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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>
master
Mark McLoughlin 2009-10-22 17:43:35 +01:00 committed by Anthony Liguori
parent 38c75be313
commit 8e0f8e5bf8
2 changed files with 84 additions and 13 deletions
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83
net.c
View File

@ -1260,14 +1260,20 @@ void do_info_usernet(Monitor *mon)
#if !defined(_WIN32) #if !defined(_WIN32)
/* Maximum GSO packet size (64k) plus plenty of room for
* the ethernet and virtio_net headers
*/
#define TAP_BUFSIZE (4096 + 65536)
typedef struct TAPState { typedef struct TAPState {
VLANClientState *vc; VLANClientState *vc;
int fd; int fd;
char down_script[1024]; char down_script[1024];
char down_script_arg[128]; char down_script_arg[128];
uint8_t buf[4096]; uint8_t buf[TAP_BUFSIZE];
unsigned int read_poll : 1; unsigned int read_poll : 1;
unsigned int write_poll : 1; unsigned int write_poll : 1;
unsigned int has_vnet_hdr : 1;
} TAPState; } TAPState;
static int launch_script(const char *setup_script, const char *ifname, int fd); static int launch_script(const char *setup_script, const char *ifname, int fd);
@ -1326,15 +1332,33 @@ static ssize_t tap_receive_iov(VLANClientState *vc, const struct iovec *iov,
int iovcnt) int iovcnt)
{ {
TAPState *s = vc->opaque; TAPState *s = vc->opaque;
const struct iovec *iovp = iov;
struct iovec iov_copy[iovcnt + 1];
struct virtio_net_hdr hdr = { 0, };
return tap_write_packet(s, iov, iovcnt); if (s->has_vnet_hdr) {
iov_copy[0].iov_base = &hdr;
iov_copy[0].iov_len = sizeof(hdr);
memcpy(&iov_copy[1], iov, iovcnt * sizeof(*iov));
iovp = iov_copy;
iovcnt++;
}
return tap_write_packet(s, iovp, iovcnt);
} }
static ssize_t tap_receive(VLANClientState *vc, const uint8_t *buf, size_t size) static ssize_t tap_receive(VLANClientState *vc, const uint8_t *buf, size_t size)
{ {
TAPState *s = vc->opaque; TAPState *s = vc->opaque;
struct iovec iov[1]; struct iovec iov[2];
int iovcnt = 0; int iovcnt = 0;
struct virtio_net_hdr hdr = { 0, };
if (s->has_vnet_hdr) {
iov[iovcnt].iov_base = &hdr;
iov[iovcnt].iov_len = sizeof(hdr);
iovcnt++;
}
iov[iovcnt].iov_base = (char *)buf; iov[iovcnt].iov_base = (char *)buf;
iov[iovcnt].iov_len = size; iov[iovcnt].iov_len = size;
@ -1380,12 +1404,19 @@ static void tap_send(void *opaque)
int size; int size;
do { do {
uint8_t *buf = s->buf;
size = tap_read_packet(s->fd, s->buf, sizeof(s->buf)); size = tap_read_packet(s->fd, s->buf, sizeof(s->buf));
if (size <= 0) { if (size <= 0) {
break; break;
} }
size = qemu_send_packet_async(s->vc, s->buf, size, tap_send_completed); if (s->has_vnet_hdr) {
buf += sizeof(struct virtio_net_hdr);
size -= sizeof(struct virtio_net_hdr);
}
size = qemu_send_packet_async(s->vc, buf, size, tap_send_completed);
if (size == 0) { if (size == 0) {
tap_read_poll(s, 0); tap_read_poll(s, 0);
} }
@ -1415,6 +1446,18 @@ static int tap_set_sndbuf(TAPState *s, QemuOpts *opts)
return 0; return 0;
} }
static int tap_probe_vnet_hdr(int fd)
{
struct ifreq ifr;
if (ioctl(fd, TUNGETIFF, &ifr) != 0) {
qemu_error("TUNGETIFF ioctl() failed: %s\n", strerror(errno));
return 0;
}
return ifr.ifr_flags & IFF_VNET_HDR;
}
static void tap_cleanup(VLANClientState *vc) static void tap_cleanup(VLANClientState *vc)
{ {
TAPState *s = vc->opaque; TAPState *s = vc->opaque;
@ -1435,12 +1478,14 @@ static void tap_cleanup(VLANClientState *vc)
static TAPState *net_tap_fd_init(VLANState *vlan, static TAPState *net_tap_fd_init(VLANState *vlan,
const char *model, const char *model,
const char *name, const char *name,
int fd) int fd,
int vnet_hdr)
{ {
TAPState *s; TAPState *s;
s = qemu_mallocz(sizeof(TAPState)); s = qemu_mallocz(sizeof(TAPState));
s->fd = fd; s->fd = fd;
s->has_vnet_hdr = vnet_hdr != 0;
s->vc = qemu_new_vlan_client(vlan, NULL, model, name, NULL, s->vc = qemu_new_vlan_client(vlan, NULL, model, name, NULL,
tap_receive, tap_receive_iov, tap_receive, tap_receive_iov,
tap_cleanup, s); tap_cleanup, s);
@ -1450,7 +1495,7 @@ static TAPState *net_tap_fd_init(VLANState *vlan,
} }
#if defined (CONFIG_BSD) || defined (__FreeBSD_kernel__) #if defined (CONFIG_BSD) || defined (__FreeBSD_kernel__)
static int tap_open(char *ifname, int ifname_size) static int tap_open(char *ifname, int ifname_size, int *vnet_hdr)
{ {
int fd; int fd;
char *dev; char *dev;
@ -1592,7 +1637,7 @@ static int tap_alloc(char *dev, size_t dev_size)
return tap_fd; return tap_fd;
} }
static int tap_open(char *ifname, int ifname_size) static int tap_open(char *ifname, int ifname_size, int *vnet_hdr)
{ {
char dev[10]=""; char dev[10]="";
int fd; int fd;
@ -1605,13 +1650,13 @@ static int tap_open(char *ifname, int ifname_size)
return fd; return fd;
} }
#elif defined (_AIX) #elif defined (_AIX)
static int tap_open(char *ifname, int ifname_size) static int tap_open(char *ifname, int ifname_size, int *vnet_hdr)
{ {
fprintf (stderr, "no tap on AIX\n"); fprintf (stderr, "no tap on AIX\n");
return -1; return -1;
} }
#else #else
static int tap_open(char *ifname, int ifname_size) static int tap_open(char *ifname, int ifname_size, int *vnet_hdr)
{ {
struct ifreq ifr; struct ifreq ifr;
int fd, ret; int fd, ret;
@ -1623,6 +1668,17 @@ static int tap_open(char *ifname, int ifname_size)
} }
memset(&ifr, 0, sizeof(ifr)); memset(&ifr, 0, sizeof(ifr));
ifr.ifr_flags = IFF_TAP | IFF_NO_PI; ifr.ifr_flags = IFF_TAP | IFF_NO_PI;
{
unsigned int features;
if (ioctl(fd, TUNGETFEATURES, &features) == 0 &&
features & IFF_VNET_HDR) {
*vnet_hdr = 1;
ifr.ifr_flags |= IFF_VNET_HDR;
}
}
if (ifname[0] != '\0') if (ifname[0] != '\0')
pstrcpy(ifr.ifr_name, IFNAMSIZ, ifname); pstrcpy(ifr.ifr_name, IFNAMSIZ, ifname);
else else
@ -1688,14 +1744,15 @@ static TAPState *net_tap_init(VLANState *vlan, const char *model,
const char *setup_script, const char *down_script) const char *setup_script, const char *down_script)
{ {
TAPState *s; TAPState *s;
int fd; int fd, vnet_hdr;
char ifname[128]; char ifname[128];
if (ifname1 != NULL) if (ifname1 != NULL)
pstrcpy(ifname, sizeof(ifname), ifname1); pstrcpy(ifname, sizeof(ifname), ifname1);
else else
ifname[0] = '\0'; ifname[0] = '\0';
TFR(fd = tap_open(ifname, sizeof(ifname))); vnet_hdr = 0;
TFR(fd = tap_open(ifname, sizeof(ifname), &vnet_hdr));
if (fd < 0) if (fd < 0)
return NULL; return NULL;
@ -1705,7 +1762,7 @@ static TAPState *net_tap_init(VLANState *vlan, const char *model,
launch_script(setup_script, ifname, fd)) { launch_script(setup_script, ifname, fd)) {
return NULL; return NULL;
} }
s = net_tap_fd_init(vlan, model, name, fd); s = net_tap_fd_init(vlan, model, name, fd, vnet_hdr);
snprintf(s->vc->info_str, sizeof(s->vc->info_str), snprintf(s->vc->info_str, sizeof(s->vc->info_str),
"ifname=%s,script=%s,downscript=%s", "ifname=%s,script=%s,downscript=%s",
ifname, setup_script, down_script); ifname, setup_script, down_script);
@ -2659,7 +2716,7 @@ static int net_init_tap(QemuOpts *opts,
fcntl(fd, F_SETFL, O_NONBLOCK); fcntl(fd, F_SETFL, O_NONBLOCK);
s = net_tap_fd_init(vlan, "tap", name, fd); s = net_tap_fd_init(vlan, "tap", name, fd, tap_probe_vnet_hdr(fd));
if (!s) { if (!s) {
close(fd); close(fd);
} }

