Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:18 as permitted sender) client-ip=2620:137:e000::1:18;
Date:   Wed, 9 Feb 2022 20:07:52 +0000
From:   Sean Christopherson <seanjc@google.com>
To:     Borislav Petkov <bp@alien8.de>
Cc:     Kai Huang <kai.huang@intel.com>,
        "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
        tglx@linutronix.de, mingo@redhat.com, dave.hansen@intel.com,
        luto@kernel.org, peterz@infradead.org,
        sathyanarayanan.kuppuswamy@linux.intel.com, aarcange@redhat.com,
        ak@linux.intel.com, dan.j.williams@intel.com, david@redhat.com,
        hpa@zytor.com, jgross@suse.com, jmattson@google.com,
        joro@8bytes.org, jpoimboe@redhat.com, knsathya@kernel.org,
        pbonzini@redhat.com, sdeep@vmware.com, tony.luck@intel.com,
        vkuznets@redhat.com, wanpengli@tencent.com, x86@kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCHv2 00/29] TDX Guest: TDX core support
Message-ID: <YgQfGKXOemtXnFau@google.com>
References: <20220124150215.36893-1-kirill.shutemov@linux.intel.com>
 <20220209235613.652f5720cd196331d7a220ec@intel.com>
 <YgOgog9Pb886lfsv@zn.tnic>
 <20220210003033.e57c2925b69bab5cfabf7292@intel.com>
 <YgOoId+vyd1VhIqQ@zn.tnic>
 <20220210004831.03dea501738bee060003d040@intel.com>
 <YgOr6tZjsooJgAi9@zn.tnic>
 <YgPwwI2+16/7jQC4@google.com>
 <YgQR/S67Fqz9PanR@zn.tnic>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <YgQR/S67Fqz9PanR@zn.tnic>
Precedence: bulk

On Wed, Feb 09, 2022, Borislav Petkov wrote:
> On Wed, Feb 09, 2022 at 04:50:08PM +0000, Sean Christopherson wrote:
> > 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. :-(

Don't forget :-)

  arch/x86/kernel/kvm.c - KVM guest stuff

> 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?

No objection to omitting "coco".  Though what about using "vmx" and "svm" instead
of "tdx" and "sev".  We lose the more explicit tie to coco, but it would mirror the
sub-directories in arch/x86/kvm/ and would avoid a mess in the scenario where tdx
or sev needs to share code with the non-coco side, e.g. I'm guessing TDX will need
to do VMXON.

  arch/x86/virt/vmx/
  	tdx.c
	vmx.c

  arch/x86/virt/svm/
  	sev.c
	sev-es.c
	sev-snp.c
  	svm.c