MLX5DV_DR_MATCHER_SET_LAYOUT(3)

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🌈 MLX5DV_DR API(3) — the mlx5 Programmer's Manual, but make it make sense 🌈

okay bestie, buckle up 💅 this is the Direct Rule API (mlx5dv_dr_*) and it's a whole thing. But it's honestly iconic once you get it. Let's go.

✨ NAME ✨

Managing all the flow things:

  • mlx5dv_dr_domain_create, mlx5dv_dr_domain_sync, mlx5dv_dr_domain_destroy, mlx5dv_dr_domain_set_reclaim_device_memory, mlx5dv_dr_domain_allow_duplicate_rules — manage flow domains 🫶
  • mlx5dv_dr_table_create, mlx5dv_dr_table_destroy — manage flow tables
  • mlx5dv_dr_matcher_create, mlx5dv_dr_matcher_destroy, mlx5dv_dr_matcher_set_layout — manage flow matchers
  • mlx5dv_dr_rule_create, mlx5dv_dr_rule_destroy — manage flow rules
  • mlx5dv_dr_action_create_drop — create drop action
  • mlx5dv_dr_action_create_default_miss — create default miss action
  • mlx5dv_dr_action_create_tag — create tag actions
  • mlx5dv_dr_action_create_dest_ibv_qp — create packet destination QP action
  • mlx5dv_dr_action_create_dest_table — create packet destination dr table action
  • mlx5dv_dr_action_create_dest_root_table — create packet destination root table action
  • mlx5dv_dr_action_create_dest_vport — create packet destination vport action
  • mlx5dv_dr_action_create_dest_ib_port — create packet destination IB port action
  • mlx5dv_dr_action_create_dest_devx_tir — create packet destination TIR action
  • mlx5dv_dr_action_create_dest_array — create destination array action
  • mlx5dv_dr_action_create_packet_reformat — create packet reformat actions
  • mlx5dv_dr_action_create_modify_header — create modify header actions
  • mlx5dv_dr_action_create_flow_counter — create devx flow counter actions
  • mlx5dv_dr_action_create_aso, mlx5dv_dr_action_modify_aso — create and modify ASO actions
  • mlx5dv_dr_action_create_flow_meter, mlx5dv_dr_action_modify_flow_meter — create and modify meter action
  • mlx5dv_dr_action_create_flow_sampler — create flow sampler action
  • mlx5dv_dr_action_create_pop_vlan — create pop vlan action
  • mlx5dv_dr_action_create_push_vlan — create push vlan action
  • mlx5dv_dr_action_destroy — destroy actions
  • mlx5dv_dr_aso_other_domain_link, mlx5dv_dr_aso_other_domain_unlink — link/unlink ASO devx object to work with different domains

🌸 SYNOPSIS 🌸

here's the whole cast, in code form 🎀

#include <infiniband/mlx5dv.h>

struct mlx5dv_dr_domain *mlx5dv_dr_domain_create(
        struct ibv_context *ctx,
        enum mlx5dv_dr_domain_type type);

int mlx5dv_dr_domain_sync(
        struct mlx5dv_dr_domain *domain,
        uint32_t flags);

int mlx5dv_dr_domain_destroy(struct mlx5dv_dr_domain *domain);

void mlx5dv_dr_domain_set_reclaim_device_memory(
        struct mlx5dv_dr_domain *dmn,
        bool enable);

void mlx5dv_dr_domain_allow_duplicate_rules(struct mlx5dv_dr_domain *dmn, bool allow);

struct mlx5dv_dr_table *mlx5dv_dr_table_create(
        struct mlx5dv_dr_domain *domain,
        uint32_t level);

int mlx5dv_dr_table_destroy(struct mlx5dv_dr_table *table);

struct mlx5dv_dr_matcher *mlx5dv_dr_matcher_create(
        struct mlx5dv_dr_table *table,
        uint16_t priority,
        uint8_t match_criteria_enable,
        struct mlx5dv_flow_match_parameters *mask);

int mlx5dv_dr_matcher_destroy(struct mlx5dv_dr_matcher *matcher);

int mlx5dv_dr_matcher_set_layout(struct mlx5dv_dr_matcher *matcher, struct mlx5dv_dr_matcher_layout *matcher_layout);