14
tap-linux.h
View File

@ -16,14 +16,28 @@
#ifndef QEMU_TAP_H #ifndef QEMU_TAP_H
#define QEMU_TAP_H #define QEMU_TAP_H
#include <stdint.h>
#include <linux/ioctl.h> #include <linux/ioctl.h>
/* Ioctl defines */ /* Ioctl defines */
#define TUNSETIFF _IOW('T', 202, int) #define TUNSETIFF _IOW('T', 202, int)
#define TUNGETFEATURES _IOR('T', 207, unsigned int)
#define TUNGETIFF _IOR('T', 210, unsigned int)
#define TUNSETSNDBUF _IOW('T', 212, int) #define TUNSETSNDBUF _IOW('T', 212, int)
/* TUNSETIFF ifr flags */ /* TUNSETIFF ifr flags */
#define IFF_TAP 0x0002 #define IFF_TAP 0x0002
#define IFF_NO_PI 0x1000 #define IFF_NO_PI 0x1000
#define IFF_VNET_HDR 0x4000
struct virtio_net_hdr
{
uint8_t flags;
uint8_t gso_type;
uint16_t hdr_len;
uint16_t gso_size;
uint16_t csum_start;
uint16_t csum_offset;
};
#endif /* QEMU_TAP_H */ #endif /* QEMU_TAP_H */