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Sender: Ingo Molnar <mingo.kernel.org@gmail.com>
Date:   Tue, 10 Jan 2023 11:59:51 +0100
From:   Ingo Molnar <mingo@kernel.org>
To:     Zeng Heng <zengheng4@huawei.com>
Cc:     michael.roth@amd.com, bp@alien8.de, hpa@zytor.com,
        tglx@linutronix.de, sathyanarayanan.kuppuswamy@linux.intel.com,
        kirill.shutemov@linux.intel.com, jroedel@suse.de,
        keescook@chromium.org, mingo@redhat.com,
        dave.hansen@linux.intel.com, brijesh.singh@amd.com,
        linux-kernel@vger.kernel.org, x86@kernel.org, liwei391@huawei.com
Subject: Re: [PATCH] x86/boot/compressed: Register NMI handler in EFI boot
 loader
Message-ID: <Y71FJ+G0NGQe3Ppq@gmail.com>
References: <20230110102745.2514694-1-zengheng4@huawei.com>
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In-Reply-To: <20230110102745.2514694-1-zengheng4@huawei.com>
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* Zeng Heng <zengheng4@huawei.com> wrote:

> +void do_boot_nmi_fault(struct pt_regs *regs, unsigned long error_code)
> +{
> +	/* ignore */
> +}
> diff --git a/arch/x86/boot/compressed/idt_64.c b/arch/x86/boot/compressed/idt_64.c
> index 6debb816e83d..b169c9728d52 100644
> --- a/arch/x86/boot/compressed/idt_64.c
> +++ b/arch/x86/boot/compressed/idt_64.c
> @@ -60,6 +60,7 @@ void load_stage2_idt(void)
>  {
>  	boot_idt_desc.address = (unsigned long)boot_idt;
>  
> +	set_idt_entry(X86_TRAP_NMI, boot_nmi_fault);
>  	set_idt_entry(X86_TRAP_PF, boot_page_fault);

So it's a bit sad to install a dummy handler that does nothing, while 
something clearly sent an NMI and expects an intelligent reaction - OTOH 
the unexpected NMIs from from watchdog during a kdump clearly make things 
worse by crashing the bootup.

Anyway, I cannot think of a better response here that the boot loading code 
could do either, so I've applied your fix to tip:x86/boot.

Thanks,

	Ingo