Re: [PATCH v3 02/10] x86/virt/tdx: Convert the version metadata reader

[Xu Yilun]

On Tue, Sep 29, 2026 at 10:38:36PM -0700, Chao Gao wrote:
> With the helper to read a table of metadata fields in place, the
> existing metadata readers can be standardized on it.
> 
> Convert the version metadata reader: add a table that pairs each field ID
> with the 'struct tdx_sys_info_version' member that holds its value, and
> read all version fields by walking that table.
> 
> Name the field IDs for readability, so the table entries don't carry raw
> hex literals.
>

[...]

> +#define TDX_SYSINFO_MAP_VERSION(_field_id, _member) \
> +	TDX_SYSINFO_MAP(_field_id, struct tdx_sys_info_version, _member)
> +
> +static const struct field_mapping version_mappings[] = {
> +	TDX_SYSINFO_MAP_VERSION(TDX_FIELD_MINOR_VERSION,  minor_version),
> +	TDX_SYSINFO_MAP_VERSION(TDX_FIELD_MAJOR_VERSION,  major_version),
> +	TDX_SYSINFO_MAP_VERSION(TDX_FIELD_UPDATE_VERSION, update_version),
> +};

[...]

I think something like the following is quite clear to me:

  static const struct field_mapping version_mappings[] = {
	FIELD_MAP(0x0800000100000003ULL, struct tdx_sys_info_version, minor_version),
	...
  }

  or even:

	FIELD_MAP(0x0800000100000003ULL, version, minor_version),

It clearly tells the mapping for the class, the field, and the field_id.

So I'm not sure what's the downside of a literal hex here. To me, a
TDX_FIELD_XX MACRO only creates duplicated names in one line and
unnecessary touch points when we add a new field.


> diff --git a/arch/x86/virt/vmx/tdx/tdx.h b/arch/x86/virt/vmx/tdx/tdx.h
> index db209541d3cd..10cbc2d77a5a 100644
> --- a/arch/x86/virt/vmx/tdx/tdx.h
> +++ b/arch/x86/virt/vmx/tdx/tdx.h
> @@ -52,6 +52,16 @@
>  #define TDH_PHYMEM_PAMT_REMOVE		59
>  #define TDH_SYS_DISABLE			69
>  
> +/*
> + * TDX global metadata field IDs.
> + *
> + * See "global_metadata.pdf" in Intel TDX Module ABI Definitions.
> + */
> +/* Class "TDX Module Version" */
> +#define TDX_FIELD_MINOR_VERSION			0x0800000100000003ULL
> +#define TDX_FIELD_MAJOR_VERSION			0x0800000100000004ULL
> +#define TDX_FIELD_UPDATE_VERSION		0x0800000100000005ULL

I think these are unnecessary touch points, metadata readers never use
these MACROs.