mlx5dv_wr_set_mkey_sig_block - Man Page

Configure a MKEY for block signature (data integrity) operation.

Synopsis

#include <infiniband/mlx5dv.h>

static inline void mlx5dv_wr_set_mkey_sig_block(struct mlx5dv_qp_ex *mqp,
                                                const struct mlx5dv_sig_block_attr *attr)

Configure a MKEY with block-level data protection properties. With this, the device can add/modify/strip/validate integrity fields per block when transmitting data from memory to network and when receiving data from network to memory.

This setter can be optionally called after a MKEY configuration work request posting has started using mlx5dv_wr_mkey_configure(3). Configuring block signature properties to a MKEY is done by describing what kind of signature is required (or expected) in two domains: the wire domain and the memory domain.

The MKEY represents a virtually contiguous memory, by configuring a layout to it. The memory signature domain describes whether data in this virtually contiguous memory includes integrity fields, and if so, what kind and what block size.

The wire signature domain describes the same kind of properties for the data as it is seen on the wire. Now, depending on the actual operation that happens (TX or RX), the device will do the “right thing” based on the signature configurations of the two domains.

Example 1

Memory signature domain is configured for CRC32 every 512B block.

Wire signature domain is configured for no signature.

A SEND is issued using the MKEY as a local key.

Result: device will gather the data with the CRC32 fields from the MKEY (using whatever layout configured to the MKEY to locate the actual memory), validate each CRC32 against the previous 512 bytes of data, strip the CRC32 field, and transmit only 512 bytes of data to the wire.

Example 1.1

Same as above, but a RECV is issued with the same key, and RX happens.

Result: device will receive the data from the wire, scatter it to the MKEY (using whatever layout configured to the MKEY to locate the actual memory), generating and scattering additional CRC32 field after every 512 bytes that are scattered.

Example 2

Memory signature domain is configured for no signature.

Wire signature domain is configured for T10DIF every 4K block.

The MKEY is sent to a remote node that issues a RDMA_READ to this MKEY.

Result: device will gather the data from the MKEY (using whatever layout configured to the MKEY to locate the actual memory), transmit it to the wire while generating an additional T10DIF field every 4K of data.

Example 2.1

Same as above, but remote node issues a RDMA_WRITE to this MKEY.

Result: Device will receive the data from the wire, validate each T10DIF field against the previous 4K of data, strip the T10DIF field, and scatter the data alone to the MKEY (using whatever layout configured to the MKEY to locate the actual memory).

Arguments

mqp

The QP where an MKEY configuration work request was created by

mlx5dv_wr_mkey_configure().

attr

Block signature attributes to set for the MKEY.

Block signature attributes

Block signature attributes describe the input and output data structures in memory and wire domains.

struct mlx5dv_sig_block_attr {
    const struct mlx5dv_sig_block_domain *mem;
    const struct mlx5dv_sig_block_domain *wire;
    uint32_t flags;
    uint8_t check_mask;
    uint8_t copy_mask;
    uint64_t comp_mask;
};

mem

A pointer to the signature configuration for the memory domain or NULL if the domain does not have a signature.

wire

A pointer to the signature configuration for the wire domain or NULL if the domain does not have a signature.

flags

A bitwise OR of the various values described below.

MLX5DV_SIG_BLOCK_ATTR_FLAG_COPY_MASK: If the bit is not set then copy_mask is ignored. See details in the copy_mask description.

check_mask

Each bit of check_mask corresponds to a byte of the signature field in input domain. Byte of the input signature is checked if corresponding bit in check_mask is set. Bits not relevant to the signature type are ignored.

Layout of check_mask.

check_mask (bits)	7	6	5	4	3	2	1	0
T10-DIF (bytes)	GUARD[1]	GUARD[0]	APP[1]	APP[0]	REF[3]	REF[2]	REF[1]	REF[0]
CRC32C/CRC32 (bytes)	3	2	1	0
CRC64_XP10 (bytes)	7	6	5	4	3	2	1	0

Common used masks are defined in enum mlx5dv_sig_mask. Other masks are also supported. Follow the above table to define a custom mask. For example, this can be useful for the application tag field of the T10DIF signature. Using the application tag is out of the scope of the T10DIF specification and depends on the implementation. check_mask allows validating a part of the application tag if needed.

copy_mask

A mask to specify what part of the signature is copied from the source domain to the destination domain. The copy mask is usually calculated automatically. The signature is copied if the same signature type is configurted on both domains. The parts of the T10-DIF are compared and handled independetly.

If MLX5DV_SIG_BLOCK_ATTR_FLAG_COPY_MASK is set the copy_mask attribute overrides the calculated value of the copy mask. Otherwise, copy_mask is ignored.

Each bit of copy_mask corresponds to a byte of the signature field. If corresponding bit in copy_mask is set, byte of the signature is copied from the input domain to the output domain. Calculation according to the output domain configuration is not performed in this case. Bits not relevant to the signature type are ignored. copy_mask may be used only if input and output domains have the same structure, i.e. same block size and signature type. The MKEY configuration will fail if MLX5DV_SIG_BLOCK_ATTR_FLAG_COPY_MASK is set but the domains have different signature structures.

