linux-kernel - Re: [RFC v2 28/32] x86/tdx: Make pages shared in ioremap()

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Message-ID: <YLUjCqdPu/8eWuB+@zn.tnic>
Date:   Mon, 31 May 2021 19:55:22 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     "Kuppuswamy, Sathyanarayanan" 
        <sathyanarayanan.kuppuswamy@...ux.intel.com>
Cc:     Tom Lendacky <thomas.lendacky@....com>,
        Sean Christopherson <seanjc@...gle.com>,
        Dave Hansen <dave.hansen@...el.com>,
        Andi Kleen <ak@...ux.intel.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Andy Lutomirski <luto@...nel.org>,
        Dan Williams <dan.j.williams@...el.com>,
        Tony Luck <tony.luck@...el.com>,
        Kirill Shutemov <kirill.shutemov@...ux.intel.com>,
        Kuppuswamy Sathyanarayanan <knsathya@...nel.org>,
        Raj Ashok <ashok.raj@...el.com>, linux-kernel@...r.kernel.org,
        Brijesh Singh <brijesh.singh@....com>
Subject: Re: [RFC v2 28/32] x86/tdx: Make pages shared in ioremap()

On Mon, May 31, 2021 at 10:32:44AM -0700, Kuppuswamy, Sathyanarayanan wrote:
> I think above requirement is satisfied in following implementation.

Well, I suggested a single protected_guest_has() function which does:

        if (AMD)
                amd_protected_guest_has(...)
        else if (Intel)
                intel_protected_guest_has(...)
        else
                WARN()

where amd_protected_guest_has() is implemented in arch/x86/kernel/sev.c
and intel_protected_guest_has() is implemented in, as far as I can
follow your paths in the diff, in arch/x86/kernel/tdx.c.

No is_protected_guest() and no ARCH_HAS_PROTECTED_GUEST.

Just the above controlled by CONFIG_INTEL_TDX_GUEST or whatever
the TDX config item is gonna end up being and on the AMD side by
CONFIG_AMD_MEM_ENCRYPT.

Thx.

-- 
Regards/Gruss,
    Boris.

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