linux-kernel - Re: [RFC PATCH] mce: don't not enable IRQ in wait_for

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: <2262c2ee-3272-987a-0bdb-a0ce55a1d43c@huawei.com>
Date:   Mon, 21 Sep 2020 19:35:50 +0800
From:   Wu Bo <wubo40@...wei.com>
To:     <linux-edac@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <openipmi-developer@...ts.sourceforge.net>
CC:     <tony.luck@...el.com>, <minyard@....org>, <bp@...en8.de>,
        <tglx@...utronix.de>, <andi@...stfloor.org>, <mingo@...hat.com>,
        <x86@...nel.org>, <hpa@...or.com>, <arnd@...db.de>,
        <gregkh@...uxfoundation.org>, <hidehiro.kawai.ez@...achi.com>,
        <linfeilong@...wei.com>, <liuzhiqiang26@...wei.com>
Subject: Re: [RFC PATCH] mce: don't not enable IRQ in wait_for_panic()

On 2020/9/17 18:37, Wu Bo wrote:
> In my virtual machine (have 4 cpus), Use mce_inject to inject errors
> into the system. After mce-inject injects an uncorrectable error,
> there is a probability that the virtual machine is not reset immediately,
> but hangs for more than 3000 seconds, and appeared unable to
> handle kernel paging request.
> 
> The analysis reasons are as follows:
> 1) MCE appears on all CPUs, Currently all CPUs are in the NMI interrupt
>     context. cpu0 is the first to seize the opportunity to run panic
>     routines, and panic event should stop the other processors before
>     do ipmi flush_messages(). but cpu1, cpu2 and cpu3 has already
>     in NMI interrupt context, So the Second NMI interrupt(IPI)
>     will not be processed again by cpu1, cpu2 and cpu3.
>     At this time, cpu1,cpu2 and cpu3 did not stopped.
> 
> 2) cpu1, cpu2 and cpu3 are waitting for cpu0 to finish the panic process.
>     if a timeout waiting for other CPUs happened, do wait_for_panic(),
>     the irq is enabled in the wait_for_panic() function.
> 
> 3) ipmi IRQ occurs on the cpu3, and the cpu0 is doing the panic,
>     they have the opportunity to call the smi_event_handler()
>     function concurrently. the ipmi IRQ affects the panic process of cpu0.
> 
>    CPU0                                    CPU3
> 
>     |-nmi_handle do mce_panic               |-nmi_handle do_machine_check
>     |                                       |
>     |-panic()                               |-wait_for_panic()
>     |                                       |
>     |-stop other cpus ---- NMI ------> (Ignore, already in nmi interrupt)
>     |                                       |
>     |-notifier call(ipmi panic_event)       |<-ipmi IRQ occurs
>     |                                       |
>    \|/                                     \|/
> do smi_event_handler()             do smi_event_handler()
> 
> My understanding is that panic() runs with only one operational CPU
> in the system, other CPUs should be stopped, if other CPUs does not stop,
> at least IRQ interrupts should be disabled. The x86 architecture,
> disable IRQ interrupt will not affect IPI when do mce panic,
> because IPI is notified through NMI interrupt. If my analysis
> is not right, please correct me, thanks.
> 
> Steps to reproduce (Have a certain probability):
> 1. # vim /tmp/uncorrected
> CPU 1 BANK 4
> STATUS uncorrected 0xc0
> MCGSTATUS  EIPV MCIP
> ADDR 0x1234
> RIP 0xdeadbabe
> RAISINGCPU 0
> MCGCAP SER CMCI TES 0x6
>   
> 2. # modprobe mce_inject
> 3. # cd /tmp
> 4. # mce-inject uncorrected
> 
Hi,

I tested the 5.9-rc5 version and found that the problem still exists. Is 
there a good solution ?

Best regards,
Wu Bo