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

[Thomas Gleixner]

Jim,

Jim Mattson <jmattson@xxxxxxxxxx> writes:
> On Thu, Apr 2, 2020 at 4:16 PM Kenneth R. Crudup <kenny@xxxxxxxxx> wrote:
>> 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?
>
> What modules are we talking about? I thought we were discussing L1
> hypervisors, which are just binary blobs. The only modules at the L0
> level are kvm and kvm_intel.

Maybe in your world, but VmWare (which got this started), VirtualBox,
Jailhouse and who knows what else _are_ L0 hypervisors. Otherwise we
wouldn't have that conversation at all.

Thanks,

        tglx