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

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Message-ID: <41e63d89f1b2debc0280f243d7c8c3212e9499ee.camel@infradead.org>
Date:   Fri, 17 Dec 2021 20:13:16 +0000
From:   David Woodhouse <dwmw2@...radead.org>
To:     Tom Lendacky <thomas.lendacky@....com>,
        Thomas Gleixner <tglx@...utronix.de>
Cc:     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 Fri, 2021-12-17 at 13:46 -0600, Tom Lendacky wrote:
> There's no WARN or PANIC, just a reset. I can look to try and capture some
> KVM trace data if that would help. If so, let me know what events you'd
> like captured.


Could start with just kvm_run_exit?

Reason 8 would be KVM_EXIT_SHUTDOWN and would potentially indicate a
triple fault.

Failing that, I'd want to start littering the real mode code with
outputting 'a' 'b' 'c' etc. to the serial port and see if the offending
CPU is really in the trampoline somewhere when something goes wrong.

I can knock up an example patch to do that (not tonight) but this would
be somewhat easier if I could find a machine I can reproduce on. Sadly
I only seem to have access to Milan *guests* without nested virt, not
bare metal. Got a machine I can log in to?

 

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