net: enable IFF_VNET_HDR on tap fds if available
For now, we just add an empty header before writing and strip the header after reading. We really only want IFF_VNET_HDR when virtio_net is using it, but it would significantly complicate matters to try and do that. There should be little or no performance impact with always adding headers. Signed-off-by: Mark McLoughlin <markmc@redhat.com> Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
This commit is contained in:
Mark McLoughlin
Anthony Liguori
parent
38c75be313
commit
8e0f8e5bf8
83
net.c
83
net.c
@ -1260,14 +1260,20 @@ void do_info_usernet(Monitor *mon)
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#if !defined(_WIN32)
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/* Maximum GSO packet size (64k) plus plenty of room for
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* the ethernet and virtio_net headers
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*/
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#define TAP_BUFSIZE (4096 + 65536)
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typedef struct TAPState {
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VLANClientState *vc;
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int fd;
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char down_script[1024];
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char down_script_arg[128];
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uint8_t buf[4096];
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uint8_t buf[TAP_BUFSIZE];
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unsigned int read_poll : 1;
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unsigned int write_poll : 1;
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unsigned int has_vnet_hdr : 1;
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} TAPState;
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static int launch_script(const char *setup_script, const char *ifname, int fd);
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@ -1326,15 +1332,33 @@ static ssize_t tap_receive_iov(VLANClientState *vc, const struct iovec *iov,
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int iovcnt)
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{
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TAPState *s = vc->opaque;
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const struct iovec *iovp = iov;
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struct iovec iov_copy[iovcnt + 1];
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struct virtio_net_hdr hdr = { 0, };
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return tap_write_packet(s, iov, iovcnt);
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if (s->has_vnet_hdr) {
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iov_copy[0].iov_base = &hdr;
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iov_copy[0].iov_len = sizeof(hdr);
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memcpy(&iov_copy[1], iov, iovcnt * sizeof(*iov));
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iovp = iov_copy;
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iovcnt++;
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}
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return tap_write_packet(s, iovp, iovcnt);
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}
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static ssize_t tap_receive(VLANClientState *vc, const uint8_t *buf, size_t size)
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{
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TAPState *s = vc->opaque;
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struct iovec iov[1];
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struct iovec iov[2];
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int iovcnt = 0;
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struct virtio_net_hdr hdr = { 0, };
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if (s->has_vnet_hdr) {
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iov[iovcnt].iov_base = &hdr;
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iov[iovcnt].iov_len = sizeof(hdr);
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iovcnt++;
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}
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iov[iovcnt].iov_base = (char *)buf;
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iov[iovcnt].iov_len = size;
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@ -1380,12 +1404,19 @@ static void tap_send(void *opaque)
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int size;
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do {
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uint8_t *buf = s->buf;
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size = tap_read_packet(s->fd, s->buf, sizeof(s->buf));
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if (size <= 0) {
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break;
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}
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size = qemu_send_packet_async(s->vc, s->buf, size, tap_send_completed);
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if (s->has_vnet_hdr) {
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buf += sizeof(struct virtio_net_hdr);
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size -= sizeof(struct virtio_net_hdr);
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}
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size = qemu_send_packet_async(s->vc, buf, size, tap_send_completed);
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if (size == 0) {
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tap_read_poll(s, 0);
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}
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@ -1415,6 +1446,18 @@ static int tap_set_sndbuf(TAPState *s, QemuOpts *opts)
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return 0;
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}
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static int tap_probe_vnet_hdr(int fd)
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{
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struct ifreq ifr;
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if (ioctl(fd, TUNGETIFF, &ifr) != 0) {
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qemu_error("TUNGETIFF ioctl() failed: %s\n", strerror(errno));
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return 0;
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}
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return ifr.ifr_flags & IFF_VNET_HDR;
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}
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static void tap_cleanup(VLANClientState *vc)
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{
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TAPState *s = vc->opaque;
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@ -1435,12 +1478,14 @@ static void tap_cleanup(VLANClientState *vc)
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static TAPState *net_tap_fd_init(VLANState *vlan,
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const char *model,
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const char *name,
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int fd)
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int fd,
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int vnet_hdr)
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{
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TAPState *s;
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s = qemu_mallocz(sizeof(TAPState));
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s->fd = fd;
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s->has_vnet_hdr = vnet_hdr != 0;
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s->vc = qemu_new_vlan_client(vlan, NULL, model, name, NULL,
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tap_receive, tap_receive_iov,
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tap_cleanup, s);
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@ -1450,7 +1495,7 @@ static TAPState *net_tap_fd_init(VLANState *vlan,
