[PATCH] KVM: arm/arm64: timer: Workaround misconfigured timer interrupt

[Christoffer Dall]

On Tue, Aug 16, 2016 at 03:03:02PM +0100, Marc Zyngier wrote:
> Similarily to f005bd7e3b84 ("clocksource/arm_arch_timer: Force
> per-CPU interrupt to be level-triggered"), make sure we can
> survive an interrupt that has been misconfigured as edge-triggered
> by forcing it to be level-triggered (active low is assumed, but
> the GIC doesn't really care whether this is high or low).
> 
> Hopefully, the amount of shouting in the kernel log will convince
> the user to do something about their firmware.
> 
> Signed-off-by: Marc Zyngier <marc.zyngier at arm.com>
> ---
>  virt/kvm/arm/arch_timer.c | 11 ++++++++++-
>  1 file changed, 10 insertions(+), 1 deletion(-)
> 
> diff --git a/virt/kvm/arm/arch_timer.c b/virt/kvm/arm/arch_timer.c
> index 4fde8c7..77e6ccf 100644
> --- a/virt/kvm/arm/arch_timer.c
> +++ b/virt/kvm/arm/arch_timer.c
> @@ -33,6 +33,7 @@
>  static struct timecounter *timecounter;
>  static struct workqueue_struct *wqueue;
>  static unsigned int host_vtimer_irq;
> +static u32 host_vtimer_irq_flags;
>  
>  void kvm_timer_vcpu_put(struct kvm_vcpu *vcpu)
>  {
> @@ -365,7 +366,7 @@ void kvm_timer_vcpu_init(struct kvm_vcpu *vcpu)
>  
>  static void kvm_timer_init_interrupt(void *info)
>  {
> -	enable_percpu_irq(host_vtimer_irq, 0);
> +	enable_percpu_irq(host_vtimer_irq, host_vtimer_irq_flags);
>  }
>  
>  int kvm_arm_timer_set_reg(struct kvm_vcpu *vcpu, u64 regid, u64 value)
> @@ -432,6 +433,14 @@ int kvm_timer_hyp_init(void)
>  	}
>  	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\n",
> +			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) {
> -- 
> 2.1.4
> 

Looks good to me.  Applied.
-Christoffer