Re: [PATCH v2 2/7] KVM: x86: Extract VMXON and EFER.SVME enablement to kernel

Sean Christopherson
2025-12-10T14:20:19Z

On Wed, Dec 10, 2025, dan.j.williams@intel.com wrote:
> Sean Christopherson wrote:
> > On Sat, Dec 06, 2025, dan.j.williams@intel.com wrote:
> > I don't think we need anything at this time. INTEL_TDX_HOST depends on KVM_INTEL,
> > and so without a user that needs VMXON without KVM_INTEL, I think we're good as-is.
> >
> > config INTEL_TDX_HOST
> > bool "Intel Trust Domain Extensions (TDX) host support"
> > depends on CPU_SUP_INTEL
> > depends on X86_64
> > depends on KVM_INTEL
>
> ...but INTEL_TDX_HOST, it turns out, does not have any functional
> dependencies on KVM_INTEL. At least, not since I last checked. Yes, it
> would be silly and result in dead code today to do a build with:
>
> CONFIG_INTEL_TDX_HOST=y
> CONFIG_KVM_INTEL=n
>
> However, when the TDX Connect support arrives you could have:
>
> CONFIG_INTEL_TDX_HOST=y
> CONFIG_KVM_INTEL=n
> CONFIG_TDX_HOST_SERVICES=y
>
> Where "TDX Host Services" is a driver for PCIe Link Encryption and TDX
> Module update. Whether such configuration freedom has any practical
> value is a separate question.
>
> I am ok if the answer is, "wait until someone shows up who really wants
> PCIe Link Encryption without KVM".

Ya, that's my answer. At the very least, wait until TDX_HOST_SERVICES comes
along.