Re: [RFC v2 10/32] x86/tdx: Wire up KVM hypercalls

[Kuppuswamy, Sathyanarayanan]

On 5/12/21 7:29 AM, Dave Hansen wrote:
> On 5/12/21 7:10 AM, Kuppuswamy, Sathyanarayanan wrote:
> > On 5/12/21 6:00 AM, Kirill A. Shutemov wrote:
> > > This has to be compiled only for TDX+KVM.
> >
> > Got it. So if we want to remove the "C" file include, we will have to
> > add #ifdef CONFIG_KVM_GUEST in Makefile.
> >
> > ifdef CONFIG_KVM_GUEST
> > obj-$(CONFIG_INTEL_TDX_GUEST) += tdx-kvm.o
> > #endif
>
> Is there truly no dependency between CONFIG_KVM_GUEST and
> CONFIG_INTEL_TDX_GUEST?

We want to re-use TDX code with other hypervisors/guests as well. So
we can't create direct dependency with CONFIG_KVM_GUEST in Kconfig.

> If there isn't, then the way we do it is adding another (invisible)
> Kconfig variable to express the dependency for tdx-kvm.o:
>
> config INTEL_TDX_GUEST_KVM
> 	bool
> 	depends on KVM_GUEST && INTEL_TDX_GUEST

Currently it will only be used for KVM hypercall code. Will it to be
overkill to create a new config over #ifdefs for this use case ? But,
if this is the preferred approach, I will go with this suggestion.

>

--
Sathyanarayanan Kuppuswamy
Linux Kernel Developer