linux-kernel - Re: [PATCH 1/2] KVM: x86: Emulate split-lock access as a write

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Date:   Mon, 10 Feb 2020 13:59:49 -0800
From:   Sean Christopherson <sean.j.christopherson@...el.com>
To:     Vitaly Kuznetsov <vkuznets@...hat.com>
Cc:     Andy Lutomirski <luto@...capital.net>,
        David Laight <David.Laight@...lab.com>,
        Xiaoyao Li <xiaoyao.li@...el.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        "x86@...nel.org" <x86@...nel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>
Subject: Re: [PATCH 1/2] KVM: x86: Emulate split-lock access as a write

On Tue, Feb 04, 2020 at 03:47:15PM +0100, Vitaly Kuznetsov wrote:
> Sean Christopherson <sean.j.christopherson@...el.com> writes:
> 
> > Exiting to host userspace with "emulation failed" is the other reasonable
> > alternative, but that's basically the same as killing the guest.  We're
> > arguing that, in the extremely unlikely event that there is a workload out
> > there that hits this, it's preferable to *maybe* corrupt guest memory and
> > log the anomaly in the kernel log, as opposed to outright killing the guest
> > with a generic "emulation failed".
> >
> 
> FWIW, if I was to cast a vote I'd pick 'kill the guest' one way or
> another. "Maybe corrupt guest memory" scares me much more and in many
> cases host and guest are different responsibility domains (think
> 'cloud').

I'm ok with that route as well.  What I don't want to do is add a bunch of
logic to inject #AC at this point.