Re: [kvm-unit-tests PATCH v2 13/18] arm64: timer: Test behavior when timer disabled or masked

[Andrew Jones <drjones@redhat.com>]

On Thu, Nov 28, 2019 at 06:04:13PM +0000, Alexandru Elisei wrote:
> When the timer is disabled (the *_CTL_EL0.ENABLE bit is clear) or the
> timer interrupt is masked at the timer level (the *_CTL_EL0.IMASK bit is
> set), timer interrupts must not be pending or asserted by the VGIC.
> However, only when the timer interrupt is masked, we can still check
> that the timer condition is met by reading the *_CTL_EL0.ISTATUS bit.
> 
> Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com>
> ---
> 
> This test was used to discover a bug and test the fix introduced by KVM
> commit 16e604a437c8 ("KVM: arm/arm64: vgic: Reevaluate level sensitive
> interrupts on enable").

This kind of information can/should go above the ---, IMO.

Thanks,
drew

> 
>  arm/timer.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/arm/timer.c b/arm/timer.c
> index d2cd5dc7a58b..09d527bb09a8 100644
> --- a/arm/timer.c
> +++ b/arm/timer.c
> @@ -230,9 +230,17 @@ static void test_timer(struct timer_info *info)
>  
>  	/* Disable the timer again and prepare to take interrupts */
>  	info->write_ctl(0);
> +	isb();
> +	info->irq_received = false;
>  	set_timer_irq_enabled(info, true);
> +	report("no interrupt when timer is disabled", !info->irq_received);
>  	report("interrupt signal no longer pending", !gic_timer_pending(info));
>  
> +	info->write_ctl(ARCH_TIMER_CTL_ENABLE | ARCH_TIMER_CTL_IMASK);
> +	isb();
> +	report("interrupt signal not pending", !gic_timer_pending(info));
> +	report("timer condition met", info->read_ctl() & ARCH_TIMER_CTL_ISTATUS);
> +
>  	report("latency within 10 ms", test_cval_10msec(info));
>  	report("interrupt received", info->irq_received);
>  
> -- 
> 2.20.1
>