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Date:   Mon, 18 Jul 2022 15:52:01 -0700
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Subject: Re: [PATCH v8 1/5] x86/tdx: Add TDX Guest attestation interface
 driver
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From:   Sathyanarayanan Kuppuswamy 
        <sathyanarayanan.kuppuswamy@linux.intel.com>
To:     Kai Huang <kai.huang@intel.com>,
        Dave Hansen <dave.hansen@intel.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        Dave Hansen <dave.hansen@linux.intel.com>, x86@kernel.org
Cc:     "H . Peter Anvin" <hpa@zytor.com>,
        "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
        Tony Luck <tony.luck@intel.com>,
        Andi Kleen <ak@linux.intel.com>,
        Wander Lairson Costa <wander@redhat.com>,
        Isaku Yamahata <isaku.yamahata@gmail.com>,
        marcelo.cerri@canonical.com, tim.gardner@canonical.com,
        khalid.elmously@canonical.com, philip.cox@canonical.com,
        linux-kernel@vger.kernel.org
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Hi Dave,

On 7/6/22 3:27 PM, Sathyanarayanan Kuppuswamy wrote:
> 
> 
> On 7/5/22 3:31 PM, Kai Huang wrote:
>> On Tue, 2022-07-05 at 14:21 -0700, Sathyanarayanan Kuppuswamy wrote:
>>> SGX is a related feature. It also uses IOCTL approach for enclave provisioning.
>>>
>>> arch/x86/kernel/cpu/sgx/ioctl.c
>>
>> SGX isn't a good example here.  The IOCTLs are used to create enclaves, but not
>> for attestation.  SGX attestation relies on enclave itself to get/verify the
>> report, etc, so has no interaction with the kernel.
> 
> If you are looking for an attestation specific example, you can only check the AMD
> code.
> 
> https://patchwork.kernel.org/project/linux-mm/patch/20220307213356.2797205-44-brijesh.singh@amd.com/
> 
> Also, sev_get_attestation_report() in arch/x86/kvm/svm/sev.c also implements attestation
> IOCTL specific to KVM.
> 

As mentioned above, AMD also uses IOCTL model for attestation use case. So you agree
with us using similar approach here? Please let me know your comments.

-- 
Sathyanarayanan Kuppuswamy
Linux Kernel Developer