Re: [kvm-unit-tests PATCH] arm64: timer: ignore ISTATUS with disabled timer

[Nadav Amit <nadav.amit@gmail.com>]

> On Jun 28, 2023, at 4:40 AM, Andrew Jones <andrew.jones@linux.dev> wrote:
> 
> On Wed, Jun 14, 2023 at 05:38:32PM -0700, Nadav Amit wrote:
>> From: Nadav Amit <nadav.amit@gmail.com>
>> 
>> According to ARM specifications for the vtimer (CNTV_CTL_EL0): "When the
>> value of the ENABLE bit is 0, the ISTATUS field is UNKNOWN."
>> 
>> Currently the test, however, does check that ISTATUS is cleared when the
>> ENABLE bit is zero. Remove this check as the value is unknown.
> 
> Hmm, does it? timer_pending() is
> 
> /* Check that the timer condition is met. */
> static bool timer_pending(struct timer_info *info)
> {
>        return (info->read_ctl() & ARCH_TIMER_CTL_ENABLE) &&
>                (info->read_ctl() & ARCH_TIMER_CTL_ISTATUS);
> }
> 
> which I would expect to short-circuit when ENABLE is zero.

Yes, my bad. Drop it.

I had a different unrelated interrupt before that turned on the ENABLE.
This just mask an additional failure.

Obviously we can reset the ENABLE before each test, but I presume it is
fair to say that in general if a certain test fails, subsequent failures
are prone to be false-positives.