linux-kernel - Re: [PATCH v3 0/9] Parallel CPU bringup for x86

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Message-ID: <02be2ef0-8a18-553f-2bd7-1754c3f53477@amd.com>
Date:   Mon, 20 Dec 2021 15:47:21 -0600
From:   Tom Lendacky <thomas.lendacky@....com>
To:     David Woodhouse <dwmw2@...radead.org>,
        Igor Mammedov <imammedo@...hat.com>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        "x86@...nel.org" <x86@...nel.org>,
        "H . Peter Anvin" <hpa@...or.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        "Paul E . McKenney" <paulmck@...nel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "rcu@...r.kernel.org" <rcu@...r.kernel.org>,
        "mimoja@...oja.de" <mimoja@...oja.de>,
        "hewenliang4@...wei.com" <hewenliang4@...wei.com>,
        "hushiyuan@...wei.com" <hushiyuan@...wei.com>,
        "luolongjun@...wei.com" <luolongjun@...wei.com>,
        "hejingxian@...wei.com" <hejingxian@...wei.com>
Subject: Re: [PATCH v3 0/9] Parallel CPU bringup for x86_64

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 change.
>> I'm unable to trigger any kind of failure with this change.
> 
> Hm... I fired up an EC2 m6a.48xlarge instance (192 CPUs) to play with.
> 
> I can reproduce your triple-fault on SMP bringup, but only with kexec.
> And I basically can't get *anything* to kexec without that triple-
> fault. Not a clean 5.16-rc2, not the Fedora stock 5.14.10 kernel.
> 
> If I *boot* instead of kexec, I have not yet seen the problem at all.
> This is using Legacy BIOS not UEFI.

Let me try with a legacy BIOS and see if I can repro. Might not be until 
tomorrow, though, since I had to let someone borrow the machine.

Thanks,
Tom

> 
>