linux-kernel - Re: [PATCH v5 13/20] x86/kexec: Mark relocate

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Message-ID: <E03AA833-B883-4249-90A8-3CD1EFC9390A@infradead.org>
Date: Fri, 13 Dec 2024 07:01:44 +0000
From: David Woodhouse <dwmw2@...radead.org>
To: "Ning, Hongyu" <hongyu.ning@...ux.intel.com>, kexec@...ts.infradead.org
CC: Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>,
 Borislav Petkov <bp@...en8.de>, Dave Hansen <dave.hansen@...ux.intel.com>,
 x86@...nel.org, "H. Peter Anvin" <hpa@...or.com>,
 "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
 Kai Huang <kai.huang@...el.com>, Nikolay Borisov <nik.borisov@...e.com>,
 linux-kernel@...r.kernel.org, Simon Horman <horms@...nel.org>,
 Dave Young <dyoung@...hat.com>, Peter Zijlstra <peterz@...radead.org>,
 jpoimboe@...nel.org, bsz@...zon.de
Subject: Re: [PATCH v5 13/20] x86/kexec: Mark relocate_kernel page as ROX instead of RWX

On 13 December 2024 06:45:18 GMT, "Ning, Hongyu" <hongyu.ning@...ux.intel.com> wrote:
>
>
>On 2024/12/12 18:13, David Woodhouse wrote:
>> On Thu, 2024-12-12 at 11:03 +0800, Ning, Hongyu wrote:
>>> 
>>> Hi David,
>>> 
>>> I've hit some kdump/kexec regression issue for guest kernel in KVM/QEMU
>>> based VM and reported in https://bugzilla.kernel.org/show_bug.cgi?id=219592.
>>> 
>>> based on further git bisect, it seems to be related with this commit,
>>> would you help to take a look?
>> 
>> Thanks for the report; I'll take a look. Please could you share your
>> kernel .config?
>> 
>
>kernel config updated in the bugzilla https://bugzilla.kernel.org/show_bug.cgi?id=219592
>
>> Also, you say that this is in QEMU running on an IA64 host. Is that
>> true, or did you mean x86_64 host? Are you using OVMF or SeaBIOS as the
>> QEMU firmware?
>> 
>
>You're right, it's x86_64 host, I miss-selected it in bugzilla.
>I'm using OVMF as the QEMU firmware.
>
>> In the short term, I think that just reverting the 'offending' commit
>> should be OK. I'd *prefer* not to leave the page RWX for the whole time
>> period that the image is loaded, but that's how it's been on i386 for
>> ever anyway.
>
>And your latest patch https://lore.kernel.org/kexec/9c68688625f409104b16164da30aa6d3eb494e5d.camel@infradead.org/ could fix this issue now.

Thanks. Does the newer patch at <https://lore.kernel.org/kexec/ed7dd45f89e8f286478791137447a21d53735dbd.camel@infradead.org/> work too? That's the cleaner option, I think.