16. NVIDIA MLX5 Crypto Driver


NVIDIA acquired Mellanox Technologies in 2020. The DPDK documentation and code might still include instances of or references to Mellanox trademarks (like BlueField and ConnectX) that are now NVIDIA trademarks.

The MLX5 crypto driver library (librte_crypto_mlx5) provides support for NVIDIA ConnectX-6, NVIDIA ConnectX-6 Dx, NVIDIA ConnectX-7, NVIDIA BlueField-2, and NVIDIA BlueField-3 family adapters.

16.1. Overview

NVIDIA MLX5 crypto driver supports AES-XTS and AES-GCM cryption.

16.1.1. AES-XTS

The device can provide disk encryption services, allowing data encryption and decryption towards a disk. Having all encryption/decryption operations done in a single device can reduce cost and overheads of the related FIPS certification, as ConnectX-6 is FIPS 140-2 level-2 ready. The encryption cipher is AES-XTS of 256/512 bit key size.

MKEY is a memory region object in the hardware, that holds address translation information and attributes per memory area. Its ID must be tied to addresses provided to the hardware. The encryption operations are performed with MKEY read/write transactions, when the MKEY is configured to perform crypto operations.

The encryption does not require text to be aligned to the AES block size (128b).

See NVIDIA MLX5 Common Driver guide for more design details.

16.1.2. AES-GCM

The supported AAD/digest/key size can be read from dev_info.

In AES-GCM mode, the HW requires continuous input and output of Additional Authenticated Data (AAD), payload, and digest (if needed). However, the API only provides a single AAD input, which means that in the out-of-place mode, the AAD will be used in both input and output. This reuse of AAD in the out-of-place mode breaks the continuous output, which degrades the performance and introduces extra UMR WQE. If digest is not continuous after payload will also lead to that extra UMR WQE.

To address this issue, the API provides min_mbuf_headroom_req and min_mbuf_tailroom_req in rte_cryptodev_info as a hint to the PMD. It indicates the PMD can use the buffer before and after the mbuf payload as AAD and digest space. With this hint, the PMD will use the buffer before and after the mbuf payload directly via copying AAD and digest. However, the application must ensure that there is enough headroom and tailroom reserved for the mbuf. Or, for non-continuous operations, extra UMR WQE will be used.

16.2. Configuration

See the mlx5 common configuration.

A device comes out of NVIDIA factory with pre-defined import methods. There are two possible import methods: wrapped or plaintext (valid for AES-XTS only).

In case the device is in wrapped mode, it needs to be moved to crypto operational mode. In order to move the device to crypto operational mode, credential and KEK (Key Encrypting Key) should be set as the first step. The credential will be used by the software in order to perform crypto login, and the KEK is the AES Key Wrap Algorithm (rfc3394) key that will be used for sensitive data wrapping. The credential and the AES-XTS keys should be provided to the hardware, as ciphertext encrypted by the KEK.

A keytag (64 bits) should be appended to the AES-XTS keys (before wrapping), and will be validated when the hardware attempts to access it.

When crypto engines are defined to work in wrapped import method, they come out of the factory in Commissioning mode, and thus, cannot be used for crypto operations yet. A dedicated tool is used for changing the mode from Commissioning to Operational, while setting the first import_KEK and credential in plaintext. The mlxreg dedicated tool should be used as follows:

  • Set CRYPTO_OPERATIONAL register to set the device in crypto operational mode.

    The input to this tool is:

    • The first credential in plaintext, 40B.
    • The first import_KEK in plaintext: kek size 0 for 16B or 1 for 32B, kek data.


    mlxreg -d /dev/mst/mt4123_pciconf0 --reg_name CRYPTO_OPERATIONAL --get

    The “wrapped_crypto_operational” value will be “0x00000000”. The command to set the register should be executed only once, and all the values mentioned above should be specified in the same command.


    mlxreg -d /dev/mst/mt4123_pciconf0 --reg_name CRYPTO_OPERATIONAL \
    --set "credential[0]=0x10000000, credential[1]=0x10000000, kek[0]=0x00000000"

    All values not specified will remain 0. “wrapped_crypto_going_to_commissioning” and “wrapped_crypto_operational” should not be specified.

