[PATCH v3 07/20] KVM: arm/arm64: Make timer_arm and timer_disarm helpers more generic

[Marc Zyngier]

On 23/09/17 01:41, Christoffer Dall wrote:
> We are about to add an additional soft timer to the arch timer state for
> a VCPU and would like to be able to reuse the functions to program and
> cancel a timer, so we make them slightly more generic and rename to make
> it more clear that these functions work on soft timers and not the
> hardware resource that this code is managing.
> 
> Signed-off-by: Christoffer Dall <cdall at linaro.org>
> ---
>  virt/kvm/arm/arch_timer.c | 33 ++++++++++++++++-----------------
>  1 file changed, 16 insertions(+), 17 deletions(-)
> 
> diff --git a/virt/kvm/arm/arch_timer.c b/virt/kvm/arm/arch_timer.c
> index 8e89d63..871d8ae 100644
> --- a/virt/kvm/arm/arch_timer.c
> +++ b/virt/kvm/arm/arch_timer.c
> @@ -56,26 +56,22 @@ u64 kvm_phys_timer_read(void)
>  	return timecounter->cc->read(timecounter->cc);
>  }
>  
> -static bool timer_is_armed(struct arch_timer_cpu *timer)
> +static bool soft_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)
> +static void soft_timer_start(struct hrtimer *hrt, u64 ns)
>  {
> -	timer->armed = true;
> -	hrtimer_start(&timer->timer, ktime_add_ns(ktime_get(), ns),
> +	hrtimer_start(hrt, ktime_add_ns(ktime_get(), ns),
>  		      HRTIMER_MODE_ABS);
>  }
>  
> -static void timer_disarm(struct arch_timer_cpu *timer)
> +static void soft_timer_cancel(struct hrtimer *hrt, struct work_struct *work)
>  {
> -	if (timer_is_armed(timer)) {
> -		hrtimer_cancel(&timer->timer);
> -		cancel_work_sync(&timer->expired);
> -		timer->armed = false;
> -	}
> +	hrtimer_cancel(hrt);
> +	if (work)

When can this happen? Something in a following patch?

> +		cancel_work_sync(work);
>  }
>  
>  static irqreturn_t kvm_arch_timer_handler(int irq, void *dev_id)
> @@ -271,7 +267,7 @@ static void kvm_timer_emulate(struct kvm_vcpu *vcpu,
>  		return;
>  
>  	/*  The timer has not yet expired, schedule a background timer */
> -	timer_arm(timer, kvm_timer_compute_delta(timer_ctx));
> +	soft_timer_start(&timer->timer, kvm_timer_compute_delta(timer_ctx));
>  }
>  
>  /*
> @@ -285,7 +281,7 @@ void kvm_timer_schedule(struct kvm_vcpu *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(soft_timer_is_armed(timer));
>  
>  	/*
>  	 * No need to schedule a background timer if any guest timer has
> @@ -306,13 +302,16 @@ void kvm_timer_schedule(struct kvm_vcpu *vcpu)
>  	 * 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));
> +	timer->armed = true;
> +	soft_timer_start(&timer->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);
> +
> +	soft_timer_cancel(&timer->timer, &timer->expired);
> +	timer->armed = false;
>  }
>  
>  static void kvm_timer_flush_hwstate_vgic(struct kvm_vcpu *vcpu)
> @@ -448,7 +447,7 @@ void kvm_timer_sync_hwstate(struct kvm_vcpu *vcpu)
>  	 * This is to cancel the background timer for the physical timer
>  	 * emulation if it is set.
>  	 */
> -	timer_disarm(timer);
> +	soft_timer_cancel(&timer->timer, &timer->expired);

timer_disarm() used to set timer->armed to false, but that's not the
case any more. Don't we risk hitting the BUG_ON() in kvm_timer_schedule
if we hit WFI?

>  
>  	/*
>  	 * The guest could have modified the timer registers or the timer
> @@ -615,7 +614,7 @@ 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);
> +	soft_timer_cancel(&timer->timer, &timer->expired);
>  	kvm_vgic_unmap_phys_irq(vcpu, vtimer->irq.irq);
>  }
>  
> 

Thanks,

	M.
-- 
Jazz is not dead. It just smells funny...