/*
   * Copyright (C) 2012 ARM Ltd.
   * Author: Marc Zyngier <marc.zyngier@arm.com>
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License version 2 as
   * published by the Free Software Foundation.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program; if not, write to the Free Software
   * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
   */
  
  #include <linux/cpu.h>

  #include <linux/kvm.h>
  #include <linux/kvm_host.h>
  #include <linux/interrupt.h>

  #include <linux/irq.h>

  #include <linux/uaccess.h>

  #include <clocksource/arm_arch_timer.h>

  #include <asm/arch_timer.h>

  #include <asm/kvm_hyp.h>

  #include <kvm/arm_vgic.h>
  #include <kvm/arm_arch_timer.h>

  #include "trace.h"

  static struct timecounter *timecounter;

  static unsigned int host_vtimer_irq;

  static u32 host_vtimer_irq_flags;

  static const struct kvm_irq_level default_ptimer_irq = {
  	.irq	= 30,
  	.level	= 1,
  };
  
  static const struct kvm_irq_level default_vtimer_irq = {
  	.irq	= 27,
  	.level	= 1,
  };

  void kvm_timer_vcpu_put(struct kvm_vcpu *vcpu)
  {

  	vcpu_vtimer(vcpu)->active_cleared_last = false;

  }

  u64 kvm_phys_timer_read(void)

  {
  	return timecounter->cc->read(timecounter->cc);
  }
  
  static bool timer_is_armed(struct arch_timer_cpu *timer)
  {
  	return timer->armed;
  }
  
  /* timer_arm: as in "arm the timer", not as in ARM the company */
  static void timer_arm(struct arch_timer_cpu *timer, u64 ns)
  {
  	timer->armed = true;
  	hrtimer_start(&timer->timer, ktime_add_ns(ktime_get(), ns),
  		      HRTIMER_MODE_ABS);
  }
  
  static void timer_disarm(struct arch_timer_cpu *timer)
  {
  	if (timer_is_armed(timer)) {
  		hrtimer_cancel(&timer->timer);
  		cancel_work_sync(&timer->expired);
  		timer->armed = false;
  	}
  }

  static irqreturn_t kvm_arch_timer_handler(int irq, void *dev_id)
  {
  	struct kvm_vcpu *vcpu = *(struct kvm_vcpu **)dev_id;
  
  	/*
  	 * We disable the timer in the world switch and let it be
  	 * handled by kvm_timer_sync_hwstate(). Getting a timer
  	 * interrupt at this point is a sure sign of some major
  	 * breakage.
  	 */
  	pr_warn("Unexpected interrupt %d on vcpu %p
  ", irq, vcpu);
  	return IRQ_HANDLED;
  }

  /*
   * Work function for handling the backup timer that we schedule when a vcpu is
   * no longer running, but had a timer programmed to fire in the future.
   */

  static void kvm_timer_inject_irq_work(struct work_struct *work)
  {
  	struct kvm_vcpu *vcpu;
  
  	vcpu = container_of(work, struct kvm_vcpu, arch.timer_cpu.expired);

  	/*
  	 * If the vcpu is blocked we want to wake it up so that it will see
  	 * the timer has expired when entering the guest.
  	 */

  	kvm_vcpu_wake_up(vcpu);

  }

  static u64 kvm_timer_compute_delta(struct arch_timer_context *timer_ctx)

  {

  	u64 cval, now;

  	cval = timer_ctx->cnt_cval;
  	now = kvm_phys_timer_read() - timer_ctx->cntvoff;

  
  	if (now < cval) {
  		u64 ns;
  
  		ns = cyclecounter_cyc2ns(timecounter->cc,
  					 cval - now,
  					 timecounter->mask,
  					 &timecounter->frac);
  		return ns;
  	}
  
  	return 0;
  }

  static bool kvm_timer_irq_can_fire(struct arch_timer_context *timer_ctx)
  {
  	return !(timer_ctx->cnt_ctl & ARCH_TIMER_CTRL_IT_MASK) &&
  		(timer_ctx->cnt_ctl & ARCH_TIMER_CTRL_ENABLE);
  }
  
