[not-matthias]

As discussed, to avoid timing differences keep the instruction feature flag enabled.

[greptile-apps]

Confidence Score: 4/5

[Medium impact] The change affects amd64 feature reporting for guests using deterministic RNG.

The PR appears safe to merge, with a non-blocking request to retain the CPUID test checks.

Findings

1.  CPUID checks are gone ▶

Fix with agent prompt

### Issue 1
none/tests/amd64/deterministic_rng.c:38
The test no longer checks the behavior this revert restores. Keep the CPUID queries and change the expected bits to `1`: `deterministic_rng.vgtest` already requires both features before running. Without those checks, hiding either feature again would leave this test passing.

Note: If this suggestion doesn't match your team's coding style, reply to this and let me know. I'll remember it for next time!

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For each issue above, determine whether it is valid and should be fixed. If so, fix it directly.

Summary

Restores host-based CPUID flags for RDRAND and RDSEED when deterministic RNG is enabled.

• Deterministic RNG keeps host-supported RDRAND and RDSEED visible in CPUID.

_{Reviews (1) · Last reviewed commit: "Revert "feat(vex): hide RDRAND and RDSEE..." · Reviewed by Greptile}

[codspeed]

Merging this PR will degrade performance by 1.61%

⚡ 1 improved benchmark
❌ 1 regressed benchmark
✅ 82 untouched benchmarks
⏩ 60 skipped benchmarks¹

Warning

Please fix the performance issues or acknowledge them on CodSpeed.

Performance Changes

	Benchmark	BASE	HEAD	Efficiency
❌	test_valgrind[valgrind.codspeed, stress-ng --cpu 1 --cpu-ops 10, full-with-inline-with-cycle-estimation]	5.4 s	8 s	-32.79%
⚡	test_valgrind[valgrind.codspeed, stress-ng --cpu 1 --cpu-ops 10, cycle-estimation]	4 s	2.8 s	+44.05%

Tip

Investigate this regression by commenting @codspeedbot fix this regression on this PR, or directly use the CodSpeed MCP with your agent.

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_{Comparing cod-3957-determinstic-rng-2 (b293afb) with master (bca1dda)}

Footnotes

1. 60 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