Re: [RFC PATCH 15/15] x86/virt/tdx: Enable TDX Quoting extension

[Tony Lindgren <tony.lindgren@linux.intel.com>]

On Fri, May 22, 2026 at 11:41:28AM +0800, Xu Yilun wrote:
> From: Peter Fang <peter.fang@intel.com>
> 
> TDX Module updates global metadata when add-on features are enabled.
> Host should update the cached tdx_sysinfo to reflect these changes.

This should be made clearer IMO. How about mention that get_tdx_sys_info()
needs to get called again to reload the TDX module global metadata?
 
> --- a/arch/x86/virt/vmx/tdx/tdx.c
> +++ b/arch/x86/virt/vmx/tdx/tdx.c
> @@ -1049,6 +1049,7 @@ static __init int construct_tdmrs(struct list_head *tmb_list,
>  static __init int config_tdx_module(struct tdmr_info_list *tdmr_list,
>  				    u64 global_keyid)
>  {
> +	u64 seamcall_fn = TDH_SYS_CONFIG_V0;
>  	struct tdx_module_args args = {};
>  	u64 *tdmr_pa_array;
>  	size_t array_sz;
> @@ -1074,8 +1075,22 @@ static __init int config_tdx_module(struct tdmr_info_list *tdmr_list,
>  	args.rcx = __pa(tdmr_pa_array);
>  	args.rdx = tdmr_list->nr_consumed_tdmrs;
>  	args.r8 = global_keyid;
> -	ret = seamcall_prerr(TDH_SYS_CONFIG, &args);
>  
> +	if (tdx_sysinfo.features.tdx_features0 & TDX_FEATURES0_QUOTE) {
> +		args.r9 |= TDX_FEATURES0_QUOTE;
> +		/* These parameters require version >= 1 */
> +		seamcall_fn = TDH_SYS_CONFIG;
> +	}
> +
> +	ret = seamcall_prerr(seamcall_fn, &args);
> +	if (ret)
> +		goto free_tdmr;
> +
> +	/* enabling TDX Quoting may change tdx_sysinfo, update it */
> +	if (tdx_sysinfo.features.tdx_features0 & TDX_FEATURES0_QUOTE)
> +		ret = get_tdx_sys_info(&tdx_sysinfo);

The comment above helps, but the change in the handling will be easy to
miss.

> +free_tdmr:
>  	/* Free the array as it is not required anymore. */
>  	kfree(tdmr_pa_array);
>  

So I think it would be good to also add a comment to get_tdx_sys_info()
to make it easier for folks to follow that it may get called multiple
times.

Regards,

Tony