zfs: merge openzfs/zfs@ef83e07db (zfs-2.1-release) into stable/13

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

/*-
 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
 *
 * Copyright (C) 2011-2014 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.
 */

/*
 * $FreeBSD$
 *
 * 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_

#define NETMAP_API      14              /* current API version */

#define NETMAP_MIN_API  14              /* min and max versions accepted */
#define NETMAP_MAX_API  15
/*
 * Some fields should be cache-aligned to reduce contention.
 * The alignment is architecture and OS dependent, but rather than
 * digging into OS headers to find the exact value we use an estimate
 * that should cover most architectures.
 */
#define NM_CACHE_ALIGN  128

/*
 * --- 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
                                          +---->+---------------+
                                              / | head,cur,tail |
   struct netmap_if (nifp, 1 per fd)         /  | buf_ofs       |
    +----------------+                      /   | other fields  |
    | 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]  |                          +---------------+
     (tx+htx entries)                           (num_slots entries)
    | txring_ofs[t]  |                          | buf_idx, len  | slot[n-1]
    +----------------+                          | flags, ptr    |
    | rxring_ofs[0]  |                          +---------------+
    | rxring_ofs[1]  |
     (rx+hrx entries)
    | rxring_ofs[r]  |
    +----------------+

 * For each "interface" (NIC, host stack, PIPE, VALE switch port) bound 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 at least one tx/rx ring
 * pair attached to the host stack (these pairs are unused for non-NIC 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
 *
 * Added in NETMAP_API 11:
 *
 * + NIOCREGIF can request the allocation of extra spare buffers from
 *   the same memory pool. The desired number of buffers must be in
 *   nr_arg3. The ioctl may return fewer buffers, depending on memory
 *   availability. nr_arg3 will return the actual value, and, once
 *   mapped, nifp->ni_bufs_head will be the index of the first buffer.
 *
 *   The buffers are linked to each other using the first uint32_t
 *   as the index. On close, ni_bufs_head must point to the list of
 *   buffers to be released.
 *
 * + NIOCREGIF can attach to PIPE rings sharing the same memory
 *   space with a parent device. The ifname indicates the parent device,
 *   which must already exist. Flags in nr_flags indicate if we want to
 *   bind the master or slave side, the index (from nr_ringid)
 *   is just a cookie and does not need to be sequential.
 *
 * + NIOCREGIF can also attach to 'monitor' rings that replicate
 *   the content of specific rings, also from the same memory space.
 *
 *   Extra flags in nr_flags support the above functions.
 *   Application libraries may use the following naming scheme:
 *      netmap:foo                      all NIC rings pairs
 *      netmap:foo^                     only host rings pairs
 *      netmap:foo^k                    the k-th host rings pair
 *      netmap:foo+                     all NIC rings + host rings pairs
 *      netmap:foo-k                    the k-th NIC rings pair
 *      netmap:foo{k                    PIPE rings pair k, master side
 *      netmap:foo}k                    PIPE rings pair k, slave side
 *
 * Some notes about host rings:
 *
 * + The RX host rings are used to store those packets that the host network
 *   stack is trying to transmit through a NIC queue, but only if that queue
 *   is currently in netmap mode. Netmap will not intercept host stack mbufs
 *   designated to NIC queues that are not in netmap mode. As a consequence,
 *   registering a netmap port with netmap:foo^ is not enough to intercept
 *   mbufs in the RX host rings; the netmap port should be registered with
 *   netmap:foo*, or another registration should be done to open at least a
 *   NIC TX queue in netmap mode.
 *
 * + Netmap is not currently able to deal with intercepted trasmit mbufs which
 *   require offloadings like TSO, UFO, checksumming offloadings, etc. It is
 *   responsibility of the user to disable those offloadings (e.g. using
 *   ifconfig on FreeBSD or ethtool -K on Linux) for an interface that is being
 *   used in netmap mode. If the offloadings are not disabled, GSO and/or
 *   unchecksummed packets may be dropped immediately or end up in the host RX
 *   rings, and will be dropped as soon as the packet reaches another netmap
 *   adapter.
 */

