to #27305291

commit 4c6926a23b76ea23403976290cd45a7a143f6500 upstream.

Add support to unlock the dimm via the kernel key management APIs. The
passphrase is expected to be pulled from userspace through keyutils.
The key management and sysfs attributes are libnvdimm generic.

Encrypted keys are used to protect the nvdimm passphrase at rest. The
master key can be a trusted-key sealed in a TPM, preferred, or an
encrypted-key, more flexible, but more exposure to a potential attacker.
Signed-off-by: NDave Jiang <dave.jiang@intel.com>
Co-developed-by: NDan Williams <dan.j.williams@intel.com>
Reported-by: NRandy Dunlap <rdunlap@infradead.org>
Signed-off-by: NDan Williams <dan.j.williams@intel.com>
Signed-off-by: NShile Zhang <shile.zhang@linux.alibaba.com>
Reviewed-by: NYang Shi <yang.shi@linux.alibaba.com>