linux-kernel - Re: [PATCH v5 3/9] x86/split_lock: Re-define the kernel param option for split_lock

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Message-ID: <87wo79d27e.fsf@nanos.tec.linutronix.de>
Date:   Tue, 24 Mar 2020 19:42:29 +0100
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Sean Christopherson <sean.j.christopherson@...el.com>
Cc:     Xiaoyao Li <xiaoyao.li@...el.com>, Ingo Molnar <mingo@...hat.com>,
        Borislav Petkov <bp@...en8.de>, hpa@...or.com,
        Paolo Bonzini <pbonzini@...hat.com>, kvm@...r.kernel.org,
        x86@...nel.org, linux-kernel@...r.kernel.org,
        Andy Lutomirski <luto@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Arvind Sankar <nivedita@...m.mit.edu>,
        Fenghua Yu <fenghua.yu@...el.com>,
        Tony Luck <tony.luck@...el.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Jim Mattson <jmattson@...gle.com>
Subject: Re: [PATCH v5 3/9] x86/split_lock: Re-define the kernel param option for split_lock_detect

Sean Christopherson <sean.j.christopherson@...el.com> writes:
> On Tue, Mar 24, 2020 at 11:40:18AM +0100, Thomas Gleixner wrote:
>> 
>> It's very much about whether the host is split lock clean.
>> 
>> If your host kernel is not, then this wants to be fixed first. If your
>> host application is broken, then either fix it or use "warn".
>
> The "kvm only" option was my suggestion.  The thought was to provide a way
> for users to leverage KVM to debug/test kernels without having to have a
> known good kernel and/or to minimize the risk of crashing their physical
> system.  E.g. debug a misbehaving driver by assigning its associated device
> to a guest.

warn is giving you that, right? I won't crash the host because the #AC
triggers in guest context.

Thanks,

        tglx