/*
 * struct netmap_slot is a buffer descriptor
 */
struct netmap_slot {
        uint32_t buf_idx;       /* buffer index */
        uint16_t len;           /* length for this slot */
        uint16_t flags;         /* buf changed, etc. */
        uint64_t ptr;           /* pointer for indirect buffers */
};

/*
 * The following flags control how the slot is used
 */

#define NS_BUF_CHANGED  0x0001  /* buf_idx changed */
        /*
         * must be set whenever buf_idx is changed (as it might be
         * necessary to recompute the physical address and mapping)
         *
         * It is also set by the kernel whenever the buf_idx is
         * changed internally (e.g., by pipes). Applications may
         * use this information to know when they can reuse the
         * contents of previously prepared buffers.
         */

#define NS_REPORT       0x0002  /* ask the hardware to report results */
        /*
         * Request notification when slot is used by the hardware.
         * Normally transmit completions are handled lazily and
         * may be unreported. This flag lets us know when a slot
         * has been sent (e.g. to terminate the sender).
         */

#define NS_FORWARD      0x0004  /* pass packet 'forward' */
        /*
         * (Only for physical ports, rx rings with NR_FORWARD set).
         * Slot released to the kernel (i.e. before ring->head) with
         * this flag set are passed to the peer ring (host/NIC),
         * thus restoring the host-NIC connection for these slots.
         * This supports efficient traffic monitoring or firewalling.
         */

#define NS_NO_LEARN     0x0008  /* disable bridge learning */
        /*
         * On a VALE switch, do not 'learn' the source port for
         * this buffer.
         */

#define NS_INDIRECT     0x0010  /* userspace buffer */
        /*
         * (VALE tx rings only) data is in a userspace buffer,
         * whose address is in the 'ptr' field in the slot.
         */

#define NS_MOREFRAG     0x0020  /* packet has more fragments */
        /*
         * (VALE ports, ptnetmap ports and some NIC ports, e.g.
         * ixgbe and i40e on Linux)
         * Set on all but the last slot of a multi-segment packet.
         * The 'len' field refers to the individual fragment.
         */

#define NS_TXMON        0x0040
        /* (monitor ports only) the packet comes from the TX
         * ring of the monitored port
         */

#define NS_PORT_SHIFT   8
#define NS_PORT_MASK    (0xff << NS_PORT_SHIFT)
        /*
         * The high 8 bits of the flag, if not zero, indicate the
         * destination port for the VALE switch, overriding
         * the lookup table.
         */

#define NS_RFRAGS(_slot)        ( ((_slot)->flags >> 8) & 0xff)
        /*
         * (VALE rx rings only) the high 8 bits
         *  are the number of fragments.
         */

#define NETMAP_MAX_FRAGS        64      /* max number of fragments */

/*
 * 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 the important fields are: head, cur, tail.
 *
 * In TX rings:
 *
 *      head    first slot available for transmission.
 *      cur     wakeup point. select() and poll() will unblock
 *              when 'tail' moves past 'cur'
 *      tail    (readonly) first slot reserved to the kernel
 *
 *      [head .. tail-1] can be used for new packets to send;
 *      'head' and 'cur' must be incremented as slots are filled
 *          with new packets to be sent;
 *      'cur' can be moved further ahead if we need more space
 *      for new transmissions. XXX todo (2014-03-12)
 *
 * In RX rings:
 *
 *      head    first valid received packet
 *      cur     wakeup point. select() and poll() will unblock
 *              when 'tail' moves past 'cur'
 *      tail    (readonly) first slot reserved to the kernel
 *
 *      [head .. tail-1] contain received packets;
 *      'head' and 'cur' must be incremented as slots are consumed
 *              and can be returned to the kernel;
 *      'cur' can be moved further ahead if we want to wait for
 *              new packets without returning the previous ones.
 *
 * DATA OWNERSHIP/LOCKING:
 *      The netmap_ring, and all slots and buffers in the range
 *      [head .. tail-1] are owned by the user program;
 *      the kernel only accesses them during a netmap system call
 *      and in the user thread context.
 *
 *      Other slots and buffers are reserved for use by the kernel
 */
struct netmap_ring {
        /*
         * buf_ofs is meant to be used through macros.
         * It contains the offset of the buffer region from this
         * descriptor.
         */
        const int64_t   buf_ofs;
        const uint32_t  num_slots;      /* number of slots in the ring. */
        const uint32_t  nr_buf_size;
        const uint16_t  ringid;
        const uint16_t  dir;            /* 0: tx, 1: rx */

        uint32_t        head;           /* (u) first user slot */
        uint32_t        cur;            /* (u) wakeup point */
        uint32_t        tail;           /* (k) first kernel slot */

        uint32_t        flags;

