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Date:   Tue, 5 Jul 2022 14:21:55 -0700
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Subject: Re: [PATCH v8 1/5] x86/tdx: Add TDX Guest attestation interface
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To:     Dave Hansen <dave.hansen@intel.com>,
        Kai Huang <kai.huang@intel.com>,
        Thomas Gleixner <tglx@linutronix.de>,
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        "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
        Tony Luck <tony.luck@intel.com>,
        Andi Kleen <ak@linux.intel.com>,
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        Isaku Yamahata <isaku.yamahata@gmail.com>,
        marcelo.cerri@canonical.com, tim.gardner@canonical.com,
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        linux-kernel@vger.kernel.org
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From:   Sathyanarayanan Kuppuswamy 
        <sathyanarayanan.kuppuswamy@linux.intel.com>
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On 7/5/22 11:52 AM, Dave Hansen wrote:
> On 7/5/22 11:45, Sathyanarayanan Kuppuswamy wrote:
>> Yes, there are many ways to design this. But I still think IOCTL is a better fit
>> for the request/response kind of use case.
> 
> Are there any other similar ABIs in the kernel?  What kind of mechanism
> do they use?

AMD also plans to add attestation support. It also uses IOCTL approach.

https://patchwork.kernel.org/project/linux-mm/patch/20220307213356.2797205-44-brijesh.singh@amd.com/

SGX is a related feature. It also uses IOCTL approach for enclave provisioning.

arch/x86/kernel/cpu/sgx/ioctl.c

Other examples (not very related) are,

drivers/platform/chrome/cros_ec_chardev.c - It is an embedded controller driver which
has IOCTL support to read memory region from the device.
drivers/s390/crypto/pkey_api.c - It has IOCTL interfaces to read/write/generate crypto
keys.
drivers/crypto/ccp/sev-dev.c - sev_ioctl() has some IOCTL to set/get keys.
drivers/platform/x86/intel_scu_ipcutil.c - Uses IOCTL to read contents of registers.


-- 
Sathyanarayanan Kuppuswamy
Linux Kernel Developer