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[dragonfly.git] / sys / net / netmap.h

/*
 * Copyright (C) 2011-2013 Matteo Landi, Luigi Rizzo. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *   1. Redistributions of source code must retain the above copyright
 *      notice, this list of conditions and the following disclaimer.
 *   2. Redistributions in binary form must reproduce the above copyright
 *      notice, this list of conditions and the following disclaimer in the
 *      documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``S IS''AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

/*
 * $FreeBSD: head/sys/net/netmap.h 251139 2013-05-30 14:07:14Z luigi $
 *
 * Definitions of constants and the structures used by the netmap
 * framework, for the part visible to both kernel and userspace.
 * Detailed info on netmap is available with "man netmap" or at
 *
 *      http://info.iet.unipi.it/~luigi/netmap/
 *
 * This API is also used to communicate with the VALE software switch
 */

#ifndef _NET_NETMAP_H_
#define _NET_NETMAP_H_

/*
 * --- Netmap data structures ---
 *
 * The userspace data structures used by netmap are shown below.
 * They are allocated by the kernel and mmap()ed by userspace threads.
 * Pointers are implemented as memory offsets or indexes,
 * so that they can be easily dereferenced in kernel and userspace.

   KERNEL (opaque, obviously)

  ====================================================================
                                         |
   USERSPACE                             |      struct netmap_ring
                                         +---->+--------------+
                                             / | cur          |
   struct netmap_if (nifp, 1 per fd)        /  | avail        |
    +---------------+                      /   | buf_ofs      |
    | ni_tx_rings   |                     /    +==============+
    | ni_rx_rings   |                    /     | buf_idx, len | slot[0]
    |               |                   /      | flags, ptr   |
    |               |                  /       +--------------+
    +===============+                 /        | buf_idx, len | slot[1]
    | txring_ofs[0] | (rel.to nifp)--'         | flags, ptr   |
    | txring_ofs[1] |                          +--------------+
  (ni_tx_rings+1 entries)                     (num_slots entries)
    | txring_ofs[t] |                          | buf_idx, len | slot[n-1]
    +---------------+                          | flags, ptr   |
    | rxring_ofs[0] |                          +--------------+
    | rxring_ofs[1] |
  (ni_rx_rings+1 entries)
    | rxring_ofs[r] |
    +---------------+

 * For each "interface" (NIC, host stack, VALE switch port) attached to a
 * file descriptor, the mmap()ed region contains a (logically readonly)
 * struct netmap_if pointing to struct netmap_ring's.
 * There is one netmap_ring per physical NIC ring, plus one tx/rx ring
 * pair attached to the host stack (this pair is unused for VALE ports).
 *
 * All physical/host stack ports share the same memory region,
 * so that zero-copy can be implemented between them.
 * VALE switch ports instead have separate memory regions.
 *
 * The netmap_ring is the userspace-visible replica of the NIC ring.
 * Each slot has the index of a buffer (MTU-sized and residing in the
 * mmapped region), its length and some flags. An extra 64-bit pointer
 * is provided for user-supplied buffers in the tx path.
 *
 * In user space, the buffer address is computed as
 *      (char *)ring + buf_ofs + index*NETMAP_BUF_SIZE
 */

/*
 * struct netmap_slot is a buffer descriptor
 *
 * buf_idx      the index of the buffer associated to the slot.
 * len          the length of the payload
 * flags        control operation on the slot, as defined below
 *
 * NS_BUF_CHANGED       must be set whenever userspace wants
 *              to change buf_idx (it might be necessary to
 *              reprogram the NIC)
 *
 * NS_REPORT    must be set if we want the NIC to generate an interrupt
 *              when this slot is used. Leaving it to 0 improves
 *              performance.
 *
 * NS_FORWARD   if set on a receive ring, and the device is in
 *              transparent mode, buffers released with the flag set
 *              will be forwarded to the 'other' side (host stack
 *              or NIC, respectively) on the next select() or ioctl()
 *
 * NS_NO_LEARN  on a VALE switch, do not 'learn' the source port for
 *              this packet.
 *
 * NS_INDIRECT  (tx rings only) data is in a userspace buffer pointed
 *              by the ptr field in the slot.
 *
 * NS_MOREFRAG  Part of a multi-segment frame. The last (or only)
 *              segment must not have this flag.
 *              Only supported on VALE ports.
 *
 * NS_PORT_MASK the high 8 bits of the flag, if not zero, indicate the
 *              destination port for the VALE switch, overriding
 *              the lookup table.
 */

struct netmap_slot {
        uint32_t buf_idx;       /* buffer index */
        uint16_t len;           /* packet length */
        uint16_t flags;         /* buf changed, etc. */
#define NS_BUF_CHANGED  0x0001  /* buf_idx changed */
#define NS_REPORT       0x0002  /* ask the hardware to report results
                                 * e.g. by generating an interrupt
                                 */
#define NS_FORWARD      0x0004  /* pass packet to the other endpoint
                                 * (host stack or device)
                                 */
#define NS_NO_LEARN     0x0008
#define NS_INDIRECT     0x0010
#define NS_MOREFRAG     0x0020
#define NS_PORT_SHIFT   8
#define NS_PORT_MASK    (0xff << NS_PORT_SHIFT)
                                /*
                                 * in rx rings, the high 8 bits
                                 *  are the number of fragments.
                                 */
#define NS_RFRAGS(_slot)        ( ((_slot)->flags >> 8) & 0xff)
        uint64_t        ptr;    /* pointer for indirect buffers */
};