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

        /* opaque room for a mutex or similar object */
#if !defined(_WIN32) || defined(__CYGWIN__)
        uint8_t __attribute__((__aligned__(NM_CACHE_ALIGN))) sem[128];
#else
        uint8_t __declspec(align(NM_CACHE_ALIGN)) sem[128];
#endif

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

/*
 * RING FLAGS
 */
#define NR_TIMESTAMP    0x0002          /* set timestamp on *sync() */
        /*
         * updates the 'ts' field on each netmap syscall. This saves
         * saves a separate gettimeofday(), and is not much worse than
         * software timestamps generated in the interrupt handler.
         */

#define NR_FORWARD      0x0004          /* enable NS_FORWARD for ring */
        /*
         * Enables the NS_FORWARD slot flag for the ring.
         */

/*
 * Helper functions for kernel and userspace
 */

/*
 * Check if space is available in the ring. We use ring->head, which
 * points to the next netmap slot to be published to netmap. It is
 * possible that the applications moves ring->cur ahead of ring->tail
 * (e.g., by setting ring->cur <== ring->tail), if it wants more slots
 * than the ones currently available, and it wants to be notified when
 * more arrive. See netmap(4) for more details and examples.
 */
static inline int
nm_ring_empty(struct netmap_ring *ring)
{
        return (ring->head == ring->tail);
}

/*
 * 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 */

        /*
         * The number of packet rings available in netmap mode.
         * Physical NICs can have different numbers of tx and rx rings.
         * Physical NICs also have at least a 'host' rings pair.
         * Additionally, clients can request additional ring pairs to
         * be used for internal communication.
         */
        const uint32_t  ni_tx_rings;    /* number of HW tx rings */
        const uint32_t  ni_rx_rings;    /* number of HW rx rings */

        uint32_t        ni_bufs_head;   /* head index for extra bufs */
        const uint32_t  ni_host_tx_rings; /* number of SW tx rings */
        const uint32_t  ni_host_rx_rings; /* number of SW rx rings */
        uint32_t        ni_spare1[3];
        /*
         * The following array contains the offset of each netmap ring
         * from this structure, in the following order:
         *     - NIC tx rings (ni_tx_rings);
         *     - host tx rings (ni_host_tx_rings);
         *     - NIC rx rings (ni_rx_rings);
         *     - host rx ring (ni_host_rx_rings);
         *
         * The area is filled up by the kernel on NETMAP_REQ_REGISTER,
         * and then only read by userspace code.
         */
        const ssize_t   ring_ofs[0];
};

/* Legacy interface to interact with a netmap control device.
 * Included for backward compatibility. The user should not include this
 * file directly. */
#include "netmap_legacy.h"

