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Subject: Re: [PATCH -v2] x86/boot/compressed: Register dummy NMI handler in
 EFI boot loader, to avoid kdump crashes
To:     Borislav Petkov <bp@alien8.de>
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References: <20230110102745.2514694-1-zengheng4@huawei.com>
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From:   Zeng Heng <zengheng4@huawei.com>
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On 2023/1/11 0:09, Borislav Petkov wrote:
> On Tue, Jan 10, 2023 at 01:57:05PM +0100, Borislav Petkov wrote:
>> I'm doubtful now as you're injecting errors so you're not really in #MC context
>> but in this contrived context which is actually an NMI one. So we need to think
>> about how to fix this case.
> I did some more thinking:
>
> *if* this really is a real issue - and not some silly qemu games - then
> native_machine_crash_shutdown() does all the cleanup before the kdump kernel is
> started.
>
> Any NMI clearing, maybe using iret_to_self() etc, #MC resetting etc should
> happen there and not anywhere else.

You mean native_machine_crash_shutdown() should cleanup the NMI 
interrupt status

before enter kexec?


But how about the watchdog raise NMI interrupt after 
native_machine_crash_shutdown()

or mce_wrmsrl(MSR_IA32_MCG_STATUS, 0) or any else cleanup function?


B.R.,

Zeng Heng