The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/net/netmap.h

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    1 /*-
    2  * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
    3  *
    4  * Copyright (C) 2011-2014 Matteo Landi, Luigi Rizzo. All rights reserved.
    5  *
    6  * Redistribution and use in source and binary forms, with or without
    7  * modification, are permitted provided that the following conditions
    8  * are met:
    9  *
   10  *   1. Redistributions of source code must retain the above copyright
   11  *      notice, this list of conditions and the following disclaimer.
   12  *   2. Redistributions in binary form must reproduce the above copyright
   13  *      notice, this list of conditions and the following disclaimer in the
   14  *      documentation and/or other materials provided with the distribution.
   15  *
   16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``S IS''AND
   17  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   19  * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   20  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   21  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   22  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   23  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   24  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   25  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   26  * SUCH DAMAGE.
   27  */
   28 
   29 /*
   30  * $FreeBSD$
   31  *
   32  * Definitions of constants and the structures used by the netmap
   33  * framework, for the part visible to both kernel and userspace.
   34  * Detailed info on netmap is available with "man netmap" or at
   35  *
   36  *      http://info.iet.unipi.it/~luigi/netmap/
   37  *
   38  * This API is also used to communicate with the VALE software switch
   39  */
   40 
   41 #ifndef _NET_NETMAP_H_
   42 #define _NET_NETMAP_H_
   43 
   44 #define NETMAP_API      14              /* current API version */
   45 
   46 #define NETMAP_MIN_API  14              /* min and max versions accepted */
   47 #define NETMAP_MAX_API  15
   48 /*
   49  * Some fields should be cache-aligned to reduce contention.
   50  * The alignment is architecture and OS dependent, but rather than
   51  * digging into OS headers to find the exact value we use an estimate
   52  * that should cover most architectures.
   53  */
   54 #define NM_CACHE_ALIGN  128
   55 
   56 /*
   57  * --- Netmap data structures ---
   58  *
   59  * The userspace data structures used by netmap are shown below.
   60  * They are allocated by the kernel and mmap()ed by userspace threads.
   61  * Pointers are implemented as memory offsets or indexes,
   62  * so that they can be easily dereferenced in kernel and userspace.
   63 
   64    KERNEL (opaque, obviously)
   65 
   66   ====================================================================
   67                                           |
   68    USERSPACE                              |      struct netmap_ring
   69                                           +---->+---------------+
   70                                               / | head,cur,tail |
   71    struct netmap_if (nifp, 1 per fd)         /  | buf_ofs       |
   72     +----------------+                      /   | other fields  |
   73     | ni_tx_rings    |                     /    +===============+
   74     | ni_rx_rings    |                    /     | buf_idx, len  | slot[0]
   75     |                |                   /      | flags, ptr    |
   76     |                |                  /       +---------------+
   77     +================+                 /        | buf_idx, len  | slot[1]
   78     | txring_ofs[0]  | (rel.to nifp)--'         | flags, ptr    |
   79     | txring_ofs[1]  |                          +---------------+
   80      (tx+htx entries)                           (num_slots entries)
   81     | txring_ofs[t]  |                          | buf_idx, len  | slot[n-1]
   82     +----------------+                          | flags, ptr    |
   83     | rxring_ofs[0]  |                          +---------------+
   84     | rxring_ofs[1]  |
   85      (rx+hrx entries)
   86     | rxring_ofs[r]  |
   87     +----------------+
   88 
   89  * For each "interface" (NIC, host stack, PIPE, VALE switch port) bound to
   90  * a file descriptor, the mmap()ed region contains a (logically readonly)
   91  * struct netmap_if pointing to struct netmap_ring's.
   92  *
   93  * There is one netmap_ring per physical NIC ring, plus at least one tx/rx ring
   94  * pair attached to the host stack (these pairs are unused for non-NIC ports).
   95  *
   96  * All physical/host stack ports share the same memory region,
   97  * so that zero-copy can be implemented between them.
   98  * VALE switch ports instead have separate memory regions.
   99  *
  100  * The netmap_ring is the userspace-visible replica of the NIC ring.
  101  * Each slot has the index of a buffer (MTU-sized and residing in the
  102  * mmapped region), its length and some flags. An extra 64-bit pointer
  103  * is provided for user-supplied buffers in the tx path.
  104  *
  105  * In user space, the buffer address is computed as
  106  *      (char *)ring + buf_ofs + index * NETMAP_BUF_SIZE
  107  *
  108  * Added in NETMAP_API 11:
  109  *
  110  * + NIOCREGIF can request the allocation of extra spare buffers from
  111  *   the same memory pool. The desired number of buffers must be in
  112  *   nr_arg3. The ioctl may return fewer buffers, depending on memory
  113  *   availability. nr_arg3 will return the actual value, and, once
  114  *   mapped, nifp->ni_bufs_head will be the index of the first buffer.
  115  *
  116  *   The buffers are linked to each other using the first uint32_t
  117  *   as the index. On close, ni_bufs_head must point to the list of
  118  *   buffers to be released.
  119  *
  120  * + NIOCREGIF can attach to PIPE rings sharing the same memory
  121  *   space with a parent device. The ifname indicates the parent device,
  122  *   which must already exist. Flags in nr_flags indicate if we want to
  123  *   bind the master or slave side, the index (from nr_ringid)
  124  *   is just a cookie and does not need to be sequential.
