Re: [PATCH v6 18/18] pc-bios: s390x: Save iplb location in lowcore

[David Hildenbrand]

On 04.03.20 14:25, Christian Borntraeger wrote:
> On 04.03.20 12:42, Janosch Frank wrote:
>> The POP states that for a list directed IPL the IPLB is stored into
>> memory by the machine loader and its address is stored at offset 0x14
>> of the lowcore.
>>
>> ZIPL currently uses the address in offset 0x14 to access the IPLB and
>> acquire flags about secure boot. If the IPLB address points into
>> memory which has an unsupported mix of flags set, ZIPL will panic
>> instead of booting the OS.
>>
>> As the lowcore can have quite a high entropy for a guest that did drop
>> out of protected mode (i.e. rebooted) we encountered the ZIPL panic
>> quite often.
>>
>> Signed-off-by: Janosch Frank <address@hidden>
>> Tested-by: Marc Hartmayer <address@hidden>
> 
> I think this makes sense even without protected virtualization, no?
> Unless somebody complains, I think I will pick this up while Conny is
> on vacation.

Yes, makes sense!


-- 
Thanks,

David / dhildenb