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Misleading display of new V5 attestation report fields (TIO_EN, PAGE_SWAP_DISABLE) on V3/V4 reports #330
Description
When parsing and displaying attestation reports, the sev crate currently shows newly introduced bitfields TIO_EN (in PLATFORM_INFO) and PAGE_SWAP_DISABLE (in GUEST_POLICY) (both added in ABI Rev 1.58) as false for older reports (e.g. V3, V4).
This behavior can be misleading because these fields did not exist in earlier versions of the attestation report. Displaying them as false may suggest that the feature is explicitly disabled, while in reality the field is simply not present.
These fields should be represented as None rather than false when parsing V3/V4 reports. This would be consistent with how other fields introduced in ABI Rev 1.58 (LAUNCH_MIT_VECTOR and CURRENT_MIT_VECTOR) are currently handled.
Example
- Azure DCasv6 (Genoa)
- OS: Ubuntu 24.04 LTS (CVM)
- Kernel: 6.11.0-1018-azure
Attestation Report of V3 (selected)
Attestation Report:
Version: 3
Guest SVN: 65547
Guest Policy (0x3001f):
ABI Major: 0
ABI Minor: 31
SMT Allowed: true
Migrate MA: false
Debug Allowed: false
Single Socket: false
CXL Allowed: false
AEX 256 XTS: false
RAPL Allowed: false
Ciphertext hiding: false
Page Swap Disable: false
...
Microcode: 84
SNP: 23
TEE: 0
Boot Loader: 10
FMC: None
Platform Info (39):
SMT Enabled: true
TSME Enabled: true
ECC Enabled: true
RAPL Disabled: false
Ciphertext Hiding Enabled: false
Alias Check Complete: true
SEV-TIO Enabled: false
...
Reported TCB:
TCB Version:
Microcode: 84
SNP: 23
TEE: 0
Boot Loader: 10
FMC: None
...
Launch Mitigation Vector: None
Current Mitigation Vector: None
...
Activity
DGonzalezVillal commentedon Apr 2, 2026
Hello @hyperfinitism I have attempted to resolve this issue in this PR:
#378
So I noticed that guest policy and platform info are their own independent structures and not necessarily tied to the version of the attestation report. So I'm using the firmware version to parse these fields rather than report version. Would love your thoughts on this approach!