  125  *
  126  * + NIOCREGIF can also attach to 'monitor' rings that replicate
  127  *   the content of specific rings, also from the same memory space.
  128  *
  129  *   Extra flags in nr_flags support the above functions.
  130  *   Application libraries may use the following naming scheme:
  131  *      netmap:foo                      all NIC rings pairs
  132  *      netmap:foo^                     only host rings pairs
  133  *      netmap:foo^k                    the k-th host rings pair
  134  *      netmap:foo+                     all NIC rings + host rings pairs
  135  *      netmap:foo-k                    the k-th NIC rings pair
  136  *      netmap:foo{k                    PIPE rings pair k, master side
  137  *      netmap:foo}k                    PIPE rings pair k, slave side
  138  *
  139  * Some notes about host rings:
  140  *
  141  * + The RX host rings are used to store those packets that the host network
  142  *   stack is trying to transmit through a NIC queue, but only if that queue
  143  *   is currently in netmap mode. Netmap will not intercept host stack mbufs
  144  *   designated to NIC queues that are not in netmap mode. As a consequence,
  145  *   registering a netmap port with netmap:foo^ is not enough to intercept
  146  *   mbufs in the RX host rings; the netmap port should be registered with
  147  *   netmap:foo*, or another registration should be done to open at least a
  148  *   NIC TX queue in netmap mode.
  149  *
  150  * + Netmap is not currently able to deal with intercepted trasmit mbufs which
  151  *   require offloadings like TSO, UFO, checksumming offloadings, etc. It is
  152  *   responsibility of the user to disable those offloadings (e.g. using
  153  *   ifconfig on FreeBSD or ethtool -K on Linux) for an interface that is being
  154  *   used in netmap mode. If the offloadings are not disabled, GSO and/or
  155  *   unchecksummed packets may be dropped immediately or end up in the host RX
  156  *   rings, and will be dropped as soon as the packet reaches another netmap
  157  *   adapter.
  158  */
  159 
  160 /*
  161  * struct netmap_slot is a buffer descriptor
  162  */
  163 struct netmap_slot {
  164         uint32_t buf_idx;       /* buffer index */
  165         uint16_t len;           /* length for this slot */
  166         uint16_t flags;         /* buf changed, etc. */
  167         uint64_t ptr;           /* pointer for indirect buffers */
  168 };
  169 
  170 /*
  171  * The following flags control how the slot is used
  172  */
  173 
  174 #define NS_BUF_CHANGED  0x0001  /* buf_idx changed */
  175         /*
  176          * must be set whenever buf_idx is changed (as it might be
  177          * necessary to recompute the physical address and mapping)
  178          *
  179          * It is also set by the kernel whenever the buf_idx is
  180          * changed internally (e.g., by pipes). Applications may
  181          * use this information to know when they can reuse the
  182          * contents of previously prepared buffers.
  183          */
  184 
  185 #define NS_REPORT       0x0002  /* ask the hardware to report results */
  186         /*
  187          * Request notification when slot is used by the hardware.
  188          * Normally transmit completions are handled lazily and
  189          * may be unreported. This flag lets us know when a slot
  190          * has been sent (e.g. to terminate the sender).
  191          */
  192 
  193 #define NS_FORWARD      0x0004  /* pass packet 'forward' */
  194         /*
  195          * (Only for physical ports, rx rings with NR_FORWARD set).
  196          * Slot released to the kernel (i.e. before ring->head) with
  197          * this flag set are passed to the peer ring (host/NIC),
  198          * thus restoring the host-NIC connection for these slots.
  199          * This supports efficient traffic monitoring or firewalling.
  200          */
  201 
  202 #define NS_NO_LEARN     0x0008  /* disable bridge learning */
  203         /*
  204          * On a VALE switch, do not 'learn' the source port for
  205          * this buffer.
  206          */
  207 
  208 #define NS_INDIRECT     0x0010  /* userspace buffer */
  209         /*
  210          * (VALE tx rings only) data is in a userspace buffer,
  211          * whose address is in the 'ptr' field in the slot.
  212          */
  213 
  214 #define NS_MOREFRAG     0x0020  /* packet has more fragments */
  215         /*
  216          * (VALE ports, ptnetmap ports and some NIC ports, e.g.
  217          * ixgbe and i40e on Linux)
  218          * Set on all but the last slot of a multi-segment packet.
  219          * The 'len' field refers to the individual fragment.
  220          */
  221 
  222 #define NS_TXMON        0x0040
  223         /* (monitor ports only) the packet comes from the TX
  224          * ring of the monitored port
  225          */
  226 
  227 #define NS_PORT_SHIFT   8
  228 #define NS_PORT_MASK    (0xff << NS_PORT_SHIFT)
  229         /*
  230          * The high 8 bits of the flag, if not zero, indicate the
  231          * destination port for the VALE switch, overriding
  232          * the lookup table.
  233          */
  234 
  235 #define NS_RFRAGS(_slot)        ( ((_slot)->flags >> 8) & 0xff)
  236         /*
  237          * (VALE rx rings only) the high 8 bits
  238          *  are the number of fragments.
  239          */
  240 
  241 #define NETMAP_MAX_FRAGS        64      /* max number of fragments */
  242 
  243 
  244 /*
  245  * struct netmap_ring
  246  *
  247  * Netmap representation of a TX or RX ring (also known as "queue").
  248  * This is a queue implemented as a fixed-size circular array.
  249  * At the software level the important fields are: head, cur, tail.