struct mlx5dv_dr_rule *mlx5dv_dr_rule_create(
        struct mlx5dv_dr_matcher *matcher,
        struct mlx5dv_flow_match_parameters *value,
        size_t num_actions,
        struct mlx5dv_dr_action *actions[]);

void mlx5dv_dr_rule_destroy(struct mlx5dv_dr_rule *rule);

struct mlx5dv_dr_action *mlx5dv_dr_action_create_drop(void);

struct mlx5dv_dr_action *mlx5dv_dr_action_create_default_miss(void);

struct mlx5dv_dr_action *mlx5dv_dr_action_create_tag(
        uint32_t tag_value);

struct mlx5dv_dr_action *mlx5dv_dr_action_create_dest_ibv_qp(
        struct ibv_qp *ibqp);

struct mlx5dv_dr_action *mlx5dv_dr_action_create_dest_table(
        struct mlx5dv_dr_table *table);

struct mlx5dv_dr_action *mlx5dv_dr_action_create_dest_root_table(
        struct mlx5dv_dr_table *table, uint16_t priority);

struct mlx5dv_dr_action *mlx5dv_dr_action_create_dest_vport(
        struct mlx5dv_dr_domain *domain,
        uint32_t vport);

struct mlx5dv_dr_action *mlx5dv_dr_action_create_dest_ib_port(
        struct mlx5dv_dr_domain *domain,
        uint32_t ib_port);

struct mlx5dv_dr_action *mlx5dv_dr_action_create_dest_devx_tir(
        struct mlx5dv_devx_obj *devx_obj);

struct mlx5dv_dr_action *mlx5dv_dr_action_create_packet_reformat(
        struct mlx5dv_dr_domain *domain,
        uint32_t flags,
        enum mlx5dv_flow_action_packet_reformat_type reformat_type,
        size_t data_sz, void *data);

struct mlx5dv_dr_action *mlx5dv_dr_action_create_modify_header(
        struct mlx5dv_dr_domain *domain,
        uint32_t flags,
        size_t actions_sz,
        __be64 actions[]);

struct mlx5dv_dr_action *mlx5dv_dr_action_create_flow_counter(
        struct mlx5dv_devx_obj *devx_obj,
        uint32_t offset);

struct mlx5dv_dr_action *
mlx5dv_dr_action_create_aso(struct mlx5dv_dr_domain *domain,
                struct mlx5dv_devx_obj *devx_obj,
                uint32_t offset,
                uint32_t flags,
                uint8_t return_reg_c);

int mlx5dv_dr_action_modify_aso(struct mlx5dv_dr_action *action,
                uint32_t offset,
                uint32_t flags,
                uint8_t return_reg_c);

struct mlx5dv_dr_action *
mlx5dv_dr_action_create_flow_meter(struct mlx5dv_dr_flow_meter_attr *attr);

int mlx5dv_dr_action_modify_flow_meter(struct mlx5dv_dr_action *action,
                               struct mlx5dv_dr_flow_meter_attr *attr,
                               __be64 modify_field_select);

struct mlx5dv_dr_action *
mlx5dv_dr_action_create_flow_sampler(struct mlx5dv_dr_flow_sampler_attr *attr);

struct mlx5dv_dr_action *
mlx5dv_dr_action_create_dest_array(struct mlx5dv_dr_domain *domain,
                           size_t num_dest,
                           struct mlx5dv_dr_action_dest_attr *dests[]);

struct mlx5dv_dr_action *mlx5dv_dr_action_create_pop_vlan(void);

struct mlx5dv_dr_action *mlx5dv_dr_action_create_push_vlan(
        struct mlx5dv_dr_domain *dmn,
        __be32 vlan_hdr)

int mlx5dv_dr_action_destroy(struct mlx5dv_dr_action *action);

int mlx5dv_dr_aso_other_domain_link(struct mlx5dv_devx_obj *devx_obj,
                            struct mlx5dv_dr_domain *peer_dmn,
                            struct mlx5dv_dr_domain *dmn,
                            uint32_t flags,
                            uint8_t return_reg_c);

int mlx5dv_dr_aso_other_domain_unlink(struct mlx5dv_devx_obj *devx_obj,
                              struct mlx5dv_dr_domain *dmn);

🦋 DESCRIPTION 🦋

so the Direct Rule API (mlx5dv_dr_*) is basically giving your verbs application complete access to the device's packet steering functionality. full send. no gatekeeping. 💅

A steering flow rule is the combination of attributes with a match pattern and a list of actions. Rules can have several distinct actions — like counting, encapsulating, decapsulating, before redirecting packets to a particular queue or port, etc. etc. ✨

And to manage the rule execution order for the packet processing matching by HW, you get multiple flow tables in an ordered chain, plus multiple flow matchers sorted by priorities. it's giving organization. 🎀

👑 Domain

mlx5dv_dr_domain_create() creates a DR domain object to be used with mlx5dv_dr_table_create() and mlx5dv_dr_action_create_*().

