virt: Add TDX guest driverTDX guest driver exposes IOCTL interfaces to service TDX guestuser-specific requests. Currently, it is only used to allow the user toget the TDREPORT to support TDX atte
virt: Add TDX guest driverTDX guest driver exposes IOCTL interfaces to service TDX guestuser-specific requests. Currently, it is only used to allow the user toget the TDREPORT to support TDX attestation.Details about the TDX attestation process are documented inDocumentation/x86/tdx.rst, and the IOCTL details are documented inDocumentation/virt/coco/tdx-guest.rst.Operations like getting TDREPORT involves sending a blob of data asinput and getting another blob of data as output. It was consideredto use a sysfs interface for this, but it doesn't fit well into thestandard sysfs model for configuring values. It would be possible todo read/write on files, but it would need multiple file descriptors,which would be somewhat messy. IOCTLs seem to be the best fittingand simplest model for this use case. The AMD sev-guest driver alsouses the IOCTL interface to support attestation.[Bagas Sanjaya: Ack is for documentation portion]Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>Reviewed-by: Bagas Sanjaya <bagasdotme@gmail.com>Reviewed-by: Tony Luck <tony.luck@intel.com>Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>Acked-by: Kai Huang <kai.huang@intel.com>Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>Acked-by: Wander Lairson Costa <wander@redhat.com>Link: https://lore.kernel.org/all/20221116223820.819090-3-sathyanarayanan.kuppuswamy%40linux.intel.com
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