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Diffstat (limited to 'include/xen/interface/io/netif.h')
| -rw-r--r-- | include/xen/interface/io/netif.h | 940 |
1 files changed, 940 insertions, 0 deletions
diff --git a/include/xen/interface/io/netif.h b/include/xen/interface/io/netif.h new file mode 100644 index 000000000..cb0c1a25d --- /dev/null +++ b/include/xen/interface/io/netif.h @@ -0,0 +1,940 @@ +/* SPDX-License-Identifier: MIT */ +/****************************************************************************** + * xen_netif.h + * + * Unified network-device I/O interface for Xen guest OSes. + * + * Copyright (c) 2003-2004, Keir Fraser + */ + +#ifndef __XEN_PUBLIC_IO_XEN_NETIF_H__ +#define __XEN_PUBLIC_IO_XEN_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" and "feature-dynamic-multicast-control" + * advertise the capability to filter ethernet multicast packets in the + * backend. If the frontend wishes to take advantage of this feature then + * it may set "request-multicast-control". If the backend only advertises + * "feature-multicast-control" then "request-multicast-control" must be set + * before the frontend moves into the connected state. The backend will + * sample the value on this state transition and any subsequent change in + * value will have no effect. However, if the backend also advertises + * "feature-dynamic-multicast-control" then "request-multicast-control" + * may be set by the frontend at any time. In this case, the backend will + * watch the value and re-sample on watch events. + * + * If the sampled value of "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. + * Note that the filter list may be amended even if the sampled value of + * "request-multicast-control" is not set, however the filter should only + * be applied if it is set. + */ + +/* + * "xdp-headroom" is used to request that extra space is added + * for XDP processing. The value is measured in bytes and passed by + * the frontend to be consistent between both ends. + * If the value is greater than zero that means that + * an RX response is going to be passed to an XDP program for processing. + * XEN_NETIF_MAX_XDP_HEADROOM defines the maximum headroom offset in bytes + * + * "feature-xdp-headroom" is set to "1" by the netback side like other features + * so a guest can check if an XDP program can be processed. + */ +#define XEN_NETIF_MAX_XDP_HEADROOM 0x7FFF + +/* + * Control ring + * ============ + * + * Some features, such as hashing (detailed below), require a + * significant amount of out-of-band data to be passed from frontend to + * backend. Use of xenstore is not suitable for large quantities of data + * because of quota limitations and so a dedicated 'control ring' is used. + * The ability of the backend to use a control ring is advertised by + * setting: + * + * /local/domain/X/backend/<domid>/<vif>/feature-ctrl-ring = "1" + * + * The frontend provides a control ring to the backend by setting: + * + * /local/domain/<domid>/device/vif/<vif>/ctrl-ring-ref = <gref> + * /local/domain/<domid>/device/vif/<vif>/event-channel-ctrl = <port> + * + * where <gref> is the grant reference of the shared page used to + * implement the control ring and <port> is an event channel to be used + * as a mailbox interrupt. These keys must be set before the frontend + * moves into the connected state. + * + * The control ring uses a fixed request/response message size and is + * balanced (i.e. one request to one response), so operationally it is much + * the same as a transmit or