FreeBSD/Linux Kernel Cross Reference
sys/xen/interface/io/netif.h

     /******************************************************************************
      * netif.h
      * 
      * Unified network-device I/O interface for Xen guest OSes.
      * 
      * Permission is hereby granted, free of charge, to any person obtaining a copy
      * of this software and associated documentation files (the "Software"), to
      * deal in the Software without restriction, including without limitation the
      * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
     * sell copies of the Software, and to permit persons to whom the Software is
     * furnished to do so, subject to the following conditions:
     *
     * The above copyright notice and this permission notice shall be included in
     * all copies or substantial portions of the Software.
     *
     * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
     * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
     * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
     * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
     * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
     * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
     * DEALINGS IN THE SOFTWARE.
     *
     * Copyright (c) 2003-2004, Keir Fraser
     */
    
    #ifndef __XEN_PUBLIC_IO_NETIF_H__
    #define __XEN_PUBLIC_IO_NETIF_H__
    
    #include "ring.h"
    #include "../grant_table.h"
    
    /*
     * Older implementation of Xen network frontend / backend has an
     * implicit dependency on the MAX_SKB_FRAGS as the maximum number of
     * ring slots a skb can use. Netfront / netback may not work as
     * expected when frontend and backend have different MAX_SKB_FRAGS.
     *
     * A better approach is to add mechanism for netfront / netback to
     * negotiate this value. However we cannot fix all possible
     * frontends, so we need to define a value which states the minimum
     * slots backend must support.
     *
     * The minimum value derives from older Linux kernel's MAX_SKB_FRAGS
     * (18), which is proved to work with most frontends. Any new backend
     * which doesn't negotiate with frontend should expect frontend to
     * send a valid packet using slots up to this value.
     */
    #define XEN_NETIF_NR_SLOTS_MIN 18
    
    /*
     * Notifications after enqueuing any type of message should be conditional on
     * the appropriate req_event or rsp_event field in the shared ring.
     * If the client sends notification for rx requests then it should specify
     * feature 'feature-rx-notify' via xenbus. Otherwise the backend will assume
     * that it cannot safely queue packets (as it may not be kicked to send them).
     */
    
    /*
     * "feature-split-event-channels" is introduced to separate guest TX
     * and RX notification. Backend either doesn't support this feature or
     * advertises it via xenstore as 0 (disabled) or 1 (enabled).
     *
     * To make use of this feature, frontend should allocate two event
     * channels for TX and RX, advertise them to backend as
     * "event-channel-tx" and "event-channel-rx" respectively. If frontend
     * doesn't want to use this feature, it just writes "event-channel"
     * node as before.
     */
    
    /*
     * Multiple transmit and receive queues:
     * If supported, the backend will write the key "multi-queue-max-queues" to
     * the directory for that vif, and set its value to the maximum supported
     * number of queues.
     * Frontends that are aware of this feature and wish to use it can write the
     * key "multi-queue-num-queues", set to the number they wish to use, which
     * must be greater than zero, and no more than the value reported by the backend
     * in "multi-queue-max-queues".
     *
     * Queues replicate the shared rings and event channels.
     * "feature-split-event-channels" may optionally be used when using
     * multiple queues, but is not mandatory.
     *
     * Each queue consists of one shared ring pair, i.e. there must be the same
     * number of tx and rx rings.
     *
     * For frontends requesting just one queue, the usual event-channel and
     * ring-ref keys are written as before, simplifying the backend processing
     * to avoid distinguishing between a frontend that doesn't understand the
     * multi-queue feature, and one that does, but requested only one queue.
     *
     * Frontends requesting two or more queues must not write the toplevel
     * event-channel (or event-channel-{tx,rx}) and {tx,rx}-ring-ref keys,
     * instead writing those keys under sub-keys having the name "queue-N" where
     * N is the integer ID of the queue for which those keys belong. Queues
     * are indexed from zero. For example, a frontend with two queues and split
     * event channels must write the following set of queue-related keys:
     *
    * /local/domain/1/device/vif/0/multi-queue-num-queues = "2"
    * /local/domain/1/device/vif/0/queue-0 = ""
    * /local/domain/1/device/vif/0/queue-0/tx-ring-ref = "<ring-ref-tx0>"
    * /local/domain/1/device/vif/0/queue-0/rx-ring-ref = "<ring-ref-rx0>"
    * /local/domain/1/device/vif/0/queue-0/event-channel-tx = "<evtchn-tx0>"
    * /local/domain/1/device/vif/0/queue-0/event-channel-rx = "<evtchn-rx0>"
    * /local/domain/1/device/vif/0/queue-1 = ""
    * /local/domain/1/device/vif/0/queue-1/tx-ring-ref = "<ring-ref-tx1>"
    * /local/domain/1/device/vif/0/queue-1/rx-ring-ref = "<ring-ref-rx1"
    * /local/domain/1/device/vif/0/queue-1/event-channel-tx = "<evtchn-tx1>"
    * /local/domain/1/device/vif/0/queue-1/event-channel-rx = "<evtchn-rx1>"
    *
    * If there is any inconsistency in the XenStore data, the backend may
    * choose not to connect any queues, instead treating the request as an
    * error. This includes scenarios where more (or fewer) queues were
    * requested than the frontend provided details for.
    *
    * Mapping of packets to queues is considered to be a function of the
    * transmitting system (backend or frontend) and is not negotiated
    * between the two. Guests are free to transmit packets on any queue
    * they choose, provided it has been set up correctly. Guests must be
    * prepared to receive packets on any queue they have requested be set up.
    */
   