  /*
   * Returns the earliest expiration time in ns among guest timers.
   * Note that it will return 0 if none of timers can fire.
   */
  static u64 kvm_timer_earliest_exp(struct kvm_vcpu *vcpu)
  {
  	u64 min_virt = ULLONG_MAX, min_phys = ULLONG_MAX;
  	struct arch_timer_context *vtimer = vcpu_vtimer(vcpu);
  	struct arch_timer_context *ptimer = vcpu_ptimer(vcpu);
  
  	if (kvm_timer_irq_can_fire(vtimer))
  		min_virt = kvm_timer_compute_delta(vtimer);
  
  	if (kvm_timer_irq_can_fire(ptimer))
  		min_phys = kvm_timer_compute_delta(ptimer);
  
  	/* If none of timers can fire, then return 0 */
  	if ((min_virt == ULLONG_MAX) && (min_phys == ULLONG_MAX))
  		return 0;
  
  	return min(min_virt, min_phys);
  }

  static enum hrtimer_restart kvm_timer_expire(struct hrtimer *hrt)
  {
  	struct arch_timer_cpu *timer;

  	struct kvm_vcpu *vcpu;
  	u64 ns;

  	timer = container_of(hrt, struct arch_timer_cpu, timer);

  	vcpu = container_of(timer, struct kvm_vcpu, arch.timer_cpu);
  
  	/*
  	 * Check that the timer has really expired from the guest's
  	 * PoV (NTP on the host may have forced it to expire
  	 * early). If we should have slept longer, restart it.
  	 */

  	ns = kvm_timer_earliest_exp(vcpu);

  	if (unlikely(ns)) {
  		hrtimer_forward_now(hrt, ns_to_ktime(ns));
  		return HRTIMER_RESTART;
  	}

  	schedule_work(&timer->expired);

  	return HRTIMER_NORESTART;
  }

  bool kvm_timer_should_fire(struct arch_timer_context *timer_ctx)

  {

  	u64 cval, now;

  	if (!kvm_timer_irq_can_fire(timer_ctx))

  		return false;

  	cval = timer_ctx->cnt_cval;
  	now = kvm_phys_timer_read() - timer_ctx->cntvoff;

  
  	return cval <= now;
  }

  /*
   * Reflect the timer output level into the kvm_run structure
   */
  void kvm_timer_update_run(struct kvm_vcpu *vcpu)
  {
  	struct arch_timer_context *vtimer = vcpu_vtimer(vcpu);
  	struct arch_timer_context *ptimer = vcpu_ptimer(vcpu);
  	struct kvm_sync_regs *regs = &vcpu->run->s.regs;

  	/* Populate the device bitmap with the timer states */
  	regs->device_irq_level &= ~(KVM_ARM_DEV_EL1_VTIMER |
  				    KVM_ARM_DEV_EL1_PTIMER);
  	if (vtimer->irq.level)
  		regs->device_irq_level |= KVM_ARM_DEV_EL1_VTIMER;
  	if (ptimer->irq.level)
  		regs->device_irq_level |= KVM_ARM_DEV_EL1_PTIMER;
  }

  static void kvm_timer_update_irq(struct kvm_vcpu *vcpu, bool new_level,
  				 struct arch_timer_context *timer_ctx)

  {
  	int ret;

  	timer_ctx->active_cleared_last = false;
  	timer_ctx->irq.level = new_level;
  	trace_kvm_timer_update_irq(vcpu->vcpu_id, timer_ctx->irq.irq,
  				   timer_ctx->irq.level);

  	if (likely(irqchip_in_kernel(vcpu->kvm))) {
  		ret = kvm_vgic_inject_irq(vcpu->kvm, vcpu->vcpu_id,
  					  timer_ctx->irq.irq,

  					  timer_ctx->irq.level,
  					  timer_ctx);

  		WARN_ON(ret);
  	}

  }
  
  /*
   * Check if there was a change in the timer state (should we raise or lower
   * the line level to the GIC).
   */

  static void kvm_timer_update_state(struct kvm_vcpu *vcpu)

  {
  	struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;

  	struct arch_timer_context *vtimer = vcpu_vtimer(vcpu);

  	struct arch_timer_context *ptimer = vcpu_ptimer(vcpu);

