@@ -244,6 +244,20 @@ config TUN
If you don't know what to use this for, you don't need it.
+config TUN_VNET_CROSS_LE
+ bool "Support for cross-endian vnet headers on little-endian kernels"
+ default n
+ ---help---
+ This option allows TUN/TAP and MACVTAP device drivers in a
+ little-endian kernel to parse vnet headers that come from a
+ big-endian legacy virtio device.
+
+ Userspace programs can control the feature using the TUNSETVNETBE
+ and TUNGETVNETBE ioctls.
+
+ Unless you have a little-endian system hosting a big-endian virtual
+ machine with a legacy virtio NIC, you should say N.
+
config VETH
tristate "Virtual ethernet pair device"
---help---
@@ -48,13 +48,63 @@ struct macvtap_queue {
#define MACVTAP_FEATURES (IFF_VNET_HDR | IFF_MULTI_QUEUE)
#define MACVTAP_VNET_LE 0x80000000
+#define MACVTAP_VNET_BE 0x40000000
+
+#ifdef CONFIG_TUN_VNET_CROSS_LE
+static inline bool macvtap_legacy_is_little_endian(struct macvtap_queue *q)
+{
+ if (q->flags & MACVTAP_VNET_BE)
+ return false;
+ return virtio_legacy_is_little_endian();
+}
+
+static long macvtap_get_vnet_be(struct macvtap_queue *q, int __user *sp)
+{
+ int s = !!(q->flags & MACVTAP_VNET_BE);
+
+ if (put_user(s, sp))
+ return -EFAULT;
+
+ return 0;
+}
+
+static long macvtap_set_vnet_be(struct macvtap_queue *q, int __user *sp)
+{
+ int s;
+
+ if (get_user(s, sp))
+ return -EFAULT;
+
+ if (s)
+ q->flags |= MACVTAP_VNET_BE;
+ else
+ q->flags &= ~MACVTAP_VNET_BE;
+
+ return 0;
+}
+#else
+static inline bool macvtap_legacy_is_little_endian(struct macvtap_queue *q)
+{
+ return virtio_legacy_is_little_endian();
+}
+
+static long macvtap_get_vnet_be(struct macvtap_queue *q, int __user *argp)
+{
+ return -EINVAL;
+}
+
+static long macvtap_set_vnet_be(struct macvtap_queue *q, int __user *argp)
+{
+ return -EINVAL;
+}
+#endif /* CONFIG_TUN_VNET_CROSS_LE */
static inline bool macvtap_is_little_endian(struct macvtap_queue *q)
{
if (q->flags & MACVTAP_VNET_LE)
return true;
else
- return virtio_legacy_is_little_endian();
+ return macvtap_legacy_is_little_endian(q);
}
static inline u16 macvtap16_to_cpu(struct macvtap_queue *q, __virtio16 val)
@@ -1098,6 +1148,12 @@ static long macvtap_ioctl(struct file *file, unsigned int cmd,
q->flags &= ~MACVTAP_VNET_LE;
return 0;
+ case TUNGETVNETBE:
+ return macvtap_get_vnet_be(q, sp);
+
+ case TUNSETVNETBE:
+ return macvtap_set_vnet_be(q, sp);
+
case TUNSETOFFLOAD:
/* let the user check for future flags */
if (arg & ~(TUN_F_CSUM | TUN_F_TSO4 | TUN_F_TSO6 |
@@ -111,6 +111,7 @@ do { \
#define TUN_FASYNC IFF_ATTACH_QUEUE
/* High bits in flags field are unused. */
#define TUN_VNET_LE 0x80000000
+#define TUN_VNET_BE 0x40000000
#define TUN_FEATURES (IFF_NO_PI | IFF_ONE_QUEUE | IFF_VNET_HDR | \
IFF_MULTI_QUEUE)
@@ -206,12 +207,61 @@ struct tun_struct {
u32 flow_count;
};
+#ifdef CONFIG_TUN_VNET_CROSS_LE
+static inline bool tun_legacy_is_little_endian(struct tun_struct *tun)
+{
+ if (tun->flags & TUN_VNET_BE)
+ return false;
+ return virtio_legacy_is_little_endian();
+}
+
+static long tun_get_vnet_be(struct tun_struct *tun, int __user *argp)
