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+/******************************************************************************
+ * 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__
+
+FILE_LICENCE ( MIT );
+
+#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.
+ */
+
+/*
+ * This is the 'wire' format for packets:
+ * Request 1: netif_tx_request -- NETTXF_* (any flags)
+ * [Request 2: netif_tx_extra] (only if request 1 has NETTXF_extra_info)
+ * [Request 3: netif_tx_extra] (only if request 2 has XEN_NETIF_EXTRA_MORE)
+ * Request 4: netif_tx_request -- NETTXF_more_data
+ * Request 5: netif_tx_request -- NETTXF_more_data
+ * ...
+ * Request N: netif_tx_request -- 0
+ */
+
+/* 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 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 and
+ * netif_rx_response 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}:
+ * Backend advertises availability via 'feature-multicast-control'
+ * xenbus node containing value '1'.
+ * Frontend requests this feature by advertising
+ * 'request-multicast-control' xenbus node containing value '1'.
+ * If multicast control is requested then multicast flooding is
+ * disabled and the frontend must explicitly register its interest
+ * in multicast groups using dummy transmit requests containing
+ * MCAST_{ADD,DEL} extra-info fragments.
+ */
+ 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. */
+ 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_tx_extra). */
+#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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