receive ring. + * Note that there is no requirement that responses are issued in the same + * order as requests. + */ + +/* + * Hash types + * ========== + * + * For the purposes of the definitions below, 'Packet[]' is an array of + * octets containing an IP packet without options, 'Array[X..Y]' means a + * sub-array of 'Array' containing bytes X thru Y inclusive, and '+' is + * used to indicate concatenation of arrays. + */ + +/* + * A hash calculated over an IP version 4 header as follows: + * + * Buffer[0..8] = Packet[12..15] (source address) + + * Packet[16..19] (destination address) + * + * Result = Hash(Buffer, 8) + */ +#define _XEN_NETIF_CTRL_HASH_TYPE_IPV4 0 +#define XEN_NETIF_CTRL_HASH_TYPE_IPV4 \ + (1 << _XEN_NETIF_CTRL_HASH_TYPE_IPV4) + +/* + * A hash calculated over an IP version 4 header and TCP header as + * follows: + * + * Buffer[0..12] = Packet[12..15] (source address) + + * Packet[16..19] (destination address) + + * Packet[20..21] (source port) + + * Packet[22..23] (destination port) + * + * Result = Hash(Buffer, 12) + */ +#define _XEN_NETIF_CTRL_HASH_TYPE_IPV4_TCP 1 +#define XEN_NETIF_CTRL_HASH_TYPE_IPV4_TCP \ + (1 << _XEN_NETIF_CTRL_HASH_TYPE_IPV4_TCP) + +/* + * A hash calculated over an IP version 6 header as follows: + * + * Buffer[0..32] = Packet[8..23] (source address ) + + * Packet[24..39] (destination address) + * + * Result = Hash(Buffer, 32) + */ +#define _XEN_NETIF_CTRL_HASH_TYPE_IPV6 2 +#define XEN_NETIF_CTRL_HASH_TYPE_IPV6 \ + (1 << _XEN_NETIF_CTRL_HASH_TYPE_IPV6) + +/* + * A hash calculated over an IP version 6 header and TCP header as + * follows: + * + * Buffer[0..36] = Packet[8..23] (source address) + + * Packet[24..39] (destination address) + + * Packet[40..41] (source port) + + * Packet[42..43] (destination port) + * + * Result = Hash(Buffer, 36) + */ +#define _XEN_NETIF_CTRL_HASH_TYPE_IPV6_TCP 3 +#define XEN_NETIF_CTRL_HASH_TYPE_IPV6_TCP \ + (1 << _XEN_NETIF_CTRL_HASH_TYPE_IPV6_TCP) + +/* + * Hash algorithms + * =============== + */ + +#define XEN_NETIF_CTRL_HASH_ALGORITHM_NONE 0 + +/* + * Toeplitz hash: + */ + +#define XEN_NETIF_CTRL_HASH_ALGORITHM_TOEPLITZ 1 + +/* + * This algorithm uses a 'key' as well as the data buffer itself. + * (Buffer[] and Key[] are treated as shift-registers where the MSB of + * Buffer/Key[0] is considered 'left-most' and the LSB of Buffer/Key[N-1] + * is the 'right-most'). + * + * Value = 0 + * For number of bits in Buffer[] + * If (left-most bit of Buffer[] is 1) + * Value ^= left-most 32 bits of Key[] + * Key[] << 1 + * Buffer[] << 1 + * + * The code below is provided for convenience where an operating system + * does not already provide an implementation. + */ +#ifdef XEN_NETIF_DEFINE_TOEPLITZ +static uint32_t xen_netif_toeplitz_hash(const uint8_t *key, + unsigned int keylen, + const uint8_t *buf, unsigned int buflen) +{ + unsigned int keyi, bufi; + uint64_t prefix = 0; + uint64_t hash = 0; + + /* Pre-load prefix with the first 8 bytes of the key */ + for (keyi = 0; keyi < 8; keyi++) { + prefix <<= 8; + prefix |= (keyi < keylen) ? key[keyi] : 0; + } + + for (bufi = 0; bufi < buflen; bufi++) { + uint8_t byte = buf[bufi]; + unsigned int bit; + + for (bit = 0; bit < 8; bit++) { + if (byte & 0x80) + hash ^= prefix; + prefix <<= 1; + byte <<= 1; + } + + /* + * 'prefix' has now been left-shifted by 8, so + * OR in the next byte. + */ + prefix |= (keyi < keylen) ? key[keyi] : 0; + keyi++; + } + + /* The valid part of the hash is in the upper 32 bits. */ + return hash >> 32; +} +#endif /* XEN_NETIF_DEFINE_TOEPLITZ */ + +/* + * Control requests (struct xen_netif_ctrl_request) + * ================================================ + * + * All requests have the following format: + * + * 0 1 2 3 4 5 6 7 octet + * +-----+-----+-----+-----+-----+-----+-----+-----+ + * | id | type | data[0] | + * +-----+-----+-----+-----+-----+-----+-----+-----+ + * | data[1] | data[2] | + * +-----+-----+-----+-----+-----------------------+ + * + * id: the request identifier, echoed in response. + * type: the type of request (see below) + * data[]: any data associated with the request (determined by type) + */ + +struct xen_netif_ctrl_request { + uint16_t id; + uint16_t type; + +#define XEN_NETIF_CTRL_TYPE_INVALID 0 +#define XEN_NETIF_CTRL_TYPE_GET_HASH_FLAGS 1 +#define XEN_NETIF_CTRL_TYPE_SET_HASH_FLAGS 2 +#define XEN_NETIF_CTRL_TYPE_SET_HASH_KEY 3 +#define XEN_NETIF_CTRL_TYPE_GET_HASH_MAPPING_SIZE 4 +#define XEN_NETIF_CTRL_TYPE_SET_HASH_MAPPING_SIZE 5 +#define XEN_NETIF_CTRL_TYPE_SET_HASH_MAPPING 6 +#define XEN_NETIF_CTRL_TYPE_SET_HASH_ALGORITHM 7 + + uint32_t data[3]; +}; + +/* + * Control responses (struct xen_netif_ctrl_response) + * ================================================== + * + * All responses have the following format: + * + * 0 1 2 3 4 5 6 7 octet + * +-----+-----+-----+-----+-----+-----+-----+-----+ + * | id | type | status | + * +-----+-----+-----+-----+-----+-----+-----+-----+ + * | data | + * +-----+-----+-----+-----+ + * + * id: the corresponding request identifier + * type: the type of the corresponding request + * status: the status of request processing + * data: any data associated with the response (determined by type and + * status) + */ + +struct xen_netif_ctrl_response { + uint16_t id; + uint16_t type; + uint32_t status; + +#define XEN_NETIF_CTRL_STATUS_SUCCESS 0 +#define XEN_NETIF_CTRL_STATUS_NOT_SUPPORTED 1 +#define XEN_NETIF_CTRL_STATUS_INVALID_PARAMETER 2 +#define XEN_NETIF_CTRL_STATUS_BUFFER_OVERFLOW 3 + + uint32_t data; +}; + +/* + * Control messages + * ================ + * + * XEN_NETIF_CTRL_TYPE_SET_HASH_ALGORITHM + * -------------------------------------- + * + * This is sent by the frontend to set the desired hash algorithm. + * + * Request: + * + * type = XEN_NETIF_CTRL_TYPE_SET_HASH_ALGORITHM + * data[0] = a XEN_NETIF_CTRL_HASH_ALGORITHM_* value + * data[1] = 0 + * data[2] = 0 + * + * Response: + * + * status = XEN_NETIF_CTRL_STATUS_NOT_SUPPORTED - Operation not + * supported + * XEN_NETIF_CTRL_STATUS_INVALID_PARAMETER - The algorithm is not + * supported + * XEN_NETIF_CTRL_STATUS_SUCCESS - Operation successful + * + * NOTE: Setting data[0] to XEN_NETIF_CTRL_HASH_ALGORITHM_NONE disables + * hashing and the backend is free to choose how it steers packets + * to queues (which is the default behaviour). + * + * XEN_NETIF_CTRL_TYPE_GET_HASH_FLAGS + * ---------------------------------- + * + * This is sent by the frontend to query the types of hash supported by + * the backend. + * + * Request: + * + * type = XEN_NETIF_CTRL_TYPE_GET_HASH_FLAGS + * data[0] = 0 + * data[1] = 0 + * data[2] = 0 + * + * Response: + * + * status = XEN_NETIF_CTRL_STATUS_NOT_SUPPORTED - Operation not supported + * XEN_NETIF_CTRL_STATUS_SUCCESS - Operation successful + * data = supported hash types (if operation was successful) + * + * NOTE: A valid hash algorithm must be selected before this operation can + * succeed. + * + * XEN_NETIF_CTRL_TYPE_SET_HASH_FLAGS + * ---------------------------------- + * + * This is sent by the frontend to set the types of hash that the backend + * should