A domain should be destroyed by calling mlx5dv_dr_domain_destroy() once all depended resources are released. (yes bestie, clean up after yourself 🫶)

The device supports the following domain types:

  • MLX5DV_DR_DOMAIN_TYPE_NIC_RX — manage ethernet packets received on the NIC. Packets in this domain can be dropped, dispatched to QP's, modified or redirected to additional tables inside the domain. Default behavior: drop packet.
  • MLX5DV_DR_DOMAIN_TYPE_NIC_TX — manage ethernet packets transmit on the NIC. Packets in this domain can be dropped, modified or redirected to additional tables inside the domain. Default behavior: forward packet to NIC vport (to eSwitch or wire).
  • MLX5DV_DR_DOMAIN_TYPE_FDB — manage ethernet packets in the eSwitch Forwarding Data Base for packets received from wire or from any other vport. Packets in this domain can be dropped, dispatched to vport, modified or redirected to additional tables inside the domain. Default behavior: forward packet to eSwitch manager vport.

mlx5dv_dr_domain_sync() is used in order to flush the rule submission queue. by default, rules in a domain are updated in HW asynchronously, so this is your "okay but actually did it happen yet" function 😭. flags should be a set of type enum mlx5dv_dr_domain_sync_flags:

  • MLX5DV_DR_DOMAIN_SYNC_FLAGS_SW: block until completion of all software queued tasks.
  • MLX5DV_DR_DOMAIN_SYNC_FLAGS_HW: clear the steering HW cache to enforce next packet hits the latest rules, in addition to the SW SYNC handling.
  • MLX5DV_DR_DOMAIN_SYNC_FLAGS_MEM: sync device memory to free cached memory.

mlx5dv_dr_domain_set_reclaim_device_memory() is used to enable the reclaiming of device memory back to the system when not in use. by default this feature is disabled 🙈.

mlx5dv_dr_domain_allow_duplicate_rules() is used to allow or prevent insertion of rules matching on same fields (duplicates) on non root tables. by default this feature is allowed ✅.

🧚 Table

mlx5dv_dr_table_create() creates a DR table in the domain, at the appropriate level, and can be used with mlx5dv_dr_matcher_create(), mlx5dv_dr_action_create_dest_table() and mlx5dv_dr_action_create_dest_root_table.

here's the key detail bestie: all packets start traversing the steering domain tree at table level zero (0). 🎯 then, using rule and action, packets can be redirected to other tables in the domain.

A table should be destroyed by calling mlx5dv_dr_table_destroy() once all depended resources are released.

still going, don't go anywhere — part 2 is coming 💖

Matcher

okay so bestie, mlx5dv_dr_matcher_create() creates a matcher object in table, at sorted priority (lower value is checked first — so lowkey the lower number gets first dibs 👀). A matcher can hold multiple rules, all with identical mask of type struct mlx5dv_flow_match_parameters — that's the exact attributes to be compared by HW steering. The match_criteria_enable and mask are defined in a device spec format. Only the fields that were masked in the matcher should be filled by the rule in mlx5dv_dr_rule_create(). Don't be out here filling unmasked fields, that's not the vibe ✨.

A matcher should be destroyed by calling mlx5dv_dr_matcher_destroy() once all dependent resources are released.

mlx5dv_dr_matcher_set_layout() is used to set specific layout parameters of a matcher. On some conditions setting some attributes might not be supported — in such cases ENOTSUP will be returned (so that's a hard no from the driver 💀). flags should be a set of type enum mlx5dv_dr_matcher_layout_flags:

  • MLX5DV_DR_MATCHER_LAYOUT_RESIZABLE — the matcher can resize its scale and resources according to the rules that are inserted or removed. It's giving flexible queen energy 💅.
  • MLX5DV_DR_MATCHER_LAYOUT_NUM_RULE — indicates a hint from the application about the number of rules the matcher is expected to handle. This allows preallocation of matcher resources for faster rule updates when using with non-resizable layout mode. Basically a heads-up so the driver can pre-game 🎮.

