From: Thomas Gleixner <tglx@linutronix.de>
To: Pingfan Liu <kernelfans@gmail.com>
Cc: Dave Young <dyoung@redhat.com>, Andy Lutomirski <luto@kernel.org>,
x86@kernel.org, Ingo Molnar <mingo@redhat.com>,
Borislav Petkov <bp@alien8.de>, "H. Peter Anvin" <hpa@zytor.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
Peter Zijlstra <peterz@infradead.org>,
Masami Hiramatsu <mhiramat@kernel.org>, Qian Cai <cai@lca.pw>,
Vlastimil Babka <vbabka@suse.cz>,
Daniel Drake <drake@endlessm.com>,
Jacob Pan <jacob.jun.pan@linux.intel.com>,
Michal Hocko <mhocko@suse.com>,
Eric Biederman <ebiederm@xmission.com>,
linux-kernel@vger.kernel.org, Baoquan He <bhe@redhat.com>,
kexec@lists.infradead.org, tony.luck@intel.com,
Xunlei Pang <xlpang@linux.alibaba.com>
Subject: Re: [PATCH 0/4] x86/mce: protect nr_cpus from rebooting by broadcast mce
Date: Wed, 7 Aug 2019 15:07:33 +0200 (CEST) [thread overview]
Message-ID: <alpine.DEB.2.21.1908071504310.24014@nanos.tec.linutronix.de> (raw)
In-Reply-To: <20190807075226.GA10392@mypc>
On Wed, 7 Aug 2019, Pingfan Liu wrote:
> On Wed, Aug 07, 2019 at 11:00:41AM +0800, Dave Young wrote:
> > Add Tony and Xunlei in cc.
> > On 08/05/19 at 04:58pm, Pingfan Liu wrote:
> > > This series include two related groups:
> > > [1-3/4]: protect nr_cpus from rebooting by broadcast mce
> > > [4/4]: improve "kexec -l" robustness against broadcast mce
> > >
> > > When I tried to fix [1], Thomas raised concern about the nr_cpus' vulnerability
> > > to unexpected rebooting by broadcast mce. After analysis, I think only the
> > > following first case suffers from the rebooting by broadcast mce. [1-3/4] aims
> > > to fix that issue.
> >
> > I did not understand and read the MCE details, but we previously had a
> > MCE problem, Xunlei fixed in below commit:
> > commit 5bc329503e8191c91c4c40836f062ef771d8ba83
> > Author: Xunlei Pang <xlpang@redhat.com>
> > Date: Mon Mar 13 10:50:19 2017 +0100
> >
> > x86/mce: Handle broadcasted MCE gracefully with kexec
> >
> > I wonder if this is same issue or not. Also the old discussion is in
> > below thread:
> > https://lore.kernel.org/patchwork/patch/753530/
> >
> > Tony raised similar questions, but I'm not sure if it is still a problem
> > or it has been fixed.
> >
>
> Xunlei's patch is the precondition of the stability for the case 2: boot
> up by "kexec -p nr_cpus="
Correct. The only dangerous issue which is then left is that an MCE hits
_before_ all CPUs have CR.MCE=1 set. That's a general issue also for cold
boot. Thanks to the brilliant hardware design, all we can do is pray....
> For case1/3, extra effort is needed.
>
> Thanks,
> Pingfan
> > >
> > > *** Back ground ***
> > >
> > > On x86 it's required to have all logical CPUs set CR4.MCE=1. Otherwise, a
> > > broadcast MCE observing CR4.MCE=0b on any core will shutdown the machine.
Pingfan, please trim your replies and remove the useless gunk after your answer.
Thanks,
tglx
next prev parent reply other threads:[~2019-08-07 13:08 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-05 8:58 [PATCH 0/4] x86/mce: protect nr_cpus from rebooting by broadcast mce Pingfan Liu
2019-08-05 8:58 ` [PATCH 1/4] x86/apic: correct the ENO in generic_processor_info() Pingfan Liu
2019-08-05 8:58 ` [PATCH 2/4] x86/apic: record capped cpu " Pingfan Liu
2019-08-08 0:17 ` kbuild test robot
2019-08-08 0:17 ` [RFC PATCH] x86/apic: __cpu_capped_mask can be static kbuild test robot
2019-08-05 8:58 ` [PATCH 3/4] x86/smp: send capped cpus to a stable state when smp_init() Pingfan Liu
2019-08-08 1:20 ` kbuild test robot
2019-08-08 1:20 ` [RFC PATCH] x86/smp: __cpu_capped_done_mask can be static kbuild test robot
2019-08-08 2:36 ` [PATCH 3/4] x86/smp: send capped cpus to a stable state when smp_init() kbuild test robot
2019-08-08 5:18 ` kbuild test robot
2019-08-05 8:58 ` [PATCH 4/4] x86/smp: disallow MCE handler on rebooting AP Pingfan Liu
2019-08-07 3:00 ` [PATCH 0/4] x86/mce: protect nr_cpus from rebooting by broadcast mce Dave Young
2019-08-07 7:52 ` Pingfan Liu
2019-08-07 13:07 ` Thomas Gleixner [this message]
2019-08-08 5:41 ` Pingfan Liu
2019-08-08 6:51 ` Thomas Gleixner
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