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net: add a vnet_hdr=on|off parameter

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This allows people to disable the IFF_VNET_HDR flag, e.g. for debugging
purposes or if they know they may migrate the guest to a machine without
IFF_VNET_HDR support.

It also allows making the lack of IFF_VNET_HDR support an error
condition, e.g. in the case where a guest is being migrated from a host
which does support it.

Signed-off-by: Mark McLoughlin <markmc@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
This commit is contained in:
Mark McLoughlin
2009-10-22 17:43:37 +01:00
committed by Anthony Liguori
parent 424a7f9674
commit baf74c9580
2 changed files with 35 additions and 11 deletions
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42
net.c
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@@ -1494,7 +1494,8 @@ static TAPState *net_tap_fd_init(VLANState *vlan,
}
#if defined (CONFIG_BSD) || defined (__FreeBSD_kernel__)
static int tap_open(char *ifname, int ifname_size, int *vnet_hdr)
static int tap_open(char *ifname, int ifname_size,
int *vnet_hdr, int vnet_hdr_required)
{
int fd;
char *dev;
@@ -1636,7 +1637,8 @@ static int tap_alloc(char *dev, size_t dev_size)
return tap_fd;
}
static int tap_open(char *ifname, int ifname_size, int *vnet_hdr)
static int tap_open(char *ifname, int ifname_size,
int *vnet_hdr, int vnet_hdr_required)
{
char dev[10]="";
int fd;
@@ -1649,13 +1651,15 @@ static int tap_open(char *ifname, int ifname_size, int *vnet_hdr)
return fd;
}
#elif defined (_AIX)
static int tap_open(char *ifname, int ifname_size, int *vnet_hdr)
static int tap_open(char *ifname, int ifname_size,
int *vnet_hdr, int vnet_hdr_required)
{
fprintf (stderr, "no tap on AIX\n");
return -1;
}
#else
static int tap_open(char *ifname, int ifname_size, int *vnet_hdr)
static int tap_open(char *ifname, int ifname_size,
int *vnet_hdr, int vnet_hdr_required)
{
struct ifreq ifr;
int fd, ret;
@@ -1668,7 +1672,7 @@ static int tap_open(char *ifname, int ifname_size, int *vnet_hdr)
memset(&ifr, 0, sizeof(ifr));
ifr.ifr_flags = IFF_TAP | IFF_NO_PI;
{
if (*vnet_hdr) {
unsigned int features;
if (ioctl(fd, TUNGETFEATURES, &features) == 0 &&
@@ -1676,6 +1680,13 @@ static int tap_open(char *ifname, int ifname_size, int *vnet_hdr)
*vnet_hdr = 1;
ifr.ifr_flags |= IFF_VNET_HDR;
}
if (vnet_hdr_required && !*vnet_hdr) {
qemu_error("vnet_hdr=1 requested, but no kernel "
"support for IFF_VNET_HDR available");
close(fd);
return -1;
}
}
if (ifname[0] != '\0')
@@ -1740,7 +1751,7 @@ static int launch_script(const char *setup_script, const char *ifname, int fd)
static int net_tap_init(QemuOpts *opts, int *vnet_hdr)
{
int fd;
int fd, vnet_hdr_required;
char ifname[128] = {0,};
const char *setup_script;
@@ -1748,8 +1759,14 @@ static int net_tap_init(QemuOpts *opts, int *vnet_hdr)
pstrcpy(ifname, sizeof(ifname), qemu_opt_get(opts, "ifname"));
}
*vnet_hdr = 0;
TFR(fd = tap_open(ifname, sizeof(ifname), vnet_hdr));
*vnet_hdr = qemu_opt_get_bool(opts, "vnet_hdr", 1);
if (qemu_opt_get(opts, "vnet_hdr")) {
vnet_hdr_required = *vnet_hdr;
} else {
vnet_hdr_required = 0;
}
TFR(fd = tap_open(ifname, sizeof(ifname), vnet_hdr, vnet_hdr_required));
if (fd < 0) {
return -1;
}
@@ -2698,8 +2715,9 @@ static int net_init_tap(QemuOpts *opts,
if (qemu_opt_get(opts, "fd")) {
if (qemu_opt_get(opts, "ifname") ||
qemu_opt_get(opts, "script") ||
qemu_opt_get(opts, "downscript")) {
qemu_error("ifname=, script= and downscript= is invalid with fd=\n");
qemu_opt_get(opts, "downscript") ||
qemu_opt_get(opts, "vnet_hdr")) {
qemu_error("ifname=, script=, downscript= and vnet_hdr= is invalid with fd=\n");
return -1;
}
@@ -3055,6 +3073,10 @@ static struct {
.name = "sndbuf",
.type = QEMU_OPT_SIZE,
.help = "send buffer limit"
}, {
.name = "vnet_hdr",
.type = QEMU_OPT_BOOL,
.help = "enable the IFF_VNET_HDR flag on the tap interface"
},
{ /* end of list */ }
},