Re: [PATCH v2 05/10] x86/virt/tdx: Move field mapping table of getting TDMR info to function local

[Dan Williams <dan.j.williams@intel.com>]

Kai Huang wrote:
> For now the kernel only reads "TD Memory Region" (TDMR) related global
> metadata fields to a 'struct tdx_tdmr_sysinfo' for initializing the TDX
> module.  The kernel populates the relevant metadata fields into the
> structure using a "field mapping table" of metadata field IDs and the
> structure members.
> 
> Currently the scope of this "field mapping table" is the entire C file.
> Future changes will need to read more global metadata fields that will
> be organized in other structures and use this kind of field mapping
> tables for other structures too.
> 
> Move the field mapping table to the function local to limit its scope so
> that the same name can also be used by other functions.
> 
> Signed-off-by: Kai Huang <kai.huang@intel.com>
> Reviewed-by: Nikolay Borisov <nik.borisov@suse.com>
> ---
> 
> v1 -> v2:
>  - Added Nikolay's tag.
> 
> ---
>  arch/x86/virt/vmx/tdx/tdx.c | 18 +++++++++---------
>  1 file changed, 9 insertions(+), 9 deletions(-)
> 
> diff --git a/arch/x86/virt/vmx/tdx/tdx.c b/arch/x86/virt/vmx/tdx/tdx.c
> index 50d49c539e63..86c47db64e42 100644
> --- a/arch/x86/virt/vmx/tdx/tdx.c
> +++ b/arch/x86/virt/vmx/tdx/tdx.c
> @@ -322,17 +322,17 @@ static int stbuf_read_sysmd_multi(const struct field_mapping *fields,
>  #define TD_SYSINFO_MAP_TDMR_INFO(_field_id, _member)	\
>  	TD_SYSINFO_MAP(_field_id, struct tdx_tdmr_sysinfo, _member)
>  
> -/* Map TD_SYSINFO fields into 'struct tdx_tdmr_sysinfo': */
> -static const struct field_mapping fields[] = {
> -	TD_SYSINFO_MAP_TDMR_INFO(MAX_TDMRS,		max_tdmrs),
> -	TD_SYSINFO_MAP_TDMR_INFO(MAX_RESERVED_PER_TDMR, max_reserved_per_tdmr),
> -	TD_SYSINFO_MAP_TDMR_INFO(PAMT_4K_ENTRY_SIZE,    pamt_entry_size[TDX_PS_4K]),
> -	TD_SYSINFO_MAP_TDMR_INFO(PAMT_2M_ENTRY_SIZE,    pamt_entry_size[TDX_PS_2M]),
> -	TD_SYSINFO_MAP_TDMR_INFO(PAMT_1G_ENTRY_SIZE,    pamt_entry_size[TDX_PS_1G]),
> -};
> -
>  static int get_tdx_tdmr_sysinfo(struct tdx_tdmr_sysinfo *tdmr_sysinfo)
>  {
> +	/* Map TD_SYSINFO fields into 'struct tdx_tdmr_sysinfo': */
> +	static const struct field_mapping fields[] = {
> +		TD_SYSINFO_MAP_TDMR_INFO(MAX_TDMRS,		max_tdmrs),
> +		TD_SYSINFO_MAP_TDMR_INFO(MAX_RESERVED_PER_TDMR, max_reserved_per_tdmr),
> +		TD_SYSINFO_MAP_TDMR_INFO(PAMT_4K_ENTRY_SIZE,    pamt_entry_size[TDX_PS_4K]),
> +		TD_SYSINFO_MAP_TDMR_INFO(PAMT_2M_ENTRY_SIZE,    pamt_entry_size[TDX_PS_2M]),
> +		TD_SYSINFO_MAP_TDMR_INFO(PAMT_1G_ENTRY_SIZE,    pamt_entry_size[TDX_PS_1G]),
> +	};
> +
>  	/* Populate 'tdmr_sysinfo' fields using the mapping structure above: */
>  	return stbuf_read_sysmd_multi(fields, ARRAY_SIZE(fields), tdmr_sysinfo);

Same symbol namespace benefits from skipping the array indirection
altogether.