mpk: temporarily disable to avoid CI failures #7446
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GitHub CI runners are showing some strange behavior: on certain runners (unknown which ones), the CPUID bits claim that MPK is supported, but running any MPK code (e.g., `RDPKRU`) causes a `SIGILL` crash. This change disables MPK until bytecodealliance#7445 is resolved.
fitzgen
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We discovered that certain CPUs claim that MPK is available but then fail when running MPK instructions; MPK support was temporarily disabled in bytecodealliance#7446; this change re-enables it. Closes bytecodealliance#7445.
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In bytecodealliance#7446 I disabled MPK support temporarily due to failures in CI runs. Looking into this further in bytecodealliance#7445, I discovered that it is due to how `has_cpuid_bit_set` works on different x86 machines: Intel's `CPUID` instruction reports support for MPK in a certain leaf bit, AMD does it some other (unknown?) way. The CI problem boiled down to occasional runs on AMD machines that would fail with `SIGILL` because the AMD machine reported that it had MPK support when it really did not. This change fixes the issue by first checking if the CPU vendor string is `GenuineIntel` before inspecting the MPK `CPUID` leaf bit. Closes bytecodealliance#7445.
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* mpk: reenable MPK support with vendor string check In #7446 I disabled MPK support temporarily due to failures in CI runs. Looking into this further in #7445, I discovered that it is due to how `has_cpuid_bit_set` works on different x86 machines: Intel's `CPUID` instruction reports support for MPK in a certain leaf bit, AMD does it some other (unknown?) way. The CI problem boiled down to occasional runs on AMD machines that would fail with `SIGILL` because the AMD machine reported that it had MPK support when it really did not. This change fixes the issue by first checking if the CPU vendor string is `GenuineIntel` before inspecting the MPK `CPUID` leaf bit. Closes #7445. * review: use `u32::from_le_bytes` to self-document the string check
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GitHub CI runners are showing some strange behavior: on certain runners (unknown which ones), the CPUID bits claim that MPK is supported, but running any MPK code (e.g.,
RDPKRU) causes aSIGILLcrash. This change disables MPK until #7445 is resolved.