  250  *
  251  * In TX rings:
  252  *
  253  *      head    first slot available for transmission.
  254  *      cur     wakeup point. select() and poll() will unblock
  255  *              when 'tail' moves past 'cur'
  256  *      tail    (readonly) first slot reserved to the kernel
  257  *
  258  *      [head .. tail-1] can be used for new packets to send;
  259  *      'head' and 'cur' must be incremented as slots are filled
  260  *          with new packets to be sent;
  261  *      'cur' can be moved further ahead if we need more space
  262  *      for new transmissions. XXX todo (2014-03-12)
  263  *
  264  * In RX rings:
  265  *
  266  *      head    first valid received packet
  267  *      cur     wakeup point. select() and poll() will unblock
  268  *              when 'tail' moves past 'cur'
  269  *      tail    (readonly) first slot reserved to the kernel
  270  *
  271  *      [head .. tail-1] contain received packets;
  272  *      'head' and 'cur' must be incremented as slots are consumed
  273  *              and can be returned to the kernel;
  274  *      'cur' can be moved further ahead if we want to wait for
  275  *              new packets without returning the previous ones.
  276  *
  277  * DATA OWNERSHIP/LOCKING:
  278  *      The netmap_ring, and all slots and buffers in the range
  279  *      [head .. tail-1] are owned by the user program;
  280  *      the kernel only accesses them during a netmap system call
  281  *      and in the user thread context.
  282  *
  283  *      Other slots and buffers are reserved for use by the kernel
  284  */
  285 struct netmap_ring {
  286         /*
  287          * buf_ofs is meant to be used through macros.
  288          * It contains the offset of the buffer region from this
  289          * descriptor.
  290          */
  291         const int64_t   buf_ofs;
  292         const uint32_t  num_slots;      /* number of slots in the ring. */
  293         const uint32_t  nr_buf_size;
  294         const uint16_t  ringid;
  295         const uint16_t  dir;            /* 0: tx, 1: rx */
  296 
  297         uint32_t        head;           /* (u) first user slot */
  298         uint32_t        cur;            /* (u) wakeup point */
  299         uint32_t        tail;           /* (k) first kernel slot */
  300 
  301         uint32_t        flags;
  302 
  303         struct timeval  ts;             /* (k) time of last *sync() */
  304 
  305         /* opaque room for a mutex or similar object */
  306 #if !defined(_WIN32) || defined(__CYGWIN__)
  307         uint8_t __attribute__((__aligned__(NM_CACHE_ALIGN))) sem[128];
  308 #else
  309         uint8_t __declspec(align(NM_CACHE_ALIGN)) sem[128];
  310 #endif
  311 
  312         /* the slots follow. This struct has variable size */
  313         struct netmap_slot slot[0];     /* array of slots. */
  314 };
  315 
  316 
  317 /*
  318  * RING FLAGS
  319  */
  320 #define NR_TIMESTAMP    0x0002          /* set timestamp on *sync() */
  321         /*
  322          * updates the 'ts' field on each netmap syscall. This saves
  323          * saves a separate gettimeofday(), and is not much worse than
  324          * software timestamps generated in the interrupt handler.
  325          */
  326 
  327 #define NR_FORWARD      0x0004          /* enable NS_FORWARD for ring */
  328         /*
  329          * Enables the NS_FORWARD slot flag for the ring.
  330          */
  331 
  332 /*
  333  * Helper functions for kernel and userspace
  334  */
  335 
  336 /*
  337  * Check if space is available in the ring. We use ring->head, which
  338  * points to the next netmap slot to be published to netmap. It is
  339  * possible that the applications moves ring->cur ahead of ring->tail
  340  * (e.g., by setting ring->cur <== ring->tail), if it wants more slots
  341  * than the ones currently available, and it wants to be notified when
  342  * more arrive. See netmap(4) for more details and examples.
  343  */
  344 static inline int
  345 nm_ring_empty(struct netmap_ring *ring)
  346 {
  347         return (ring->head == ring->tail);
  348 }
  349 
  350 /*
  351  * Netmap representation of an interface and its queue(s).
  352  * This is initialized by the kernel when binding a file
  353  * descriptor to a port, and should be considered as readonly
  354  * by user programs. The kernel never uses it.
  355  *
  356  * There is one netmap_if for each file descriptor on which we want
  357  * to select/poll.
  358  * select/poll operates on one or all pairs depending on the value of
  359  * nmr_queueid passed on the ioctl.
  360  */
  361 struct netmap_if {
  362         char            ni_name[IFNAMSIZ]; /* name of the interface. */
  363         const uint32_t  ni_version;     /* API version, currently unused */
  364         const uint32_t  ni_flags;       /* properties */
  365 #define NI_PRIV_MEM     0x1             /* private memory region */
  366 
  367         /*
  368          * The number of packet rings available in netmap mode.
  369          * Physical NICs can have different numbers of tx and rx rings.
  370          * Physical NICs also have at least a 'host' rings pair.
  371          * Additionally, clients can request additional ring pairs to
  372          * be used for internal communication.
