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

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Date:   Wed, 2 Jun 2021 11:25:43 -0700
From:   "Kuppuswamy, Sathyanarayanan" 
        <sathyanarayanan.kuppuswamy@...ux.intel.com>
To:     Tom Lendacky <thomas.lendacky@....com>,
        Sean Christopherson <seanjc@...gle.com>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Andy Lutomirski <luto@...nel.org>,
        Dave Hansen <dave.hansen@...el.com>,
        Tony Luck <tony.luck@...el.com>,
        Borislav Petkov <bp@...en8.de>,
        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>, linux-kernel@...r.kernel.org
Subject: Re: [RFC v2-fix-v2 1/1] x86: Introduce generic protected guest
 abstraction



On 6/2/21 11:15 AM, Tom Lendacky wrote:
> The original suggestion from Boris, IIRC, was for protected_guest_has()
> function (below) to be:
> 
> 	if (intel)
> 		return intel_protected_guest_has();

Yes. But for Intel, I think currently we can only check for is_tdx_guest() here.

if (is_tdx_guest())
	return intel_protected_guest_has();

So if we use is_tdx_guest(), it is better to call tdx_protected_guest_has() here.

Once we start using protected_guest_has for other Intel technologies, may be
we can generalize it. Let me know your comments.

> 	else if (amd)
> 		return amd_protected_guest_has();
> 	else
> 		return false;
> 
> And then you could check for TDX or SME/SEV in the respective functions.

-- 
Sathyanarayanan Kuppuswamy
Linux Kernel Developer