[RFC PATCH 0/4] TDX KVM selftests

[Erdem Aktas]

TDX stands for Trust Domain Extensions which isolates VMs from the
virtual-machine manager (VMM)/hypervisor and any other software on the
platform.

Intel has recently submitted a set of RFC patches for KVM support for
TDX and more information can be found on the latest TDX Support 
Patches: https://lkml.org/lkml/2021/7/2/558

Due to the nature of the confidential computing environment that TDX
provides, it is very difficult to verify/test the KVM support. TDX
requires UEFI and the guest kernel to be enlightened which are all under
development.

We are working on a set of selftests to close this gap and be able to
verify the KVM functionality to support TDX lifecycle and GHCI [1]
interface.

We are looking for any feedback on:
- Patch series itself
- Any suggestion on how we should approach testing TDX functionality.
Does selftests seems reasonable or should we switch to using KVM
unit tests. I would be happy to get some perspective on how KVM unit
tests can help us more.
- Any test case or scenario that we should add.
- Anything else I have not thought of yet.

Current patch series provide the following capabilities:

- Provide helper functions to create a TD (Trusted Domain) using the KVM
  ioctls
- Provide helper functions to create a guest image that can include any
  testing code
- Provide helper functions and wrapper functions to write testing code
  using GHCI interface
- Add a test case that verifies TDX life cycle 
- Add a test case that verifies TDX GHCI port IO 

TODOs:
- Use existing function to create page tables dynamically 
  (ie __virt_pg_map())
- Remove arbitrary defined magic numbers for data structure offsets
- Add TDVMCALL for error reporting
- Add additional test cases as some listed below
- Add #VE handlers to help testing more complicated test cases

Other test cases that we are planning to add:
(with credit to sagis@xxxxxxxxxx)

VM call interface        Input                        Output                Result
GetTdVmCallInfo          R12=0                        None                VMCALL_SUCCESS
MapGPA                   Map private page (GPA.S=0)                       VMCALL_SUCCESS
MapGPA                   Map shared page (GPA.S=1)                        VMCALL_SUCCESS
MapGPA                   Map already private page as private              VMCALL_INVALID_OPERAND
MapGPA                   Map already shared page as shared                VMCALL_INVALID_OPERAND
GetQuote                        
ReportFatalError                        
SetupEventNotifyInterrupt   Valid interrupt value (32:255)                 VMCALL_SUCCESS
SetupEventNotifyInterrupt   Invalid value (>255)                          VMCALL_INVALID_OPERAND
Instruction.CPUID        R12(EAX)=1, R13(ECX)=0       EBX[8:15]=0x8        
                                                      EBX[16:23]=X        
                                                      EBX[24:31]=vcpu_id        
                                                      ECX[0]=1        
                                                      ECX[12]=Y        
Instruction.CPUID       R12(EAX)=1, R13(ECX)=4                            VMCALL_INVALID_OPERAND
VE.RequestMMIO                        
Instruction.HLT                                                           VMCALL_SUCCESS
Instruction.IO          Read/Write 1/2/4 bytes                            VMCALL_SUCCESS
Instruction.IO          Read/Write 3 bytes                                VMCALL_INVALID_OPERAND
Instruction.RDMSR       Accessible register           R11=msr_value       VMCALL_SUCCESS
                        Inaccessible register                             VMCALL_INVALID_OPERAND
Instruction.RDMSR       Accessible register                               VMCALL_SUCCESS
                        Inaccessible register                             VMCALL_INVALID_OPERAND
INSTRUCTION.PCONFIG                        

[1] Intel TDX Guest-Hypervisor Communication Interface
    https://software.intel.com/content/dam/develop/external/us/en/documents/intel-tdx-guest-hypervisor-communication-interface.pdf


Erdem Aktas (4):
  KVM: selftests: Add support for creating non-default type VMs
  KVM: selftest: Add helper functions to create TDX VMs
  KVM: selftest: Adding TDX life cycle test.
  KVM: selftest: Adding test case for TDX port IO

 tools/testing/selftests/kvm/Makefile          |   6 +-
 .../testing/selftests/kvm/include/kvm_util.h  |   1 +
 .../selftests/kvm/include/x86_64/processor.h  |   5 +
 tools/testing/selftests/kvm/lib/kvm_util.c    |  29 +-
 .../selftests/kvm/lib/x86_64/processor.c      |  23 ++
 tools/testing/selftests/kvm/lib/x86_64/tdx.h  | 220 ++++++++++++
 .../selftests/kvm/lib/x86_64/tdx_lib.c        | 314 ++++++++++++++++++
 .../selftests/kvm/x86_64/tdx_vm_tests.c       | 209 ++++++++++++
 8 files changed, 800 insertions(+), 7 deletions(-)
 create mode 100644 tools/testing/selftests/kvm/lib/x86_64/tdx.h
 create mode 100644 tools/testing/selftests/kvm/lib/x86_64/tdx_lib.c
 create mode 100644 tools/testing/selftests/kvm/x86_64/tdx_vm_tests.c

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