  373          */
  374         const uint32_t  ni_tx_rings;    /* number of HW tx rings */
  375         const uint32_t  ni_rx_rings;    /* number of HW rx rings */
  376 
  377         uint32_t        ni_bufs_head;   /* head index for extra bufs */
  378         const uint32_t  ni_host_tx_rings; /* number of SW tx rings */
  379         const uint32_t  ni_host_rx_rings; /* number of SW rx rings */
  380         uint32_t        ni_spare1[3];
  381         /*
  382          * The following array contains the offset of each netmap ring
  383          * from this structure, in the following order:
  384          *     - NIC tx rings (ni_tx_rings);
  385          *     - host tx rings (ni_host_tx_rings);
  386          *     - NIC rx rings (ni_rx_rings);
  387          *     - host rx ring (ni_host_rx_rings);
  388          *
  389          * The area is filled up by the kernel on NETMAP_REQ_REGISTER,
  390          * and then only read by userspace code.
  391          */
  392         const ssize_t   ring_ofs[0];
  393 };
  394 
  395 /* Legacy interface to interact with a netmap control device.
  396  * Included for backward compatibility. The user should not include this
  397  * file directly. */
  398 #include "netmap_legacy.h"
  399 
  400 /*
  401  * New API to control netmap control devices. New applications should only use
  402  * nmreq_xyz structs with the NIOCCTRL ioctl() command.
  403  *
  404  * NIOCCTRL takes a nmreq_header struct, which contains the required
  405  * API version, the name of a netmap port, a command type, and pointers
  406  * to request body and options.
  407  *
  408  *      nr_name (in)
  409  *              The name of the port (em0, valeXXX:YYY, eth0{pn1 etc.)
  410  *
  411  *      nr_version (in/out)
  412  *              Must match NETMAP_API as used in the kernel, error otherwise.
  413  *              Always returns the desired value on output.
  414  *
  415  *      nr_reqtype (in)
  416  *              One of the NETMAP_REQ_* command types below
  417  *
  418  *      nr_body (in)
  419  *              Pointer to a command-specific struct, described by one
  420  *              of the struct nmreq_xyz below.
  421  *
  422  *      nr_options (in)
  423  *              Command specific options, if any.
  424  *
  425  * A NETMAP_REQ_REGISTER command activates netmap mode on the netmap
  426  * port (e.g. physical interface) specified by nmreq_header.nr_name.
  427  * The request body (struct nmreq_register) has several arguments to
  428  * specify how the port is to be registered.
  429  *
  430  *      nr_tx_slots, nr_tx_slots, nr_tx_rings, nr_rx_rings,
  431  *      nr_host_tx_rings, nr_host_rx_rings (in/out)
  432  *              On input, non-zero values may be used to reconfigure the port
  433  *              according to the requested values, but this is not guaranteed.
  434  *              On output the actual values in use are reported.
  435  *
  436  *      nr_mode (in)
  437  *              Indicate what set of rings must be bound to the netmap
  438  *              device (e.g. all NIC rings, host rings only, NIC and
  439  *              host rings, ...). Values are in NR_REG_*.
  440  *
  441  *      nr_ringid (in)
  442  *              If nr_mode == NR_REG_ONE_NIC (only a single couple of TX/RX
  443  *              rings), indicate which NIC TX and/or RX ring is to be bound
  444  *              (0..nr_*x_rings-1).
  445  *
  446  *      nr_flags (in)
  447  *              Indicate special options for how to open the port.
  448  *
  449  *              NR_NO_TX_POLL can be OR-ed to make select()/poll() push
  450  *                      packets on tx rings only if POLLOUT is set.
  451  *                      The default is to push any pending packet.
  452  *
  453  *              NR_DO_RX_POLL can be OR-ed to make select()/poll() release
  454  *                      packets on rx rings also when POLLIN is NOT set.
  455  *                      The default is to touch the rx ring only with POLLIN.
  456  *                      Note that this is the opposite of TX because it
  457  *                      reflects the common usage.
  458  *
  459  *              Other options are NR_MONITOR_TX, NR_MONITOR_RX, NR_ZCOPY_MON,
  460  *              NR_EXCLUSIVE, NR_RX_RINGS_ONLY, NR_TX_RINGS_ONLY and
  461  *              NR_ACCEPT_VNET_HDR.
  462  *
  463  *      nr_mem_id (in/out)
  464  *              The identity of the memory region used.
  465  *              On input, 0 means the system decides autonomously,
  466  *              other values may try to select a specific region.
  467  *              On return the actual value is reported.
  468  *              Region '1' is the global allocator, normally shared
  469  *              by all interfaces. Other values are private regions.
  470  *              If two ports the same region zero-copy is possible.
  471  *
  472  *      nr_extra_bufs (in/out)
  473  *              Number of extra buffers to be allocated.
  474  *
  475  * The other NETMAP_REQ_* commands are described below.
