[PATCH v5 2/4] ARM: KVM: arch_timers: Add guest timer core support

[Will Deacon]

On Tue, Jan 08, 2013 at 06:43:20PM +0000, Christoffer Dall wrote:
> From: Marc Zyngier <marc.zyngier at arm.com>
> 
> Add some the architected timer related infrastructure, and support timer
> interrupt injection, which can happen as a resultof three possible
> events:
> 
> - The virtual timer interrupt has fired while we were still
>   executing the guest
> - The timer interrupt hasn't fired, but it expired while we
>   were doing the world switch
> - A hrtimer we programmed earlier has fired

[...]

> +void kvm_timer_sync_to_cpu(struct kvm_vcpu *vcpu)
> +{
> +       struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
> +
> +       /*
> +        * We're about to run this vcpu again, so there is no need to
> +        * keep the background timer running, as we're about to
> +        * populate the CPU timer again.
> +        */
> +       timer_disarm(timer);
> +}
> +
> +void kvm_timer_sync_from_cpu(struct kvm_vcpu *vcpu)
> +{
> +       struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
> +       cycle_t cval, now;
> +       u64 ns;
> +
> +       /* Check if the timer is enabled and unmasked first */
> +       if ((timer->cntv_ctl & 3) != 1)
> +               return;
> +
> +       cval = timer->cntv_cval;
> +       now = kvm_phys_timer_read() - vcpu->kvm->arch.timer.cntvoff;
> +
> +       BUG_ON(timer_is_armed(timer));
> +
> +       if (cval <= now) {
> +               /*
> +                * Timer has already expired while we were not
> +                * looking. Inject the interrupt and carry on.
> +                */
> +               kvm_timer_inject_irq(vcpu);
> +               return;
> +       }
> +
> +       ns = cyclecounter_cyc2ns(timecounter->cc, cval - now);
> +       timer_arm(timer, ns);
> +}

Please use flush/sync terminology to match the rest of arch/arm/.

Will