Re: [PATCH v1 3/3] virt: tdx-guest: Increase Quote buffer size to 128KB

[Kiryl Shutsemau]

On Tue, Feb 10, 2026 at 04:17:12PM -0800, Kuppuswamy Sathyanarayanan wrote:
> Intel platforms are transitioning from traditional SGX-based
> attestation toward DICE-based attestation as part of a broader move
> toward open and standardized attestation models. DICE enables layered
> and extensible attestation, where evidence is accumulated across
> multiple boot stages.
> 
> With SGX-based attestation, Quote sizes are typically under 8KB, as the
> payload consists primarily of Quote data and a small certificate bundle.
> Existing TDX guest code sizes the Quote buffer accordingly.
> 
> DICE-based attestation produces significantly larger Quotes due to the
> inclusion of evidence (certificate chains) from multiple boot layers.
> The cumulative Quote size can reach approximately 100KB.
> 
> Increase GET_QUOTE_BUF_SIZE to 128KB to ensure sufficient buffer
> capacity for DICE-based Quote payloads.

It worth noting that it requires guest physically-contiguous memory.

Single order-5 allocation is not that bad as long as the driver
initialized during the boot.

-- 
  Kiryl Shutsemau / Kirill A. Shutemov