From: Alex Williamson <alex.william...@redhat.com> Date: Mon, 27 Jul 2015 17:18:28 -0600
> When running a Windows 2012 R2 guest with a pair of VFs assigned > through vfio-pci, we run into a problem trying to hot-unplug those VFs > after the PF has unregistered the netdev. This is a common scenario > if the PF is unbound from the driver while VFs are active. In the > case of igb, the resulting guest behavior differs slightly between the > Microsoft provided and Intel add-on guest drivers. With the Microsoft > driver, the guest seems to stumble through ejecting both VFs, but > takes longer than normal to do so. With the Intel drivers, only one > VF is unplugged, but Device Manager still shows it as present. The > second VF is non-functional but also still shown in Device Manager. > At this point, the guest is in such a state that it will not cleanly > shutdown. With ixgbe VFs, both the Microsoft and Intel drivers take > on this latter behavior. > > For both, I've found that disabling SR-IOV before unregistering the PF > netdev device allows the hot-unplug to proceed without interruption or > further ill behavior in the guest. This is true regardless of which > driver is used. I don't fully understand what dependency is broken > by unregistering the netdev prior to disabling SR-IOV, but I also > don't see the benefit in delaying SR-IOV teardown in this call path. > It could potentially be moved even earlier, but I'll let those more > familiar with the hardware and code make that determination. In any > case, the VM behavior is substantially improved by this slight > re-ordering. > > I don't have an i40e for testing, but it already appears to disable > SR-IOV much earlier in the unbind path, so I wouldn't expect to find > similar issues. Thanks, Patch #2 does not apply cleanly, please respin this series against my 'net' GIT tree, thanks. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