  476  *
  477  */
  478 
  479 /* maximum size of a request, including all options */
  480 #define NETMAP_REQ_MAXSIZE      4096
  481 
  482 /* Header common to all request options. */
  483 struct nmreq_option {
  484         /* Pointer ot the next option. */
  485         uint64_t                nro_next;
  486         /* Option type. */
  487         uint32_t                nro_reqtype;
  488         /* (out) status of the option:
  489          * 0: recognized and processed
  490          * !=0: errno value
  491          */
  492         uint32_t                nro_status;
  493         /* Option size, used only for options that can have variable size
  494          * (e.g. because they contain arrays). For fixed-size options this
  495          * field should be set to zero. */
  496         uint64_t                nro_size;
  497 };
  498 
  499 /* Header common to all requests. Do not reorder these fields, as we need
  500  * the second one (nr_reqtype) to know how much to copy from/to userspace. */
  501 struct nmreq_header {
  502         uint16_t                nr_version;     /* API version */
  503         uint16_t                nr_reqtype;     /* nmreq type (NETMAP_REQ_*) */
  504         uint32_t                nr_reserved;    /* must be zero */
  505 #define NETMAP_REQ_IFNAMSIZ     64
  506         char                    nr_name[NETMAP_REQ_IFNAMSIZ]; /* port name */
  507         uint64_t                nr_options;     /* command-specific options */
  508         uint64_t                nr_body;        /* ptr to nmreq_xyz struct */
  509 };
  510 
  511 enum {
  512         /* Register a netmap port with the device. */
  513         NETMAP_REQ_REGISTER = 1,
  514         /* Get information from a netmap port. */
  515         NETMAP_REQ_PORT_INFO_GET,
  516         /* Attach a netmap port to a VALE switch. */
  517         NETMAP_REQ_VALE_ATTACH,
  518         /* Detach a netmap port from a VALE switch. */
  519         NETMAP_REQ_VALE_DETACH,
  520         /* List the ports attached to a VALE switch. */
  521         NETMAP_REQ_VALE_LIST,
  522         /* Set the port header length (was virtio-net header length). */
  523         NETMAP_REQ_PORT_HDR_SET,
  524         /* Get the port header length (was virtio-net header length). */
  525         NETMAP_REQ_PORT_HDR_GET,
  526         /* Create a new persistent VALE port. */
  527         NETMAP_REQ_VALE_NEWIF,
  528         /* Delete a persistent VALE port. */
  529         NETMAP_REQ_VALE_DELIF,
  530         /* Enable polling kernel thread(s) on an attached VALE port. */
  531         NETMAP_REQ_VALE_POLLING_ENABLE,
  532         /* Disable polling kernel thread(s) on an attached VALE port. */
  533         NETMAP_REQ_VALE_POLLING_DISABLE,
  534         /* Get info about the pools of a memory allocator. */
  535         NETMAP_REQ_POOLS_INFO_GET,
  536         /* Start an in-kernel loop that syncs the rings periodically or
  537          * on notifications. The loop runs in the context of the ioctl
  538          * syscall, and only stops on NETMAP_REQ_SYNC_KLOOP_STOP. */
  539         NETMAP_REQ_SYNC_KLOOP_START,
  540         /* Stops the thread executing the in-kernel loop. The thread
  541          * returns from the ioctl syscall. */
  542         NETMAP_REQ_SYNC_KLOOP_STOP,
  543         /* Enable CSB mode on a registered netmap control device. */
  544         NETMAP_REQ_CSB_ENABLE,
  545 };
  546 
  547 enum {
  548         /* On NETMAP_REQ_REGISTER, ask netmap to use memory allocated
  549          * from user-space allocated memory pools (e.g. hugepages).
  550          */
  551         NETMAP_REQ_OPT_EXTMEM = 1,
  552 
  553         /* ON NETMAP_REQ_SYNC_KLOOP_START, ask netmap to use eventfd-based
  554          * notifications to synchronize the kernel loop with the application.
  555          */
  556         NETMAP_REQ_OPT_SYNC_KLOOP_EVENTFDS,
  557 
  558         /* On NETMAP_REQ_REGISTER, ask netmap to work in CSB mode, where
  559          * head, cur and tail pointers are not exchanged through the
  560          * struct netmap_ring header, but rather using an user-provided
  561          * memory area (see struct nm_csb_atok and struct nm_csb_ktoa).
  562          */
  563         NETMAP_REQ_OPT_CSB,
  564 
  565         /* An extension to NETMAP_REQ_OPT_SYNC_KLOOP_EVENTFDS, which specifies
  566          * if the TX and/or RX rings are synced in the context of the VM exit.
  567          * This requires the 'ioeventfd' fields to be valid (cannot be < 0).
  568          */
  569         NETMAP_REQ_OPT_SYNC_KLOOP_MODE,
  570 
  571         /* This is a marker to count the number of available options.
  572          * New options must be added above it. */
  573         NETMAP_REQ_OPT_MAX,
  574 };
  575 
  576 /*
  577  * nr_reqtype: NETMAP_REQ_REGISTER
  578  * Bind (register) a netmap port to this control device.
  579  */
  580 struct nmreq_register {
  581         uint64_t        nr_offset;      /* nifp offset in the shared region */
  582         uint64_t        nr_memsize;     /* size of the shared region */
  583         uint32_t        nr_tx_slots;    /* slots in tx rings */
  584         uint32_t        nr_rx_slots;    /* slots in rx rings */
  585         uint16_t        nr_tx_rings;    /* number of tx rings */
  586         uint16_t        nr_rx_rings;    /* number of rx rings */
  587         uint16_t        nr_host_tx_rings; /* number of host tx rings */
  588         uint16_t        nr_host_rx_rings; /* number of host rx rings */
  589 
  590         uint16_t        nr_mem_id;      /* id of the memory allocator */
  591         uint16_t        nr_ringid;      /* ring(s) we care about */
  592         uint32_t        nr_mode;        /* specify NR_REG_* modes */
  593         uint32_t        nr_extra_bufs;  /* number of requested extra buffers */
  594 
  595         uint64_t        nr_flags;       /* additional flags (see below) */
  596 /* monitors use nr_ringid and nr_mode to select the rings to monitor */
  597 #define NR_MONITOR_TX   0x100
  598 #define NR_MONITOR_RX   0x200
  599 #define NR_ZCOPY_MON    0x400
  600 /* request exclusive access to the selected rings */
  601 #define NR_EXCLUSIVE    0x800
  602 /* 0x1000 unused */
  603 #define NR_RX_RINGS_ONLY        0x2000
  604 #define NR_TX_RINGS_ONLY        0x4000
  605 /* Applications set this flag if they are able to deal with virtio-net headers,
  606  * that is send/receive frames that start with a virtio-net header.
