Milestone 7
Milestone 7 Status
This milestone is delivered and in review by the upstream OP-TEE community.
The submitted floating-point and vector context-switch patchsets correspond to the two implementation deliverables. The work has been split into separate upstream pull requests that remain under review, so the milestone is delivered but not yet done.
Upstream Submissions
The following OP-TEE upstream submissions relate to this milestone:
| Date Submitted | Submission | Patchset Links | Patchset Status |
|---|---|---|---|
| June 23, 2026 | RFC series introducing RISC-V floating-point and vector extension context tracking | OP-TEE mailing-list thread; GitHub RFC pull request #7861 | Superseded by pull request #7870 |
| July 6, 2026 | Review request for the revised RISC-V floating-point and vector context patchset | OP-TEE mailing-list thread; GitHub pull request #7870 | Superseded by floating-point pull request #7872 and vector pull request #7876 |
| July 6, 2026 | RISC-V floating-point context-switch state | GitHub pull request #7872 | Under Review |
| July 8, 2026 | RISC-V vector context-switch state | GitHub pull request #7876 | Under Review |
Background
OP-TEE's architecture-specific trusted-application context management must preserve floating-point and vector registers in addition to the associated control state. Lazy switching is unsuitable because supervisor mode can modify the FS and VS status bits without reliably revealing actual register use across privilege levels. Hidden state changes can cause correctness failures, data leakage, or side-channel exposure. Frequent floating-point and vector use also reduces the expected performance benefit of trapping lazily, making eager save and restore the preferred approach.
Milestone Description
Milestone 7 extends the architecture-specific trusted-application context so that floating-point and vector registers and their associated control state are preserved across context switches.
Requirements
- Use eager context switching for floating-point and vector state.
- Save and restore the complete floating-point register state required by a trusted application.
- Save and restore the complete vector register state required by a trusted application.
- Preserve the associated floating-point, vector, and status CSRs.
- Do not rely on lazy switching based only on supervisor-controlled FS and VS status.
- Prevent register contents from leaking between trusted-application contexts or across privilege boundaries.
- Validate repeated switches between contexts with distinct floating-point and vector state.
Deliverables
- OP-TEE changes that eagerly save and restore trusted-application floating-point registers.
- OP-TEE changes that eagerly save and restore trusted-application vector registers.
- Tests demonstrating correct state preservation and isolation.