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Commit fb280e97 authored by Jintack Lim's avatar Jintack Lim Committed by Marc Zyngier
Browse files

KVM: arm/arm64: Set a background timer to the earliest timer expiration 



When scheduling a background timer, consider both of the virtual and
physical timer and pick the earliest expiration time.

Signed-off-by: default avatarJintack Lim <jintack@cs.columbia.edu>
Reviewed-by: default avatarChristoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: default avatarMarc Zyngier <marc.zyngier@arm.com>
parent 58e0c973

arch/arm/kvm/arm.c

+2 −1
Original line number Original line Diff line number Diff line
@@ -300,7 +300,8 @@ void kvm_arch_vcpu_destroy(struct kvm_vcpu *vcpu) 




int kvm_cpu_has_pending_timer(struct kvm_vcpu *vcpu)

int kvm_cpu_has_pending_timer(struct kvm_vcpu *vcpu)

{

{

	return kvm_timer_should_fire(vcpu_vtimer(vcpu));

	return kvm_timer_should_fire(vcpu_vtimer(vcpu)) ||

	       kvm_timer_should_fire(vcpu_ptimer(vcpu));

}

}





void kvm_arch_vcpu_blocking(struct kvm_vcpu *vcpu)

void kvm_arch_vcpu_blocking(struct kvm_vcpu *vcpu)

virt/kvm/arm/arch_timer.c

+40 −13
Original line number Original line Diff line number Diff line
@@ -118,6 +118,35 @@ static u64 kvm_timer_compute_delta(struct arch_timer_context *timer_ctx) 
	return 0;

	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)

static enum hrtimer_restart kvm_timer_expire(struct hrtimer *hrt)

{

{

	struct arch_timer_cpu *timer;

	struct arch_timer_cpu *timer;
@@ -132,7 +161,7 @@ static enum hrtimer_restart kvm_timer_expire(struct hrtimer *hrt) 
	 * PoV (NTP on the host may have forced it to expire

	 * PoV (NTP on the host may have forced it to expire

	 * early). If we should have slept longer, restart it.

	 * early). If we should have slept longer, restart it.

	 */

	 */

	ns = kvm_timer_compute_delta(vcpu_vtimer(vcpu));

	ns = kvm_timer_earliest_exp(vcpu);

	if (unlikely(ns)) {

	if (unlikely(ns)) {

		hrtimer_forward_now(hrt, ns_to_ktime(ns));

		hrtimer_forward_now(hrt, ns_to_ktime(ns));

		return HRTIMER_RESTART;

		return HRTIMER_RESTART;
@@ -142,12 +171,6 @@ static enum hrtimer_restart kvm_timer_expire(struct hrtimer *hrt) 
	return HRTIMER_NORESTART;

	return HRTIMER_NORESTART;

}

}





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);

}



bool kvm_timer_should_fire(struct arch_timer_context *timer_ctx)

bool kvm_timer_should_fire(struct arch_timer_context *timer_ctx)

{

{

	u64 cval, now;

	u64 cval, now;
@@ -215,26 +238,30 @@ void kvm_timer_schedule(struct kvm_vcpu *vcpu) 
{

{

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

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

	struct arch_timer_context *vtimer = vcpu_vtimer(vcpu);

	struct arch_timer_context *vtimer = vcpu_vtimer(vcpu);

	struct arch_timer_context *ptimer = vcpu_ptimer(vcpu);





	BUG_ON(timer_is_armed(timer));

	BUG_ON(timer_is_armed(timer));





	/*

	/*

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

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

	 * already expired, because kvm_vcpu_block will return before putting

	 * already expired, because kvm_vcpu_block will return before putting

	 * the thread to sleep.

	 * the thread to sleep.

	 */

	 */

	if (kvm_timer_should_fire(vtimer))

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

		return;

		return;





	/*

	/*

	 * If the timer is not capable of raising interrupts (disabled or

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

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

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

	 */

	 */

	if (!kvm_timer_irq_can_fire(vtimer))

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

		return;

		return;





	/*  The timer has not yet expired, schedule a background timer */

	/*

	timer_arm(timer, kvm_timer_compute_delta(vtimer));

	 * 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)

void kvm_timer_unschedule(struct kvm_vcpu *vcpu)