As documented in issue C215 in the known issues list for DDI0487I.a [1] Arm will be making a retroactive change to SVE to remove the possibility of selecting non power of two vector lengths. This has no impact on existing physical implementations but most virtual implementations have implemented the full range of permissible vector lengths.
Since virtual implementations are noticeably slow in general and the larger vector lengths amplify the issue there's a useful improvement in runtime from only covering the vector lengths that will exist in practical systems, adjust our enumeration accordingly. We have other tests that aim to cover the enumeration interfaces.
For symmetry we apply the same change to the eumeration for SME vector lengths, though the power of two restriction was already present for SME so there is no impact on the set of vector lengths tested.
[1] https://developer.arm.com/documentation/102105/ia-00/
Signed-off-by: Mark Brown broonie@kernel.org --- tools/testing/selftests/arm64/abi/syscall-abi.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/tools/testing/selftests/arm64/abi/syscall-abi.c b/tools/testing/selftests/arm64/abi/syscall-abi.c index 7c9b6e947040..8afcbf6861fd 100644 --- a/tools/testing/selftests/arm64/abi/syscall-abi.c +++ b/tools/testing/selftests/arm64/abi/syscall-abi.c @@ -444,7 +444,7 @@ void sve_count_vls(void) /* * Enumerate up to SVE_VQ_MAX vector lengths */ - for (vq = SVE_VQ_MAX; vq > 0; --vq) { + for (vq = SVE_VQ_MAX; vq > 0; vq /= 2) { vl = prctl(PR_SVE_SET_VL, vq * 16); if (vl == -1) ksft_exit_fail_msg("PR_SVE_SET_VL failed: %s (%d)\n", @@ -470,7 +470,7 @@ void sme_count_vls(void) /* * Enumerate up to SVE_VQ_MAX vector lengths */ - for (vq = SVE_VQ_MAX; vq > 0; --vq) { + for (vq = SVE_VQ_MAX; vq > 0; vq /= 2) { vl = prctl(PR_SME_SET_VL, vq * 16); if (vl == -1) ksft_exit_fail_msg("PR_SME_SET_VL failed: %s (%d)\n",