/*
 * New API to control netmap control devices. New applications should only use
 * nmreq_xyz structs with the NIOCCTRL ioctl() command.
 *
 * NIOCCTRL takes a nmreq_header struct, which contains the required
 * API version, the name of a netmap port, a command type, and pointers
 * to request body and options.
 *
 *      nr_name (in)
 *              The name of the port (em0, valeXXX:YYY, eth0{pn1 etc.)
 *
 *      nr_version (in/out)
 *              Must match NETMAP_API as used in the kernel, error otherwise.
 *              Always returns the desired value on output.
 *
 *      nr_reqtype (in)
 *              One of the NETMAP_REQ_* command types below
 *
 *      nr_body (in)
 *              Pointer to a command-specific struct, described by one
 *              of the struct nmreq_xyz below.
 *
 *      nr_options (in)
 *              Command specific options, if any.
 *
 * A NETMAP_REQ_REGISTER command activates netmap mode on the netmap
 * port (e.g. physical interface) specified by nmreq_header.nr_name.
 * The request body (struct nmreq_register) has several arguments to
 * specify how the port is to be registered.
 *
 *      nr_tx_slots, nr_tx_slots, nr_tx_rings, nr_rx_rings,
 *      nr_host_tx_rings, nr_host_rx_rings (in/out)
 *              On input, non-zero values may be used to reconfigure the port
 *              according to the requested values, but this is not guaranteed.
 *              On output the actual values in use are reported.
 *
 *      nr_mode (in)
 *              Indicate what set of rings must be bound to the netmap
 *              device (e.g. all NIC rings, host rings only, NIC and
 *              host rings, ...). Values are in NR_REG_*.
 *
 *      nr_ringid (in)
 *              If nr_mode == NR_REG_ONE_NIC (only a single couple of TX/RX
 *              rings), indicate which NIC TX and/or RX ring is to be bound
 *              (0..nr_*x_rings-1).
 *
 *      nr_flags (in)
 *              Indicate special options for how to open the port.
 *
 *              NR_NO_TX_POLL can be OR-ed to make select()/poll() push
 *                      packets on tx rings only if POLLOUT is set.
 *                      The default is to push any pending packet.
 *
 *              NR_DO_RX_POLL can be OR-ed to make select()/poll() release
 *                      packets on rx rings also when POLLIN is NOT set.
 *                      The default is to touch the rx ring only with POLLIN.
 *                      Note that this is the opposite of TX because it
 *                      reflects the common usage.
 *
 *              Other options are NR_MONITOR_TX, NR_MONITOR_RX, NR_ZCOPY_MON,
 *              NR_EXCLUSIVE, NR_RX_RINGS_ONLY, NR_TX_RINGS_ONLY and
 *              NR_ACCEPT_VNET_HDR.
 *
 *      nr_mem_id (in/out)
 *              The identity of the memory region used.
 *              On input, 0 means the system decides autonomously,
 *              other values may try to select a specific region.
 *              On return the actual value is reported.
 *              Region '1' is the global allocator, normally shared
 *              by all interfaces. Other values are private regions.
 *              If two ports the same region zero-copy is possible.
 *
 *      nr_extra_bufs (in/out)
 *              Number of extra buffers to be allocated.
 *
 * The other NETMAP_REQ_* commands are described below.
 *
 */

/* maximum size of a request, including all options */
#define NETMAP_REQ_MAXSIZE      4096

/* Header common to all request options. */
struct nmreq_option {
        /* Pointer ot the next option. */
        uint64_t                nro_next;
        /* Option type. */
        uint32_t                nro_reqtype;
        /* (out) status of the option:
         * 0: recognized and processed
         * !=0: errno value
         */
        uint32_t                nro_status;
        /* Option size, used only for options that can have variable size
         * (e.g. because they contain arrays). For fixed-size options this
         * field should be set to zero. */
        uint64_t                nro_size;
};

/* Header common to all requests. Do not reorder these fields, as we need
 * the second one (nr_reqtype) to know how much to copy from/to userspace. */
struct nmreq_header {
        uint16_t                nr_version;     /* API version */
        uint16_t                nr_reqtype;     /* nmreq type (NETMAP_REQ_*) */
        uint32_t                nr_reserved;    /* must be zero */
#define NETMAP_REQ_IFNAMSIZ     64
        char                    nr_name[NETMAP_REQ_IFNAMSIZ]; /* port name */
        uint64_t                nr_options;     /* command-specific options */
        uint64_t                nr_body;        /* ptr to nmreq_xyz struct */
};