+{
+ int be = !!(tun->flags & TUN_VNET_BE);
+
+ if (put_user(be, argp))
+ return -EFAULT;
+
+ return 0;
+}
+
+static long tun_set_vnet_be(struct tun_struct *tun, int __user *argp)
+{
+ int be;
+
+ if (get_user(be, argp))
+ return -EFAULT;
+
+ if (be)
+ tun->flags |= TUN_VNET_BE;
+ else
+ tun->flags &= ~TUN_VNET_BE;
+
+ return 0;
+}
+#else
+static inline bool tun_legacy_is_little_endian(struct tun_struct *tun)
+{
+ return virtio_legacy_is_little_endian();
+}
+
+static long tun_get_vnet_be(struct tun_struct *tun, int __user *argp)
+{
+ return -EINVAL;
+}
+
+static long tun_set_vnet_be(struct tun_struct *tun, int __user *argp)
+{
+ return -EINVAL;
+}
+#endif /* CONFIG_TUN_VNET_CROSS_LE */
+
static inline bool tun_is_little_endian(struct tun_struct *tun)
{
if (tun->flags & TUN_VNET_LE)
return true;
else
- return virtio_legacy_is_little_endian();
+ return tun_legacy_is_little_endian(tun);
}
static inline u16 tun16_to_cpu(struct tun_struct *tun, __virtio16 val)
@@ -2066,6 +2116,14 @@ static long __tun_chr_ioctl(struct file *file, unsigned int cmd,
tun->flags &= ~TUN_VNET_LE;
break;
+ case TUNGETVNETBE:
+ ret = tun_get_vnet_be(tun, argp);
+ break;
+
+ case TUNSETVNETBE:
+ ret = tun_set_vnet_be(tun, argp);
+ break;
+
case TUNATTACHFILTER:
/* Can be set only for TAPs */
ret = -EINVAL;
@@ -50,6 +50,12 @@
#define TUNGETFILTER _IOR('T', 219, struct sock_fprog)
#define TUNSETVNETLE _IOW('T', 220, int)
#define TUNGETVNETLE _IOR('T', 221, int)
+/* The TUNSETVNETBE and TUNGETVNETBE ioctls are for cross-endian support on
+ * little-endian hosts. Not all kernel configurations support them, but all
+ * configurations that support SET also support GET.
+ */
+#define TUNSETVNETBE _IOW('T', 222, int)
+#define TUNGETVNETBE _IOR('T', 223, int)
/* TUNSETIFF ifr flags */
#define IFF_TUN 0x0001
The VNET_LE flag was introduced to fix accesses to virtio 1.0 headers that are always little-endian. It can also be used to handle the special case of a legacy little-endian device implemented by a big-endian host. Let's add a flag and ioctls for big-endian devices as well. If both flags are set, little-endian wins. Since this is isn't a common usecase, the feature is controlled by a kernel config option (not set by default). Both macvtap and tun are covered by this patch since they share the same API with userland. Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com> --- Changes since v4: - rewrote patch title to mention cross-endian - renamed config to TUN_VNET_CROSS_LE - rewrote config description and help - moved ifdefery to top of tun.c and macvtap.c - updated comment in <uapi/linux/if_tun.h> to mention that the availibility of both SET and GET ioctls depends on the kernel config drivers/net/Kconfig | 14 ++++++++++ drivers/net/macvtap.c | 58 +++++++++++++++++++++++++++++++++++++++++- drivers/net/tun.c | 60 ++++++++++++++++++++++++++++++++++++++++++- include/uapi/linux/if_tun.h | 6 ++++ 4 files changed, 136 insertions(+), 2 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html