Re: [PATCH 2/9] x86/virt/tdx: Unbind global metadata read with 'struct tdx_tdmr_sysinfo'

[Nikolay Borisov <nik.borisov@suse.com>]

On 16.06.24 г. 15:01 ч., Kai Huang wrote:
> The TDX module provides a set of "global metadata fields".  They report
> things like TDX module version, supported features, and fields related
> to create/run TDX guests and so on.
> 
> 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, and the metadata reading code can only work with that structure.
> 
> Future changes will need to read other metadata fields that don't make
> sense to populate to the "struct tdx_tdmr_sysinfo".  It's essential to
> provide a generic metadata read infrastructure which is not bound to any
> specific structure.
> 
> To start providing such infrastructure, unbind the metadata reading code
> with the 'struct tdx_tdmr_sysinfo'.
> 
> Note the kernel has a helper macro, TD_SYSINFO_MAP(), for marshaling the
> metadata into the 'struct tdx_tdmr_sysinfo', and currently the macro
> hardcodes the structure name.  As part of unbinding the metadata reading
> code with 'struct tdx_tdmr_sysinfo', it is extended to accept different
> structures.
> 
> Unfortunately, this will result in the usage of TD_SYSINFO_MAP() for
> populating 'struct tdx_tdmr_sysinfo' to be changed to use the structure
> name explicitly for each structure member and make the code longer.  Add
> a wrapper macro which hides the 'struct tdx_tdmr_sysinfo' internally to
> make the code shorter thus better readability.
> 
> Signed-off-by: Kai Huang <kai.huang@intel.com>
> Reviewed-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
> Reviewed-by: Binbin Wu <binbin.wu@linux.intel.com>
> ---
>   arch/x86/virt/vmx/tdx/tdx.c | 25 ++++++++++++++-----------
>   1 file changed, 14 insertions(+), 11 deletions(-)
> 
> diff --git a/arch/x86/virt/vmx/tdx/tdx.c b/arch/x86/virt/vmx/tdx/tdx.c
> index fbde24ea3b3e..854312e97eff 100644
> --- a/arch/x86/virt/vmx/tdx/tdx.c
> +++ b/arch/x86/virt/vmx/tdx/tdx.c
> @@ -272,9 +272,9 @@ static int read_sys_metadata_field(u64 field_id, u64 *data)
>   
>   static int read_sys_metadata_field16(u64 field_id,
>   				     int offset,
> -				     struct tdx_tdmr_sysinfo *ts)
> +				     void *stbuf)
>   {
> -	u16 *ts_member = ((void *)ts) + offset;
> +	u16 *st_member = stbuf + offset;

This st_* prefix is completely arbitrary, Just name it "member" since 
this function can be used for any arbitrary member.

>   	u64 tmp;
>   	int ret;
>   

<snip>