enum {
        /* Register a netmap port with the device. */
        NETMAP_REQ_REGISTER = 1,
        /* Get information from a netmap port. */
        NETMAP_REQ_PORT_INFO_GET,
        /* Attach a netmap port to a VALE switch. */
        NETMAP_REQ_VALE_ATTACH,
        /* Detach a netmap port from a VALE switch. */
        NETMAP_REQ_VALE_DETACH,
        /* List the ports attached to a VALE switch. */
        NETMAP_REQ_VALE_LIST,
        /* Set the port header length (was virtio-net header length). */
        NETMAP_REQ_PORT_HDR_SET,
        /* Get the port header length (was virtio-net header length). */
        NETMAP_REQ_PORT_HDR_GET,
        /* Create a new persistent VALE port. */
        NETMAP_REQ_VALE_NEWIF,
        /* Delete a persistent VALE port. */
        NETMAP_REQ_VALE_DELIF,
        /* Enable polling kernel thread(s) on an attached VALE port. */
        NETMAP_REQ_VALE_POLLING_ENABLE,
        /* Disable polling kernel thread(s) on an attached VALE port. */
        NETMAP_REQ_VALE_POLLING_DISABLE,
        /* Get info about the pools of a memory allocator. */
        NETMAP_REQ_POOLS_INFO_GET,
        /* Start an in-kernel loop that syncs the rings periodically or
         * on notifications. The loop runs in the context of the ioctl
         * syscall, and only stops on NETMAP_REQ_SYNC_KLOOP_STOP. */
        NETMAP_REQ_SYNC_KLOOP_START,
        /* Stops the thread executing the in-kernel loop. The thread
         * returns from the ioctl syscall. */
        NETMAP_REQ_SYNC_KLOOP_STOP,
        /* Enable CSB mode on a registered netmap control device. */
        NETMAP_REQ_CSB_ENABLE,
};

enum {
        /* On NETMAP_REQ_REGISTER, ask netmap to use memory allocated
         * from user-space allocated memory pools (e.g. hugepages).
         */
        NETMAP_REQ_OPT_EXTMEM = 1,

        /* ON NETMAP_REQ_SYNC_KLOOP_START, ask netmap to use eventfd-based
         * notifications to synchronize the kernel loop with the application.
         */
        NETMAP_REQ_OPT_SYNC_KLOOP_EVENTFDS,

        /* On NETMAP_REQ_REGISTER, ask netmap to work in CSB mode, where
         * head, cur and tail pointers are not exchanged through the
         * struct netmap_ring header, but rather using an user-provided
         * memory area (see struct nm_csb_atok and struct nm_csb_ktoa).
         */
        NETMAP_REQ_OPT_CSB,

        /* An extension to NETMAP_REQ_OPT_SYNC_KLOOP_EVENTFDS, which specifies
         * if the TX and/or RX rings are synced in the context of the VM exit.
         * This requires the 'ioeventfd' fields to be valid (cannot be < 0).
         */
        NETMAP_REQ_OPT_SYNC_KLOOP_MODE,

        /* This is a marker to count the number of available options.
         * New options must be added above it. */
        NETMAP_REQ_OPT_MAX,
};

/*
 * nr_reqtype: NETMAP_REQ_REGISTER
 * Bind (register) a netmap port to this control device.
 */
struct nmreq_register {
        uint64_t        nr_offset;      /* nifp offset in the shared region */
        uint64_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_host_tx_rings; /* number of host tx rings */
        uint16_t        nr_host_rx_rings; /* number of host rx rings */

        uint16_t        nr_mem_id;      /* id of the memory allocator */
        uint16_t        nr_ringid;      /* ring(s) we care about */
        uint32_t        nr_mode;        /* specify NR_REG_* modes */
        uint32_t        nr_extra_bufs;  /* number of requested extra buffers */

        uint64_t        nr_flags;       /* additional flags (see below) */
/* monitors use nr_ringid and nr_mode to select the rings to monitor */
#define NR_MONITOR_TX   0x100
#define NR_MONITOR_RX   0x200
#define NR_ZCOPY_MON    0x400
/* request exclusive access to the selected rings */
#define NR_EXCLUSIVE    0x800
/* 0x1000 unused */
#define NR_RX_RINGS_ONLY        0x2000
#define NR_TX_RINGS_ONLY        0x4000
/* Applications set this flag if they are able to deal with virtio-net headers,
 * that is send/receive frames that start with a virtio-net header.
 * If not set, NETMAP_REQ_REGISTER will fail with netmap ports that require
 * applications to use those headers. If the flag is set, the application can
 * use the NETMAP_VNET_HDR_GET command to figure out the header length. */
#define NR_ACCEPT_VNET_HDR      0x8000
/* The following two have the same meaning of NETMAP_NO_TX_POLL and
 * NETMAP_DO_RX_POLL. */
#define NR_DO_RX_POLL           0x10000
#define NR_NO_TX_POLL           0x20000
};

