linux-kernel - Re: [PATCH v2] x86/nmi: Add an emergency handler in nmi_desc & use it in nmi_shootdown

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <87r06mqnnv.ffs@tglx>
Date: Thu, 05 Dec 2024 14:12:20 +0100
From: Thomas Gleixner <tglx@...utronix.de>
To: Waiman Long <llong@...hat.com>, Waiman Long <llong@...hat.com>, Ingo
 Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>, Dave Hansen
 <dave.hansen@...ux.intel.com>, Peter Zijlstra <peterz@...radead.org>
Cc: x86@...nel.org, linux-kernel@...r.kernel.org, "H. Peter Anvin"
 <hpa@...or.com>
Subject: Re: [PATCH v2] x86/nmi: Add an emergency handler in nmi_desc & use
 it in nmi_shootdown_cpus()

On Wed, Dec 04 2024 at 23:01, Waiman Long wrote:
> On 12/4/24 2:28 PM, Waiman Long wrote:
>>> I'm not convinced that this should be used as a general mechanism. It's
>>> for emergency situations and that's where it stops. If the thing
>>> returns, it's a bug IMO.
>>
>> OK, I am fine with that. I will put a BUG_ON() after that in the next 
>> version.
>
> Actually, crash_nmi_callback() can return in the case of the crashing 
> CPUs, though all the other CPUs will not return once called. So I 
> believe the current form is correct. I will update the comment to 
> reflect that.

Why would you continue servicing the NMI on a CPU which just crashed?