linux-kernel - Re: [PATCH 3/3] KVM: VMX: Extend VMX's #AC interceptor to handle split lock #AC in guest

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Message-ID: <alpine.DEB.2.21.2004021613110.10453@xps-7390>
Date:   Thu, 2 Apr 2020 16:16:25 -0700 (PDT)
From:   "Kenneth R. Crudup" <kenny@...ix.com>
To:     Steven Rostedt <rostedt@...dmis.org>
cc:     Nadav Amit <namit@...are.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        x86 <x86@...nel.org>, Paolo Bonzini <pbonzini@...hat.com>,
        Fenghua Yu <fenghua.yu@...el.com>,
        Xiaoyao Li <xiaoyao.li@...el.com>,
        Thomas Hellstrom <thellstrom@...are.com>,
        Tony Luck <tony.luck@...el.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Jessica Yu <jeyu@...nel.org>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>, kvm <kvm@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Doug Covelli <dcovelli@...are.com>
Subject: Re: [PATCH 3/3] KVM: VMX: Extend VMX's #AC interceptor to handle
 split lock #AC in guest


On Thu, 2 Apr 2020, Steven Rostedt wrote:

> If we go the approach of not letting VM modules load if it doesn't have the
> sld_safe flag set, how is this different than a VM module not loading due
> to kabi breakage?

Why not a compromise: if such a module is attempted to be loaded, print up
a message saying something akin to "turn the parameter 'split_lock_detect'
off" as we reject loading it- and if we see that we've booted with it off
just splat a WARN_ON() if someone tries to load such modules?

	-Kenny

-- 
Kenneth R. Crudup  Sr. SW Engineer, Scott County Consulting, Silicon Valley