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configfs-tsm-report: tdx_guest: Increase Quote buffer size to 128KB

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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.

Reviewed-by: Fang Peter <peter.fang@intel.com>
Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Link: https://patch.msgid.link/20260211001712.1531955-4-sathyanarayanan.kuppuswamy@linux.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
This commit is contained in:
Kuppuswamy Sathyanarayanan 2026-02-10 16:17:12 -08:00 • committed by Dan Williams
parent 9342bf3d67
commit 43185067c6
2 changed files with 7 additions and 1 deletions
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4
Documentation/ABI/testing/configfs-tsm-report
View file

@ -73,6 +73,10 @@ Description:
Library Revision 0.8 Appendix 4,5
https://download.01.org/intel-sgx/latest/dcap-latest/linux/docs/Intel_TDX_DCAP_Quoting_Library_API.pdf
Intel TDX platforms with DICE-based attestation use CBOR Web Token
(CWT) format for the Quote payload. This is indicated by the Quote
size exceeding 8KB.
What: /sys/kernel/config/tsm/report/$name/generation
Date: September, 2023
KernelVersion: v6.7

4
drivers/virt/coco/tdx-guest/tdx-guest.c
View file

@ -160,8 +160,10 @@ static void tdx_mr_deinit(const struct attribute_group *mr_grp)
/*
* Intel's SGX QE implementation generally uses Quote size less
* than 8K (2K Quote data + ~5K of certificate blob).
* DICE-based attestation uses layered evidence that requires
* larger Quote size (~100K).
*/
#define GET_QUOTE_BUF_SIZE SZ_8K
#define GET_QUOTE_BUF_SIZE SZ_128K
#define GET_QUOTE_CMD_VER 1