  
  	/*
  	 * If userspace modified the timer registers via SET_ONE_REG before

  	 * the vgic was initialized, we mustn't set the vtimer->irq.level value

  	 * because the guest would never see the interrupt.  Instead wait
  	 * until we call this function from kvm_timer_flush_hwstate.
  	 */

  	if (unlikely(!timer->enabled))

  		return;

  	if (kvm_timer_should_fire(vtimer) != vtimer->irq.level)
  		kvm_timer_update_irq(vcpu, !vtimer->irq.level, vtimer);

  	if (kvm_timer_should_fire(ptimer) != ptimer->irq.level)
  		kvm_timer_update_irq(vcpu, !ptimer->irq.level, ptimer);

  }

  /* Schedule the background timer for the emulated timer. */
  static void kvm_timer_emulate(struct kvm_vcpu *vcpu,
  			      struct arch_timer_context *timer_ctx)
  {
  	struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
  
  	if (kvm_timer_should_fire(timer_ctx))
  		return;
  
  	if (!kvm_timer_irq_can_fire(timer_ctx))
  		return;
  
  	/*  The timer has not yet expired, schedule a background timer */
  	timer_arm(timer, kvm_timer_compute_delta(timer_ctx));
  }

  /*
   * Schedule the background timer before calling kvm_vcpu_block, so that this
   * thread is removed from its waitqueue and made runnable when there's a timer
   * interrupt to handle.
   */
  void kvm_timer_schedule(struct kvm_vcpu *vcpu)
  {
  	struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;

  	struct arch_timer_context *vtimer = vcpu_vtimer(vcpu);

  	struct arch_timer_context *ptimer = vcpu_ptimer(vcpu);

  
  	BUG_ON(timer_is_armed(timer));
  
  	/*

  	 * No need to schedule a background timer if any guest timer has

  	 * already expired, because kvm_vcpu_block will return before putting
  	 * the thread to sleep.
  	 */

  	if (kvm_timer_should_fire(vtimer) || kvm_timer_should_fire(ptimer))

  		return;
  
  	/*

  	 * If both timers are not capable of raising interrupts (disabled or

  	 * masked), then there's no more work for us to do.
  	 */

  	if (!kvm_timer_irq_can_fire(vtimer) && !kvm_timer_irq_can_fire(ptimer))

  		return;

  	/*
  	 * The guest timers have not yet expired, schedule a background timer.
  	 * Set the earliest expiration time among the guest timers.
  	 */
  	timer_arm(timer, kvm_timer_earliest_exp(vcpu));

  }
  
  void kvm_timer_unschedule(struct kvm_vcpu *vcpu)
  {
  	struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
  	timer_disarm(timer);
  }

  static void kvm_timer_flush_hwstate_vgic(struct kvm_vcpu *vcpu)

  {

  	struct arch_timer_context *vtimer = vcpu_vtimer(vcpu);

  	bool phys_active;
  	int ret;

  	/*

  	* If we enter the guest with the virtual input level to the VGIC
  	* asserted, then we have already told the VGIC what we need to, and
  	* we don't need to exit from the guest until the guest deactivates
  	* the already injected interrupt, so therefore we should set the
  	* hardware active state to prevent unnecessary exits from the guest.
  	*
  	* Also, if we enter the guest with the virtual timer interrupt active,
  	* then it must be active on the physical distributor, because we set
  	* the HW bit and the guest must be able to deactivate the virtual and
  	* physical interrupt at the same time.
  	*
  	* Conversely, if the virtual input level is deasserted and the virtual
  	* interrupt is not active, then always clear the hardware active state
  	* to ensure that hardware interrupts from the timer triggers a guest
  	* exit.
  	*/

  	phys_active = vtimer->irq.level ||
  			kvm_vgic_map_is_active(vcpu, vtimer->irq.irq);

