linux-kernel - Re: [RFC v2-fix-v2 1/1] x86: Introduce generic protected guest abstractionn

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Date:   Mon, 7 Jun 2021 22:14:30 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     "Kirill A. Shutemov" <kirill@...temov.name>
Cc:     Kuppuswamy Sathyanarayanan 
        <sathyanarayanan.kuppuswamy@...ux.intel.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Andy Lutomirski <luto@...nel.org>,
        Dave Hansen <dave.hansen@...el.com>,
        Tony Luck <tony.luck@...el.com>,
        Andi Kleen <ak@...ux.intel.com>,
        Kirill Shutemov <kirill.shutemov@...ux.intel.com>,
        Kuppuswamy Sathyanarayanan <knsathya@...nel.org>,
        Dan Williams <dan.j.williams@...el.com>,
        Raj Ashok <ashok.raj@...el.com>,
        Sean Christopherson <seanjc@...gle.com>,
        linux-kernel@...r.kernel.org,
        Tom Lendacky <thomas.lendacky@....com>
Subject: Re: [RFC v2-fix-v2 1/1] x86: Introduce generic protected guest
 abstractionn

On Mon, Jun 07, 2021 at 10:55:44PM +0300, Kirill A. Shutemov wrote:
> I think conversions like this are wrong: relocate_kernel(), which got
> called here, only knows how to deal with SME, not how to handle some
> generic case.

What do you mean wrong? Wrong for TDX?

If so, then that can be

protected_guest_has(SME)

or so, which would be false on Intel.

And this patch was only a mechanical conversion to see how it would look
like.

> If code is written to handle a specific technology we need to stick
> with a check that makes it clear. Trying to make sound generic only
> leads to confusion.

Sure, fine by me.

And I don't want a zoo of gazillion small checking functions per
technology. sev_<something>, tdx_<something>, yadda yadda.

So stuff better be unified. Even if you'd have vendor-specific defines
you hand into that function - and you will have such - it is still much
saner than what it turns into with the AMD side of things.

-- 
Regards/Gruss,
    Boris.

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