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SubjectRe: [FYI PATCH 0/7] Mitigation for CVE-2018-12207
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On 13.11.19 22:24, Dave Hansen wrote:
> On 11/13/19 12:23 AM, Paolo Bonzini wrote:
>> On 13/11/19 07:38, Jan Kiszka wrote:
>>> When reading MCE, error code 0150h, ie. SRAR, I was wondering if that
>>> couldn't simply be handled by the host. But I suppose the symptom of
>>> that erratum is not "just" regular recoverable MCE, rather
>>> sometimes/always an unrecoverable CPU state, despite the error code, right?
>> The erratum documentation talks explicitly about hanging the system, but
>> it's not clear if it's just a result of the OS mishandling the MCE, or
>> something worse. So I don't know. :( Pawan, do you?
>
> It's "something worse".
>
> I built a kernel module reproducer for this a long time ago. The
> symptom I observed was the whole system hanging hard, requiring me to go
> hit the power button. The MCE software machinery was not involved at
> all from what I could tell.

Thanks for clarifying this - too bad.

>
> About creating a unit test, I'd be personally happy to share my
> reproducer, but I built it before this issue was root-caused. There are
> actually quite a few underlying variants and a good unit test would make
> sure to exercise all of them. My reproducer probably only exercised a
> single case.
>

Would be interesting to see this. Ralf and tried something quickly, but
there seems to be a detail missing or wrong.

Jan

--
Siemens AG, Corporate Technology, CT RDA IOT SES-DE
Corporate Competence Center Embedded Linux

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