  	/*
  	 * We want to avoid hitting the (re)distributor as much as
  	 * possible, as this is a potentially expensive MMIO access
  	 * (not to mention locks in the irq layer), and a solution for
  	 * this is to cache the "active" state in memory.
  	 *
  	 * Things to consider: we cannot cache an "active set" state,
  	 * because the HW can change this behind our back (it becomes
  	 * "clear" in the HW). We must then restrict the caching to
  	 * the "clear" state.
  	 *
  	 * The cache is invalidated on:
  	 * - vcpu put, indicating that the HW cannot be trusted to be
  	 *   in a sane state on the next vcpu load,
  	 * - any change in the interrupt state
  	 *
  	 * Usage conditions:
  	 * - cached value is "active clear"
  	 * - value to be programmed is "active clear"
  	 */

  	if (vtimer->active_cleared_last && !phys_active)

  		return;

  	ret = irq_set_irqchip_state(host_vtimer_irq,

  				    IRQCHIP_STATE_ACTIVE,
  				    phys_active);
  	WARN_ON(ret);

  	vtimer->active_cleared_last = !phys_active;

  }

  bool kvm_timer_should_notify_user(struct kvm_vcpu *vcpu)
  {
  	struct arch_timer_context *vtimer = vcpu_vtimer(vcpu);
  	struct arch_timer_context *ptimer = vcpu_ptimer(vcpu);
  	struct kvm_sync_regs *sregs = &vcpu->run->s.regs;
  	bool vlevel, plevel;
  
  	if (likely(irqchip_in_kernel(vcpu->kvm)))
  		return false;
  
  	vlevel = sregs->device_irq_level & KVM_ARM_DEV_EL1_VTIMER;
  	plevel = sregs->device_irq_level & KVM_ARM_DEV_EL1_PTIMER;
  
  	return vtimer->irq.level != vlevel ||
  	       ptimer->irq.level != plevel;
  }
  
  static void kvm_timer_flush_hwstate_user(struct kvm_vcpu *vcpu)
  {
  	struct arch_timer_context *vtimer = vcpu_vtimer(vcpu);
  
  	/*
  	 * To prevent continuously exiting from the guest, we mask the
  	 * physical interrupt such that the guest can make forward progress.
  	 * Once we detect the output level being deasserted, we unmask the
  	 * interrupt again so that we exit from the guest when the timer
  	 * fires.
  	*/
  	if (vtimer->irq.level)
  		disable_percpu_irq(host_vtimer_irq);
  	else
  		enable_percpu_irq(host_vtimer_irq, 0);
  }
  
  /**
   * kvm_timer_flush_hwstate - prepare timers before running the vcpu
   * @vcpu: The vcpu pointer
   *
   * Check if the virtual timer has expired while we were running in the host,
   * and inject an interrupt if that was the case, making sure the timer is
   * masked or disabled on the host so that we keep executing.  Also schedule a
   * software timer for the physical timer if it is enabled.
   */
  void kvm_timer_flush_hwstate(struct kvm_vcpu *vcpu)
  {
  	struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
  
  	if (unlikely(!timer->enabled))
  		return;
  
  	kvm_timer_update_state(vcpu);
  
  	/* Set the background timer for the physical timer emulation. */
  	kvm_timer_emulate(vcpu, vcpu_ptimer(vcpu));
  
  	if (unlikely(!irqchip_in_kernel(vcpu->kvm)))
  		kvm_timer_flush_hwstate_user(vcpu);
  	else
  		kvm_timer_flush_hwstate_vgic(vcpu);
  }

  /**
   * kvm_timer_sync_hwstate - sync timer state from cpu
   * @vcpu: The vcpu pointer
   *

   * Check if any of the timers have expired while we were running in the guest,

   * and inject an interrupt if that was the case.

