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SubjectRe: [PATCH -v2] x86/boot/compressed: Register dummy NMI handler in EFI boot loader, to avoid kdump crashes
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On 2023/1/10 20:34, Ingo Molnar wrote:
> * Borislav Petkov <bp@alien8.de> wrote:
>
>>> mce_panic -> panic -> __crash_kexec()
>>>
>>> Yes?
>>>
>>> If so, then we should make sure we have *exited* #MC context before calling
>>> panic() and not have to add hacks like this one of adding an empty NMI handler.
>>>
>>> But I'm only speculating as it is hard to make sense of all this text.
>> IOW, does this help?
>>
>> ---
>> diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c
>> index 7832a69d170e..55437d8a4fad 100644
>> --- a/arch/x86/kernel/cpu/mce/core.c
>> +++ b/arch/x86/kernel/cpu/mce/core.c
>> @@ -287,6 +287,7 @@ static noinstr void mce_panic(const char *msg, struct mce *final, char *exp)
>> if (panic_timeout == 0)
>> panic_timeout = mca_cfg.panic_timeout;
>> panic(msg);
>> + mce_wrmsrl(MSR_IA32_MCG_STATUS, 0);

I'm willing to test any patch provided, but the panic() is never return
and the

mce_wrmsrl() would be never called. Am I wrong?

B.R.,

Zeng Heng

> So your suggestion was to exit MC context 'before' the panic() call - but
> the patch calls it 'after' - was that intentional?
>
> Thanks,
>
> Ingo

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