Re: [Xen-devel] Linux 4.19.5 fails to boot as Xen dom0

[Juergen Gross <jgross@xxxxxxxx>]

On 06/12/2018 12:46, Greg KH wrote:
> On Thu, Dec 06, 2018 at 12:31:15PM +0100, Juergen Gross wrote:
>> On 06/12/2018 12:13, Greg KH wrote:
>>> On Thu, Nov 29, 2018 at 02:35:17PM +0100, Juergen Gross wrote:
>>>> On 29/11/2018 14:26, Kirill A. Shutemov wrote:
>>>>> On Thu, Nov 29, 2018 at 09:41:25AM +0000, Juergen Gross wrote:
>>>>>> On 29/11/2018 02:22, Hans van Kranenburg wrote:
>>>>>>> Hi,
>>>>>>>
>>>>>>> As also seen at:
>>>>>>> https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=914951
>>>>>>>
>>>>>>> Attached there are two serial console output logs. One is starting with
>>>>>>> Xen 4.11 (from debian unstable) as dom0, and the other one without Xen.
>>>>>>>
>>>>>>> [    2.085543] BUG: unable to handle kernel paging request at
>>>>>>> ffff888d9fffc000
>>>>>>> [    2.085610] PGD 200c067 P4D 200c067 PUD 0
>>>>>>> [    2.085674] Oops: 0000 [#1] SMP NOPTI
>>>>>>> [    2.085736] CPU: 1 PID: 1 Comm: swapper/0 Not tainted
>>>>>>> 4.19.0-trunk-amd64 #1 Debian 4.19.5-1~exp1+pvh1
>>>>>>> [    2.085823] Hardware name: HP ProLiant DL360 G7, BIOS P68 05/21/2018
>>>>>>> [    2.085895] RIP: e030:ptdump_walk_pgd_level_core+0x1fd/0x490
>>>>>>> [...]
>>>>>>
>>>>>> The offending stable commit is 4074ca7d8a1832921c865d250bbd08f3441b3657
>>>>>> ("x86/mm: Move LDT remap out of KASLR region on 5-level paging"), this
>>>>>> is commit d52888aa2753e3063a9d3a0c9f72f94aa9809c15 upstream.
>>>>>>
>>>>>> Current upstream kernel is booting fine under Xen, so in general the
>>>>>> patch should be fine. Using an upstream kernel built from above commit
>>>>>> (with the then needed Xen fixup patch 1457d8cf7664f34c4ba534) is fine,
>>>>>> too.
>>>>>>
>>>>>> Kirill, are you aware of any prerequisite patch from 4.20 which could be
>>>>>> missing in 4.19.5?
>>>>>
>>>>> I'm not.
>>>>>
>>>>> Let me look into this.
>>>>>
>>>>
>>>> What is making me suspicious is the failure happening just after
>>>> releasing the init memory. Maybe there is an access to .init.data
>>>> segment or similar? The native kernel booting could be related to the
>>>> usage of 2M mappings not being available in a PV-domain.
>>>
>>> Did this ever get fixed anywhere that I can properly backport it to the
>>> 4.19.y tree?
>>
>> https://lore.kernel.org/lkml/20181130202328.65359-2-kirill.shutemov@xxxxxxxxxxxxxxx/
>>
>> Still pending upstream. Just pinged tglx.
> 
> Thanks, it should have gotten a cc: stable@ tag, but I can watch out for
> it...

It's upstream now: commit 16877a5570e0c5f4270d5b17f9bab427bcae9514


Juergen


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