"We then modified the inline encryption block driver to pass this to the hardware. As with ext4 encryption, keys are managed by the Linux keyring. To see our implementation, take a look at the source code for the Pixel kernel."

It doesn't sound like they got these changes into mainline. They link here to their source: https://android.googlesource.com/kernel/msm/+/android-msm-ma...

From that file:

    /* TODO(mhalcrow): Just for proof-of-concept */

WHOOPS!