   /*
    * "feature-no-csum-offload" should be used to turn IPv4 TCP/UDP checksum
    * offload off or on. If it is missing then the feature is assumed to be on.
    * "feature-ipv6-csum-offload" should be used to turn IPv6 TCP/UDP checksum
    * offload on or off. If it is missing then the feature is assumed to be off.
    */
   
   /*
    * "feature-gso-tcpv4" and "feature-gso-tcpv6" advertise the capability to
    * handle large TCP packets (in IPv4 or IPv6 form respectively). Neither
    * frontends nor backends are assumed to be capable unless the flags are
    * present.
    */
   
   /*
    * "feature-multicast-control" advertises the capability to filter ethernet
    * multicast packets in the backend. To enable use of this capability the
    * frontend must set "request-multicast-control" before moving into the
    * connected state.
    *
    * If "request-multicast-control" is set then the backend transmit side should
    * no longer flood multicast packets to the frontend, it should instead drop any
    * multicast packet that does not match in a filter list. The list is
    * amended by the frontend by sending dummy transmit requests containing
    * XEN_NETIF_EXTRA_TYPE_MCAST_{ADD,DEL} extra-info fragments as specified below.
    * Once enabled by the frontend, the feature cannot be disabled except by
    * closing and re-connecting to the backend.
    */
   
   /*
    * This is the 'wire' format for packets:
    *  Request 1: netif_tx_request_t -- NETTXF_* (any flags)
    * [Request 2: netif_extra_info_t] (only if request 1 has NETTXF_extra_info)
    * [Request 3: netif_extra_info_t] (only if request 2 has XEN_NETIF_EXTRA_MORE)
    *  Request 4: netif_tx_request_t -- NETTXF_more_data
    *  Request 5: netif_tx_request_t -- NETTXF_more_data
    *  ...
    *  Request N: netif_tx_request_t -- 0
    */
   