   */
  void kvm_timer_sync_hwstate(struct kvm_vcpu *vcpu)
  {
  	struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;

  	/*
  	 * This is to cancel the background timer for the physical timer
  	 * emulation if it is set.
  	 */
  	timer_disarm(timer);

  	/*
  	 * The guest could have modified the timer registers or the timer
  	 * could have expired, update the timer state.
  	 */
  	kvm_timer_update_state(vcpu);

  }

  int kvm_timer_vcpu_reset(struct kvm_vcpu *vcpu)

  {

  	struct arch_timer_context *vtimer = vcpu_vtimer(vcpu);

  	struct arch_timer_context *ptimer = vcpu_ptimer(vcpu);

  
  	/*

  	 * The bits in CNTV_CTL are architecturally reset to UNKNOWN for ARMv8
  	 * and to 0 for ARMv7.  We provide an implementation that always
  	 * resets the timer to be disabled and unmasked and is compliant with
  	 * the ARMv7 architecture.
  	 */

  	vtimer->cnt_ctl = 0;

  	ptimer->cnt_ctl = 0;

  	kvm_timer_update_state(vcpu);

  	return 0;

  }

  /* Make the updates of cntvoff for all vtimer contexts atomic */
  static void update_vtimer_cntvoff(struct kvm_vcpu *vcpu, u64 cntvoff)
  {
  	int i;
  	struct kvm *kvm = vcpu->kvm;
  	struct kvm_vcpu *tmp;
  
  	mutex_lock(&kvm->lock);
  	kvm_for_each_vcpu(i, tmp, kvm)
  		vcpu_vtimer(tmp)->cntvoff = cntvoff;
  
  	/*
  	 * When called from the vcpu create path, the CPU being created is not
  	 * included in the loop above, so we just set it here as well.
  	 */
  	vcpu_vtimer(vcpu)->cntvoff = cntvoff;
  	mutex_unlock(&kvm->lock);
  }

  void kvm_timer_vcpu_init(struct kvm_vcpu *vcpu)
  {
  	struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;

  	struct arch_timer_context *vtimer = vcpu_vtimer(vcpu);
  	struct arch_timer_context *ptimer = vcpu_ptimer(vcpu);

  	/* Synchronize cntvoff across all vtimers of a VM. */
  	update_vtimer_cntvoff(vcpu, kvm_phys_timer_read());

  	vcpu_ptimer(vcpu)->cntvoff = 0;

  	INIT_WORK(&timer->expired, kvm_timer_inject_irq_work);
  	hrtimer_init(&timer->timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
  	timer->timer.function = kvm_timer_expire;

  
  	vtimer->irq.irq = default_vtimer_irq.irq;
  	ptimer->irq.irq = default_ptimer_irq.irq;

  }
  
  static void kvm_timer_init_interrupt(void *info)
  {

  	enable_percpu_irq(host_vtimer_irq, host_vtimer_irq_flags);

  }

  int kvm_arm_timer_set_reg(struct kvm_vcpu *vcpu, u64 regid, u64 value)
  {

  	struct arch_timer_context *vtimer = vcpu_vtimer(vcpu);

  
  	switch (regid) {
  	case KVM_REG_ARM_TIMER_CTL:

  		vtimer->cnt_ctl = value;

  		break;
  	case KVM_REG_ARM_TIMER_CNT:

  		update_vtimer_cntvoff(vcpu, kvm_phys_timer_read() - value);

  		break;
  	case KVM_REG_ARM_TIMER_CVAL:

  		vtimer->cnt_cval = value;

  		break;
  	default:
  		return -1;
  	}

  
  	kvm_timer_update_state(vcpu);

  	return 0;
  }
  
  u64 kvm_arm_timer_get_reg(struct kvm_vcpu *vcpu, u64 regid)
  {

  	struct arch_timer_context *vtimer = vcpu_vtimer(vcpu);

  
  	switch (regid) {
  	case KVM_REG_ARM_TIMER_CTL:

  		return vtimer->cnt_ctl;

  	case KVM_REG_ARM_TIMER_CNT:

  		return kvm_phys_timer_read() - vtimer->cntvoff;

  	case KVM_REG_ARM_TIMER_CVAL:

  		return vtimer->cnt_cval;

  	}
  	return (u64)-1;
  }

  static int kvm_timer_starting_cpu(unsigned int cpu)

  {

  	kvm_timer_init_interrupt(NULL);
  	return 0;

