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

Auger Eric
2021-04-28T15:26:41Z

Hi,

On 4/28/21 4:36 PM, Marc Zyngier wrote:
> On Wed, 28 Apr 2021 15:00:15 +0100,
> Alexandru Elisei <alexandru.elisei@arm.com> wrote:
>>
>> I interpret that as that an INVALL guarantees that a change is
>> visible, but it the change can become visible even without the
>> INVALL.
>
> Yes. Expecting the LPI to be delivered or not in the absence of an
> invalidate when its configuration has been altered is wrong. The
> architecture doesn't guarantee anything of the sort.
>
>> The test relies on the fact that changes to the LPI tables are not
>> visible *under KVM* until the INVALL command, but that's not
>> necessarily the case on real hardware. To match the spec, I think
>> the test "dev2/eventid=20 still does not trigger any LPI" should be
>> removed and the stats reset should take place before the
>> configuration for LPI 8195 is set to the default.

Yes I do agree with Alexandru and Marc after another reading of the
spec. I initially thought the INVALL was the gate keeper for the new
config but that sounds wrong. This test shall be removed then.

Eric
>
> If that's what the test expects (I haven't tried to investigate), it
> should be dropped completely, rather than trying to sidestep it for
> TCG.
>
> Thanks,
>
> M.
>