/*
 * struct netmap_ring
 *
 * Netmap representation of a TX or RX ring (also known as "queue").
 * This is a queue implemented as a fixed-size circular array.
 * At the software level, two fields are important: avail and cur.
 *
 * In TX rings:
 *
 *      avail   tells how many slots are available for transmission.
 *              It is updated by the kernel in each netmap system call.
 *              It MUST BE decremented by the user when it
 *              adds a new packet to send.
 *
 *      cur     indicates the slot to use for the next packet
 *              to send (i.e. the "tail" of the queue).
 *              It MUST BE incremented by the user before
 *              netmap system calls to reflect the number of newly
 *              sent packets.
 *              It is checked by the kernel on netmap system calls
 *              (normally unmodified by the kernel unless invalid).
 *
 * In RX rings:
 *
 *      avail   is the number of packets available (possibly 0).
 *              It is updated by the kernel in each netmap system call.
 *              It MUST BE decremented by the user when it
 *              consumes a packet.
 *
 *      cur     indicates the first slot that contains a packet not
 *              yet processed (the "head" of the queue).
 *              It MUST BE incremented by the user when it consumes
 *              a packet.
 *
 *      reserved        indicates the number of buffers before 'cur'
 *              that the user has not released yet. Normally 0,
 *              it MUST BE incremented by the user when it
 *              does not return the buffer immediately, and decremented
 *              when the buffer is finally freed.
 *
 *
 * DATA OWNERSHIP/LOCKING:
 *      The netmap_ring, all slots, and buffers in the range
 *      [reserved-cur , cur+avail[ are owned by the user program,
 *      and the kernel only touches them in the same thread context
 *      during a system call.
 *      Other buffers are reserved for use by the NIC's DMA engines.
 *
 * FLAGS
 *      NR_TIMESTAMP    updates the 'ts' field on each syscall. This is
 *                      a global timestamp for all packets.
 *      NR_RX_TSTMP     if set, the last 64 byte in each buffer will
 *                      contain a timestamp for the frame supplied by
 *                      the hardware (if supported)
 *      NR_FORWARD      if set, the NS_FORWARD flag in each slot of the
 *                      RX ring is checked, and if set the packet is
 *                      passed to the other side (host stack or device,
 *                      respectively). This permits bpf-like behaviour
 *                      or transparency for selected packets.
 */
struct netmap_ring {
        /*
         * buf_ofs is meant to be used through macros.
         * It contains the offset of the buffer region from this
         * descriptor.
         */
        const ssize_t   buf_ofs;
        const uint32_t  num_slots;      /* number of slots in the ring. */
        uint32_t        avail;          /* number of usable slots */
        uint32_t        cur;            /* 'current' r/w position */
        uint32_t        reserved;       /* not refilled before current */

        const uint16_t  nr_buf_size;
        uint16_t        flags;
#define NR_TIMESTAMP    0x0002          /* set timestamp on *sync() */
#define NR_FORWARD      0x0004          /* enable NS_FORWARD for ring */
#define NR_RX_TSTMP     0x0008          /* set rx timestamp in slots */

        struct timeval  ts;             /* time of last *sync() */

        /* the slots follow. This struct has variable size */
        struct netmap_slot slot[0];     /* array of slots. */
};


/*
 * Netmap representation of an interface and its queue(s).
 * This is initialized by the kernel when binding a file
 * descriptor to a port, and should be considered as readonly
 * by user programs. The kernel never uses it.
 *
 * There is one netmap_if for each file descriptor on which we want
 * to select/poll.
 * select/poll operates on one or all pairs depending on the value of
 * nmr_queueid passed on the ioctl.
 */
struct netmap_if {
        char            ni_name[IFNAMSIZ]; /* name of the interface. */
        const uint32_t  ni_version;     /* API version, currently unused */
        const uint32_t  ni_flags;       /* properties */
#define NI_PRIV_MEM     0x1             /* private memory region */

        const uint32_t  ni_rx_rings;    /* number of rx rings */
        const uint32_t  ni_tx_rings;    /* number of tx rings */
        /*
         * The following array contains the offset of each netmap ring
         * from this structure. The first ni_tx_rings+1 entries refer
         * to the tx rings, the next ni_rx_rings+1 refer to the rx rings
         * (the last entry in each block refers to the host stack rings).
         * The area is filled up by the kernel on NIOCREGIF,
         * and then only read by userspace code.
         */
        const ssize_t   ring_ofs[0];
};

