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? > 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