On 30.03.2016 20:01, Michael S. Tsirkin wrote: > On Wed, Mar 30, 2016 at 06:14:05PM +0300, Ilya Maximets wrote: >> Currently QEMU always crashes in following scenario (assume that >> vhost-user application is Open vSwitch with 'dpdkvhostuser' port): > > In fact, wouldn't the right thing to do be stopping the VM?
I don't think that is reasonable to stop VM on failure of just one of network interfaces. There may be still working vhost-kernel interfaces. Even connection can still be established if vhost-user interface was in bonding with kernel interface. Anyway user should be able to save all his data before QEMU restart. > >> 1. # Check that link in guest is in a normal state. >> [guest]# ip link show eth0 >> 2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc <...> >> link/ether 00:16:35:af:aa:4b brd ff:ff:ff:ff:ff:ff >> >> 2. # Kill vhost-user application (using SIGSEGV just to be sure). >> [host]# kill -11 `pgrep ovs-vswitchd` >> >> 3. # Check that guest still thinks that all is good. >> [guest]# ip link show eth0 >> 2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc <...> >> link/ether 00:16:35:af:aa:4b brd ff:ff:ff:ff:ff:ff >> >> 4. # Try to unbind virtio-pci driver and observe QEMU crash. >> [guest]# echo -n '0000:00:01.0' > /sys/bus/pci/drivers/virtio-pci/unbind >> qemu: Failed to read msg header. Read 0 instead of 12. Original request >> 11. >> qemu: Failed to read msg header. Read 0 instead of 12. Original request >> 11. >> qemu: Failed to read msg header. Read 0 instead of 12. Original request >> 11. >> >> Child terminated with signal = 0xb (SIGSEGV) >> GDBserver exiting >> >> After the applying of this patch-set: >> >> 4. # Try to unbind virtio-pci driver. Unbind works fine with only few errors. >> [guest]# echo -n '0000:00:01.0' > /sys/bus/pci/drivers/virtio-pci/unbind >> qemu: Failed to read msg header. Read 0 instead of 12. Original request >> 11. >> qemu: Failed to read msg header. Read 0 instead of 12. Original request >> 11. >> >> 5. # Bind virtio-pci driver back. >> [guest]# echo -n '0000:00:01.0' > /sys/bus/pci/drivers/virtio-pci/bind >> >> 6. # Check link in guest. No crashes here, link in DOWN state. >> [guest]# ip link show eth0 >> 7: eth0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc <...> >> link/ether 00:16:35:af:aa:4b brd ff:ff:ff:ff:ff:ff >> >> 7. QEMU may be gracefully restarted to restore communication after restarting >> of vhost-user application. >> >> Ilya Maximets (4): >> vhost-user: fix crash on socket disconnect. >> vhost: prevent double stop of vhost_net device. >> vhost: check for vhost_net device validity. >> net: notify about link status only if it changed. >> >> hw/net/vhost_net.c | 48 >> ++++++++++++++++++++++++++++++++++++++---- >> hw/net/virtio-net.c | 33 ++++++++++++++++++++++------- >> include/hw/virtio/virtio-net.h | 1 + >> include/net/vhost-user.h | 1 + >> include/net/vhost_net.h | 1 + >> net/filter.c | 1 + >> net/net.c | 7 +++--- >> net/vhost-user.c | 43 +++++++++++++++++++++++++++++-------- >> 8 files changed, 111 insertions(+), 24 deletions(-) >> >> -- >> 2.5.0 > >
