• Eugenia Emantayev's avatar
    net/mlx4: Change QP allocation scheme · ddae0349
    Eugenia Emantayev authored
    When using BF (Blue-Flame), the QPN overrides the VLAN, CV, and SV fields
    in the WQE. Thus, BF may only be used for QPNs with bits 6,7 unset.
    
    The current Ethernet driver code reserves a Tx QP range with 256b alignment.
    
    This is wrong because if there are more than 64 Tx QPs in use,
    QPNs >= base + 65 will have bits 6/7 set.
    
    This problem is not specific for the Ethernet driver, any entity that
    tries to reserve more than 64 BF-enabled QPs should fail. Also, using
    ranges is not necessary here and is wasteful.
    
    The new mechanism introduced here will support reservation for
    "Eth QPs eligible for BF" for all drivers: bare-metal, multi-PF, and VFs
    (when hypervisors support WC in VMs). The flow we use is:
    
    1. In mlx4_en, allocate Tx QPs one by one instead of a range allocation,
       and request "BF enabled QPs" if BF is supported for the function
    
    2. In the ALLOC_RES FW command, change param1 to:
    a. param1[23:0]  - number of QPs
    b. param1[31-24] - flags controlling QPs reservation
    
    Bit 31 refers to Eth blueflame supported QPs. Those QPs must have
    bits 6 and 7 unset in order to be used in Ethernet.
    
    Bits 24-30 of the flags are currently reserved.
    
    When a function tries to allocate a QP, it states the required attributes
    for this QP. Those attributes are considered "best-effort". If an attribute,
    such as Ethernet BF enabled QP, is a must-have attribute, the function has
    to check that attribute is supported before trying to do the allocation.
    
    In a lower layer of the code, mlx4_qp_reserve_range masks out the bits
    which are unsupported. If SRIOV is used, the PF validates those attributes
    and masks out unsupported attributes as well. In order to notify VFs which
    attributes are supported, the VF uses QUERY_FUNC_CAP command. This command's
    mailbox is filled by the PF, which notifies which QP allocation attributes
    it supports.
    Signed-off-by: default avatarEugenia Emantayev <eugenia@mellanox.co.il>
    Signed-off-by: default avatarMatan Barak <matanb@mellanox.com>
    Signed-off-by: default avatarOr Gerlitz <ogerlitz@mellanox.com>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
    ddae0349
en_tx.c 27.3 KB