  607  * If not set, NETMAP_REQ_REGISTER will fail with netmap ports that require
  608  * applications to use those headers. If the flag is set, the application can
  609  * use the NETMAP_VNET_HDR_GET command to figure out the header length. */
  610 #define NR_ACCEPT_VNET_HDR      0x8000
  611 /* The following two have the same meaning of NETMAP_NO_TX_POLL and
  612  * NETMAP_DO_RX_POLL. */
  613 #define NR_DO_RX_POLL           0x10000
  614 #define NR_NO_TX_POLL           0x20000
  615 };
  616 
  617 /* Valid values for nmreq_register.nr_mode (see above). */
  618 enum {  NR_REG_DEFAULT  = 0,    /* backward compat, should not be used. */
  619         NR_REG_ALL_NIC  = 1,
  620         NR_REG_SW       = 2,
  621         NR_REG_NIC_SW   = 3,
  622         NR_REG_ONE_NIC  = 4,
  623         NR_REG_PIPE_MASTER = 5, /* deprecated, use "x{y" port name syntax */
  624         NR_REG_PIPE_SLAVE = 6,  /* deprecated, use "x}y" port name syntax */
  625         NR_REG_NULL     = 7,
  626         NR_REG_ONE_SW   = 8,
  627 };
  628 
  629 /* A single ioctl number is shared by all the new API command.
  630  * Demultiplexing is done using the hdr.nr_reqtype field.
  631  * FreeBSD uses the size value embedded in the _IOWR to determine
  632  * how much to copy in/out, so we define the ioctl() command
  633  * specifying only nmreq_header, and copyin/copyout the rest. */
  634 #define NIOCCTRL        _IOWR('i', 151, struct nmreq_header)
  635 
  636 /* The ioctl commands to sync TX/RX netmap rings.
  637  * NIOCTXSYNC, NIOCRXSYNC synchronize tx or rx queues,
  638  *      whose identity is set in NETMAP_REQ_REGISTER through nr_ringid.
  639  *      These are non blocking and take no argument. */
  640 #define NIOCTXSYNC      _IO('i', 148) /* sync tx queues */
  641 #define NIOCRXSYNC      _IO('i', 149) /* sync rx queues */
  642 
  643 /*
  644  * nr_reqtype: NETMAP_REQ_PORT_INFO_GET
  645  * Get information about a netmap port, including number of rings.
  646  * slots per ring, id of the memory allocator, etc. The netmap
  647  * control device used for this operation does not need to be bound
  648  * to a netmap port.
  649  */
  650 struct nmreq_port_info_get {
  651         uint64_t        nr_memsize;     /* size of the shared region */
  652         uint32_t        nr_tx_slots;    /* slots in tx rings */
  653         uint32_t        nr_rx_slots;    /* slots in rx rings */
  654         uint16_t        nr_tx_rings;    /* number of tx rings */
  655         uint16_t        nr_rx_rings;    /* number of rx rings */
  656         uint16_t        nr_host_tx_rings; /* number of host tx rings */
  657         uint16_t        nr_host_rx_rings; /* number of host rx rings */
  658         uint16_t        nr_mem_id;      /* memory allocator id (in/out) */
  659         uint16_t        pad[3];
  660 };
  661 
  662 #define NM_BDG_NAME             "vale"  /* prefix for bridge port name */
  663 
  664 /*
  665  * nr_reqtype: NETMAP_REQ_VALE_ATTACH
  666  * Attach a netmap port to a VALE switch. Both the name of the netmap
  667  * port and the VALE switch are specified through the nr_name argument.
  668  * The attach operation could need to register a port, so at least
  669  * the same arguments are available.
  670  * port_index will contain the index where the port has been attached.
  671  */
  672 struct nmreq_vale_attach {
  673         struct nmreq_register reg;
  674         uint32_t port_index;
  675         uint32_t pad1;
  676 };
  677 
  678 /*
  679  * nr_reqtype: NETMAP_REQ_VALE_DETACH
  680  * Detach a netmap port from a VALE switch. Both the name of the netmap
  681  * port and the VALE switch are specified through the nr_name argument.
  682  * port_index will contain the index where the port was attached.
  683  */
  684 struct nmreq_vale_detach {
  685         uint32_t port_index;
  686         uint32_t pad1;
  687 };
  688 
  689 /*
  690  * nr_reqtype: NETMAP_REQ_VALE_LIST
  691  * List the ports of a VALE switch.
  692  */
  693 struct nmreq_vale_list {
  694         /* Name of the VALE port (valeXXX:YYY) or empty. */
  695         uint16_t        nr_bridge_idx;
  696         uint16_t        pad1;
  697         uint32_t        nr_port_idx;
  698 };
  699 
  700 /*
  701  * nr_reqtype: NETMAP_REQ_PORT_HDR_SET or NETMAP_REQ_PORT_HDR_GET
  702  * Set or get the port header length of the port identified by hdr.nr_name.
