Re: [PATCH v5 5/6] x86/tdx: Add a helper to query maximum Quote size

["Edgecombe, Rick P" <rick.p.edgecombe@intel.com>]

On Mon, 2026-09-28 at 14:13 -0700, Peter Fang wrote:
> On Mon, Sep 28, 2026 at 11:50:32AM -0700, Edgecombe, Rick P wrote:
> > On Mon, 2026-09-28 at 03:08 -0700, Peter Fang wrote:
> > > [1] Intel TDX Module ABI Definitions, August 2026, TD-scope metadata
> > >     field "TD_QUOTE_MAX_SIZE"
> > 
> > The latest seems to be June 2026:
> > https://www.intel.com/content/www/us/en/developer/tools/trust-domain-extensions/documentation.html
> 
> I think that's "Intel TDX Module ABI Specification". "Intel TDX Module
> ABI Definitions" was updated in August. Yeah these names can be
> confusing sometimes.

I see: Intel TDX Module ABI Definitions - ABI definitions in PDF, CSV and JSON
format - June 2026

Ah! There are two listed: one from June and one from August. The August ones are
still labeled for community review. "These documents are not final and are
subject to change based on feedback."

This means that we are upstreaming head of the spec being finalized. And TDX
module will not be able to change anything we depend on. We need to make sure
they know what we are locked onto.

> 
> > 
> > So where is this? Does it say anything about being page aligned already?
> 
> In the pdf the wording is "Maximum size of the buffer that must be
> allocated to contain the TDX Quote received from TDX Module". It doesn't
> say anything about page alignment. I can confirm with the TDX module
> folks.
> 
> But even if the reported size is always page aligned, the driver would
> still need to slap the GHCI header in front of it, and that would make
> the total buffer size again not page aligned. So would it be useful in
> the end?

Ah right.