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

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Date:   Wed, 9 Jun 2021 07:01:13 -0700
From:   "Kuppuswamy, Sathyanarayanan" 
        <sathyanarayanan.kuppuswamy@...ux.intel.com>
To:     Borislav Petkov <bp@...en8.de>
Cc:     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
 abstraction



On 6/7/21 11:26 AM, Borislav Petkov wrote:
>> This header only exists in x86 arch code. So it is better to protect
>> it with x86 specific header file.
> That doesn't sound like a special reason to me. And compilers are
> usually very able at discarding unused symbols so I don't see a problem
> with keeping all includes at the top, like it is usually done.

I am still not clear. What happens when a driver which includes
linux/protected-guest.h is compiled for non-x86 arch (s390 or arm64)?

Since asm/sev.h and asm/tdx.h exists only in x86_64 arch, IMO, it
should be placed under CONFIG_INTEL_TDX_GUEST or CONFIG_AMD_MEM_ENCRYPT

did I miss anything?

-- 
Sathyanarayanan Kuppuswamy
Linux Kernel Developer