Re: [kvm-unit-tests PATCH v1 1/4] arm64: split its-trigger test into KVM and TCG variants

[Marc Zyngier]

On 2021-04-28 11:18, Alex Bennée wrote:
> A few of the its-trigger tests rely on IMPDEF behaviour where caches
> aren't flushed before invall events. However TCG emulation doesn't
> model any invall behaviour and as we can't probe for it we need to be
> told. Split the test into a KVM and TCG variant and skip the invall
> tests when under TCG.
>
> Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
> Cc: Shashi Mallela <shashi.mallela@linaro.org>
> ---
>  arm/gic.c         | 60 +++++++++++++++++++++++++++--------------------
>  arm/unittests.cfg | 11 ++++++++-
>  2 files changed, 45 insertions(+), 26 deletions(-)
>
> diff --git a/arm/gic.c b/arm/gic.c
> index 98135ef..96a329d 100644
> --- a/arm/gic.c
> +++ b/arm/gic.c
> @@ -36,6 +36,7 @@ static struct gic *gic;
>  static int acked[NR_CPUS], spurious[NR_CPUS];
>  static int irq_sender[NR_CPUS], irq_number[NR_CPUS];
>  static cpumask_t ready;
> +static bool under_tcg;
>
>  static void nr_cpu_check(int nr)
>  {
> @@ -734,32 +735,38 @@ static void test_its_trigger(void)
>         /*
>          * re-enable the LPI but willingly do not call invall
>          * so the change in config is not taken into account.
> -        * The LPI should not hit
> +        * The LPI should not hit. This does however depend on
> +        * implementation defined behaviour - under QEMU TCG emulation
> +        * it can quite correctly process the event directly.

It looks to me that you are using an IMPDEF behaviour of *TCG*
here. The programming model mandates that there is an invalidation
if you change the configuration of the LPI.

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