   /*
    * Guest transmit
    * ==============
    *
    * Ring slot size is 12 octets, however not all request/response
    * structs use the full size.
    *
    * tx request data (netif_tx_request_t)
    * ------------------------------------
    *
    *    0     1     2     3     4     5     6     7  octet
    * +-----+-----+-----+-----+-----+-----+-----+-----+
    * | grant ref             | offset    | flags     |
    * +-----+-----+-----+-----+-----+-----+-----+-----+
    * | id        | size      |
    * +-----+-----+-----+-----+
    *
    * grant ref: Reference to buffer page.
    * offset: Offset within buffer page.
    * flags: NETTXF_*.
    * id: request identifier, echoed in response.
    * size: packet size in bytes.
    *
    * tx response (netif_tx_response_t)
    * ---------------------------------
    *
    *    0     1     2     3     4     5     6     7  octet
    * +-----+-----+-----+-----+-----+-----+-----+-----+
    * | id        | status    | unused                |
    * +-----+-----+-----+-----+-----+-----+-----+-----+
    * | unused                |
    * +-----+-----+-----+-----+
    *
    * id: reflects id in transmit request
    * status: NETIF_RSP_*
    *
    * Guest receive
    * =============
    *
    * Ring slot size is 8 octets.
    *
    * rx request (netif_rx_request_t)
    * -------------------------------
    *
    *    0     1     2     3     4     5     6     7  octet
    * +-----+-----+-----+-----+-----+-----+-----+-----+
    * | id        | pad       | gref                  |
    * +-----+-----+-----+-----+-----+-----+-----+-----+
    *
    * id: request identifier, echoed in response.
    * gref: reference to incoming granted frame.
    *
    * rx response (netif_rx_response_t)
    * ---------------------------------
    *
    *    0     1     2     3     4     5     6     7  octet
    * +-----+-----+-----+-----+-----+-----+-----+-----+
    * | id        | offset    | flags     | status    |
    * +-----+-----+-----+-----+-----+-----+-----+-----+
    *
    * id: reflects id in receive request
    * offset: offset in page of start of received packet
    * flags: NETRXF_*
    * status: -ve: NETIF_RSP_*; +ve: Rx'ed pkt size.
    *
    * Extra Info
    * ==========
    *
    * Can be present if initial request has NET{T,R}XF_extra_info, or
    * previous extra request has XEN_NETIF_EXTRA_MORE.
    *
    * The struct therefore needs to fit into either a tx or rx slot and
    * is therefore limited to 8 octets.
    *
    * extra info (netif_extra_info_t)
    * -------------------------------
    *
    * General format:
    *
    *    0     1     2     3     4     5     6     7  octet
    * +-----+-----+-----+-----+-----+-----+-----+-----+
    * |type |flags| type specfic data                 |
    * +-----+-----+-----+-----+-----+-----+-----+-----+
    * | padding for tx        |
    * +-----+-----+-----+-----+
    *
    * type: XEN_NETIF_EXTRA_TYPE_*
    * flags: XEN_NETIF_EXTRA_FLAG_*
    * padding for tx: present only in the tx case due to 8 octet limit
    *     from rx case. Not shown in type specific entries below.
    *
    * XEN_NETIF_EXTRA_TYPE_GSO:
    *
    *    0     1     2     3     4     5     6     7  octet
    * +-----+-----+-----+-----+-----+-----+-----+-----+
    * |type |flags| size      |type | pad | features  |
    * +-----+-----+-----+-----+-----+-----+-----+-----+
    *
    * type: Must be XEN_NETIF_EXTRA_TYPE_GSO
    * flags: XEN_NETIF_EXTRA_FLAG_*
    * size: Maximum payload size of each segment.
    * type: XEN_NETIF_GSO_TYPE_*
    * features: EN_NETIF_GSO_FEAT_*
    *
    * XEN_NETIF_EXTRA_TYPE_MCAST_{ADD,DEL}:
    *
    *    0     1     2     3     4     5     6     7  octet
    * +-----+-----+-----+-----+-----+-----+-----+-----+
    * |type |flags| addr                              |
    * +-----+-----+-----+-----+-----+-----+-----+-----+
    *
    * type: Must be XEN_NETIF_EXTRA_TYPE_MCAST_{ADD,DEL}
    * flags: XEN_NETIF_EXTRA_FLAG_*
    * addr: address to add/remove
    */
   
   /* Protocol checksum field is blank in the packet (hardware offload)? */
   #define _NETTXF_csum_blank     (0)
   #define  NETTXF_csum_blank     (1U<<_NETTXF_csum_blank)
   
   /* Packet data has been validated against protocol checksum. */
   #define _NETTXF_data_validated (1)
   #define  NETTXF_data_validated (1U<<_NETTXF_data_validated)
   
   /* Packet continues in the next request descriptor. */
   #define _NETTXF_more_data      (2)
   #define  NETTXF_more_data      (1U<<_NETTXF_more_data)
   
   /* Packet to be followed by extra descriptor(s). */
   #define _NETTXF_extra_info     (3)
   #define  NETTXF_extra_info     (1U<<_NETTXF_extra_info)
   
   #define XEN_NETIF_MAX_TX_SIZE 0xFFFF
   struct netif_tx_request {
       grant_ref_t gref;      /* Reference to buffer page */
       uint16_t offset;       /* Offset within buffer page */
       uint16_t flags;        /* NETTXF_* */
       uint16_t id;           /* Echoed in response message. */
       uint16_t size;         /* Packet size in bytes.       */
   };
   typedef struct netif_tx_request netif_tx_request_t;
   
   /* Types of netif_extra_info descriptors. */
   #define XEN_NETIF_EXTRA_TYPE_NONE      (0)  /* Never used - invalid */
   #define XEN_NETIF_EXTRA_TYPE_GSO       (1)  /* u.gso */
   #define XEN_NETIF_EXTRA_TYPE_MCAST_ADD (2)  /* u.mcast */
   #define XEN_NETIF_EXTRA_TYPE_MCAST_DEL (3)  /* u.mcast */
   #define XEN_NETIF_EXTRA_TYPE_MAX       (4)
   
