This patch adds a new netbe_peek_recvlen() function to the net backend API. The new function allows the virtio-net receive code to know in advance how many virtio descriptors chains will be needed to receive the next packet. As a result, the implementation of the virtio-net mergeable rx buffers feature becomes efficient, so that we can enable it also with the tap(4) backend. For the tap(4) backend, a bounce buffer is introduced to implement the peeck_recvlen() callback, which implies an additional packet copy on the receive datapath. In the future, it should be possible to remove the bounce buffer (and so the additional copy), by obtaining the length of the next packet from kevent data. Reviewed by: grehan, aleksandr.fedorov@itglobal.com MFC after: 1 week Differential Revision: https://reviews.freebsd.org/D23472
94 lines
4.1 KiB
C
94 lines
4.1 KiB
C
/*-
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* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
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*
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* Copyright (c) 2019 Vincenzo Maffione <vmaffione@FreeBSD.org>
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS
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* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
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* OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
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* OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
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* BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
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* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
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* OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
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* EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* $FreeBSD$
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*/
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#ifndef __NET_BACKENDS_H__
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#define __NET_BACKENDS_H__
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#include <stdint.h>
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/* Opaque type representing a network backend. */
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typedef struct net_backend net_backend_t;
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/* Interface between network frontends and the network backends. */
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typedef void (*net_be_rxeof_t)(int, enum ev_type, void *param);
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int netbe_init(net_backend_t **be, const char *devname, net_be_rxeof_t cb,
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void *param);
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void netbe_cleanup(net_backend_t *be);
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uint64_t netbe_get_cap(net_backend_t *be);
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int netbe_set_cap(net_backend_t *be, uint64_t cap,
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unsigned vnet_hdr_len);
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size_t netbe_get_vnet_hdr_len(net_backend_t *be);
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ssize_t netbe_send(net_backend_t *be, const struct iovec *iov, int iovcnt);
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ssize_t netbe_peek_recvlen(net_backend_t *be);
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ssize_t netbe_recv(net_backend_t *be, const struct iovec *iov, int iovcnt);
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ssize_t netbe_rx_discard(net_backend_t *be);
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void netbe_rx_disable(net_backend_t *be);
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void netbe_rx_enable(net_backend_t *be);
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/*
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* Network device capabilities taken from the VirtIO standard.
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* Despite the name, these capabilities can be used by different frontents
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* (virtio-net, ptnet) and supported by different backends (netmap, tap, ...).
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*/
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#define VIRTIO_NET_F_CSUM (1 << 0) /* host handles partial cksum */
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#define VIRTIO_NET_F_GUEST_CSUM (1 << 1) /* guest handles partial cksum */
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#define VIRTIO_NET_F_MAC (1 << 5) /* host supplies MAC */
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#define VIRTIO_NET_F_GSO_DEPREC (1 << 6) /* deprecated: host handles GSO */
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#define VIRTIO_NET_F_GUEST_TSO4 (1 << 7) /* guest can rcv TSOv4 */
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#define VIRTIO_NET_F_GUEST_TSO6 (1 << 8) /* guest can rcv TSOv6 */
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#define VIRTIO_NET_F_GUEST_ECN (1 << 9) /* guest can rcv TSO with ECN */
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#define VIRTIO_NET_F_GUEST_UFO (1 << 10) /* guest can rcv UFO */
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#define VIRTIO_NET_F_HOST_TSO4 (1 << 11) /* host can rcv TSOv4 */
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#define VIRTIO_NET_F_HOST_TSO6 (1 << 12) /* host can rcv TSOv6 */
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#define VIRTIO_NET_F_HOST_ECN (1 << 13) /* host can rcv TSO with ECN */
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#define VIRTIO_NET_F_HOST_UFO (1 << 14) /* host can rcv UFO */
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#define VIRTIO_NET_F_MRG_RXBUF (1 << 15) /* host can merge RX buffers */
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#define VIRTIO_NET_F_STATUS (1 << 16) /* config status field available */
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#define VIRTIO_NET_F_CTRL_VQ (1 << 17) /* control channel available */
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#define VIRTIO_NET_F_CTRL_RX (1 << 18) /* control channel RX mode support */
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#define VIRTIO_NET_F_CTRL_VLAN (1 << 19) /* control channel VLAN filtering */
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#define VIRTIO_NET_F_GUEST_ANNOUNCE \
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(1 << 21) /* guest can send gratuitous pkts */
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/*
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* Fixed network header size
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*/
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struct virtio_net_rxhdr {
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uint8_t vrh_flags;
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uint8_t vrh_gso_type;
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uint16_t vrh_hdr_len;
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uint16_t vrh_gso_size;
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uint16_t vrh_csum_start;
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uint16_t vrh_csum_offset;
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uint16_t vrh_bufs;
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} __packed;
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#endif /* __NET_BACKENDS_H__ */
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