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    SubjectRe: [PATCHv2 00/29] TDX Guest: TDX core support
    On Wed, Feb 09, 2022 at 04:50:08PM +0000, Sean Christopherson wrote:
    > On Wed, Feb 09, 2022, Borislav Petkov wrote:
    > > On Thu, Feb 10, 2022 at 12:48:31AM +1300, Kai Huang wrote:
    > > > Are you suggesting even for now we can start to put TDX host support to
    > > > arch/x86/coco/tdx/ ?
    > >
    > > That's exactly what I'm suggesting. The TDX stuff is not upstream so
    > > nothing's cast in stone yet. This way there won't be any unpleasant code
    > > movements later.
    >
    > I strongly prefer we put the guest and host code in separate directories. Both
    > TDX and SEV are big enough that they'll benefit from splitting up files, having
    > to fight over file names or tag all files with guest/host will get annoying.
    >
    > I do like the idea of arch/x86/coco though. The most straightforward approach
    > would be:
    >
    > arch/x86/coco/guest/
    > arch/x86/coco/host/
    >
    > but that doesn't provide any extensibility on the host virtualization side, e.g.
    > to land non-coco, non-KVM-specific host virtualization code (we have a potential
    > use case for this). If that happens, we'd end up with x86 KVM having code and
    > dependencies split across:
    >
    > arch/x86/coco/host
    > arch/x86/kvm/
    > arch/x86/???/
    >
    > An alternative idea would be to mirror what generic KVM does (virt/kvm/), and do:
    >
    > arch/x86/coco/<guest stuff>
    > arch/x86/virt/<"generic" x86 host virtualization stuff>
    > arch/x86/virt/coco/<host coco stuff>
    > arch/x86/virt/kvm/
    >
    > Though I can already hear the stable trees and downstream kernels crying out in
    > horror at moving arch/x86/kvm :-)

    Hmmm, so I am still thinking about guest-only when we're talking about
    arch/x86/coco/.

    Lemme look at the other virt things:

    the kvm host virt stuff is in:

    arch/x86/kvm/

    (btw, this is where the SEV host stuff is: arch/x86/kvm/svm/sev.c)

    arch/x86/hyperv/ - looks like hyperv guest stuff

    arch/x86/xen/ - xen guest stuff

    arch/x86/kernel/cpu/vmware.c - vmware guest stuff

    arch/x86/kernel/cpu/acrn.c - Acorn guest stuff

    So we have a real mess. :-(

    Not surprised though. So that last thing you're suggesting kinda makes
    sense but lemme tweak it a bit:

    arch/x86/coco/<guest stuff>
    arch/x86/virt/<"generic" x86 host virtualization stuff>
    arch/x86/virt/tdx/ - no need for the "coco" thing - TDX is nothing but coco. TDX host
    stuff

    arch/x86/virt/sev/ - ditto

    and we'll keep arch/x86/kvm because of previous precedents with other
    things I've enumerated above.

    Hmmm?

    --
    Regards/Gruss,
    Boris.

    https://people.kernel.org/tglx/notes-about-netiquette

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