  }

  static int kvm_timer_dying_cpu(unsigned int cpu)
  {
  	disable_percpu_irq(host_vtimer_irq);
  	return 0;
  }

  int kvm_timer_hyp_init(void)
  {

  	struct arch_timer_kvm_info *info;

  	int err;

  	info = arch_timer_get_kvm_info();
  	timecounter = &info->timecounter;

  	if (!timecounter->cc) {
  		kvm_err("kvm_arch_timer: uninitialized timecounter
  ");
  		return -ENODEV;
  	}

  	if (info->virtual_irq <= 0) {
  		kvm_err("kvm_arch_timer: invalid virtual timer IRQ: %d
  ",
  			info->virtual_irq);

  		return -ENODEV;
  	}

  	host_vtimer_irq = info->virtual_irq;

  	host_vtimer_irq_flags = irq_get_trigger_type(host_vtimer_irq);
  	if (host_vtimer_irq_flags != IRQF_TRIGGER_HIGH &&
  	    host_vtimer_irq_flags != IRQF_TRIGGER_LOW) {
  		kvm_err("Invalid trigger for IRQ%d, assuming level low
  ",
  			host_vtimer_irq);
  		host_vtimer_irq_flags = IRQF_TRIGGER_LOW;
  	}

  	err = request_percpu_irq(host_vtimer_irq, kvm_arch_timer_handler,

  				 "kvm guest timer", kvm_get_running_vcpus());
  	if (err) {
  		kvm_err("kvm_arch_timer: can't request interrupt %d (%d)
  ",

  			host_vtimer_irq, err);

  		return err;

  	}

  	kvm_debug("virtual timer IRQ%d
  ", host_vtimer_irq);

  	cpuhp_setup_state(CPUHP_AP_KVM_ARM_TIMER_STARTING,

  			  "kvm/arm/timer:starting", kvm_timer_starting_cpu,

  			  kvm_timer_dying_cpu);

  	return err;
  }
  
  void kvm_timer_vcpu_terminate(struct kvm_vcpu *vcpu)
  {
  	struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;

  	struct arch_timer_context *vtimer = vcpu_vtimer(vcpu);

  
  	timer_disarm(timer);

  	kvm_vgic_unmap_phys_irq(vcpu, vtimer->irq.irq);

  }

  static bool timer_irqs_are_valid(struct kvm_vcpu *vcpu)

  {

  	int vtimer_irq, ptimer_irq;

  	int i, ret;

  	vtimer_irq = vcpu_vtimer(vcpu)->irq.irq;

  	ret = kvm_vgic_set_owner(vcpu, vtimer_irq, vcpu_vtimer(vcpu));
  	if (ret)
  		return false;

  	ptimer_irq = vcpu_ptimer(vcpu)->irq.irq;
  	ret = kvm_vgic_set_owner(vcpu, ptimer_irq, vcpu_ptimer(vcpu));
  	if (ret)

  		return false;

  	kvm_for_each_vcpu(i, vcpu, vcpu->kvm) {

  		if (vcpu_vtimer(vcpu)->irq.irq != vtimer_irq ||
  		    vcpu_ptimer(vcpu)->irq.irq != ptimer_irq)
  			return false;
  	}
  
  	return true;
  }

  int kvm_timer_enable(struct kvm_vcpu *vcpu)

  {

  	struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;

  	struct arch_timer_context *vtimer = vcpu_vtimer(vcpu);

  	struct irq_desc *desc;
  	struct irq_data *data;
  	int phys_irq;
  	int ret;
  
  	if (timer->enabled)
  		return 0;

  	/* Without a VGIC we do not map virtual IRQs to physical IRQs */
  	if (!irqchip_in_kernel(vcpu->kvm))
  		goto no_vgic;
  
  	if (!vgic_initialized(vcpu->kvm))
  		return -ENODEV;

  	if (!timer_irqs_are_valid(vcpu)) {

  		kvm_debug("incorrectly configured timer irqs
  ");
  		return -EINVAL;
  	}

  	/*
  	 * Find the physical IRQ number corresponding to the host_vtimer_irq
  	 */
  	desc = irq_to_desc(host_vtimer_irq);
  	if (!desc) {
  		kvm_err("%s: no interrupt descriptor
  ", __func__);
  		return -EINVAL;
  	}
  
  	data = irq_desc_get_irq_data(desc);
  	while (data->parent_data)
  		data = data->parent_data;
  
  	phys_irq = data->hwirq;
  
