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

[Xiaoyao Li]

On 5/25/2026 1:17 PM, Tony Lindgren wrote:
> On Fri, May 22, 2026 at 11:41:28AM +0800, Xu Yilun wrote:
> > From: Peter Fang <peter.fang@xxxxxxxxx>
> >
> > 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?

Ah ha! This patch answers my comment to patch 1:
https://lore.kernel.org/all/956fa1e6-2920-4b2e-8037-d4b9d812ae53@xxxxxxxxx/

sysinfo_ext->memory_pool_required_pages and sysinfo_ext->ext_required 
will be updated after extensions are enabled by TDH.SYS.CONFIG.

Patch 06 in this series already reads the tdx_sys_info_quote out of 
get_tdx_sys_info(), which mean get_tdx_sys_info() doesn't ensure all the 
global metadata will be update again.

So how about move the read of memory_pool_required_pages and 
ext_required out of get_tdx_sys_info() and put them after 
TDH.SYS.CONFIG, so that we don't need call get_tdx_sys_info() again?

> > --- 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