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Re: [Qemu-devel] [PATCH 0/4] Fix QEMU crash on vhost-user socket disconn
From: |
Michael S. Tsirkin |
Subject: |
Re: [Qemu-devel] [PATCH 0/4] Fix QEMU crash on vhost-user socket disconnect. |
Date: |
Wed, 30 Mar 2016 20:01:55 +0300 |
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