Re: [PATCH 03/16] x86/tsc: Add helper to register CPU and TSC freq calibration routines

[Sean Christopherson <seanjc@xxxxxxxxxx>]

On Tue, Feb 11, 2025, Borislav Petkov wrote:
> On Fri, Jan 31, 2025 at 06:17:05PM -0800, Sean Christopherson wrote:
> 
> > Add a TODO to call out that AMD_MEM_ENCRYPT is a mess and doesn't depend on
> > HYPERVISOR_GUEST because it gates both guest and host code.
> 
> Why is it a mess?
> 
> I don't see it, frankly.

It conflates two very different things: host/bare metal support for memory
encryption, and SEV guest support.  For kernels that will never run in a VM,
pulling in all the SEV guest code just to enable host-side support for SME (and
SEV) is very undesirable.

And in this case, because AMD_MEM_ENCRYPT gates both host and guest code, it
can't depend on HYPERVISOR_GUEST like it should, because taking a dependency on
HYPERVISOR_GUEST to enable SME is obviously wrong.