  703  * The control device does not need to be bound to a netmap port.
  704  */
  705 struct nmreq_port_hdr {
  706         uint32_t        nr_hdr_len;
  707         uint32_t        pad1;
  708 };
  709 
  710 /*
  711  * nr_reqtype: NETMAP_REQ_VALE_NEWIF
  712  * Create a new persistent VALE port.
  713  */
  714 struct nmreq_vale_newif {
  715         uint32_t        nr_tx_slots;    /* slots in tx rings */
  716         uint32_t        nr_rx_slots;    /* slots in rx rings */
  717         uint16_t        nr_tx_rings;    /* number of tx rings */
  718         uint16_t        nr_rx_rings;    /* number of rx rings */
  719         uint16_t        nr_mem_id;      /* id of the memory allocator */
  720         uint16_t        pad1;
  721 };
  722 
  723 /*
  724  * nr_reqtype: NETMAP_REQ_VALE_POLLING_ENABLE or NETMAP_REQ_VALE_POLLING_DISABLE
  725  * Enable or disable polling kthreads on a VALE port.
  726  */
  727 struct nmreq_vale_polling {
  728         uint32_t        nr_mode;
  729 #define NETMAP_POLLING_MODE_SINGLE_CPU 1
  730 #define NETMAP_POLLING_MODE_MULTI_CPU 2
  731         uint32_t        nr_first_cpu_id;
  732         uint32_t        nr_num_polling_cpus;
  733         uint32_t        pad1;
  734 };
  735 
  736 /*
  737  * nr_reqtype: NETMAP_REQ_POOLS_INFO_GET
  738  * Get info about the pools of the memory allocator of the netmap
  739  * port specified by hdr.nr_name and nr_mem_id. The netmap control
  740  * device used for this operation does not need to be bound to a netmap
  741  * port.
  742  */
  743 struct nmreq_pools_info {
  744         uint64_t        nr_memsize;
  745         uint16_t        nr_mem_id; /* in/out argument */
  746         uint16_t        pad1[3];
  747         uint64_t        nr_if_pool_offset;
  748         uint32_t        nr_if_pool_objtotal;
  749         uint32_t        nr_if_pool_objsize;
  750         uint64_t        nr_ring_pool_offset;
  751         uint32_t        nr_ring_pool_objtotal;
  752         uint32_t        nr_ring_pool_objsize;
  753         uint64_t        nr_buf_pool_offset;
  754         uint32_t        nr_buf_pool_objtotal;
  755         uint32_t        nr_buf_pool_objsize;
  756 };
  757 
  758 /*
  759  * nr_reqtype: NETMAP_REQ_SYNC_KLOOP_START
  760  * Start an in-kernel loop that syncs the rings periodically or on
  761  * notifications. The loop runs in the context of the ioctl syscall,
  762  * and only stops on NETMAP_REQ_SYNC_KLOOP_STOP.
  763  * The registered netmap port must be open in CSB mode.
  764  */
  765 struct nmreq_sync_kloop_start {
  766         /* Sleeping is the default synchronization method for the kloop.
  767          * The 'sleep_us' field specifies how many microseconds to sleep for
  768          * when there is no work to do, before doing another kloop iteration.
  769          */
  770         uint32_t        sleep_us;
  771         uint32_t        pad1;
  772 };
  773 
  774 /* A CSB entry for the application --> kernel direction. */
  775 struct nm_csb_atok {
  776         uint32_t head;            /* AW+ KR+ the head of the appl netmap_ring */
  777         uint32_t cur;             /* AW+ KR+ the cur of the appl netmap_ring */
  778         uint32_t appl_need_kick;  /* AW+ KR+ kern --> appl notification enable */
  779         uint32_t sync_flags;      /* AW+ KR+ the flags of the appl [tx|rx]sync() */
  780         uint32_t pad[12];         /* pad to a 64 bytes cacheline */
  781 };
  782 
  783 /* A CSB entry for the application <-- kernel direction. */
  784 struct nm_csb_ktoa {
  785         uint32_t hwcur;           /* AR+ KW+ the hwcur of the kern netmap_kring */
  786         uint32_t hwtail;          /* AR+ KW+ the hwtail of the kern netmap_kring */
  787         uint32_t kern_need_kick;  /* AR+ KW+ appl-->kern notification enable */
  788         uint32_t pad[13];
  789 };
  790 
  791 #ifdef __linux__
  792 
  793 #ifdef __KERNEL__
  794 #define nm_stst_barrier smp_wmb
  795 #define nm_ldld_barrier smp_rmb
  796 #define nm_stld_barrier smp_mb
  797 #else  /* !__KERNEL__ */
  798 static inline void nm_stst_barrier(void)
  799 {
  800         /* A memory barrier with release semantic has the combined
  801          * effect of a store-store barrier and a load-store barrier,
  802          * which is fine for us. */
  803         __atomic_thread_fence(__ATOMIC_RELEASE);
  804 }
  805 static inline void nm_ldld_barrier(void)
  806 {
  807         /* A memory barrier with acquire semantic has the combined
  808          * effect of a load-load barrier and a store-load barrier,
  809          * which is fine for us. */
  810         __atomic_thread_fence(__ATOMIC_ACQUIRE);
  811 }
  812 #endif /* !__KERNEL__ */
  813 
  814 #elif defined(__FreeBSD__)
  815 
  816 #ifdef _KERNEL
  817 #define nm_stst_barrier atomic_thread_fence_rel
  818 #define nm_ldld_barrier atomic_thread_fence_acq
  819 #define nm_stld_barrier atomic_thread_fence_seq_cst
  820 #else  /* !_KERNEL */
  821 #include <stdatomic.h>
  822 static inline void nm_stst_barrier(void)
  823 {
  824         atomic_thread_fence(memory_order_release);
  825 }
  826 static inline void nm_ldld_barrier(void)
  827 {
  828         atomic_thread_fence(memory_order_acquire);
  829 }
  830 #endif /* !_KERNEL */
  831 
  832 #else  /* !__linux__ && !__FreeBSD__ */
  833 #error "OS not supported"
  834 #endif /* !__linux__ && !__FreeBSD__ */
  835 
  836 /* Application side of sync-kloop: Write ring pointers (cur, head) to the CSB.