Actions

A set of action create APIs are defined by mlx5dv_dr_action_create_*() — the whole squad 🫶. All actions are created as struct mlx5dv_dr_action. An action should be destroyed by calling mlx5dv_dr_action_destroy() once all dependent rules are destroyed.

When an action handle is reused for multiple rules, the same action will be executed. e.g.: action count will count multiple flows rules on the same HW flow counter context. action drop will drop packets of different rule from any matcher.

  • Action: Drop — mlx5dv_dr_action_create_drop creates a terminating action which drops packets.
🚫 no cap: this one cannot be mixed with Destination actions.
  • Action: Default miss — mlx5dv_dr_action_create_default_miss creates a terminating action which will execute the default behavior based on the domain type.
  • Action: Tag — mlx5dv_dr_action_create_tag creates a non-terminating action which tags packets with tag_value. The tag_value is available in the CQE of the packet received. Valid only on domain type NIC_RX.
  • Action: Destination — mlx5dv_dr_action_create_dest_ibv_qp creates a terminating action delivering the packet to a QP, defined by ibqp. Valid only on domain type NIC_RX. mlx5dv_dr_action_create_dest_table creates a forwarding action to another flow table, defined by table. The destination table must be from the same domain with a level higher than zero. mlx5dv_dr_action_create_dest_root_table creates a forwarding action to another priority inside a root flow table, defined by table and priority. mlx5dv_dr_action_create_dest_vport creates a forwarding action to a vport on the same domain. Valid only on domain type FDB. mlx5dv_dr_action_create_dest_ib_port creates a forwarding action to a ib_port on the same domain. The valid range of ports is based on the capability phys_port_cnt_ex provided by ibq_query_device_ex and it is possible to query the ports details using mlx5dv_query_port. Action is supported only on domain type FDB. mlx5dv_dr_action_create_dest_devx_tir creates a terminating action delivering the packet to a TIR, defined by devx_obj. Valid only on domain type NIC_RX.
  • Action: Array — mlx5dv_dr_action_create_dest_array creates an action which replicates a packet to multiple destinations. num_dest defines the number of replication destinations. Each dests destination array entry can be of different type. Use type MLX5DV_DR_ACTION_DEST for direct forwarding to an action destination. Use type MLX5DV_DR_ACTION_DEST_REFORMAT when reformat action should be performed on the packet before it is forwarding to the destination action.
  • Action: Packet Reformat — mlx5dv_dr_action_create_packet_reformat create a packet reformat context and action in the domain. The reformat_type, data_sz and data are defined in man mlx5dv_create_flow_action_packet_reformat.
  • Action: Modify Header — mlx5dv_dr_action_create_modify_header create a modify header context and action in the domain. The actions_sz and actions are defined in man mlx5dv_create_flow_action_modify_header.
  • Action: Flow Count — mlx5dv_dr_action_create_flow_counter creates a flow counter action from a DEVX flow counter object, based on devx_obj and specific counter index from offset in the counter bulk.
  • Action: ASO — mlx5dv_dr_action_create_aso receives a domain pointer and creates an ASO action from the DEVX ASO object, based on devx_obj. Use offset to select the specific ASO object in the devx_obj bulk. DR rules using this action can optionally update the ASO object value according to flags to choose the specific wanted behavior of this object. After a packet hits the rule with the ASO object the value of the ASO object will be copied into the chosen return_reg_c which can be used for match in following DR rules. mlx5dv_dr_action_modify_aso modifies ASO action action with new values for offset, return_reg_c and flags. Only new DR rules using this action will use the modified values. Existing DR rules do not change the HW action values stored. flags can be set to one of the types of mlx5dv_dr_action_aso_first_hit_flags or mlx5dv_dr_action_aso_flow_meter_flags or mlx5dv_dr_action_aso_ct_flags:
    • MLX5DV_DR_ACTION_ASO_FIRST_HIT_FLAGS_SET — is used to set the ASO first hit object context, else the context is only copied to the return_reg_c.
    • MLX5DV_DR_ACTION_FLAGS_ASO_FLOW_METER_RED — is used to indicate to update the initial color in ASO flow meter object value to red.
    • MLX5DV_DR_ACTION_FLAGS_ASO_FLOW_METER_YELLOW — is used to indicate to update the initial color in ASO flow meter object value to yellow.
    • MLX5DV_DR_ACTION_FLAGS_ASO_FLOW_METER_GREEN — is used to indicate to update the initial color in ASO flow meter object value to green.
    • MLX5DV_DR_ACTION_FLAGS_ASO_FLOW_METER_UNDEFINED — is used to indicate to update the initial color in ASO flow meter object value to undefined.
    • MLX5DV_DR_ACTION_FLAGS_ASO_CT_DIRECTION_INITIATOR — is used to indicate the TCP connection direction the SYN packet was sent on.
    • MLX5DV_DR_ACTION_FLAGS_ASO_CT_DIRECTION_RESPONDER — is used to indicate the TCP connection direction the SYN-ACK packet was sent on.
  • Action: Meter — mlx5dv_dr_action_create_flow_meter creates a meter action based on the flow meter parameters. The parameters are according to the device specification. mlx5dv_dr_action_modify_flow_meter modifies existing flow meter action based on modify_field_select. modify_field_select is according to the device specification.
  • Action: Sampler — mlx5dv_dr_action_create_flow_sampler creates a sampler action, allowing us to duplicate and sample a portion of traffic. Packets steered to the sampler action will be sampled with an approximate probability of 1/sample_ratio provided in attr, and sample_actions provided in attr will be executed over them. All original packets will be steered to default_next_table in attr. A modify header format SET_ACTION data can be provided in action of attr, which can be executed on packets before going to default flow table. On some devices, this is required to set register value.
  • Action Flags: action flags can be set to one of the types of enum mlx5dv_dr_action_flags:
    • Action: Pop Vlan — mlx5dv_dr_action_create_pop_vlan creates a pop vlan action which removes VLAN tags from packets layer 2.
    • Action: Push Vlan — mlx5dv_dr_action_create_push_vlan creates a push vlan action which adds VLAN tags to packets layer 2.
    • MLX5DV_DR_ACTION_FLAGS_ROOT_LEVEL — is used to indicate the action is targeted for flow table in level=0 (ROOT) of the specific domain.

