TDX Guest API Documentation

1. General description

The TDX guest driver exposes IOCTL interfaces via the /dev/tdx-guest misc device to allow userspace to get certain TDX guest-specific details.

2. API description

In this section, for each supported IOCTL, the following information is provided along with a generic description.

Input parameters:

Parameters passed to the IOCTL and related details.


Details about output data and return value (with details about the non common error values).


Input parameters:

struct tdx_report_req


Upon successful execution, TDREPORT data is copied to tdx_report_req.tdreport and return 0. Return -EINVAL for invalid operands, -EIO on TDCALL failure or standard error number on other common failures.

The TDX_CMD_GET_REPORT0 IOCTL can be used by the attestation software to get the TDREPORT0 (a.k.a. TDREPORT subtype 0) from the TDX module using TDCALL[TDG.MR.REPORT].

A subtype index is added at the end of this IOCTL CMD to uniquely identify the subtype-specific TDREPORT request. Although the subtype option is mentioned in the TDX Module v1.0 specification, section titled "TDG.MR.REPORT", it is not currently used, and it expects this value to be 0. So to keep the IOCTL implementation simple, the subtype option was not included as part of the input ABI. However, in the future, if the TDX Module supports more than one subtype, a new IOCTL CMD will be created to handle it. To keep the IOCTL naming consistent, a subtype index is added as part of the IOCTL CMD.


TDX reference material is collected here:

The driver is based on TDX module specification v1.0 and TDX GHCI specification v1.0.