trap signals for "-serial mon:stdio"
[qemu.git] / net / tap-linux.c
1 /*
2 * QEMU System Emulator
3 *
4 * Copyright (c) 2003-2008 Fabrice Bellard
5 * Copyright (c) 2009 Red Hat, Inc.
6 *
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:
13 *
14 * The above copyright notice and this permission notice shall be included in
15 * all copies or substantial portions of the Software.
16 *
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
23 * THE SOFTWARE.
24 */
25
26 #include "tap_int.h"
27 #include "tap-linux.h"
28 #include "net/tap.h"
29
30 #include <net/if.h>
31 #include <sys/ioctl.h>
32
33 #include "sysemu/sysemu.h"
34 #include "qemu-common.h"
35 #include "qemu/error-report.h"
36
37 #define PATH_NET_TUN "/dev/net/tun"
38
39 int tap_open(char *ifname, int ifname_size, int *vnet_hdr,
40 int vnet_hdr_required, int mq_required)
41 {
42 struct ifreq ifr;
43 int fd, ret;
44 int len = sizeof(struct virtio_net_hdr);
45 unsigned int features;
46
47 TFR(fd = open(PATH_NET_TUN, O_RDWR));
48 if (fd < 0) {
49 error_report("could not open %s: %m", PATH_NET_TUN);
50 return -1;
51 }
52 memset(&ifr, 0, sizeof(ifr));
53 ifr.ifr_flags = IFF_TAP | IFF_NO_PI;
54
55 if (ioctl(fd, TUNGETFEATURES, &features) == 0 &&
56 features & IFF_ONE_QUEUE) {
57 ifr.ifr_flags |= IFF_ONE_QUEUE;
58 }
59
60 if (*vnet_hdr) {
61 if (ioctl(fd, TUNGETFEATURES, &features) == 0 &&
62 features & IFF_VNET_HDR) {
63 *vnet_hdr = 1;
64 ifr.ifr_flags |= IFF_VNET_HDR;
65 } else {
66 *vnet_hdr = 0;
67 }
68
69 if (vnet_hdr_required && !*vnet_hdr) {
70 error_report("vnet_hdr=1 requested, but no kernel "
71 "support for IFF_VNET_HDR available");
72 close(fd);
73 return -1;
74 }
75 /*
76 * Make sure vnet header size has the default value: for a persistent
77 * tap it might have been modified e.g. by another instance of qemu.
78 * Ignore errors since old kernels do not support this ioctl: in this
79 * case the header size implicitly has the correct value.
80 */
81 ioctl(fd, TUNSETVNETHDRSZ, &len);
82 }
83
84 if (mq_required) {
85 if ((ioctl(fd, TUNGETFEATURES, &features) != 0) ||
86 !(features & IFF_MULTI_QUEUE)) {
87 error_report("multiqueue required, but no kernel "
88 "support for IFF_MULTI_QUEUE available");
89 close(fd);
90 return -1;
91 } else {
92 ifr.ifr_flags |= IFF_MULTI_QUEUE;
93 }
94 }
95
96 if (ifname[0] != '\0')
97 pstrcpy(ifr.ifr_name, IFNAMSIZ, ifname);
98 else
99 pstrcpy(ifr.ifr_name, IFNAMSIZ, "tap%d");
100 ret = ioctl(fd, TUNSETIFF, (void *) &ifr);
101 if (ret != 0) {
102 if (ifname[0] != '\0') {
103 error_report("could not configure %s (%s): %m", PATH_NET_TUN, ifr.ifr_name);
104 } else {
105 error_report("could not configure %s: %m", PATH_NET_TUN);
106 }
107 close(fd);
108 return -1;
109 }
110 pstrcpy(ifname, ifname_size, ifr.ifr_name);
111 fcntl(fd, F_SETFL, O_NONBLOCK);
112 return fd;
113 }
114
115 /* sndbuf implements a kind of flow control for tap.
116 * Unfortunately when it's enabled, and packets are sent
117 * to other guests on the same host, the receiver
118 * can lock up the transmitter indefinitely.
119 *
120 * To avoid packet loss, sndbuf should be set to a value lower than the tx
121 * queue capacity of any destination network interface.
122 * Ethernet NICs generally have txqueuelen=1000, so 1Mb is
123 * a good value, given a 1500 byte MTU.
