[PATCH v16 00/20] TDX KVM selftests

[Lisa Wang <wyihan@google.com>]

This patch series focuses on setting up a TDX VM and adding all code
necessary to run a basic lifecycle test.

Unlike standard KVM selftests can set up the VM through guest registers,
TDX module protects TDs' register state from the host. This feature of
TDX causes problems on VM boot state initialization and the ucall
implementation.

In standard KVM selftests, the host directly initializes the guest state
by manipulating Special Registers (SREGs) and General Purpose Registers
(GPRs) via IOCTLs (KVM_SET_SREGS, etc.) before the first KVM_RUN.

To bypass direct register initialization by the host, we utilize the
standard x86 reset vector as the default entry point.

The mechanism works as follows:
1. The host places register values into a specific memory region and
   inserts boot code at the VM's default starting point.
2. When the VM starts, it executes this boot code to "pull" values from
   memory and manually set up its own SREGs and GPRs.
3. Once the environment is ready, the boot code jumps to the guest code.

The standard x86 ucall() implementation uses PIO, but it does not
actually transmit data through the 4-byte PIO data. Instead, it relies
on the host reading the ucall address directly from the guest's RDI
register.

TDX selftests cannot utilize the standard x86 ucall implementation
because the host is unable to access the guest's RDI register. Between
the two alternatives, TDVMCALL_MMIO and TDVMCALL_REPORT_FATAL_ERROR,
TDVMCALL_MMIO has fragility concerns and requires hardcoding a magic
address while ignoring mmio_gpa. Therefore, the Report Fatal Error
TDVMCALL is the cleanest and most efficient solution for TDX ucalls.

Main Changes from v15[1]:
1. Rebase onto kvm/next:
    - Replace vm_phy_pages_alloc() with ____vm_phy_pages_alloc(...,
      true, false) in tdx_vm_setup_boot_code_region() and
      tdx_vm_setup_boot_parameters_region() to allocate protected pages
      at fixed GPAs in custom memslots (TD_BOOT_CODE_SLOT and
      TD_BOOT_PARAMETERS_SLOT), as vm_phy_pages_alloc() now takes an
      enum kvm_mem_region_type.
    - Drop 3 patches.
2. Simplify tdx_init_vm() by dropping the intermediate CPUID allocation
   and clearing init_vm->cpuid.padding.
3. Move tdx_vcpu_init() to tdx_util.c, use PRIx64 for hw_error in
   tdx_vm_ioctl(), and align tdx_vcpu_ioctl() error formatting with
   tdx_vm_ioctl().
4. Decouple tdx_load_private_memory() from tdx_vm_finalize() and call
   both explicitly in kvm_arch_vm_finalize_vcpus().
5. Check 32-bit address bounds on idt, gdt, and esp_gva before assigning
   them to 32-bit boot parameter fields.
6. Refine comments, commit messages, and __tdvmcall().

Thanks for the reviews from Binbin and Xiaoyao!

Series is organized by:
Patches 1 - 3: Initialize the TDX VM
Patches 4 - 7: Add the TDX boot code
Patches 8 - 11: Set up the boot region
Patches 12 - 14: Set up the vCPU
Patches 15 - 16: Finalize the TDX VM
Patches 17 - 20: Implement the ucall and run the TDX test

[1]: https://lore.kernel.org/all/20261001-tdx-selftests-v15-0-7c62a5d8a992@google.com/

Signed-off-by: Lisa Wang <wyihan@google.com>
---
Ackerley Tng (1):
      KVM: selftests: Add helpers to init TDX memory and finalize VM

Erdem Aktas (2):
      KVM: selftests: Add TDX boot code
      KVM: selftests: Add a helper to issue TDVMCALLs from the TDX vm

Isaku Yamahata (1):
      KVM: selftests: Update kvm_init_vm_address_properties() for TDX

Lisa Wang (1):
      KVM: selftests: Require guest_memfd for TDX VMs

Sagi Shahar (12):
      KVM: selftests: Initialize the TDX VM
      KVM: selftests: Expose segment definitions to assembly files
      tools: include: Add kbuild.h for assembly structure offsets
      KVM: selftests: Introduce structures for TDX guest boot parameters
      KVM: selftests: Expose functions to get default sregs values
      KVM: selftests: Set up TDX boot code region
      KVM: selftests: Set up TDX boot parameters region
      KVM: selftests: Call KVM_TDX_INIT_VCPU when creating a new TDX vcpu
      KVM: selftests: Load per-vCPU guest stack in TDX boot parameters
      KVM: selftests: Set entry point for TDX guest code
      KVM: selftests: Load private memory and finalize TDX VM in kvm_arch_vm_finalize_vcpus()
      KVM: selftests: Add TDX lifecycle test

Sean Christopherson (3):
      KVM: selftests: Add macros to simplify creating VM shapes for non-default types
      KVM: selftests: Add support for per-VM ucall ops on x86
      KVM: selftests: Add support for TDX ucalls, via TDVMCALL_REPORT_FATAL_ERROR

 tools/include/linux/kbuild.h                       |  11 +
 tools/testing/selftests/kvm/.gitignore             |   3 +-
 tools/testing/selftests/kvm/Makefile.kvm           |  33 ++-
 tools/testing/selftests/kvm/include/kvm_util.h     |  27 +-
 .../testing/selftests/kvm/include/x86/processor.h  |  42 +++
 .../selftests/kvm/include/x86/processor_asm.h      |  12 +
 tools/testing/selftests/kvm/include/x86/sev.h      |   2 -
 .../selftests/kvm/include/x86/tdx/td_boot.h        |  81 ++++++
 tools/testing/selftests/kvm/include/x86/tdx/tdx.h  |  16 ++
 .../selftests/kvm/include/x86/tdx/tdx_util.h       |  85 ++++++
 tools/testing/selftests/kvm/include/x86/ucall.h    |   6 +-
 tools/testing/selftests/kvm/lib/kvm_util.c         |   2 +-
 tools/testing/selftests/kvm/lib/x86/processor.c    | 105 +++++---
 tools/testing/selftests/kvm/lib/x86/sev.c          |  16 --
 tools/testing/selftests/kvm/lib/x86/tdx/td_boot.S  |  71 +++++
 .../selftests/kvm/lib/x86/tdx/td_boot_offsets.c    |  21 ++
 tools/testing/selftests/kvm/lib/x86/tdx/tdx.S      |  39 +++
 tools/testing/selftests/kvm/lib/x86/tdx/tdx_util.c | 300 +++++++++++++++++++++
 tools/testing/selftests/kvm/lib/x86/ucall.c        |  58 +++-
 tools/testing/selftests/kvm/x86/sev_dbg_test.c     |  13 +-
 tools/testing/selftests/kvm/x86/sev_smoke_test.c   |  40 +--
 tools/testing/selftests/kvm/x86/tdx_vm_test.c      |  33 +++
 22 files changed, 913 insertions(+), 103 deletions(-)
---
base-commit: 1689c80fca308978ea1c9f03d15a500f4e44e2e1
change-id: 20260722-tdx-selftests-1da5587cf047

Best regards,
-- 
Lisa Wang <wyihan@google.com>