#ifndef NIOCREGIF
/*
 * ioctl names and related fields
 *
 * NIOCGINFO takes a struct ifreq, the interface name is the input,
 *      the outputs are number of queues and number of descriptor
 *      for each queue (useful to set number of threads etc.).
 *      The info returned is only advisory and may change before
 *      the interface is bound to a file descriptor.
 *
 * NIOCREGIF takes an interface name within a struct ifreq,
 *      and activates netmap mode on the interface (if possible).
 *
 *   nr_name    is the name of the interface
 *
 *   nr_tx_slots, nr_tx_slots, nr_tx_rings, nr_rx_rings
 *      indicate the configuration of the port on return.
 *
 *      On input, non-zero values for nr_tx_rings, nr_tx_slots and the
 *      rx counterparts may be used to reconfigure the port according
 *      to the requested values, but this is not guaranteed.
 *      The actual values are returned on completion of the ioctl().
 *
 *   nr_ringid
 *      indicates how rings should be bound to the file descriptors.
 *      The default (0) means all physical rings of a NIC are bound.
 *      NETMAP_HW_RING plus a ring number lets you bind just
 *      a single ring pair.
 *      NETMAP_SW_RING binds only the host tx/rx rings
 *      NETMAP_NO_TX_POLL prevents select()/poll() from pushing
 *      out packets on the tx ring unless POLLOUT is specified.
 *
 *      NETMAP_PRIV_MEM is a return value used to indicate that
 *      this ring is in a private memory region hence buffer
 *      swapping cannot be used
 *
 *   nr_cmd     is used to configure NICs attached to a VALE switch,
 *      or to dump the configuration of a VALE switch.
 *
 *      nr_cmd = NETMAP_BDG_ATTACH and nr_name = vale*:ifname
 *      attaches the NIC to the switch, with nr_ringid specifying
 *      which rings to use
 *
 *      nr_cmd = NETMAP_BDG_DETACH and nr_name = vale*:ifname
 *      disconnects a previously attached NIC
 *
 *      nr_cmd = NETMAP_BDG_LIST is used to list the configuration
 *      of VALE switches, with additional arguments.
 *
 * NIOCTXSYNC, NIOCRXSYNC synchronize tx or rx queues,
 *      whose identity is set in NIOCREGIF through nr_ringid
 *
 * NETMAP_API is the API version.
 */

/*
 * struct nmreq overlays a struct ifreq
 */
struct nmreq {
        char            nr_name[IFNAMSIZ];
        uint32_t        nr_version;     /* API version */
#define NETMAP_API      5               /* current version */
        uint32_t        nr_offset;      /* nifp offset in the shared region */
        uint32_t        nr_memsize;     /* size of the shared region */
        uint32_t        nr_tx_slots;    /* slots in tx rings */
        uint32_t        nr_rx_slots;    /* slots in rx rings */
        uint16_t        nr_tx_rings;    /* number of tx rings */
        uint16_t        nr_rx_rings;    /* number of rx rings */
        uint16_t        nr_ringid;      /* ring(s) we care about */
#define NETMAP_PRIV_MEM 0x8000          /* rings use private memory */
#define NETMAP_HW_RING  0x4000          /* low bits indicate one hw ring */
#define NETMAP_SW_RING  0x2000          /* process the sw ring */
#define NETMAP_NO_TX_POLL       0x1000  /* no automatic txsync on poll */
#define NETMAP_RING_MASK 0xfff          /* the ring number */
        uint16_t        nr_cmd;
#define NETMAP_BDG_ATTACH       1       /* attach the NIC */
#define NETMAP_BDG_DETACH       2       /* detach the NIC */
#define NETMAP_BDG_LOOKUP_REG   3       /* register lookup function */
#define NETMAP_BDG_LIST         4       /* get bridge's info */
        uint16_t        nr_arg1;
#define NETMAP_BDG_HOST         1       /* attach the host stack on ATTACH */
        uint16_t        nr_arg2;
        uint32_t        spare2[3];
};

/*
 * FreeBSD uses the size value embedded in the _IOWR to determine
 * how much to copy in/out. So we need it to match the actual
 * data structure we pass. We put some spares in the structure
 * to ease compatibility with other versions
 */
#define NIOCGINFO       _IOWR('i', 145, struct nmreq) /* return IF info */
#define NIOCREGIF       _IOWR('i', 146, struct nmreq) /* interface register */
#define NIOCUNREGIF     _IO('i', 147) /* deprecated. Was interface unregister */
#define NIOCTXSYNC      _IO('i', 148) /* sync tx queues */
#define NIOCRXSYNC      _IO('i', 149) /* sync rx queues */
#endif /* !NIOCREGIF */

#endif /* _NET_NETMAP_H_ */