Rule

mlx5dv_dr_rule_create() creates a HW steering rule entry in matcher. The value of type struct mlx5dv_flow_match_parameters holds the exact attribute values of the steering rule to be matched, in a device spec format. Only the fields that were masked in the matcher should be filled. HW will perform the set of num_actions from the action array of type struct mlx5dv_dr_action, once a packet matches the exact value of the rule (referred to as a hit).

mlx5dv_dr_rule_destroy() destroys the rule.

Other

mlx5dv_dr_aso_other_domain_link() links the ASO devx object, devx_obj to a domain dmn, this will allow creating a rule with ASO action using the given object on the linked domain dmn. peer_dmn is the domain that the ASO devx object was created on. dmn is the domain that ASO devx object will be linked to. flags choose the specific wanted behavior of this object according to the flags, same as for ASO action creation flags. regc_index — after a packet hits the rule with the ASO object the value of the ASO object will be copied into the regc register indicated by this param, and then we can use the value for matching in the following DR rules.

mlx5dv_dr_aso_other_domain_unlink() will unlink the devx_obj from the linked dmn. dmn is the domain that ASO devx object is linked to.

RETURN VALUE

The create API calls will return a pointer to the relevant object: table, matcher, action, rule. On failure, NULL will be returned and errno will be set.

The destroy API calls will return 0 on success, or the value of errno on failure (which indicates the failure reason).

LIMITATIONS

Application can verify if a feature is supported by trial and error. No capabilities are exposed, as the combination of all the options exposed are way too large to define.

Tables are size-less by definition. They are expected to grow and shrink to accommodate for all rules, according to driver capabilities. Once reaching a limit, an error is returned.

Matchers in same priority, in the same table, will have undefined order.

A rule with identical value pattern to another rule on a given matcher are rejected.

IP version in matcher mask and rule should be equal and set to 4, 6 or 0.

SEE ALSO

mlx5dv_open_device(3), mlx5dv_create_flow_action_packet_reformat(3), mlx5dv_create_flow_action_modify_header(3).

AUTHOR

Alex Rosenbaum <alexr@mellanox.com> Alex Vesker <valex@mellanox.com>

💖 that's the whole page, bestie! source: mlx5 · date: 2019-03-28 · version: MLX5DV_DR API(3) — no cap, periodt. 🫶

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