Add README for tdx-compliance.

Signed-off-by: Yi Sun <[email protected]>

tdx-compliance/README.md

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+Intel® Trust Domain Extensions (Intel® TDX) is an Intel technology that
+expands Virtual Machine Extensions (VMX) with a new type of virtual
+machine guest known as a Trust Domain (TD).
+
+A TD is intended to secure the confidentiality of its memory contents,
+CPU state, and so on. This patch set aims to develop a TDX compliance
+test suite to verify the TDX's consistency to the specification,
+preventing potential security risks in the TD environment.
+
+TDX compliance tests contain a series of compliance tests, including
+CPUID, CR, MSR. They are designed to verify the security and
+functionality of the TD environment, which should work exactly as
+designed in the TDX Specification. That will increase the credibility
+of Intel TDX.
+
+## Usage
+TDX-compliance is designed to work as a kernel module. Before using it,
+you need to build it.
+
+### Step 1: Prepare your environment to build kernel modules
+Build and install the kernel locally (in TD guest)
+Install the source code from distribution
+
+### Step 2: Build tdx-compliance
+To build tdx-compliance, follow these steps:
+
+```bash
+git clone https://github.com/intel/lkvs.git
+cd lkvs/tdx-compliance
+make
+insmod tdx-compliance
+```
+### Step 3: Run test cases
+To run all kinds of compliance tests, simply enter the following command:
+
+```bash
+echo all > /sys/kernel/debug/tdx/tdx-tests
+```
+
+To view the results and logs, use this command:
+```bash
+cat /sys/kernel/debug/tdx/tdx-tests
+```
+If you want to learn more about tdx-compliance, please refer to the
+following resources.
+
+* CPUID
+
+CPUID compliance is part of TDX-compliance tests to make sure whether
+the current virtualized TD environment is compliant with the CPUID
+instruction, especially for the ones with fixed type, confirming the
+expected outputs, and no exceptions occur.
+
+A CPUID compliance test calls the instruction 'cpuid' with leaf or
+sub-leaf specified, then check the bits of outputs. All tests are
+from the table 2.4(CPUID Virtualization Overview) in Intel® Trust
+Domain Extensions (Intel® TDX) Module Architecture Application
+Binary Interface (ABI) Reference Specification
+
+Users can execute the compliance test and dump results via the Kernel
+interface /sys/kernel/debug/tdx/tdx-tests.
+
+Usage:
+Run cpuid compliance tests:
+```
+echo cpuid > /sys/kernel/debug/tdx/tdx-tests
+```
+
+* MSR
+
+The Model Specific Registers (MSR) are special registers in the CPU that
+store information related to the processor model. Intel TDX virtualizes
+the behavior of the MSRs' read and write.
+
+Usage:
+Run MSR compliance tests:
+```
+each msr > /sys/kernel/debug/tdx/tdx-tests
+```
+
+* CR(Control Registers)
+
+CR(Control Register) is a set of registers in the processor used to control
+operations. They contain many different control bits that are used to
+control how the processor operates. For example, control bits in the CR0
+can be used to enable or disable the pagination mechanism, etc.
+
+Usage:
+```
+echo cr > /sys/kernel/debug/tdx/tdx-tests
+```
+
+## Contact:
+Sun, Yi ([email protected])
+