linux-kernel - Re: [Bug Report] Linux v6.15-rc7 boot failure on Xen-4.17

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Message-ID: <400ee15a-12fa-4477-ba03-123eb8e07dc2@zytor.com>
Date: Wed, 28 May 2025 01:26:52 -0700
From: Xin Li <xin@...or.com>
To: Juergen Gross <jgross@...e.com>
Cc: Gupta Pawan <pawan.kumar.gupta@...ux.intel.com>,
        linux-kernel@...r.kernel.org, x86@...nel.org,
        Zijlstra Peter <peterz@...radead.org>,
        Hansen Dave <dave.hansen@...ux.intel.com>,
        alexandre.chartre@...cle.com,
        Andrew Cooper <andrew.cooper3@...rix.com>,
        Zhang Tao1 <tao1.zhang@...el.com>
Subject: Re: [Bug Report] Linux v6.15-rc7 boot failure on Xen-4.17

On 5/28/2025 12:27 AM, Xin Li wrote:
> On 5/27/2025 11:49 PM, Juergen Gross wrote:
>> On 28.05.25 07:11, Jürgen Groß wrote:
>>> On 27.05.25 21:29, Andrew Cooper wrote:
>>>> On 27/05/2025 8:21 pm, Xin Li wrote:
>>>>>> On May 27, 2025, at 11:36 AM, Jürgen Groß <jgross@...e.com> wrote:
>>>>>>
>>>>>> On 27.05.25 19:54, Xin Li wrote:
>>>>>>> On 5/27/2025 10:46 AM, Pawan Gupta wrote:
>>>>>>>>> Attached is the serial console log and my kernel config.
>>>>>>>> Serial logs aren't telling much. I do not have a Xen setup to 
>>>>>>>> test, without
>>>>>>>> Xen the config that you provided is booting a KVM guest just fine.
>>>>>>> Yeah, as I replied to Juergen, the same kernel binary boots fine as
>>>>>>> "native".
>>>>>>> Unfortunately when booting as dom0 on Xen, it keeps rebooting w/o
>>>>>>> helpful log.
>>>>>> What about booting Xen on bare metal, i.e. no KVM being involved?
>>>>> The same exact problem happens on Intel Simics.  And I got to see 
>>>>> it’s a NX page fault in dom0 kernel during apply alternatives.
>>>>
>>>> In which case it's likely that there's an opencoded PTE update, rather
>>>> than using the hooks (which are suitably paravirt'd).
>>>
>>> I'd suspect a bug when NOT using 2M pages for execmem.
>>>
>>> I'll have a look.
>>
>> Could you have a try using "nohugevmalloc" dom0 kernel boot parameter?
>>
> 
> Tried in a KVM guest, still the same problem, and nothing new in the
> serial log.

Attached is a dom0 log with stack traces.

But I really did NOT change anything to make it happen...
View attachment "xen-ubt.serial.log" of type "text/plain" (214976 bytes)