Here's the test https://cs.corp.google.com/chromeos_public/src/third_party/autotest/files/client/site_tests/firmware_LockedME/firmware_LockedME.py

Here's the manual execution

1- dump bios to local file
localhost ~ # flashrom -r -p host /tmp/bios.bin
flashrom v0.9.4  : 2842dd9 : Jun 05 2017 23:54:51 UTC on Linux 4.4.64-09098-g4504f6dcbb08 (x86_64)
flashrom v0.9.4  : 2842dd9 : Jun 05 2017 23:54:51 UTC on Linux 4.4.64-09098-g4504f6dcbb08 (x86_64)
Calibrating delay loop... OK.
coreboot table found at 0x7ab39000.
WARNING: SPI Configuration Lockdown activated.
Reading flash... SUCCESS

2-create dummy file 
dd if=/dev/urandom of=/tmp/newdata count=1 bs=524288

3- attemp to over ride
# flashrom -w /tmp/bios.bin -i DEVICE_EXTENSION:/tmp/newdata --fast-verify
flashrom v0.9.4  : 2842dd9 : Jun 05 2017 23:54:51 UTC on Linux 4.4.64-09098-g4504f6dcbb08 (x86_64)
flashrom v0.9.4  : 2842dd9 : Jun 05 2017 23:54:51 UTC on Linux 4.4.64-09098-g4504f6dcbb08 (x86_64)
Calibrating delay loop... OK.
coreboot table found at 0x7ab39000.
WARNING: SPI Configuration Lockdown activated.
Erasing and writing flash chip... Verifying flash... flash partial verify failed.Your flash chip is in an unknown state.
Get help on IRC at irc.freenode.net (channel #flashrom) or
mail flashrom@flashrom.org with FAILED: your board name in the subject line!
-------------------------------------------------------------------------------
DO NOT REBOOT OR POWEROFF!
FAILED
localhost ~ # echo $?
255

#3 is expected when ME is locked, however the test is run on a device without ME lock.

Here are the diff from .122 to .125 https://crosland.corp.google.com/log/9042.122.0..9042.125.0
and the CL that locked ME post .122 https://chromium-review.googlesource.com/c/583983

After remove the write protection, the test now failed with .122

08/11 10:13:08.580 WARNI|              test:0616| The test failed with the following exception
Traceback (most recent call last):
  File "/usr/local/autotest/common_lib/test.py", line 610, in _exec
    _call_test_function(self.execute, *p_args, **p_dargs)
  File "/usr/local/autotest/common_lib/test.py", line 818, in _call_test_function
    return func(*args, **dargs)
  File "/usr/local/autotest/common_lib/test.py", line 471, in execute
    dargs)
  File "/usr/local/autotest/common_lib/test.py", line 348, in _call_run_once_with_retry
    postprocess_profiled_run, args, dargs)
  File "/usr/local/autotest/common_lib/test.py", line 381, in _call_run_once
    self.run_once(*args, **dargs)
  File "/usr/local/autotest/tests/firmware_LockedME/firmware_LockedME.py", line 129, in run_once
    self.try_to_rewrite('SI_DESC')
  File "/usr/local/autotest/tests/firmware_LockedME/firmware_LockedME.py", line 53, in try_to_rewrite
    raise error.TestFail('%s is writable, ME is unlocked' % sectname)
TestFail: SI_DESC is writable, ME is unlocked


So may be this is now a new requirement to remove WP before running ME lock.

+lhui please update test case to have WP remove before running tests.

if the region is locked, the MElock will always pass

# mosys eeprom map | grep WP_RO
host_firmware | WP_RO | 0x00000000 | 0x00400000 | 

# flashrom -p host --wp-enable --wp-range 0x00000000 0x00400000
flashrom v0.9.4  : 2842dd9 : Jun 05 2017 23:54:51 UTC on Linux 4.4.64-09098-g4504f6dcbb08 (x86_64)
flashrom v0.9.4  : 2842dd9 : Jun 05 2017 23:54:51 UTC on Linux 4.4.64-09098-g4504f6dcbb08 (x86_64)
coreboot table found at 0x7ab39000.
WARNING: SPI Configuration Lockdown activated.
spi_send_command called, but SPI is unsupported on this hardware. Please report a bug at flashrom@flashrom.org
SUCCESS


# flashrom -p host --wp-status
flashrom v0.9.4  : 2842dd9 : Jun 05 2017 23:54:51 UTC on Linux 4.4.64-09098-g4504f6dcbb08 (x86_64)
flashrom v0.9.4  : 2842dd9 : Jun 05 2017 23:54:51 UTC on Linux 4.4.64-09098-g4504f6dcbb08 (x86_64)
coreboot table found at 0x7ab39000.
WARNING: SPI Configuration Lockdown activated.
WP: status: 0x34
WP: status.srp0: 0
WP: write protect is disabled.
WP: write protect range: spi_send_command called, but SPI is unsupported on this hardware. Please report a bug at flashrom@flashrom.org
start=0x00000000, len=0x00400000


noted the start and len value match the WP_RO values.  This indicate the region is locked.
With ME unlocked on firmware .122, lockedME test will always passed.

+venkataraju see c#4, the WP_RO is locked even wp-status reported as disabled.

+lhui, please double check you setting when running ME lock to ensure WP is truelly disabled.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromiumos/third_party/autotest/+/85542e0acc3c4c2a71df927b8f72cfd6edce7e47

commit 85542e0acc3c4c2a71df927b8f72cfd6edce7e47
Author: venkata srinivasa raju penmetcha <venkataraju@google.com>
Date: Tue Nov 28 06:50:43 2017

firmware_LockedME: Check for SW WP status

Prior to Apollolake only the contents of SI_DESC was used to protect SI_DESC.
Starting with Apollolake, the SPI flash part can also protect SI_DESC, so this
adds a check for software write protect.

BUG= chromium:754760 
TEST=test_that --board=soraka 172.22.18.16 firmware_LockedME with dut having
     wp on and off.

Change-Id: If50a3db7903e380331d7a47cb7d577a8807754b1
Reviewed-on: https://chromium-review.googlesource.com/719427
Commit-Ready: ChromeOS CL Exonerator Bot <chromiumos-cl-exonerator@appspot.gserviceaccount.com>
Tested-by: Venkata Srinivasa Raju Penmetcha <venkataraju@chromium.org>
Reviewed-by: Kevin Shelton <kmshelton@chromium.org>

[modify] https://crrev.com/85542e0acc3c4c2a71df927b8f72cfd6edce7e47/client/site_tests/firmware_LockedME/firmware_LockedME.py