hw/virtio: qtest failure in virtio_init_region_cache() on macOS

[Philippe Mathieu-Daudé]

Hi,

On macOS, the fuzz-virtio-scsi-test triggers
virtio_error(vdev, "Cannot map used") from
virtio_init_region_cache():

QTEST_QEMU_BINARY=./qemu-system-x86_64 tests/qtest/fuzz-virtio-scsi-test
# Start of x86_64 tests
# Start of fuzz tests
# starting QEMU: exec ./qemu-system-x86_64 ...
  -M pc-q35-5.2 -m 512M
  -device virtio-scsi,num_queues=8,addr=03.0  -accel qtest
qemu-system-x86_64: Cannot map used
                    ^^^^^^^^^^^^^^^
ok 1 /x86_64/fuzz/test_mmio_oob_from_memory_region_cache
# End of fuzz tests
# End of x86_64 tests

virtio_init_region_cache() is not documented, is it OK to ignore
failures that way?

Thanks,

Phil.