  837  * This routine is coupled with sync_kloop_kernel_read(). */
  838 static inline void
  839 nm_sync_kloop_appl_write(struct nm_csb_atok *atok, uint32_t cur,
  840                          uint32_t head)
  841 {
  842         /* Issue a first store-store barrier to make sure writes to the
  843          * netmap ring do not overcome updates on atok->cur and atok->head. */
  844         nm_stst_barrier();
  845 
  846         /*
  847          * We need to write cur and head to the CSB but we cannot do it atomically.
  848          * There is no way we can prevent the host from reading the updated value
  849          * of one of the two and the old value of the other. However, if we make
  850          * sure that the host never reads a value of head more recent than the
  851          * value of cur we are safe. We can allow the host to read a value of cur
  852          * more recent than the value of head, since in the netmap ring cur can be
  853          * ahead of head and cur cannot wrap around head because it must be behind
  854          * tail. Inverting the order of writes below could instead result into the
  855          * host to think head went ahead of cur, which would cause the sync
  856          * prologue to fail.
  857          *
  858          * The following memory barrier scheme is used to make this happen:
  859          *
  860          *          Guest                Host
  861          *
  862          *          STORE(cur)           LOAD(head)
  863          *          wmb() <----------->  rmb()
  864          *          STORE(head)          LOAD(cur)
  865          *
  866          */
  867         atok->cur = cur;
  868         nm_stst_barrier();
  869         atok->head = head;
  870 }
  871 
  872 /* Application side of sync-kloop: Read kring pointers (hwcur, hwtail) from
  873  * the CSB. This routine is coupled with sync_kloop_kernel_write(). */
  874 static inline void
  875 nm_sync_kloop_appl_read(struct nm_csb_ktoa *ktoa, uint32_t *hwtail,
  876                         uint32_t *hwcur)
  877 {
  878         /*
  879          * We place a memory barrier to make sure that the update of hwtail never
  880          * overtakes the update of hwcur.
  881          * (see explanation in sync_kloop_kernel_write).
  882          */
  883         *hwtail = ktoa->hwtail;
  884         nm_ldld_barrier();
  885         *hwcur = ktoa->hwcur;
  886 
  887         /* Make sure that loads from ktoa->hwtail and ktoa->hwcur are not delayed
  888          * after the loads from the netmap ring. */
  889         nm_ldld_barrier();
  890 }
  891 
  892 /*
  893  * data for NETMAP_REQ_OPT_* options
  894  */
  895 
  896 struct nmreq_opt_sync_kloop_eventfds {
  897         struct nmreq_option     nro_opt;        /* common header */
  898         /* An array of N entries for bidirectional notifications between
  899          * the kernel loop and the application. The number of entries and
  900          * their order must agree with the CSB arrays passed in the
  901          * NETMAP_REQ_OPT_CSB option. Each entry contains a file descriptor
  902          * backed by an eventfd.
  903          *
  904          * If any of the 'ioeventfd' entries is < 0, the event loop uses
  905          * the sleeping synchronization strategy (according to sleep_us),
  906          * and keeps kern_need_kick always disabled.
  907          * Each 'irqfd' can be < 0, and in that case the corresponding queue
  908          * is never notified.
  909          */
  910         struct {
  911                 /* Notifier for the application --> kernel loop direction. */
  912                 int32_t ioeventfd;
  913                 /* Notifier for the kernel loop --> application direction. */
  914                 int32_t irqfd;
  915         } eventfds[0];
  916 };
  917 
  918 struct nmreq_opt_sync_kloop_mode {
  919         struct nmreq_option     nro_opt;        /* common header */
  920 #define NM_OPT_SYNC_KLOOP_DIRECT_TX (1 << 0)
  921 #define NM_OPT_SYNC_KLOOP_DIRECT_RX (1 << 1)
  922         uint32_t mode;
  923 };
  924 
  925 struct nmreq_opt_extmem {
  926         struct nmreq_option     nro_opt;        /* common header */
  927         uint64_t                nro_usrptr;     /* (in) ptr to usr memory */
  928         struct nmreq_pools_info nro_info;       /* (in/out) */
  929 };
  930 
  931 struct nmreq_opt_csb {
  932         struct nmreq_option     nro_opt;
  933 
  934         /* Array of CSB entries for application --> kernel communication
  935          * (N entries). */
  936         uint64_t                csb_atok;
  937 
  938         /* Array of CSB entries for kernel --> application communication
  939          * (N entries). */
  940         uint64_t                csb_ktoa;
  941 };
  942 
  943 #endif /* _NET_NETMAP_H_ */

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