The predefined masks are available in enum mlx5dv_sig_mask. It is also supported to specify a user-defined mask. Follow the table in check_mask description to define a custom mask.

copy_mask can be useful when some bytes of the signature are not known in advance, hence can’t be checked, but shall be preserved. In this case corresponding bits should be cleared in check_mask and set in copy_mask.

comp_mask

Reserved for future extension, must be 0 now.

Block signature domain

struct mlx5dv_sig_block_domain {
    enum mlx5dv_sig_type sig_type;
    union {
        const struct mlx5dv_sig_t10dif *dif;
        const struct mlx5dv_sig_crc *crc;
    } sig;
    enum mlx5dv_block_size block_size;
    uint64_t comp_mask;
};

sig_type

The signature type for this domain, one of the following

MLX5DV_SIG_TYPE_T10DIF: The block-level data protection defined in the T10 specifications (T10 SBC-3).
MLX5DV_SIG_TYPE_CRC: The block-level data protection based on cyclic redundancy check (CRC). The specific type of CRC is defined in sig.

sig

Depending on sig_type, this is the per signature type specific configuration.

block_size

The block size for this domain, one of enum mlx5dv_sig_block_size.

comp_mask

Reserved for future extension, must be 0 now.

CRC signature

struct mlx5dv_sig_crc {
    enum mlx5dv_sig_crc_type type;
    uint64_t seed;
};

type

The specific CRC type, one of the following.

MLX5DV_SIG_CRC_TYPE_CRC32: CRC32 signature is created by calculating a 32-bit CRC defined in Fibre Channel Physical and Signaling Interface (FC-PH), ANSI X3.230:1994.
MLX5DV_SIG_CRC_TYPE_CRC32C: CRC32C signature is created by calculating a 32-bit CRC called the Castagnoli CRC, defined in the Internet Small Computer Systems Interface (iSCSI) rfc3720.
MLX5DV_SIG_CRC_TYPE_CRC64_XP10: CRC64_XP10 signature is created by calculating a 64-bit CRC defined in Microsoft XP10 compression standard.

seed

A seed for the CRC calculation per block. Bits not relevant to the CRC type are ignored. For example, all bits are used for CRC64_XP10, but only the 32 least significant bits are used for CRC32/CRC32C.

Only the following values are supported as a seed: CRC32/CRC32C - 0, 0xFFFFFFFF(UINT32_MAX); CRC64_XP10 - 0, 0xFFFFFFFFFFFFFFFF(UINT64_MAX).

T10DIF signature

T10DIF signature is defined in the T10 specifications (T10 SBC-3) for block-level data protection. The size of data block protected by T10DIF must be modulo 8bytes as required in the T10DIF specifications. Note that when setting the initial LBA value to ref_tag, it should be the value of the first block to be transmitted.

struct mlx5dv_sig_t10dif {
    enum mlx5dv_sig_t10dif_bg_type bg_type;
    uint16_t bg;
    uint16_t app_tag;
    uint32_t ref_tag;
    uint16_t flags;
};

bg_type

The block guard type to be used, one of the following.

MLX5DV_SIG_T10DIF_CRC: Use CRC in the block guard field as required in the T10DIF specifications.
MLX5DV_SIG_T10DIF_CSUM: Use IP checksum instead of CRC in the block guard field.

bg

A seed for the block guard calculation per block.

The following values are supported as a seed: 0, 0xFFFF(UINT16_MAX).

app_tag

An application tag to generate or validate.

ref_tag

A reference tag to generate or validate.

flags

Flags for the T10DIF attributes, one of the following.

MLX5DV_SIG_T10DIF_FLAG_REF_REMAP: Increment reference tag per block.
MLX5DV_SIG_T10DIF_FLAG_APP_ESCAPE: Do not check block guard if application tag is 0xFFFF.
MLX5DV_SIG_T10DIF_FLAG_APP_REF_ESCAPE: Do not check block guard if application tag is 0xFFFF and reference tag is 0xFFFFFFFF.

Return Value

This function does not return a value.

In case of error, user will be notified later when completing the DV WRs chain.

Notes

A DEVX context should be opened by using mlx5dv_open_device(3).

MKEY must be created with MLX5DV_MKEY_INIT_ATTR_FLAGS_BLOCK_SIGNATURE flag.

The last operation posted on the supplied QP should be mlx5dv_wr_mkey_configure(3), or one of its related setters, and the operation must still be open (no doorbell issued).

In case of ibv_wr_complete() failure or calling to ibv_wr_abort(), the MKey may be left in an unknown state. The next configuration of it should not assume any previous state of the MKey, i.e. signature/crypto should be re-configured or reset, as required. For example, assuming mlx5dv_wr_set_mkey_sig_block() and then ibv_wr_abort() were called, then on the next configuration of the MKey, if signature is not needed, it should be reset using MLX5DV_MKEY_CONF_FLAG_RESET_SIG_ATTR.