Re: [PATCH v4 07/10] x86/virt/tdx: Convert the td_conf metadata reader

[Xu Yilun]

On Mon, Oct 12, 2026 at 02:47:34AM -0700, Chao Gao wrote:
> Continue converting the metadata readers to the table-driven helper.
> 
> The "TD Configurability" class holds several scalar fields plus two CPUID
> arrays. The arrays have a fixed capacity, but the number of entries to
> read is variable and reported by the num_cpuid_config scalar field.
> 
> Add a table that pairs each scalar field ID with the 'struct
> tdx_sys_info_td_conf' member that holds its value, and read those fields
> by walking that table.
> 
> Annotate the table as __initconst as it is referenced only during init.
> 
> Leave the two arrays open coded. 'struct field_mapping' pairs one field ID
> with one structure member, so describing an array would require a field ID
> per field plus an entry count that is unknown until num_cpuid_config has
> been read. That is not worth building for the only two arrays the kernel
> reads.
> 
> Read both arrays in a single loop, as both have num_cpuid_config
> entries. Store each value directly into its array member instead of
> into a temporary u64 first. The members are u64 already, so the extra
> copies serve no purpose.
> 
> The inner dimension of cpuid_config_values[] is fixed at 2. Read the
> two values with two calls instead of an inner loop. This saves a level
> of indentation and is simpler to read.
> 
> AI was used under supervision to review code and workshop logs.
> 
> Signed-off-by: Chao Gao <chao.gao@xxxxxxxxx>

Reviewed-by: Xu Yilun <yilun.xu@xxxxxxxxxxxxxxx>