/* Valid values for nmreq_register.nr_mode (see above). */
enum {  NR_REG_DEFAULT  = 0,    /* backward compat, should not be used. */
        NR_REG_ALL_NIC  = 1,
        NR_REG_SW       = 2,
        NR_REG_NIC_SW   = 3,
        NR_REG_ONE_NIC  = 4,
        NR_REG_PIPE_MASTER = 5, /* deprecated, use "x{y" port name syntax */
        NR_REG_PIPE_SLAVE = 6,  /* deprecated, use "x}y" port name syntax */
        NR_REG_NULL     = 7,
        NR_REG_ONE_SW   = 8,
};

/* A single ioctl number is shared by all the new API command.
 * Demultiplexing is done using the hdr.nr_reqtype field.
 * FreeBSD uses the size value embedded in the _IOWR to determine
 * how much to copy in/out, so we define the ioctl() command
 * specifying only nmreq_header, and copyin/copyout the rest. */
#define NIOCCTRL        _IOWR('i', 151, struct nmreq_header)

/* The ioctl commands to sync TX/RX netmap rings.
 * NIOCTXSYNC, NIOCRXSYNC synchronize tx or rx queues,
 *      whose identity is set in NETMAP_REQ_REGISTER through nr_ringid.
 *      These are non blocking and take no argument. */
#define NIOCTXSYNC      _IO('i', 148) /* sync tx queues */
#define NIOCRXSYNC      _IO('i', 149) /* sync rx queues */

/*
 * nr_reqtype: NETMAP_REQ_PORT_INFO_GET
 * Get information about a netmap port, including number of rings.
 * slots per ring, id of the memory allocator, etc. The netmap
 * control device used for this operation does not need to be bound
 * to a netmap port.
 */
struct nmreq_port_info_get {
        uint64_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_host_tx_rings; /* number of host tx rings */
        uint16_t        nr_host_rx_rings; /* number of host rx rings */
        uint16_t        nr_mem_id;      /* memory allocator id (in/out) */
        uint16_t        pad[3];
};

#define NM_BDG_NAME             "vale"  /* prefix for bridge port name */

/*
 * nr_reqtype: NETMAP_REQ_VALE_ATTACH
 * Attach a netmap port to a VALE switch. Both the name of the netmap
 * port and the VALE switch are specified through the nr_name argument.
 * The attach operation could need to register a port, so at least
 * the same arguments are available.
 * port_index will contain the index where the port has been attached.
 */
struct nmreq_vale_attach {
        struct nmreq_register reg;
        uint32_t port_index;
        uint32_t pad1;
};

/*
 * nr_reqtype: NETMAP_REQ_VALE_DETACH
 * Detach a netmap port from a VALE switch. Both the name of the netmap
 * port and the VALE switch are specified through the nr_name argument.
 * port_index will contain the index where the port was attached.
 */
struct nmreq_vale_detach {
        uint32_t port_index;
        uint32_t pad1;
};

/*
 * nr_reqtype: NETMAP_REQ_VALE_LIST
 * List the ports of a VALE switch.
 */
struct nmreq_vale_list {
        /* Name of the VALE port (valeXXX:YYY) or empty. */
        uint16_t        nr_bridge_idx;
        uint16_t        pad1;
        uint32_t        nr_port_idx;
};

/*
 * nr_reqtype: NETMAP_REQ_PORT_HDR_SET or NETMAP_REQ_PORT_HDR_GET
 * Set or get the port header length of the port identified by hdr.nr_name.
 * The control device does not need to be bound to a netmap port.
 */
struct nmreq_port_hdr {
        uint32_t        nr_hdr_len;
        uint32_t        pad1;
};

/*
 * nr_reqtype: NETMAP_REQ_VALE_NEWIF
 * Create a new persistent VALE port.
 */
struct nmreq_vale_newif {
        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_mem_id;      /* id of the memory allocator */
        uint16_t        pad1;
};

