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From: David Hildenbrand <david@redhat.com>
To: Janosch Frank <frankja@linux.ibm.com>, qemu-devel@nongnu.org
Cc: borntraeger@de.ibm.com, qemu-s390x@nongnu.org, cohuck@redhat.com
Subject: Re: [PATCH] pc-bios: s390x: Save iplb location in lowcore
Date: Wed, 4 Mar 2020 10:05:55 +0100	[thread overview]
Message-ID: <ac3ee690-408c-42e0-db45-2d0b4cbc637e@redhat.com> (raw)
In-Reply-To: <7eee8f67-d1a1-39e5-af8b-4bd6dc815005@linux.ibm.com>

On 04.03.20 09:59, Janosch Frank wrote:
> On 3/3/20 5:13 PM, David Hildenbrand wrote:
>> On 03.03.20 16:50, 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.
>>
>> How did this ever work? Or does this only become relevant with secure boot?
> 
> I'd guess that until secure boot ZIPL never touched this and with it we
> never hit the right combination of flags to trigger a ZIPL panic.
> 
> This way of getting to the IPLB was used before diag308 was available,
> i.e. way before KVM got to IBM Z. It looks like ZIPL only uses it for
> secure boot for some reason and hence we never implemented it before.
> 
> I'm also in discussion with the ZIPL developers to make this more robust.
> 

Thanks for the clarification!

[...]

> 
> Do you want to add a patch or shall I add it to my cleanup series?

Would be great if you could add a cleanup.

-- 
Thanks,

David / dhildenb



      reply	other threads:[~2020-03-04  9:06 UTC|newest]

Thread overview: 62+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-26 12:20 [PATCH v5 00/18] s390x: Protected Virtualization support Janosch Frank
2020-02-26 12:20 ` [PATCH v5 01/18] s390x: Use constant for ESA PSW address Janosch Frank
2020-02-26 13:46   ` Christian Borntraeger
2020-02-26 13:47     ` Janosch Frank
2020-02-26 14:27   ` David Hildenbrand
2020-02-26 17:51     ` Cornelia Huck
2020-02-26 17:52       ` David Hildenbrand
2020-02-27  7:53       ` Janosch Frank
2020-02-27  8:09         ` Janosch Frank
2020-02-27  9:06           ` Cornelia Huck
2020-02-27  9:23             ` [PATCH v6] s390x: Rename and use constants for short PSW address and mask Janosch Frank
2020-02-27  9:27               ` David Hildenbrand
2020-02-27 10:36               ` Cornelia Huck
2020-02-26 12:20 ` [PATCH v5 02/18] Sync pv Janosch Frank
2020-02-26 12:20 ` [PATCH v5 03/18] s390x: protvirt: Add diag308 subcodes 8 - 10 Janosch Frank
2020-02-26 12:20 ` [PATCH v5 04/18] s390x: protvirt: Support unpack facility Janosch Frank
2020-02-26 12:20 ` [PATCH v5 05/18] s390x: protvirt: Add migration blocker Janosch Frank
2020-02-26 14:05   ` Christian Borntraeger
2020-02-26 14:08     ` Janosch Frank
2020-02-26 12:20 ` [PATCH v5 06/18] s390x: protvirt: Handle diag 308 subcodes 0,1,3,4 Janosch Frank
2020-02-26 15:00   ` Christian Borntraeger
2020-02-26 15:11     ` Janosch Frank
2020-02-26 12:20 ` [PATCH v5 07/18] s390x: protvirt: Inhibit balloon when switching to protected mode Janosch Frank
2020-02-26 14:59   ` David Hildenbrand
2020-02-26 15:06     ` Christian Borntraeger
2020-02-26 15:16       ` David Hildenbrand
2020-02-26 15:30         ` Janosch Frank
2020-02-26 15:31           ` David Hildenbrand
2020-02-26 18:24           ` Cornelia Huck
2020-03-03 12:42             ` Christian Borntraeger
2020-02-26 15:11     ` Janosch Frank
2020-02-26 15:13       ` Christian Borntraeger
2020-02-26 15:15         ` David Hildenbrand
2020-02-27 12:24       ` Halil Pasic
2020-03-19 13:42         ` Halil Pasic
2020-03-19 13:54         ` David Hildenbrand
2020-03-19 15:40           ` Halil Pasic
2020-03-19 17:31             ` David Hildenbrand
2020-03-20 18:43               ` Halil Pasic
2020-03-24 21:07                 ` Brijesh Singh
2020-03-27 10:50                 ` David Hildenbrand
2020-03-19 17:45           ` Michael S. Tsirkin
2020-03-20  9:36             ` David Hildenbrand
2020-03-29 14:48               ` Michael S. Tsirkin
2020-03-31  8:59                 ` David Hildenbrand
2020-02-26 12:20 ` [PATCH v5 08/18] s390x: protvirt: KVM intercept changes Janosch Frank
2020-02-26 12:20 ` [PATCH v5 09/18] s390x: Add SIDA memory ops Janosch Frank
2020-02-26 12:20 ` [PATCH v5 10/18] s390x: protvirt: Move STSI data over SIDAD Janosch Frank
2020-02-26 12:20 ` [PATCH v5 11/18] s390x: protvirt: SCLP interpretation Janosch Frank
2020-02-26 12:20 ` [PATCH v5 12/18] s390x: protvirt: Set guest IPL PSW Janosch Frank
2020-02-26 12:20 ` [PATCH v5 13/18] s390x: protvirt: Move diag 308 data over SIDAD Janosch Frank
2020-02-26 12:20 ` [PATCH v5 14/18] s390x: protvirt: Disable address checks for PV guest IO emulation Janosch Frank
2020-02-26 12:20 ` [PATCH v5 15/18] s390x: protvirt: Move IO control structures over SIDA Janosch Frank
2020-02-26 12:20 ` [PATCH v5 16/18] s390x: protvirt: Handle SIGP store status correctly Janosch Frank
2020-02-26 12:20 ` [PATCH v5 17/18] s390x: Add unpack facility feature to GA1 Janosch Frank
2020-02-26 12:20 ` [PATCH v5 18/18] docs: Add protvirt docs Janosch Frank
2020-02-26 20:09 ` [PATCH v5 00/18] s390x: Protected Virtualization support Cornelia Huck
2020-02-27  8:32   ` Janosch Frank
2020-03-03 15:50 ` [PATCH] pc-bios: s390x: Save iplb location in lowcore Janosch Frank
2020-03-03 16:13   ` David Hildenbrand
2020-03-04  8:59     ` Janosch Frank
2020-03-04  9:05       ` David Hildenbrand [this message]

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