Date:   Tue, 21 Dec 2021 22:33:04 +0000
From:   David Woodhouse <dwmw2@infradead.org>
To:     Tom Lendacky <thomas.lendacky@amd.com>,
        Igor Mammedov <imammedo@redhat.com>
CC:     Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        "x86@kernel.org" <x86@kernel.org>,
        "H . Peter Anvin" <hpa@zytor.com>,
        Paolo Bonzini <pbonzini@redhat.com>,
        "Paul E . McKenney" <paulmck@kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "kvm@vger.kernel.org" <kvm@vger.kernel.org>,
        "rcu@vger.kernel.org" <rcu@vger.kernel.org>,
        "mimoja@mimoja.de" <mimoja@mimoja.de>,
        "hewenliang4@huawei.com" <hewenliang4@huawei.com>,
        "hushiyuan@huawei.com" <hushiyuan@huawei.com>,
        "luolongjun@huawei.com" <luolongjun@huawei.com>,
        "hejingxian@huawei.com" <hejingxian@huawei.com>
Subject: Re: [PATCH v3 0/9] Parallel CPU bringup for x86_64
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On 21 December 2021 22:25:35 GMT, Tom Lendacky <thomas=2Elendacky@amd=2Eco=
m> wrote:
>On 12/20/21 3:47 PM, Tom Lendacky wrote:
>> On 12/20/21 3:29 PM, David Woodhouse wrote:
>>> On Mon, 2021-12-20 at 12:54 -0600, Tom Lendacky wrote:
>>>> Took the tree back to commit df9726cb7178 and then applied this chang=
e=2E
>>>> I'm unable to trigger any kind of failure with this change=2E
>>>
>>> Hm=2E=2E=2E I fired up an EC2 m6a=2E48xlarge instance (192 CPUs) to pl=
ay with=2E
>>>
>>> I can reproduce your triple-fault on SMP bringup, but only with kexec=
=2E
>>> And I basically can't get *anything* to kexec without that triple-
>>> fault=2E Not a clean 5=2E16-rc2, not the Fedora stock 5=2E14=2E10 kern=
el=2E
>>>
>>> If I *boot* instead of kexec, I have not yet seen the problem at all=
=2E
>>> This is using Legacy BIOS not UEFI=2E
>>=20
>> Let me try with a legacy BIOS and see if I can repro=2E Might not be un=
til=20
>> tomorrow, though, since I had to let someone borrow the machine=2E
>
>I still encounter the issue using a legacy BIOS (SeaBIOS)=2E

I haven't had much time to play but have seen it with a stock kernel at le=
ast as far back as v5=2E0=2E They all triple-fault on bringing up secondary=
 CPUs, on kexec=2E

--=20
Sent from my Android device with K-9 Mail=2E Please excuse my brevity=2E