124 */
125 #define TAP_DEFAULT_SNDBUF 0
126
127 int tap_set_sndbuf(int fd, const NetdevTapOptions *tap)
128 {
129 int sndbuf;
130
131 sndbuf = !tap->has_sndbuf ? TAP_DEFAULT_SNDBUF :
132 tap->sndbuf > INT_MAX ? INT_MAX :
133 tap->sndbuf;
134
135 if (!sndbuf) {
136 sndbuf = INT_MAX;
137 }
138
139 if (ioctl(fd, TUNSETSNDBUF, &sndbuf) == -1 && tap->has_sndbuf) {
140 error_report("TUNSETSNDBUF ioctl failed: %s", strerror(errno));
141 return -1;
142 }
143 return 0;
144 }
145
146 int tap_probe_vnet_hdr(int fd)
147 {
148 struct ifreq ifr;
149
150 if (ioctl(fd, TUNGETIFF, &ifr) != 0) {
151 error_report("TUNGETIFF ioctl() failed: %s", strerror(errno));
152 return 0;
153 }
154
155 return ifr.ifr_flags & IFF_VNET_HDR;
156 }
157
158 int tap_probe_has_ufo(int fd)
159 {
160 unsigned offload;
161
162 offload = TUN_F_CSUM | TUN_F_UFO;
163
164 if (ioctl(fd, TUNSETOFFLOAD, offload) < 0)
165 return 0;
166
167 return 1;
168 }
169
170 /* Verify that we can assign given length */
171 int tap_probe_vnet_hdr_len(int fd, int len)
172 {
173 int orig;
174 if (ioctl(fd, TUNGETVNETHDRSZ, &orig) == -1) {
175 return 0;
176 }
177 if (ioctl(fd, TUNSETVNETHDRSZ, &len) == -1) {
178 return 0;
179 }
180 /* Restore original length: we can't handle failure. */
181 if (ioctl(fd, TUNSETVNETHDRSZ, &orig) == -1) {
182 fprintf(stderr, "TUNGETVNETHDRSZ ioctl() failed: %s. Exiting.\n",
183 strerror(errno));
184 abort();
185 return -errno;
186 }
187 return 1;
188 }
189
190 void tap_fd_set_vnet_hdr_len(int fd, int len)
191 {
192 if (ioctl(fd, TUNSETVNETHDRSZ, &len) == -1) {
193 fprintf(stderr, "TUNSETVNETHDRSZ ioctl() failed: %s. Exiting.\n",
194 strerror(errno));
195 abort();
196 }
197 }
198
199 void tap_fd_set_offload(int fd, int csum, int tso4,
200 int tso6, int ecn, int ufo)
201 {
202 unsigned int offload = 0;
203
204 /* Check if our kernel supports TUNSETOFFLOAD */
205 if (ioctl(fd, TUNSETOFFLOAD, 0) != 0 && errno == EINVAL) {
206 return;
207 }
208
209 if (csum) {
210 offload |= TUN_F_CSUM;
211 if (tso4)
212 offload |= TUN_F_TSO4;
213 if (tso6)
214 offload |= TUN_F_TSO6;
215 if ((tso4 || tso6) && ecn)
216 offload |= TUN_F_TSO_ECN;
217 if (ufo)
218 offload |= TUN_F_UFO;
219 }
220
221 if (ioctl(fd, TUNSETOFFLOAD, offload) != 0) {
222 offload &= ~TUN_F_UFO;
223 if (ioctl(fd, TUNSETOFFLOAD, offload) != 0) {
224 fprintf(stderr, "TUNSETOFFLOAD ioctl() failed: %s\n",
225 strerror(errno));
226 }
227 }
228 }
229
230 /* Enable a specific queue of tap. */
231 int tap_fd_enable(int fd)
232 {
233 struct ifreq ifr;
234 int ret;
235
236 memset(&ifr, 0, sizeof(ifr));
237
238 ifr.ifr_flags = IFF_ATTACH_QUEUE;
239 ret = ioctl(fd, TUNSETQUEUE, (void *) &ifr);
240
241 if (ret != 0) {
242 error_report("could not enable queue");
243 }
244
245 return ret;
246 }
247
248 /* Disable a specific queue of tap/ */
249 int tap_fd_disable(int fd)
250 {
251 struct ifreq ifr;
252 int ret;
253
254 memset(&ifr, 0, sizeof(ifr));
255
256 ifr.ifr_flags = IFF_DETACH_QUEUE;
257 ret = ioctl(fd, TUNSETQUEUE, (void *) &ifr);
258
259 if (ret != 0) {
260 error_report("could not disable queue");
261 }
262
263 return ret;
264 }
265
266 int tap_fd_get_ifname(int fd, char *ifname)
267 {
268 struct ifreq ifr;
269
270 if (ioctl(fd, TUNGETIFF, &ifr) != 0) {
271 error_report("TUNGETIFF ioctl() failed: %s",
272 strerror(errno));
273 return -1;
274 }
275
276 pstrcpy(ifname, sizeof(ifr.ifr_name), ifr.ifr_name);
277 return 0;
278 }