• Björn Töpel's avatar
    xsk: Introduce AF_XDP buffer allocation API · 2b43470a
    Björn Töpel authored
    In order to simplify AF_XDP zero-copy enablement for NIC driver
    developers, a new AF_XDP buffer allocation API is added. The
    implementation is based on a single core (single producer/consumer)
    buffer pool for the AF_XDP UMEM.
    
    A buffer is allocated using the xsk_buff_alloc() function, and
    returned using xsk_buff_free(). If a buffer is disassociated with the
    pool, e.g. when a buffer is passed to an AF_XDP socket, a buffer is
    said to be released. Currently, the release function is only used by
    the AF_XDP internals and not visible to the driver.
    
    Drivers using this API should register the XDP memory model with the
    new MEM_TYPE_XSK_BUFF_POOL type.
    
    The API is defined in net/xdp_sock_drv.h.
    
    The buffer type is struct xdp_buff, and follows the lifetime of
    regular xdp_buffs, i.e.  the lifetime of an xdp_buff is restricted to
    a NAPI context. In other words, the API is not replacing xdp_frames.
    
    In addition to introducing the API and implementations, the AF_XDP
    core is migrated to use the new APIs.
    
    rfc->v1: Fixed build errors/warnings for m68k and riscv. (kbuild test
             robot)
             Added headroom/chunk size getter. (Maxim/Björn)
    
    v1->v2: Swapped SoBs. (Maxim)
    
    v2->v3: Initialize struct xdp_buff member frame_sz. (Björn)
            Add API to query the DMA address of a frame. (Maxim)
            Do DMA sync for CPU till the end of the frame to handle
            possible growth (frame_sz). (Maxim)
    Signed-off-by: default avatarBjörn Töpel <bjorn.topel@intel.com>
    Signed-off-by: default avatarMaxim Mikityanskiy <maximmi@mellanox.com>
    Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
    Link: https://lore.kernel.org/bpf/20200520192103.355233-6-bjorn.topel@gmail.com
    2b43470a
xsk_buff_pool.c 10.3 KB