2 tests are failing on PPC64 when running
make run-test TEST="gtest:ZIndexDistributorTest"

test/hotspot/gtest/gc/z/test_zIndexDistributor.cpp:41: Failure
Expected equality of these values:
  ZIndexDistributorClaimTree::claim_level_end_index(0)
    Which is: 32
  16

test/hotspot/gtest/gc/z/test_zIndexDistributor.cpp:73: Failure
Expected equality of these values:
  ZIndexDistributorClaimTree::claim_index(indices, 1)
    Which is: 32
  second_level_start
    Which is: 16

ZIndexDistributorStriped uses ZCacheLineSize which is twice as high as on the other supported platforms.
Seems like the test only works for ZCacheLineSize = 64. So, I guess the issue is not limited to PPC64 in general (e.g. s390 would also be affected, but currently has no ZGC support).