linux-kernel - Re: [PATCH v1 1/3] x86/tdx: Check for TDX partitioning during early TDX init

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Message-ID: <20231129164049.GVZWdpkVlc8nUvl/jx@fat_crate.local>
Date:   Wed, 29 Nov 2023 17:40:49 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     Jeremi Piotrowski <jpiotrowski@...ux.microsoft.com>
Cc:     linux-hyperv@...r.kernel.org, stefan.bader@...onical.com,
        tim.gardner@...onical.com, roxana.nicolescu@...onical.com,
        cascardo@...onical.com, kys@...rosoft.com, haiyangz@...rosoft.com,
        wei.liu@...nel.org, sashal@...nel.org, stable@...r.kernel.org,
        linux-kernel@...r.kernel.org, "H. Peter Anvin" <hpa@...or.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Ingo Molnar <mingo@...hat.com>,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        Michael Kelley <mhkelley58@...il.com>,
        Nikolay Borisov <nik.borisov@...e.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Tom Lendacky <thomas.lendacky@....com>, x86@...nel.org,
        Dexuan Cui <decui@...rosoft.com>
Subject: Re: [PATCH v1 1/3] x86/tdx: Check for TDX partitioning during early
 TDX init

On Wed, Nov 22, 2023 at 06:19:20PM +0100, Jeremi Piotrowski wrote:
> Which approach do you prefer?

I'm trying to figure out from the whole thread, what this guest is.

* A HyperV second-level guest

* of type TDX

* Needs to defer cc_mask and page visibility bla...

* needs to disable TDX module calls

* stub out tdx_accept_memory

Anything else?

And my worry is that this is going to become a mess and your patches
already show that it is going in that direction because you need to run
the TDX side but still have *some* things done differently. Which is
needed because this is a different type of guest, even if it is a TDX
one.

Which reminds me, we have amd_cc_platform_vtom() which is a similar type
of thing.

And the TDX side could do something similar and at least *try* to
abstract away all that stuff.

Would it be nice? Of course not!

How can one model a virt zoo of at least a dozen guest types but still
keep code sane... :-\

-- 
Regards/Gruss,
    Boris.

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