/*
 * nr_reqtype: NETMAP_REQ_VALE_POLLING_ENABLE or NETMAP_REQ_VALE_POLLING_DISABLE
 * Enable or disable polling kthreads on a VALE port.
 */
struct nmreq_vale_polling {
        uint32_t        nr_mode;
#define NETMAP_POLLING_MODE_SINGLE_CPU 1
#define NETMAP_POLLING_MODE_MULTI_CPU 2
        uint32_t        nr_first_cpu_id;
        uint32_t        nr_num_polling_cpus;
        uint32_t        pad1;
};

/*
 * nr_reqtype: NETMAP_REQ_POOLS_INFO_GET
 * Get info about the pools of the memory allocator of the netmap
 * port specified by hdr.nr_name and nr_mem_id. The netmap control
 * device used for this operation does not need to be bound to a netmap
 * port.
 */
struct nmreq_pools_info {
        uint64_t        nr_memsize;
        uint16_t        nr_mem_id; /* in/out argument */
        uint16_t        pad1[3];
        uint64_t        nr_if_pool_offset;
        uint32_t        nr_if_pool_objtotal;
        uint32_t        nr_if_pool_objsize;
        uint64_t        nr_ring_pool_offset;
        uint32_t        nr_ring_pool_objtotal;
        uint32_t        nr_ring_pool_objsize;
        uint64_t        nr_buf_pool_offset;
        uint32_t        nr_buf_pool_objtotal;
        uint32_t        nr_buf_pool_objsize;
};

/*
 * nr_reqtype: NETMAP_REQ_SYNC_KLOOP_START
 * Start an in-kernel loop that syncs the rings periodically or on
 * notifications. The loop runs in the context of the ioctl syscall,
 * and only stops on NETMAP_REQ_SYNC_KLOOP_STOP.
 * The registered netmap port must be open in CSB mode.
 */
struct nmreq_sync_kloop_start {
        /* Sleeping is the default synchronization method for the kloop.
         * The 'sleep_us' field specifies how many microsconds to sleep for
         * when there is no work to do, before doing another kloop iteration.
         */
        uint32_t        sleep_us;
        uint32_t        pad1;
};

/* A CSB entry for the application --> kernel direction. */
struct nm_csb_atok {
        uint32_t head;            /* AW+ KR+ the head of the appl netmap_ring */
        uint32_t cur;             /* AW+ KR+ the cur of the appl netmap_ring */
        uint32_t appl_need_kick;  /* AW+ KR+ kern --> appl notification enable */
        uint32_t sync_flags;      /* AW+ KR+ the flags of the appl [tx|rx]sync() */
        uint32_t pad[12];         /* pad to a 64 bytes cacheline */
};

/* A CSB entry for the application <-- kernel direction. */
struct nm_csb_ktoa {
        uint32_t hwcur;           /* AR+ KW+ the hwcur of the kern netmap_kring */
        uint32_t hwtail;          /* AR+ KW+ the hwtail of the kern netmap_kring */
        uint32_t kern_need_kick;  /* AR+ KW+ appl-->kern notification enable */
        uint32_t pad[13];
};

#ifdef __linux__

#ifdef __KERNEL__
#define nm_stst_barrier smp_wmb
#define nm_ldld_barrier smp_rmb
#define nm_stld_barrier smp_mb
#else  /* !__KERNEL__ */
static inline void nm_stst_barrier(void)
{
        /* A memory barrier with release semantic has the combined
         * effect of a store-store barrier and a load-store barrier,
         * which is fine for us. */
        __atomic_thread_fence(__ATOMIC_RELEASE);
}
static inline void nm_ldld_barrier(void)
{
        /* A memory barrier with acquire semantic has the combined
         * effect of a load-load barrier and a store-load barrier,
         * which is fine for us. */
        __atomic_thread_fence(__ATOMIC_ACQUIRE);
}
#endif /* !__KERNEL__ */

#elif defined(__FreeBSD__)

#ifdef _KERNEL
#define nm_stst_barrier atomic_thread_fence_rel
#define nm_ldld_barrier atomic_thread_fence_acq
#define nm_stld_barrier atomic_thread_fence_seq_cst
#else  /* !_KERNEL */
#include <stdatomic.h>
static inline void nm_stst_barrier(void)
{
        atomic_thread_fence(memory_order_release);
}
static inline void nm_ldld_barrier(void)
{
        atomic_thread_fence(memory_order_acquire);
}
#endif /* !_KERNEL */

