Re: [PATCH v4 16/21] i386: track explicit 'hv-*' features enablement/disablement

[Igor Mammedov]

On Fri, 12 Feb 2021 16:26:03 +0100
Vitaly Kuznetsov <vkuznets@redhat.com> wrote:

> Vitaly Kuznetsov <vkuznets@redhat.com> writes:
> 
> > Igor Mammedov <imammedo@redhat.com> writes:
> >  
> >>
> >> Please try reusing scratch CPU approach, see
> >>   kvm_arm_get_host_cpu_features()
> >> for an example. You will very likely end up with simpler series,
> >> compared to reinventing wheel.  
> >
> > Even if I do that (and I serioulsy doubt it's going to be easier than
> > just adding two 'u64's, kvm_arm_get_host_cpu_features() alone is 200
> > lines long) this is not going to give us what we need to distinguish
> > between
> >
> > 'hv-passthrough,hv-evmcs'
> >
> > and 
> >
> > 'hv-passthrough'
> >
> > when 'hv-evmcs' *is* supported by the host. When guest CPU lacks VMX we
> > don't want to enable it unless it was requested explicitly (former but
> > not the later).  
> 
> ... and if for whatever reason we decide that this is also bad/not
> needed, I can just drop patches 16-18 from the series (leaving
> 'hv-passthrough,hv-feature=off' problem to better times).
that's also an option,
we would need to make sure that hv-passthrough is mutually exclusive
with ''all'' other hv- properties to avoid above combination being
ever (mis)used.