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

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Message-ID: <1226c371-5d44-4206-973f-3c10152c4195@zytor.com>
Date: Wed, 28 May 2025 00:27:06 -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 5/27/2025 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.

Thanks!
     Xin