   /* netif_extra_info_t flags. */
   #define _XEN_NETIF_EXTRA_FLAG_MORE (0)
   #define XEN_NETIF_EXTRA_FLAG_MORE  (1U<<_XEN_NETIF_EXTRA_FLAG_MORE)
   
   /* GSO types */
   #define XEN_NETIF_GSO_TYPE_NONE         (0)
   #define XEN_NETIF_GSO_TYPE_TCPV4        (1)
   #define XEN_NETIF_GSO_TYPE_TCPV6        (2)
   
   /*
    * This structure needs to fit within both netif_tx_request_t and
    * netif_rx_response_t for compatibility.
    */
   struct netif_extra_info {
       uint8_t type;  /* XEN_NETIF_EXTRA_TYPE_* */
       uint8_t flags; /* XEN_NETIF_EXTRA_FLAG_* */
   
       union {
           /*
            * XEN_NETIF_EXTRA_TYPE_GSO:
            */
           struct {
               /*
                * Maximum payload size of each segment. For example, for TCP this
                * is just the path MSS.
                */
               uint16_t size;
   
               /*
                * GSO type. This determines the protocol of the packet and any
                * extra features required to segment the packet properly.
                */
               uint8_t type; /* XEN_NETIF_GSO_TYPE_* */
   
               /* Future expansion. */
               uint8_t pad;
   
               /*
                * GSO features. This specifies any extra GSO features required
                * to process this packet, such as ECN support for TCPv4.
                */
               uint16_t features; /* XEN_NETIF_GSO_FEAT_* */
           } gso;
   
           /*
            * XEN_NETIF_EXTRA_TYPE_MCAST_{ADD,DEL}:
            */
           struct {
               uint8_t addr[6]; /* Address to add/remove. */
           } mcast;
   
           uint16_t pad[3];
       } u;
   };
   typedef struct netif_extra_info netif_extra_info_t;
   
   struct netif_tx_response {
       uint16_t id;
       int16_t  status;       /* NETIF_RSP_* */
   };
   typedef struct netif_tx_response netif_tx_response_t;
   
   struct netif_rx_request {
       uint16_t    id;        /* Echoed in response message.        */
       uint16_t    pad;
       grant_ref_t gref;      /* Reference to incoming granted frame */
   };
   typedef struct netif_rx_request netif_rx_request_t;
   
   /* Packet data has been validated against protocol checksum. */
   #define _NETRXF_data_validated (0)
   #define  NETRXF_data_validated (1U<<_NETRXF_data_validated)
   
   /* Protocol checksum field is blank in the packet (hardware offload)? */
   #define _NETRXF_csum_blank     (1)
   #define  NETRXF_csum_blank     (1U<<_NETRXF_csum_blank)
   
   /* Packet continues in the next request descriptor. */
   #define _NETRXF_more_data      (2)
   #define  NETRXF_more_data      (1U<<_NETRXF_more_data)
   
   /* Packet to be followed by extra descriptor(s). */
   #define _NETRXF_extra_info     (3)
   #define  NETRXF_extra_info     (1U<<_NETRXF_extra_info)
   
   struct netif_rx_response {
       uint16_t id;
       uint16_t offset;       /* Offset in page of start of received packet  */
       uint16_t flags;        /* NETRXF_* */
       int16_t  status;       /* -ve: NETIF_RSP_* ; +ve: Rx'ed pkt size. */
   };
   typedef struct netif_rx_response netif_rx_response_t;
   
   /*
    * Generate netif ring structures and types.
    */
   
   DEFINE_RING_TYPES(netif_tx, struct netif_tx_request, struct netif_tx_response);
   DEFINE_RING_TYPES(netif_rx, struct netif_rx_request, struct netif_rx_response);
   
   #define NETIF_RSP_DROPPED         -2
   #define NETIF_RSP_ERROR           -1
   #define NETIF_RSP_OKAY             0
   /* No response: used for auxiliary requests (e.g., netif_extra_info_t). */
   #define NETIF_RSP_NULL             1
   
   #endif
   
   /*
    * Local variables:
    * mode: C
    * c-file-style: "BSD"
    * c-basic-offset: 4
    * tab-width: 4
    * indent-tabs-mode: nil
    * End:
    */

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