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/* SPDX-License-Identifier: BSD-3-Clause
* Copyright(c) 2016 Intel Corporation
*/
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <net/if.h>
#include <errno.h>
#include <string.h>
#include <limits.h>
#include "vhost_kernel_tap.h"
#include "../virtio_logs.h"
int
vhost_kernel_open_tap(char **p_ifname, int hdr_size, int req_mq)
{
unsigned int tap_features;
int sndbuf = INT_MAX;
struct ifreq ifr;
int tapfd;
unsigned int offload =
TUN_F_CSUM |
TUN_F_TSO4 |
TUN_F_TSO6 |
TUN_F_TSO_ECN |
TUN_F_UFO;
/* TODO:
* 1. verify we can get/set vnet_hdr_len, tap_probe_vnet_hdr_len
* 2. get number of memory regions from vhost module parameter
* max_mem_regions, supported in newer version linux kernel
*/
tapfd = open(PATH_NET_TUN, O_RDWR);
if (tapfd < 0) {
PMD_DRV_LOG(ERR, "fail to open %s: %s",
PATH_NET_TUN, strerror(errno));
return -1;
}
/* Construct ifr */
memset(&ifr, 0, sizeof(ifr));
ifr.ifr_flags = IFF_TAP | IFF_NO_PI;
if (ioctl(tapfd, TUNGETFEATURES, &tap_features) == -1) {
PMD_DRV_LOG(ERR, "TUNGETFEATURES failed: %s", strerror(errno));
goto error;
}
if (tap_features & IFF_ONE_QUEUE)
ifr.ifr_flags |= IFF_ONE_QUEUE;
/* Let tap instead of vhost-net handle vnet header, as the latter does
* not support offloading. And in this case, we should not set feature
* bit VHOST_NET_F_VIRTIO_NET_HDR.
*/
if (tap_features & IFF_VNET_HDR) {
ifr.ifr_flags |= IFF_VNET_HDR;
} else {
PMD_DRV_LOG(ERR, "TAP does not support IFF_VNET_HDR");
goto error;
}
if (req_mq)
ifr.ifr_flags |= IFF_MULTI_QUEUE;
if (*p_ifname)
strncpy(ifr.ifr_name, *p_ifname, IFNAMSIZ - 1);
else
strncpy(ifr.ifr_name, "tap%d", IFNAMSIZ - 1);
if (ioctl(tapfd, TUNSETIFF, (void *)&ifr) == -1) {
PMD_DRV_LOG(ERR, "TUNSETIFF failed: %s", strerror(errno));
goto error;
}
fcntl(tapfd, F_SETFL, O_NONBLOCK);
if (ioctl(tapfd, TUNSETVNETHDRSZ, &hdr_size) < 0) {
PMD_DRV_LOG(ERR, "TUNSETVNETHDRSZ failed: %s", strerror(errno));
goto error;
}
if (ioctl(tapfd, TUNSETSNDBUF, &sndbuf) < 0) {
PMD_DRV_LOG(ERR, "TUNSETSNDBUF failed: %s", strerror(errno));
goto error;
}
/* TODO: before set the offload capabilities, we'd better (1) check
* negotiated features to see if necessary to offload; (2) query tap
* to see if it supports the offload capabilities.
*/
if (ioctl(tapfd, TUNSETOFFLOAD, offload) != 0)
PMD_DRV_LOG(ERR, "TUNSETOFFLOAD ioctl() failed: %s",
strerror(errno));
if (!(*p_ifname))
*p_ifname = strdup(ifr.ifr_name);
return tapfd;
error:
close(tapfd);
return -1;
}
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