calculate. (See above for hash type definitions). + * Note that the 'maximal' type of hash should always be chosen. For + * example, if the frontend sets both IPV4 and IPV4_TCP hash types then + * the latter hash type should be calculated for any TCP packet and the + * former only calculated for non-TCP packets. + * + * Request: + * + * type = XEN_NETIF_CTRL_TYPE_SET_HASH_FLAGS + * data[0] = bitwise OR of XEN_NETIF_CTRL_HASH_TYPE_* values + * data[1] = 0 + * data[2] = 0 + * + * Response: + * + * status = XEN_NETIF_CTRL_STATUS_NOT_SUPPORTED - Operation not + * supported + * XEN_NETIF_CTRL_STATUS_INVALID_PARAMETER - One or more flag + * value is invalid or + * unsupported + * XEN_NETIF_CTRL_STATUS_SUCCESS - Operation successful + * data = 0 + * + * NOTE: A valid hash algorithm must be selected before this operation can + * succeed. + * Also, setting data[0] to zero disables hashing and the backend + * is free to choose how it steers packets to queues. + * + * XEN_NETIF_CTRL_TYPE_SET_HASH_KEY + * -------------------------------- + * + * This is sent by the frontend to set the key of the hash if the algorithm + * requires it. (See hash algorithms above). + * + * Request: + * + * type = XEN_NETIF_CTRL_TYPE_SET_HASH_KEY + * data[0] = grant reference of page containing the key (assumed to + * start at beginning of grant) + * data[1] = size of key in octets + * data[2] = 0 + * + * Response: + * + * status = XEN_NETIF_CTRL_STATUS_NOT_SUPPORTED - Operation not + * supported + * XEN_NETIF_CTRL_STATUS_INVALID_PARAMETER - Key size is invalid + * XEN_NETIF_CTRL_STATUS_BUFFER_OVERFLOW - Key size is larger + * than the backend + * supports + * XEN_NETIF_CTRL_STATUS_SUCCESS - Operation successful + * data = 0 + * + * NOTE: Any key octets not specified are assumed to be zero (the key + * is assumed to be empty by default) and specifying a new key + * invalidates any previous key, hence specifying a key size of + * zero will clear the key (which ensures that the calculated hash + * will always be zero). + * The maximum size of key is algorithm and backend specific, but + * is also limited by the single grant reference. + * The grant reference may be read-only and must remain valid until + * the response has been processed. + * + * XEN_NETIF_CTRL_TYPE_GET_HASH_MAPPING_SIZE + * ----------------------------------------- + * + * This is sent by the frontend to query the maximum size of mapping + * table supported by the backend. The size is specified in terms of + * table entries. + * + * Request: + * + * type = XEN_NETIF_CTRL_TYPE_GET_HASH_MAPPING_SIZE + * data[0] = 0 + * data[1] = 0 + * data[2] = 0 + * + * Response: + * + * status = XEN_NETIF_CTRL_STATUS_NOT_SUPPORTED - Operation not supported + * XEN_NETIF_CTRL_STATUS_SUCCESS - Operation successful + * data = maximum number of entries allowed in the mapping table + * (if operation was successful) or zero if a mapping table is + * not supported (i.e. hash mapping is done only by modular + * arithmetic). + * + * XEN_NETIF_CTRL_TYPE_SET_HASH_MAPPING_SIZE + * ------------------------------------- + * + * This is sent by the frontend to set the actual size of the mapping + * table to be used by the backend. The size is specified in terms of + * table entries. + * Any previous table is invalidated by this message and any new table + * is assumed to be zero filled. + * + * Request: + * + * type = XEN_NETIF_CTRL_TYPE_SET_HASH_MAPPING_SIZE + * data[0] = number of entries in mapping table + * data[1] = 0 + * data[2] = 0 + * + * Response: + * + * status = XEN_NETIF_CTRL_STATUS_NOT_SUPPORTED - Operation not + * supported + * XEN_NETIF_CTRL_STATUS_INVALID_PARAMETER - Table size is invalid + * XEN_NETIF_CTRL_STATUS_SUCCESS - Operation successful + * data = 0 + * + * NOTE: Setting data[0] to 0 means that hash mapping should be done + * using modular arithmetic. + * + * XEN_NETIF_CTRL_TYPE_SET_HASH_MAPPING + * ------------------------------------ + * + * This is sent by the frontend to set the content of the table mapping + * hash value to queue number. The backend should calculate the hash from + * the packet header, use it as an index into the table (modulo the size + * of the table) and then steer the packet to the queue number found at + * that index. + * + * Request: + * + * type = XEN_NETIF_CTRL_TYPE_SET_HASH_MAPPING + * data[0] = grant reference of page containing the mapping (sub-)table + * (assumed to start at beginning of grant) + * data[1] = size of (sub-)table in entries + * data[2] = offset, in entries, of sub-table within overall table + * + * Response: + * + * status = XEN_NETIF_CTRL_STATUS_NOT_SUPPORTED - Operation not + * supported + * XEN_NETIF_CTRL_STATUS_INVALID_PARAMETER - Table size or content + * is invalid + * XEN_NETIF_CTRL_STATUS_BUFFER_OVERFLOW - Table size is larger + * than the backend + * supports + * XEN_NETIF_CTRL_STATUS_SUCCESS - Operation successful + * data = 0 + * + * NOTE: The overall table has the following format: + * + * 0 1 2 3 4 5 6 7 octet + * +-----+-----+-----+-----+-----+-----+-----+-----+ + * | mapping[0] | mapping[1] | + * +-----+-----+-----+-----+-----+-----+-----+-----+ + * | . | + * | . | + * | . | + * +-----+-----+-----+-----+-----+-----+-----+-----+ + * | mapping[N-2] | mapping[N-1] | + * +-----+-----+-----+-----+-----+-----+-----+-----+ + * + * where N is specified by a XEN_NETIF_CTRL_TYPE_SET_HASH_MAPPING_SIZE + * message and each mapping must specifies a queue between 0 and + * "multi-queue-num-queues" (see above). + * The backend may support a mapping table larger than can be + * mapped by a single grant reference. Thus sub-tables within a + * larger table can be individually set by sending multiple messages + * with differing offset values. Specifying a new sub-table does not + * invalidate any table data outside that range. + * The grant reference may be read-only and must remain valid until + * the response has been processed. + */ + +DEFINE_RING_TYPES(xen_netif_ctrl, + struct xen_netif_ctrl_request, + struct xen_netif_ctrl_response); + +/* + * Guest transmit + * ============== + * + * This is the 'wire' format for transmit (frontend -> backend) packets: + * + * Fragment 1: xen_netif_tx_request_t - flags = XEN_NETTXF_* + * size = total packet size + * [Extra 1: xen_netif_extra_info_t] - (only if fragment 1 flags include + * XEN_NETTXF_extra_info) + * ... + * [Extra N: xen_netif_extra_info_t] - (only if extra N-1 flags include + * XEN_NETIF_EXTRA_MORE) + * ... + * Fragment N: xen_netif_tx_request_t - (only if fragment N-1 flags include + * XEN_NETTXF_more_data - flags on preceding + * extras are not relevant here) + * flags = 0 + * size = fragment size + * + * NOTE: + * + * This format slightly is different from that used for receive + * (backend -> frontend) packets. Specifically, in a multi-fragment + * packet the actual size of fragment 1 can only be determined by + * subtracting the sizes of fragments 2..N from the total packet size. + * + * Ring slot size is 12 octets, however not all request/response + * structs use the full size. + * + * tx request data (xen_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: XEN_NETTXF_*. + * id: request identifier, echoed in response. + * size: packet size in bytes. + * + * tx response (xen_netif_tx_response_t) + * --------------------------------- + * + * 0 1 2 3 4 5 6 7 octet + * +-----+-----+-----+-----+-----+-----+-----+-----+ + * | id | status | unused | + * +-----+-----+-----+-----+-----+-----+-----+-----+ + * | unused | + * +-----+-----+-----+-----+ + * + * id: reflects id in transmit request + * status: XEN_NETIF_RSP_* + * + * Guest receive + * ============= + * + * This is the 'wire' format for receive (backend -> frontend) packets: + * + * Fragment 1: xen_netif_rx_request_t - flags = XEN_NETRXF_* + * size = fragment size + * [Extra 1: xen_netif_extra_info_t] - (only if fragment 1 flags include + * XEN_NETRXF_extra_info) + * ... + * [Extra N: xen_netif_extra_info_t] - (only if extra N-1 flags include + * XEN_NETIF_EXTRA_MORE) + * ... + * Fragment N: xen_netif_rx_request_t - (only if fragment N-1 flags include + * XEN_NETRXF_more_data - flags on preceding + * extras are not relevant here) + * flags = 0 + * size = fragment size + * + * NOTE: + * + * This format slightly is different from that used for transmit + * (frontend -> backend) packets. Specifically, in a multi-fragment + * packet the size of the packet can only be determined by summing the + * sizes of fragments 1..N. + * + * Ring slot size is 8 octets. + * + * rx request (xen_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 (xen_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: XEN_NETRXF_* + * status: -ve: XEN_NETIF_RSP_*; +ve: Rx'ed pkt size. + * + * NOTE: Historically, to support GSO on the frontend receive side, Linux + * netfront does not make use of the rx response id (because, as + * described below, extra info structures overlay the id field). + * Instead it assumes that responses always appear in the same ring + * slot as their corresponding request. Thus, to maintain + * compatibility, backends must make sure this is the case. + * + * Extra Info + * ========== + * + * Can be present if initial request or response 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. + * + * NOTE: Because extra info data overlays the usual request/response + * structures, there is no id information in the opposite direction. + * So, if an extra info overlays an rx response the frontend can + * assume that it is in the same ring slot as the request that was + * consumed to make the slot available, and the backend must ensure + * this assumption is true. + * + * extra info (xen_netif_extra_info_t) + * ------------------------------- + * + * General format: + * + * 0 1 2 3 4 5 6 7 octet + * +-----+-----+-----+-----+-----+-----+-----+-----+ + * |type |flags| type specific 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. For example, + * for TCP this is just the path MSS. + * type: XEN_NETIF_GSO_TYPE_*: This determines the protocol of + * the packet and any extra features required to segment the + * packet properly. + * features: EN_XEN_NETIF_GSO_FEAT_*: This specifies any extra GSO + * features required to process this packet, such as ECN + * support for TCPv4. + * + * 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 + * + * XEN_NETIF_EXTRA_TYPE_HASH: + * + * A backend that supports teoplitz hashing is assumed to accept + * this type of extra info in transmit packets. + * A frontend that enables hashing is assumed to accept + * this type of extra info in receive packets. + * + * 0 1 2 3 4 5 6 7 octet + * +-----+-----+-----+-----+-----+-----+-----+-----+ + * |type |flags|htype| alg |LSB ---- value ---- MSB| + * +-----+-----+-----+-----+-----+-----+-----+-----+ + * + * type: Must be XEN_NETIF_EXTRA_TYPE_HASH + * flags: XEN_NETIF_EXTRA_FLAG_* + * htype: Hash type (one of _XEN_NETIF_CTRL_HASH_TYPE_* - see above) + * alg: The algorithm used to calculate the hash (one of + * XEN_NETIF_CTRL_HASH_TYPE_ALGORITHM_* - see above) + * value: Hash value + */ + +/* Protocol checksum field is blank in the packet (hardware offload)? */ +#define _XEN_NETTXF_csum_blank (0) +#define XEN_NETTXF_csum_blank (1U<<_XEN_NETTXF_csum_blank) + +/* Packet data has been validated against protocol checksum. */ +#define _XEN_NETTXF_data_validated (1) +#define XEN_NETTXF_data_validated (1U<<_XEN_NETTXF_data_validated) + +/* Packet continues in the next request descriptor. */ +#define _XEN_NETTXF_more_data (2) +#define XEN_NETTXF_more_data (1U<<_XEN_NETTXF_more_data) + +/* Packet to be followed by extra descriptor(s). */ +#define _XEN_NETTXF_extra_info (3) +#define XEN_NETTXF_extra_info (1U<<_XEN_NETTXF_extra_info) + +#define XEN_NETIF_MAX_TX_SIZE 0xFFFF +struct xen_netif_tx_request { + grant_ref_t gref; + uint16_t offset; + uint16_t flags; + uint16_t id; + uint16_t size; +}; + +/* Types of xen_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_HASH (4) /* u.hash */ +#define XEN_NETIF_EXTRA_TYPE_XDP (5) /* u.xdp */ +#define XEN_NETIF_EXTRA_TYPE_MAX (6) + +/* xen_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 xen_netif_tx_request_t and + * xen_netif_rx_response_t for compatibility. + */ +struct xen_netif_extra_info { + uint8_t type; + uint8_t flags; + union { + struct { + uint16_t size; + uint8_t type; + uint8_t pad; + uint16_t features; + } gso; + struct { + uint8_t addr[6]; + } mcast; + struct { + uint8_t type; + uint8_t algorithm; + uint8_t value[4]; + } hash; + struct { + uint16_t headroom; + uint16_t pad[2]; + } xdp; + uint16_t pad[3]; + } u; +}; + +struct xen_netif_tx_response { + uint16_t id; + int16_t status; +}; + +struct xen_netif_rx_request { + uint16_t id; /* Echoed in response message. */ + uint16_t pad; + grant_ref_t gref; +}; + +/* Packet data has been validated against protocol checksum. */ +#define _XEN_NETRXF_data_validated (0) +#define XEN_NETRXF_data_validated (1U<<_XEN_NETRXF_data_validated) + +/* Protocol checksum field is blank in the packet (hardware offload)? */ +#define _XEN_NETRXF_csum_blank (1) +#define XEN_NETRXF_csum_blank (1U<<_XEN_NETRXF_csum_blank) + +/* Packet continues in the next request descriptor. */ +#define _XEN_NETRXF_more_data (2) +#define XEN_NETRXF_more_data (1U<<_XEN_NETRXF_more_data) + +/* Packet to be followed by extra descriptor(s). */ +#define _XEN_NETRXF_extra_info (3) +#define XEN_NETRXF_extra_info (1U<<_XEN_NETRXF_extra_info) + +/* Packet has GSO prefix. Deprecated but included for compatibility */ +#define _XEN_NETRXF_gso_prefix (4) +#define XEN_NETRXF_gso_prefix (1U<<_XEN_NETRXF_gso_prefix) + +struct xen_netif_rx_response { + uint16_t id; + uint16_t offset; + uint16_t flags; + int16_t status; +}; + +/* + * Generate xen_netif ring structures and types. + */ + +DEFINE_RING_TYPES(xen_netif_tx, struct xen_netif_tx_request, + struct xen_netif_tx_response); +DEFINE_RING_TYPES(xen_netif_rx, struct xen_netif_rx_request, + struct xen_netif_rx_response); + +#define XEN_NETIF_RSP_DROPPED -2 +#define XEN_NETIF_RSP_ERROR -1 +#define XEN_NETIF_RSP_OKAY 0 +/* No response: used for auxiliary requests (e.g., xen_netif_extra_info_t). */ +#define XEN_NETIF_RSP_NULL 1 + +#endif |