  	/*
  	 * Tell the VGIC that the virtual interrupt is tied to a
  	 * physical interrupt. We do that once per VCPU.
  	 */

  	ret = kvm_vgic_map_phys_irq(vcpu, vtimer->irq.irq, phys_irq);

  	if (ret)
  		return ret;

  no_vgic:

  	timer->enabled = 1;

  	return 0;

  }

  /*
   * On VHE system, we only need to configure trap on physical timer and counter
   * accesses in EL0 and EL1 once, not for every world switch.
   * The host kernel runs at EL2 with HCR_EL2.TGE == 1,
   * and this makes those bits have no effect for the host kernel execution.
   */
  void kvm_timer_init_vhe(void)
  {
  	/* When HCR_EL2.E2H ==1, EL1PCEN and EL1PCTEN are shifted by 10 */
  	u32 cnthctl_shift = 10;
  	u64 val;
  
  	/*
  	 * Disallow physical timer access for the guest.
  	 * Physical counter access is allowed.
  	 */
  	val = read_sysreg(cnthctl_el2);
  	val &= ~(CNTHCTL_EL1PCEN << cnthctl_shift);
  	val |= (CNTHCTL_EL1PCTEN << cnthctl_shift);
  	write_sysreg(val, cnthctl_el2);
  }

  
  static void set_timer_irqs(struct kvm *kvm, int vtimer_irq, int ptimer_irq)
  {
  	struct kvm_vcpu *vcpu;
  	int i;
  
  	kvm_for_each_vcpu(i, vcpu, kvm) {
  		vcpu_vtimer(vcpu)->irq.irq = vtimer_irq;
  		vcpu_ptimer(vcpu)->irq.irq = ptimer_irq;
  	}
  }
  
  int kvm_arm_timer_set_attr(struct kvm_vcpu *vcpu, struct kvm_device_attr *attr)
  {
  	int __user *uaddr = (int __user *)(long)attr->addr;
  	struct arch_timer_context *vtimer = vcpu_vtimer(vcpu);
  	struct arch_timer_context *ptimer = vcpu_ptimer(vcpu);
  	int irq;
  
  	if (!irqchip_in_kernel(vcpu->kvm))
  		return -EINVAL;
  
  	if (get_user(irq, uaddr))
  		return -EFAULT;
  
  	if (!(irq_is_ppi(irq)))
  		return -EINVAL;
  
  	if (vcpu->arch.timer_cpu.enabled)
  		return -EBUSY;
  
  	switch (attr->attr) {
  	case KVM_ARM_VCPU_TIMER_IRQ_VTIMER:
  		set_timer_irqs(vcpu->kvm, irq, ptimer->irq.irq);
  		break;
  	case KVM_ARM_VCPU_TIMER_IRQ_PTIMER:
  		set_timer_irqs(vcpu->kvm, vtimer->irq.irq, irq);
  		break;
  	default:
  		return -ENXIO;
  	}
  
  	return 0;
  }
  
  int kvm_arm_timer_get_attr(struct kvm_vcpu *vcpu, struct kvm_device_attr *attr)
  {
  	int __user *uaddr = (int __user *)(long)attr->addr;
  	struct arch_timer_context *timer;
  	int irq;
  
  	switch (attr->attr) {
  	case KVM_ARM_VCPU_TIMER_IRQ_VTIMER:
  		timer = vcpu_vtimer(vcpu);
  		break;
  	case KVM_ARM_VCPU_TIMER_IRQ_PTIMER:
  		timer = vcpu_ptimer(vcpu);
  		break;
  	default:
  		return -ENXIO;
  	}
  
  	irq = timer->irq.irq;
  	return put_user(irq, uaddr);
  }
  
  int kvm_arm_timer_has_attr(struct kvm_vcpu *vcpu, struct kvm_device_attr *attr)
  {
  	switch (attr->attr) {
  	case KVM_ARM_VCPU_TIMER_IRQ_VTIMER:
  	case KVM_ARM_VCPU_TIMER_IRQ_PTIMER:
  		return 0;
  	}
  
  	return -ENXIO;
  }