drivers/net/virtio/virtio_user/vhost_kernel_tap.c

   1 /* SPDX-License-Identifier: BSD-3-Clause
   2  * Copyright(c) 2016 Intel Corporation
   3  */
   4
   5 #include <unistd.h>
   6 #include <sys/types.h>
   7 #include <sys/stat.h>
   8 #include <fcntl.h>
   9 #include <net/if.h>
  10 #include <net/if_arp.h>
  11 #include <errno.h>
  12 #include <string.h>
  13 #include <limits.h>
  14
  15 #include <rte_ether.h>
  16
  17 #include "vhost_kernel_tap.h"
  18 #include "../virtio_logs.h"
  19
  20 int
  21 vhost_kernel_open_tap(char **p_ifname, int hdr_size, int req_mq,
  22                          const char *mac)
  23 {
  24         unsigned int tap_features;
  25         int sndbuf = INT_MAX;
  26         struct ifreq ifr;
  27         int tapfd;
  28         unsigned int offload =
  29                         TUN_F_CSUM |
  30                         TUN_F_TSO4 |
  31                         TUN_F_TSO6 |
  32                         TUN_F_TSO_ECN |
  33                         TUN_F_UFO;
  34
  35         /* TODO:
  36          * 1. verify we can get/set vnet_hdr_len, tap_probe_vnet_hdr_len
  37          * 2. get number of memory regions from vhost module parameter
  38          * max_mem_regions, supported in newer version linux kernel
  39          */
  40         tapfd = open(PATH_NET_TUN, O_RDWR);
  41         if (tapfd < 0) {
  42                 PMD_DRV_LOG(ERR, "fail to open %s: %s",
  43                             PATH_NET_TUN, strerror(errno));
  44                 return -1;
  45         }
  46
  47         /* Construct ifr */
  48         memset(&ifr, 0, sizeof(ifr));
  49         ifr.ifr_flags = IFF_TAP | IFF_NO_PI;
  50
  51         if (ioctl(tapfd, TUNGETFEATURES, &tap_features) == -1) {
  52                 PMD_DRV_LOG(ERR, "TUNGETFEATURES failed: %s", strerror(errno));
  53                 goto error;
  54         }
  55         if (tap_features & IFF_ONE_QUEUE)
  56                 ifr.ifr_flags |= IFF_ONE_QUEUE;
  57
  58         /* Let tap instead of vhost-net handle vnet header, as the latter does
  59          * not support offloading. And in this case, we should not set feature
  60          * bit VHOST_NET_F_VIRTIO_NET_HDR.
  61          */
  62         if (tap_features & IFF_VNET_HDR) {
  63                 ifr.ifr_flags |= IFF_VNET_HDR;
  64         } else {
  65                 PMD_DRV_LOG(ERR, "TAP does not support IFF_VNET_HDR");
  66                 goto error;
  67         }
  68
  69         if (req_mq)
  70                 ifr.ifr_flags |= IFF_MULTI_QUEUE;
  71
  72         if (*p_ifname)
  73                 strncpy(ifr.ifr_name, *p_ifname, IFNAMSIZ - 1);
  74         else
  75                 strncpy(ifr.ifr_name, "tap%d", IFNAMSIZ - 1);
  76         if (ioctl(tapfd, TUNSETIFF, (void *)&ifr) == -1) {
  77                 PMD_DRV_LOG(ERR, "TUNSETIFF failed: %s", strerror(errno));
  78                 goto error;
  79         }
  80
  81         fcntl(tapfd, F_SETFL, O_NONBLOCK);
  82
  83         if (ioctl(tapfd, TUNSETVNETHDRSZ, &hdr_size) < 0) {
  84                 PMD_DRV_LOG(ERR, "TUNSETVNETHDRSZ failed: %s", strerror(errno));
  85                 goto error;
  86         }
  87
  88         if (ioctl(tapfd, TUNSETSNDBUF, &sndbuf) < 0) {
  89                 PMD_DRV_LOG(ERR, "TUNSETSNDBUF failed: %s", strerror(errno));
  90                 goto error;
  91         }
  92
  93         /* TODO: before set the offload capabilities, we'd better (1) check
  94          * negotiated features to see if necessary to offload; (2) query tap
  95          * to see if it supports the offload capabilities.
  96          */
  97         if (ioctl(tapfd, TUNSETOFFLOAD, offload) != 0)
  98                 PMD_DRV_LOG(ERR, "TUNSETOFFLOAD ioctl() failed: %s",
  99                            strerror(errno));
 100
 101         memset(&ifr, 0, sizeof(ifr));
 102         ifr.ifr_hwaddr.sa_family = ARPHRD_ETHER;
 103         memcpy(ifr.ifr_hwaddr.sa_data, mac, ETHER_ADDR_LEN);
 104         if (ioctl(tapfd, SIOCSIFHWADDR, (void *)&ifr) == -1) {
 105                 PMD_DRV_LOG(ERR, "SIOCSIFHWADDR failed: %s", strerror(errno));
 106                 goto error;
 107         }
 108
 109         if (!(*p_ifname))
 110                 *p_ifname = strdup(ifr.ifr_name);
 111
 112         return tapfd;
 113 error:
 114         close(tapfd);
 115         return -1;
 116 }