    All the device ports should set it in order to move to operational mode. For BlueField-2, BlueField-3 the internal ports in the ARM system should also be set.

  • Query CRYPTO_OPERATIONAL register to make sure the device is in Operational mode.


    mlxreg -d /dev/mst/mt4123_pciconf0 --reg_name CRYPTO_OPERATIONAL --get

    The “wrapped_crypto_operational” value will be “0x00000001” if the mode was successfully changed to operational mode.

On the other hand, in case of plaintext mode, there is no need for all the above, DEK is passed in plaintext without keytag.

The mlx5 crypto PMD can be verified by running the test application::
Wrapped mode:
dpdk-test -c 1 -n 1 -w <dev>,class=crypto,wcs_file=<file_path> RTE>>cryptodev_mlx5_autotest
Plaintext mode:
dpdk-test -c 1 -n 1 -w <dev>,class=crypto RTE>>cryptodev_mlx5_autotest

16.3. Driver options

Please refer to mlx5 common options for an additional list of options shared with other mlx5 drivers.

  • algo parameter [int]

      1. AES-XTS crypto.
      1. AES-GCM crypto.

    Set to zero (AES-XTS) by default.

  • wcs_file parameter [string] - mandatory in wrapped mode

    File path including only the wrapped credential in string format of hexadecimal numbers, represent 48 bytes (8 bytes IV added by the AES key wrap algorithm). This option is valid only for AES-XTS.

  • import_kek_id parameter [int]

    The identifier of the KEK, default value is 0 represents the operational register import_kek.. This option is valid only for AES-XTS.

  • credential_id parameter [int]

    The identifier of the credential, default value is 0 represents the operational register credential. This option is valid only for AES-XTS.

  • keytag parameter [int]

    The plaintext of the keytag appended to the AES-XTS keys, default value is 0. This option is valid only for AES-XTS.

  • max_segs_num parameter [int]

    Maximum number of mbuf chain segments(src or dest), default value is 8.

  • crypto_mode parameter [string]

    Only valid in AES-GCM mode. Will be ignored in AES-XTS mode.

    • full_capable Use UMR WQE for inputs not as contiguous AAD/Payload/Digest.
    • ipsec_opt Do software AAD shrink for inputs as contiguous AAD/IV/Payload/Digest. The PMD relies on the IPsec layout, expecting the memory to align with AAD/IV/Payload/Digest in a contiguous manner, all within a single mbuf for any given OP. The PMD extracts the ESP.IV bytes from the input memory and binds the AAD (ESP SPI and SN) to the payload during enqueue OP. It then restores the original memory layout in the decrypt OP. The ESP.IV size supported range is [0,16] bytes. For OOP case, the PMD will replace the bytes preceding the OP destination address to match the information found between the AAD pointer and the OP source address. User should prepare this headroom in this case.

    Set to full_capable by default.

16.4. Supported NICs

  • NVIDIA® ConnectX®-6 200G MCX654106A-HCAT (2x200G)
  • NVIDIA® ConnectX®-6 Dx
  • NVIDIA® ConnectX®-7
  • NVIDIA® BlueField®-2 SmartNIC
  • NVIDIA® BlueField®-3 SmartNIC

16.5. Limitations

  • AES-XTS keys provided in xform must include keytag and should be wrapped.
  • The supported data-unit lengths are 512B and 4KB and 1MB. In case the dataunit_len is not provided in the cipher xform, the OP length is limited to the above values.
  • AES-GCM is supported only on BlueField-3.
  • AES-GCM supports only key import plaintext mode.
  • AES-GCM ipsec_opt mode does not support non-contiguous AAD/Payload/Digest and multi-segment mode.

16.6. Prerequisites

16.6.1. FW Prerequisites

  • xx.31.0328 for ConnectX-6.
  • xx.32.0108 for ConnectX-6 Dx and BlueField-2.
  • xx.36.xxxx for ConnectX-7 and BlueField-3.
  • xx.37.3010 for BlueField-3 and newer for AES-GCM.

16.6.2. Linux Prerequisites

  • NVIDIA MLNX_OFED version: 5.3.

  • Compilation can be done also with rdma-core v15+.

    See mlx5 common prerequisites for more details.

16.6.3. Windows Prerequisites