[pull] master from veracrypt:master#175
Merged
Merged
Conversation
AVX2 support is advertised by CPUID leaf 7, subleaf 0, EBX bit 5. The previous early assignment used cpuid1[1] bit 5, which is CPUID leaf 1 EBX and is not the AVX2 feature bit. Record the leaf 7 AVX2 bit separately and assign g_hasAVX2 only after vendor-specific detection has completed. The final value is now gated by g_hasAVX, which reflects the OS/XCR0 AVX state check, so AVX2 code is not selected unless both the CPU and OS state support it.
BMI2 support is advertised by CPUID leaf 7, subleaf 0, EBX bit 8. The previous early assignment used CPUID leaf 1 EBX bit 8, which is not the BMI2 feature bit and could leave a bogus fallback value before vendor-specific leaf 7 detection. Keep BMI2 detection based on the leaf 7 result only. Unlike AVX2, BMI2 is GPR-only and does not require an OS/XCR0 state gate. Also save the max basic CPUID leaf immediately after CPUID leaf 0. The AMD/Hygon path reuses the cpuid buffer for leaf 0x80000005 before checking whether leaf 7 is available, so using the saved max basic leaf prevents RDSEED, AVX2, and BMI2 detection from being skipped because that buffer was clobbered.
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to subscribe to this conversation on GitHub.
Already have an account?
Sign in.
1 participant
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
See Commits and Changes for more details.
Created by
pull[bot] (v2.0.0-alpha.4)
Can you help keep this open source service alive? 💖 Please sponsor : )