Re: Regressed XSA-286, was [xen-unstable test] 161917: regressions - FAIL

[Jan Beulich <jbeulich@xxxxxxxx>]

On 17.05.2021 10:43, Jan Beulich wrote:
> On 13.05.2021 22:15, Andrew Cooper wrote:
>> Second, the unexplained OSSTest behaviour.
>>
>> When I repro'd this on pinot1, test-pv32pae-xsa-286 failing was totally
>> deterministic and repeatable (I tried 100 times because the test is a
>> fraction of a second).
>>
>> From the log trawling which Ian already did, the first recorded failure
>> was flight 160912 on April 11th.  All failures (12, but this number is a
>> few flights old now) were on pinot*.
>>
>> What would be interesting to see is whether there have been any passes
>> on pinot since 160912.
>>
>> I can't see any reason why the test would be reliable for me, but
>> unreliable for OSSTest, so I'm wondering whether it is actually
>> reliable, and something is wrong with the stickiness heuristic.
> 
> Isn't (un)reliability of this test, besides the sensitivity to IRQs
> and context switches, tied to hardware behavior, in particular TLB
> capacity and replacement policy? Aiui the test has
> 
>     xtf_success("Success: Probably not vulnerable to XSA-286\n");
> 
> for the combination of all of these reasons.

I've just done a dozen runs on my Skylake - all reported SUCCESS.

Jan