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}
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#if defined (CONFIG_BSD) || defined (__FreeBSD_kernel__)
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static int tap_open(char *ifname, int ifname_size)
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static int tap_open(char *ifname, int ifname_size, int *vnet_hdr)
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{
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int fd;
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char *dev;
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@ -1592,7 +1637,7 @@ static int tap_alloc(char *dev, size_t dev_size)
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return tap_fd;
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}
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static int tap_open(char *ifname, int ifname_size)
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static int tap_open(char *ifname, int ifname_size, int *vnet_hdr)
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{
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char dev[10]="";
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int fd;
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@ -1605,13 +1650,13 @@ static int tap_open(char *ifname, int ifname_size)
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return fd;
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}
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#elif defined (_AIX)
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static int tap_open(char *ifname, int ifname_size)
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static int tap_open(char *ifname, int ifname_size, int *vnet_hdr)
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{
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fprintf (stderr, "no tap on AIX\n");
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return -1;
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}
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#else
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static int tap_open(char *ifname, int ifname_size)
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static int tap_open(char *ifname, int ifname_size, int *vnet_hdr)
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{
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struct ifreq ifr;
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int fd, ret;
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@ -1623,6 +1668,17 @@ static int tap_open(char *ifname, int ifname_size)
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}
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memset(&ifr, 0, sizeof(ifr));
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ifr.ifr_flags = IFF_TAP | IFF_NO_PI;
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{
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unsigned int features;
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if (ioctl(fd, TUNGETFEATURES, &features) == 0 &&
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features & IFF_VNET_HDR) {
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*vnet_hdr = 1;
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ifr.ifr_flags |= IFF_VNET_HDR;
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}
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}
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if (ifname[0] != '\0')
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pstrcpy(ifr.ifr_name, IFNAMSIZ, ifname);
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else
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@ -1688,14 +1744,15 @@ static TAPState *net_tap_init(VLANState *vlan, const char *model,
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const char *setup_script, const char *down_script)
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{
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TAPState *s;
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int fd;
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int fd, vnet_hdr;
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char ifname[128];
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if (ifname1 != NULL)
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pstrcpy(ifname, sizeof(ifname), ifname1);
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else
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ifname[0] = '\0';
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TFR(fd = tap_open(ifname, sizeof(ifname)));
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vnet_hdr = 0;
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TFR(fd = tap_open(ifname, sizeof(ifname), &vnet_hdr));
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if (fd < 0)
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return NULL;
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@ -1705,7 +1762,7 @@ static TAPState *net_tap_init(VLANState *vlan, const char *model,
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launch_script(setup_script, ifname, fd)) {
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return NULL;
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}
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s = net_tap_fd_init(vlan, model, name, fd);
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s = net_tap_fd_init(vlan, model, name, fd, vnet_hdr);
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snprintf(s->vc->info_str, sizeof(s->vc->info_str),
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"ifname=%s,script=%s,downscript=%s",
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ifname, setup_script, down_script);
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@ -2659,7 +2716,7 @@ static int net_init_tap(QemuOpts *opts,
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fcntl(fd, F_SETFL, O_NONBLOCK);
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s = net_tap_fd_init(vlan, "tap", name, fd);
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s = net_tap_fd_init(vlan, "tap", name, fd, tap_probe_vnet_hdr(fd));
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if (!s) {
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close(fd);
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}
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14
tap-linux.h
14
tap-linux.h
@ -16,14 +16,28 @@
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#ifndef QEMU_TAP_H
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#define QEMU_TAP_H
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#include <stdint.h>
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#include <linux/ioctl.h>
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/* Ioctl defines */
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#define TUNSETIFF _IOW('T', 202, int)
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#define TUNGETFEATURES _IOR('T', 207, unsigned int)
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#define TUNGETIFF _IOR('T', 210, unsigned int)
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#define TUNSETSNDBUF _IOW('T', 212, int)
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/* TUNSETIFF ifr flags */
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#define IFF_TAP 0x0002
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#define IFF_NO_PI 0x1000
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#define IFF_VNET_HDR 0x4000
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struct virtio_net_hdr
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{
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uint8_t flags;
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uint8_t gso_type;
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uint16_t hdr_len;
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uint16_t gso_size;
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uint16_t csum_start;
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uint16_t csum_offset;
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};
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#endif /* QEMU_TAP_H */
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