linux-hardening - Re: [PATCH] x86/hpet: Read HPET directly if panic in progress

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Message-ID: <d8952567-f97d-45ae-976e-5fe5d172df41@zhaoxin.com>
Date: Wed, 29 May 2024 16:15:37 +0800
From: Tony W Wang-oc <TonyWWang-oc@...oxin.com>
To: Thomas Gleixner <tglx@...utronix.de>, Dave Hansen <dave.hansen@...el.com>,
	<mingo@...hat.com>, <bp@...en8.de>, <dave.hansen@...ux.intel.com>,
	<x86@...nel.org>, <hpa@...or.com>, <keescook@...omium.org>,
	<tony.luck@...el.com>, <gpiccoli@...lia.com>, <mat.jonczyk@...pl>,
	<rdunlap@...radead.org>, <alexandre.belloni@...tlin.com>,
	<mario.limonciello@....com>, <yaolu@...inos.cn>, <bhelgaas@...gle.com>,
	<justinstitt@...gle.com>, <linux-kernel@...r.kernel.org>,
	<linux-hardening@...r.kernel.org>
CC: <CobeChen@...oxin.com>, <TimGuo@...oxin.com>, <LeoLiu-oc@...oxin.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [PATCH] x86/hpet: Read HPET directly if panic in progress



On 2024/5/29 15:45, Thomas Gleixner wrote:
> 
> 
> [这封邮件来自外部发件人 谨防风险]
> 
> On Wed, May 29 2024 at 14:44, Tony W Wang-oc wrote:
>> Actually, this scenario is what this patch is trying to solve.
>>
>> We encountered hpet_lock deadlock from the call path of the MCE handler,
>> and this hpet_lock deadlock scenario may happen when others exceptions'
>> handler like #PF/#GP... to call the panic. So read_hpet should avoid
>> deadlock if panic in progress.
> 
> That's not what your changelog says.

Yes.
The example flow I gave with the MCE handler in my changelog is misleading.