, struct kvm_pic, dev_eclr),
	addr, len, val);
	}

	/*
	* callback when PIC0 irq status changed
	*/
	static void pic_irq_request(struct kvm *kvm, int level)
	{
	struct kvm_pic *s = pic_irqchip(kvm);

	if (!s->output)
	s->wakeup_needed = true;
	s->output = level;
	}

	static const struct kvm_io_device_ops picdev_master_ops = {
	.read = picdev_master_read,
	.write = picdev_master_write,
	};

	static const struct kvm_io_device_ops picdev_slave_ops = {
	.read = picdev_slave_read,
	.write = picdev_slave_write,
	};

	static const struct kvm_io_device_ops picdev_eclr_ops = {
	.read = picdev_eclr_read,
	.write = picdev_eclr_write,
	};

	struct kvm_pic kvm_create_pic(struct kvm kvm)
	{
	struct kvm_pic *s;
	int ret;

	s = kzalloc(sizeof(struct kvm_pic), GFP_KERNEL);
	if (!s)
	return NULL;
	spin_lock_init(&s->lock);
	s->kvm = kvm;
	s->pics[0].elcr_mask = 0xf8;
	s->pics[1].elcr_mask = 0xde;
	s->pics[0].pics_state = s;
	s->pics[1].pics_state = s;

	/*
	* Initialize PIO device
	*/
	kvm_iodevice_init(&s->dev_master, &picdev_master_ops);
	kvm_iodevice_init(&s->dev_slave, &picdev_slave_ops);
	kvm_iodevice_init(&s->dev_eclr, &picdev_eclr_ops);
	mutex_lock(&kvm->slots_lock);
	ret = kvm_io_bus_register_dev(kvm, KVM_PIO_BUS, 0x20, 2,
	&s->dev_master);
	if (ret < 0)
	goto fail_unlock;

	ret = kvm_io_bus_register_dev(kvm, KVM_PIO_BUS, 0xa0, 2, &s->dev_slave);
	if (ret < 0)
	goto fail_unreg_2;

	ret = kvm_io_bus_register_dev(kvm, KVM_PIO_BUS, 0x4d0, 2, &s->dev_eclr);
	if (ret < 0)
	goto fail_unreg_1;

	mutex_unlock(&kvm->slots_lock);

	return s;

	fail_unreg_1:
	kvm_io_bus_unregister_dev(kvm, KVM_PIO_BUS, &s->dev_slave);

	fail_unreg_2:
	kvm_io_bus_unregister_dev(kvm, KVM_PIO_BUS, &s->dev_master);

	fail_unlock:
	mutex_unlock(&kvm->slots_lock);

	kfree(s);

	return NULL;
	}

	void kvm_destroy_pic(struct kvm *kvm)
	{
	struct kvm_pic *vpic = kvm->arch.vpic;

	if (vpic) {
	kvm_io_bus_unregister_dev(kvm, KVM_PIO_BUS, &vpic->dev_master);
	kvm_io_bus_unregister_dev(kvm, KVM_PIO_BUS, &vpic->dev_slave);
	kvm_io_bus_unregister_dev(kvm, KVM_PIO_BUS, &vpic->dev_eclr);
	kvm->arch.vpic = NULL;
	kfree(vpic);
	}
	}