Re: [PATCH 04/15] x86/virt/tdx: Enable the Extensions right after basic TDX Module init

[Tony Lindgren]

On Fri, May 22, 2026 at 11:41:17AM +0800, Xu Yilun wrote:
> The detailed initialization flow for TDX Module Extensions has been
> fully implemented. Enable the flow after basic TDX Module
> initialization.
> 
> Theoretically, the Extensions doesn't need to be enabled right after
> basic TDX initialization. It could be enabled right before the first
> Extension SEAMCALL is issued. That would save or postpone memory usage.
> But it isn't worth the complexity, the needs for the Extensions are vast
> but the savings are little for a typical TDX capable system (about
> 0.001% of memory). So the Linux decision is to just enable it along with
> the basic TDX.
> 
> Note that the Extensions initialization flow will still not start if no
> add-on features require Extensions. The enabling of add-on features will
> be in later patches. Until then, the system hasn't consumed extra memory.

Looking at patch 15/15, we need to reload the TDX module metadata at least
for the attestation. We need to do that early, so to me it seems that
everything can be just tagged __init from the start.

So you can just call init_tdx_ext() in patch 3/15, and this patch is not
needed at all?

Regards,

Tony