Re: [PATCH v9 8/8] x86/split_lock: Enable split lock detection initialization when running as an guest on KVM

[Xiaoyao Li]

On 5/10/2020 1:15 PM, Andy Lutomirski wrote:
> On Fri, May 8, 2020 at 8:04 PM Xiaoyao Li <xiaoyao.li@xxxxxxxxx> wrote:
> > When running as guest, enumerating feature split lock detection through
> > CPU model is not easy since CPU model is configurable by host VMM.
> >
> > If running upon KVM, it can be enumerated through
> > KVM_FEATURE_SPLIT_LOCK_DETECT,
>
> This needs crystal clear documentation.  What, exactly, is the host
> telling the guest if it sets this flag?
>
> > and if KVM_HINTS_SLD_FATAL is set, it
> > needs to be set to sld_fatal mode.
>
>
> This needs much better docs.  Do you mean:
>
> "If KVM_HINTS_SLD_FATAL is set, then the guest will get #AC if it does
> a split-lock regardless of what is written to MSR_TEST_CTRL?"

Hi Andy,

KVM_FEATURE_SPLIT_LOCK_DETECT, KVM_HINTS_SLD_FATAL and their docs are 
introduced in Patch 5. Do I still need to explain them in detail in this 
patch?