Received-SPF: pass (google.com: domain of linux-kernel+bounces-193709-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:45d1:ec00::1 as permitted sender) client-ip=2604:1380:45d1:ec00::1;
Message-ID: <d8952567-f97d-45ae-976e-5fe5d172df41@zhaoxin.com>
Date: Wed, 29 May 2024 16:15:37 +0800
Precedence: bulk
MIME-Version: 1.0
User-Agent: Mozilla Thunderbird
Subject: Re: [PATCH] x86/hpet: Read HPET directly if panic in progress
To: Thomas Gleixner <tglx@linutronix.de>, Dave Hansen <dave.hansen@intel.com>,
	<mingo@redhat.com>, <bp@alien8.de>, <dave.hansen@linux.intel.com>,
	<x86@kernel.org>, <hpa@zytor.com>, <keescook@chromium.org>,
	<tony.luck@intel.com>, <gpiccoli@igalia.com>, <mat.jonczyk@o2.pl>,
	<rdunlap@infradead.org>, <alexandre.belloni@bootlin.com>,
	<mario.limonciello@amd.com>, <yaolu@kylinos.cn>, <bhelgaas@google.com>,
	<justinstitt@google.com>, <linux-kernel@vger.kernel.org>,
	<linux-hardening@vger.kernel.org>
CC: <CobeChen@zhaoxin.com>, <TimGuo@zhaoxin.com>, <LeoLiu-oc@zhaoxin.com>,
	Linus Torvalds <torvalds@linux-foundation.org>
References: <20240528063836.5248-1-TonyWWang-oc@zhaoxin.com>
 <50fc1bd3-909e-41c4-a991-9d81e32ef92c@intel.com> <87wmnda8mc.ffs@tglx>
 <2553dd17-f763-4894-89b7-5f76c03d3a37@zhaoxin.com>
 <199ba55d-8eb8-47df-9f42-55a865b51ab7@zhaoxin.com> <87fru19i3x.ffs@tglx>
Content-Language: en-US
From: Tony W Wang-oc <TonyWWang-oc@zhaoxin.com>
In-Reply-To: <87fru19i3x.ffs@tglx>
Content-Type: text/plain; charset="UTF-8"; format=flowed
Content-Transfer-Encoding: 8bit


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.