4 * Copyright (c) 2003-2008 Fabrice Bellard
5 * Copyright (c) 2009 Red Hat, Inc.
7 * Permission is hereby granted, free of charge, to any person obtaining a copy
8 * of this software and associated documentation files (the "Software"), to deal
9 * in the Software without restriction, including without limitation the rights
10 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
11 * copies of the Software, and to permit persons to whom the Software is
12 * furnished to do so, subject to the following conditions:
14 * The above copyright notice and this permission notice shall be included in
15 * all copies or substantial portions of the Software.
17 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
18 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
19 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
20 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
21 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
22 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
26 #include "qemu/osdep.h"
28 #include "tap-linux.h"
32 #include <sys/ioctl.h>
34 #include "qapi/error.h"
35 #include "qemu/error-report.h"
36 #include "qemu/cutils.h"
38 #define PATH_NET_TUN "/dev/net/tun"
40 int tap_open(char *ifname, int ifname_size, int *vnet_hdr,
41 int vnet_hdr_required, int mq_required, Error **errp)
45 int len = sizeof(struct virtio_net_hdr);
46 unsigned int features;
48 fd = RETRY_ON_EINTR(open(PATH_NET_TUN, O_RDWR));
50 error_setg_errno(errp, errno, "could not open %s", PATH_NET_TUN);
53 memset(&ifr, 0, sizeof(ifr));
54 ifr.ifr_flags = IFF_TAP | IFF_NO_PI;
56 if (ioctl(fd, TUNGETFEATURES, &features) == -1) {
57 warn_report("TUNGETFEATURES failed: %s", strerror(errno));
61 if (features & IFF_ONE_QUEUE) {
62 ifr.ifr_flags |= IFF_ONE_QUEUE;
66 if (features & IFF_VNET_HDR) {
68 ifr.ifr_flags |= IFF_VNET_HDR;
73 if (vnet_hdr_required && !*vnet_hdr) {
74 error_setg(errp, "vnet_hdr=1 requested, but no kernel "
75 "support for IFF_VNET_HDR available");
80 * Make sure vnet header size has the default value: for a persistent
81 * tap it might have been modified e.g. by another instance of qemu.
82 * Ignore errors since old kernels do not support this ioctl: in this
83 * case the header size implicitly has the correct value.
85 ioctl(fd, TUNSETVNETHDRSZ, &len);
89 if (!(features & IFF_MULTI_QUEUE)) {
90 error_setg(errp, "multiqueue required, but no kernel "
91 "support for IFF_MULTI_QUEUE available");
95 ifr.ifr_flags |= IFF_MULTI_QUEUE;
99 if (ifname[0] != '\0')
100 pstrcpy(ifr.ifr_name, IFNAMSIZ, ifname);
102 pstrcpy(ifr.ifr_name, IFNAMSIZ, "tap%d");
103 ret = ioctl(fd, TUNSETIFF, (void *) &ifr);
105 if (ifname[0] != '\0') {
106 error_setg_errno(errp, errno, "could not configure %s (%s)",
107 PATH_NET_TUN, ifr.ifr_name);
109 error_setg_errno(errp, errno, "could not configure %s",
115 pstrcpy(ifname, ifname_size, ifr.ifr_name);
116 g_unix_set_fd_nonblocking(fd, true, NULL);
120 /* sndbuf implements a kind of flow control for tap.
121 * Unfortunately when it's enabled, and packets are sent
122 * to other guests on the same host, the receiver
123 * can lock up the transmitter indefinitely.
125 * To avoid packet loss, sndbuf should be set to a value lower than the tx
126 * queue capacity of any destination network interface.
127 * Ethernet NICs generally have txqueuelen=1000, so 1Mb is
128 * a good value, given a 1500 byte MTU.
130 #define TAP_DEFAULT_SNDBUF 0
132 void tap_set_sndbuf(int fd, const NetdevTapOptions *tap, Error **errp)
136 sndbuf = !tap->has_sndbuf ? TAP_DEFAULT_SNDBUF :
137 tap->sndbuf > INT_MAX ? INT_MAX :
144 if (ioctl(fd, TUNSETSNDBUF, &sndbuf) == -1 && tap->has_sndbuf) {
145 error_setg_errno(errp, errno, "TUNSETSNDBUF ioctl failed");
149 int tap_probe_vnet_hdr(int fd, Error **errp)
152 memset(&ifr, 0, sizeof(ifr));
154 if (ioctl(fd, TUNGETIFF, &ifr) != 0) {
155 /* TUNGETIFF is available since kernel v2.6.27 */
156 error_setg_errno(errp, errno,
157 "Unable to query TUNGETIFF on FD %d", fd);
161 return ifr.ifr_flags & IFF_VNET_HDR;
164 int tap_probe_has_ufo(int fd)
168 offload = TUN_F_CSUM | TUN_F_UFO;
170 if (ioctl(fd, TUNSETOFFLOAD, offload) < 0)
176 int tap_probe_has_uso(int fd)
180 offload = TUN_F_CSUM | TUN_F_USO4 | TUN_F_USO6;
182 if (ioctl(fd, TUNSETOFFLOAD, offload) < 0) {
188 /* Verify that we can assign given length */
189 int tap_probe_vnet_hdr_len(int fd, int len)
192 if (ioctl(fd, TUNGETVNETHDRSZ, &orig) == -1) {
195 if (ioctl(fd, TUNSETVNETHDRSZ, &len) == -1) {
198 /* Restore original length: we can't handle failure. */
199 if (ioctl(fd, TUNSETVNETHDRSZ, &orig) == -1) {
200 fprintf(stderr, "TUNGETVNETHDRSZ ioctl() failed: %s. Exiting.\n",
208 void tap_fd_set_vnet_hdr_len(int fd, int len)
210 if (ioctl(fd, TUNSETVNETHDRSZ, &len) == -1) {
211 fprintf(stderr, "TUNSETVNETHDRSZ ioctl() failed: %s. Exiting.\n",
217 int tap_fd_set_vnet_le(int fd, int is_le)
219 int arg = is_le ? 1 : 0;
221 if (!ioctl(fd, TUNSETVNETLE, &arg)) {
225 /* Check if our kernel supports TUNSETVNETLE */
226 if (errno == EINVAL) {
230 error_report("TUNSETVNETLE ioctl() failed: %s.", strerror(errno));
234 int tap_fd_set_vnet_be(int fd, int is_be)
236 int arg = is_be ? 1 : 0;
238 if (!ioctl(fd, TUNSETVNETBE, &arg)) {
242 /* Check if our kernel supports TUNSETVNETBE */
243 if (errno == EINVAL) {
247 error_report("TUNSETVNETBE ioctl() failed: %s.", strerror(errno));
251 void tap_fd_set_offload(int fd, int csum, int tso4,
252 int tso6, int ecn, int ufo, int uso4, int uso6)
254 unsigned int offload = 0;
256 /* Check if our kernel supports TUNSETOFFLOAD */
257 if (ioctl(fd, TUNSETOFFLOAD, 0) != 0 && errno == EINVAL) {
262 offload |= TUN_F_CSUM;
264 offload |= TUN_F_TSO4;
266 offload |= TUN_F_TSO6;
267 if ((tso4 || tso6) && ecn)
268 offload |= TUN_F_TSO_ECN;
270 offload |= TUN_F_UFO;
272 offload |= TUN_F_USO4;
275 offload |= TUN_F_USO6;
279 if (ioctl(fd, TUNSETOFFLOAD, offload) != 0) {
280 offload &= ~(TUN_F_USO4 | TUN_F_USO6);
281 if (ioctl(fd, TUNSETOFFLOAD, offload) != 0) {
282 offload &= ~TUN_F_UFO;
283 if (ioctl(fd, TUNSETOFFLOAD, offload) != 0) {
284 fprintf(stderr, "TUNSETOFFLOAD ioctl() failed: %s\n",
291 /* Enable a specific queue of tap. */
292 int tap_fd_enable(int fd)
297 memset(&ifr, 0, sizeof(ifr));
299 ifr.ifr_flags = IFF_ATTACH_QUEUE;
300 ret = ioctl(fd, TUNSETQUEUE, (void *) &ifr);
303 error_report("could not enable queue");
309 /* Disable a specific queue of tap/ */
310 int tap_fd_disable(int fd)
315 memset(&ifr, 0, sizeof(ifr));
317 ifr.ifr_flags = IFF_DETACH_QUEUE;
318 ret = ioctl(fd, TUNSETQUEUE, (void *) &ifr);
321 error_report("could not disable queue");
327 int tap_fd_get_ifname(int fd, char *ifname)
331 if (ioctl(fd, TUNGETIFF, &ifr) != 0) {
332 error_report("TUNGETIFF ioctl() failed: %s",
337 pstrcpy(ifname, sizeof(ifr.ifr_name), ifr.ifr_name);
341 int tap_fd_set_steering_ebpf(int fd, int prog_fd)
343 if (ioctl(fd, TUNSETSTEERINGEBPF, (void *) &prog_fd) != 0) {
344 error_report("Issue while setting TUNSETSTEERINGEBPF:"
345 " %s with fd: %d, prog_fd: %d",
346 strerror(errno), fd, prog_fd);