** Description changed: + + [Impact] + + "ip a" command on a guest VM shows UNKNOWN status. + + [Test Case] + + * Environment : Running a guest VM with a virtio-net adaptor interface, running on DPDK. + * Perform "ip a" inside the guest VM shows state "UNKNOWN" as follow example: + + 2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UNKNOWN group default qlen 1000 + ..... + + [Regression Potential] + + * Regression is low, the patch fix the operstate logic for virtio when no VIRTIO_NET_F_STATUS.[1] + * The patch has been first accepted in net-next, then move into Linus's git. + + [1] - VIRTIO_NET_F_STATUS + Allow the host to inform us that the link is down by adding a VIRTIO_NET_F_STATUS which indicates that device status is available in virtio_net config. + + [Other Info] + + * Linus: https://github.com/torvalds/linux/commit/bda7fab54828bbef2164bb23c0f6b1a7d05cc718 + + * Net-next: + https://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git/commit/?id=bda7fab54828bbe + + [Original Description] It has been brought to our attention the following bug : ------------------------------------------------ Environment: The guest VM is using a canonical ubuntu image, and the eth0 is a virtio-net adaptor, running on DPDK. Background: "ip a" command relies on the operstate variable of the net_device structure maintained by the kernel. This is based on the operational state as defined in the IF MIB (RFC 2863). Device drivers are expected to update this member. But many older drivers don’t seem to be using this. So in general, IF_OPER_UP and IF_OPER_UNKNOWN are treated as equal, in some sense, to maintain backward compatibility. Even if we look at https://elixir.free- electrons.com/linux/v4.15-rc2/source/include/linux/netdevice.h#L3468, the function to check if interface is up, is written as follows, which says that OPER_UNKNOWN is not something to be alarmed about, and just reflective of a state that some drivers don’t care to update about. static inline bool netif_oper_up(const struct net_device *dev) { return (dev->operstate == IF_OPER_UP || dev->operstate == IF_OPER_UNKNOWN /* backward compat */); } Code Ref: 1. https://elixir.free-electrons.com/linux/v4.15-rc2/source/include/linux/netdevice.h#L1739 2. https://elixir.free-electrons.com/linux/v4.15-rc2/source/include/linux/netdevice.h#L3468 3. https://www.kernel.org/doc/Documentation/networking/operstates.txt Now, for traditional kernel mode network adapter drivers, this state is supposed to be manipulated by the driver. And we can safely assume that most current kernel model drivers do keep this updated. ------------------------------------------------
-- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1761534 Title: "ip a" command on a guest VM shows UNKNOWN status To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1761534/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
