[PATCH v1 0/8] TDX: Stop auto-generating the global metadata code

[Chao Gao <chao.gao@intel.com>]

This is a long-overdue cleanup of the TDX global metadata, based on work
from Dave [1].  Patches 1-6 keep Dave's authorship -- I only reworded the
commit messages and comments, with no significant changes to the code.
Note that they are missing Dave's Signed-off-by.

Changes on top of the original:

  - Rebased onto the latest tip/x86/tdx branch
  - Converted the newly added metadata (tdx module handoff)
  - Fixed up the __init annotations. The version and handoff tables must
    not be __initconst
  - Refined the commit messages and comments: dropped forward references
    to later patches and stopped restating what the code already says.
  - Added two patches: cleaning up error handling in get_tdx_sys_info(),
    and turning the runtime size check into a build-time one.

The series is also available at:
  https://github.com/gaochaointel/linux-dev.git tdx-metadata-v1

---
The TDX module exposes its capabilities and limits through "Global Scope
Metadata" fields, defined in the Intel TDX Module ABI spec.  The kernel
mirrors a small subset of those fields in C structures under struct
tdx_sys_info, populated by reading each field via TDH.SYS.RD.

Both the structures and the code that fills them are nominally generated
by an out-of-tree script from a JSON file describing the module's
metadata.  That made it trivial to add a new field, but everything else
suffered for it:

  - The generated files are edited by hand in practice, for different
    reasons.  The VMXON rework added __init annotations to the readers,
    and the handoff metadata is read at module shutdown into a
    caller-local struct rather than into tdx_sys_info.  In-flight series
    will add more: DPAMT and TDX module extension metadata may only be
    read when the corresponding TDX_FEATURES0 bit is set.  Regenerating
    the files would clobber all of these edits.

  - The generated code is opaque to anyone who doesn't have the script
    and the JSON file handy.  Each field is identified by a bare 64-bit
    hex literal, so verifying any one line means cross-referencing the
    JSON file.

  - The script ships outside the tree, so reproducing changes requires
    fetching it from a mailing list link.

  - The structures are short and stable, so the script's value over
    hand-maintained code is small.

So switch to a hand-maintained implementation.  Name each field ID after
the spec, then describe the field-ID-to-C-member mapping as a table: one
row per field, pairing the named spec field ID with the C member that
holds it.  Reading is then a walk over the table.

[1]: https://git.kernel.org/pub/scm/linux/kernel/git/daveh/devel.git/log/?h=tdxtable

Chao Gao (2):
  x86/virt/tdx: Clean up error handling in get_tdx_sys_info()
  x86/virt/tdx: Verify the C member size against the metadata field ID

Dave Hansen (6):
  x86/virt/tdx: Stop treating tdx_global_metadata.h as auto-generated
  x86/virt/tdx: Name the TDX module global metadata field IDs
  x86/virt/tdx: Add a table-driven TDX global metadata reader
  x86/virt/tdx: Convert version/tdmr/td_ctrl/handoff readers
  x86/virt/tdx: Convert td_conf reader
  x86/virt/tdx: Remove the auto-generated tdx_global_metadata.c

 arch/x86/include/asm/tdx_global_metadata.h  |  13 +-
 arch/x86/virt/vmx/tdx/tdx.c                 | 216 +++++++++++++++++++-
 arch/x86/virt/vmx/tdx/tdx.h                 |  66 ++++++
 arch/x86/virt/vmx/tdx/tdx_global_metadata.c | 133 ------------
 4 files changed, 290 insertions(+), 138 deletions(-)
 delete mode 100644 arch/x86/virt/vmx/tdx/tdx_global_metadata.c

-- 
2.52.0