#else  /* !__linux__ && !__FreeBSD__ */
#error "OS not supported"
#endif /* !__linux__ && !__FreeBSD__ */

/* Application side of sync-kloop: Write ring pointers (cur, head) to the CSB.
 * This routine is coupled with sync_kloop_kernel_read(). */
static inline void
nm_sync_kloop_appl_write(struct nm_csb_atok *atok, uint32_t cur,
                         uint32_t head)
{
        /* Issue a first store-store barrier to make sure writes to the
         * netmap ring do not overcome updates on atok->cur and atok->head. */
        nm_stst_barrier();

        /*
         * We need to write cur and head to the CSB but we cannot do it atomically.
         * There is no way we can prevent the host from reading the updated value
         * of one of the two and the old value of the other. However, if we make
         * sure that the host never reads a value of head more recent than the
         * value of cur we are safe. We can allow the host to read a value of cur
         * more recent than the value of head, since in the netmap ring cur can be
         * ahead of head and cur cannot wrap around head because it must be behind
         * tail. Inverting the order of writes below could instead result into the
         * host to think head went ahead of cur, which would cause the sync
         * prologue to fail.
         *
         * The following memory barrier scheme is used to make this happen:
         *
         *          Guest                Host
         *
         *          STORE(cur)           LOAD(head)
         *          wmb() <----------->  rmb()
         *          STORE(head)          LOAD(cur)
         *
         */
        atok->cur = cur;
        nm_stst_barrier();
        atok->head = head;
}

/* Application side of sync-kloop: Read kring pointers (hwcur, hwtail) from
 * the CSB. This routine is coupled with sync_kloop_kernel_write(). */
static inline void
nm_sync_kloop_appl_read(struct nm_csb_ktoa *ktoa, uint32_t *hwtail,
                        uint32_t *hwcur)
{
        /*
         * We place a memory barrier to make sure that the update of hwtail never
         * overtakes the update of hwcur.
         * (see explanation in sync_kloop_kernel_write).
         */
        *hwtail = ktoa->hwtail;
        nm_ldld_barrier();
        *hwcur = ktoa->hwcur;

        /* Make sure that loads from ktoa->hwtail and ktoa->hwcur are not delayed
         * after the loads from the netmap ring. */
        nm_ldld_barrier();
}

/*
 * data for NETMAP_REQ_OPT_* options
 */

struct nmreq_opt_sync_kloop_eventfds {
        struct nmreq_option     nro_opt;        /* common header */
        /* An array of N entries for bidirectional notifications between
         * the kernel loop and the application. The number of entries and
         * their order must agree with the CSB arrays passed in the
         * NETMAP_REQ_OPT_CSB option. Each entry contains a file descriptor
         * backed by an eventfd.
         *
         * If any of the 'ioeventfd' entries is < 0, the event loop uses
         * the sleeping synchronization strategy (according to sleep_us),
         * and keeps kern_need_kick always disabled.
         * Each 'irqfd' can be < 0, and in that case the corresponding queue
         * is never notified.
         */
        struct {
                /* Notifier for the application --> kernel loop direction. */
                int32_t ioeventfd;
                /* Notifier for the kernel loop --> application direction. */
                int32_t irqfd;
        } eventfds[0];
};

struct nmreq_opt_sync_kloop_mode {
        struct nmreq_option     nro_opt;        /* common header */
#define NM_OPT_SYNC_KLOOP_DIRECT_TX (1 << 0)
#define NM_OPT_SYNC_KLOOP_DIRECT_RX (1 << 1)
        uint32_t mode;
};

struct nmreq_opt_extmem {
        struct nmreq_option     nro_opt;        /* common header */
        uint64_t                nro_usrptr;     /* (in) ptr to usr memory */
        struct nmreq_pools_info nro_info;       /* (in/out) */
};

struct nmreq_opt_csb {
        struct nmreq_option     nro_opt;

        /* Array of CSB entries for application --> kernel communication
         * (N entries). */
        uint64_t                csb_atok;

        /* Array of CSB entries for kernel --> application communication
         * (N entries). */
        uint64_t                csb_ktoa;
};

#endif /* _NET_NETMAP_H_ */