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[libvirt-users] Guest startup process blocks if a hook's child process is still running (i.e : after forking)
by Nicolas Roy-Renaud 08 Nov '16

08 Nov '16

I've been having issues with KVM lately where I sometimes put my host into sleep while a guest is still running, which prevents it from waking up properly. This is somewhat expected due to my setup, but I have mistakenly done this more than once and could use a workaround to stop this from happening. So I've been trying to setup a libvirt hook to fork an instance of systemd-inhibit when the start hook is called and keep it running until the shutdown hook is called. This seems to work well when I run the hook script in a normal bash shell, but running it through libvirt simply blocks the starting process until systemd-inhibit quits. Here's the script : LOCK_FILE="/tmp/vfio-lock-$OBJECT" if [ "$OPERATION" == "start" ]; then ( touch "$LOCK_FILE"; systemd-inhibit --what="sleep" \ --who="libvirt" \ --mode="block" \ inotifywait -qq -e delete "$LOCK_FILE" ) & disown $! exit fi if [ "$OPERATION" == "shutdown" ]; then rm "$LOCK_FILE" fi Is there some way to make it so libvirt sees the hook script exiting and carries on with the rest of its guest startup process even after a process fork or would that require changes in the internal hook handling functions? - Nicolas

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[libvirt-users] Sharing network namespace between containers
by Harish Vishwanath 08 Nov '16

08 Nov '16

Hello Based on the lxc driver documentation, I am trying to create an xml to share an existing network namespace with another container. I am running libvirt 1.2.15. Here is the xml: <domain type='lxc' xmlns:lxc='http://libvirt.org/schemas/domain/lxc/1.0'> <name>nt</name> <uuid>43c00192-e114-4e29-8ce7-4b5487f60a75</uuid> <memory unit='KiB'>65536</memory> <currentMemory unit='KiB'>65536</currentMemory> <vcpu placement='static'>1</vcpu> <cputune> <shares>2000</shares> </cputune> <resource> <partition>/apphosting.partition</partition> </resource> <os> <type arch='x86_64'>exe</type> <init>/sbin/init</init> </os> <clock offset='utc'/> <on_poweroff>destroy</on_poweroff> <on_reboot>restart</on_reboot> <on_crash>destroy</on_crash> <devices> <emulator>/usr/lib/libvirt/libvirt_lxc</emulator> <filesystem type='mount' accessmode='passthrough'> <source dir='/work/repo-lxc/nt/rootfs_mnt'/> <target dir='/'/> </filesystem> <filesystem type='mount' accessmode='squash'> <driver type='path' wrpolicy='immediate'/> <source dir='/local/local1/core_dir/nt'/> <target dir='/local/local1/core_dir'/> </filesystem>  <console type='pty'> <target type='lxc' port='0'/> </console> </devices> * <lxc:namespace>* * <lxc:sharenet type='netns' value='node'/>* * </lxc:namespace>* </domain> However, the virsh edit is unable to save this file: error: XML document failed to validate against schema: Unable to validate doc against /usr/share/libvirt/schemas/domain.rng Element domain has extra content: namespace Failed. Try again? [y,n,i,f,?]: Is this supported in libvirt 1.2.15 - the document doesnt specify a minimum version of libvirt. Appreciate your help. Regards, Harish

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[libvirt-users] virtual wlan0
by Michael Ströder 07 Nov '16

07 Nov '16

HI! My goal is to run a virtualized access point with hostapd. Is it possible to use the host's WIFI interface in a VM created with libvirt? I can add the interface in bridged mode but it appears just as normal eth1 without wireless extensions. Ciao, Michael.

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[libvirt-users] pci-assign fails with read error on config-space file
by Henning Schild 02 Nov '16

02 Nov '16

Hey, i am running an unusual setup where i assign pci devices behind the back of libvirt. I have two options to do that: 1. a wrapper script for qemu that takes care of suid-root and appends arguments for pci-assign 2. virsh qemu-monitor-command ... 'device_add pci-assign...' I know i should probably not be doing this, it is a workaround to introduce fine-grained pci-assignment in an openstack setup, where vendor and device id are not enough to pick the right device for a vm. In both cases qemu will crash with the following output: > qemu: hardware error: pci read failed, ret = 0 errno = 22 followed by the usual machine state dump. With strace i found it to be a failing read on the config space file of my device. /sys/bus/pci/devices/0000:xx:xx.x/config A few reads out of that file succeeded, as well as accesses on vendor etc. Manually launching a qemu with the pci-assign works without a problem, so i "blame" libvirt and the cgroup environment the qemu ends up in. So i put a bash into the exact same cgroup setup - next to a running qemu, expecting a dd or hexdump on the config-space file to fail. But from that bash i can read the file without a problem. Has anyone seen that problem before? Right now i do not know what i am missing, maybe qemu is hitting some limits configured for the cgroups or whatever. I can not use pci-assign from libvirt, but if i did would it configure cgroups in a different way or relax some limits? What would be a good next step to debug that? Right now i am looking at kernel event traces, but the machine is pretty big and so is the trace. That assignment used to work and i do not know how it broke, i have tried combinations of several kernels, versions of libvirt and qemu. (kernel 3.18 and 4.4, libvirt 1.3.2 and 2.0.0, and qemu 2.2.1 and 2.7) All combinations show the same problem, even the ones that work on other machines. So when it comes to software versions the problem could well be caused by a software update of another component, that i got with the package manager and did not compile myself. It is a debian 8.6 with all recent updates installed. My guess would be that systemd could have an influence on cgroups or limits causing such a problem. regards, Henning

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[libvirt-users] pass-through hwrng
by lejeczek 02 Nov '16

02 Nov '16

hi all I have in my centos 7 this: crw-------. 1 root root 10, 183 Oct 11 21:28 /dev/hwrng and VM fails, complains like this: virsh # start volatile-work6 error: Failed to start domain volatile-work6 error: internal error: process exited while connecting to monitor: 2016-10-19T09:42:05.988142Z qemu-kvm: -object rng-random,id=objrng0,filename=/dev/hwrng: Could not open '/dev/hwrng': Permission denied which reads logical. Now - is this normal that hwrng is created with these permissions? And if yes then how to pass-through it to the VMs? How to aid VMs with hardware random numbers generator? many thanks. L

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[libvirt-users] How do you set real time bandwidth for a container?
by Peter Steele 31 Oct '16

31 Oct '16

When I create a VM using libvirt, the VM comes up the path /sys/fs/cgroup/cpu/cpu.rt_runtime_us set to something like 1000000. When I create a container however, the path /sys/fs/cgroup/cpu/cpu.rt_runtime_us is 0. This prevents my containers from being able to run any real time applications. I have to explicitly echo a value into this field in order to give the container some real time bandwidth and allow it to run real time processes. Is it possible to define this in a container's XML config? Or is there another method I should be using to enable real time capability in a container? Peter

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[libvirt-users] command guest-file-open failed to open file - Permission denied
by 刘梦可 31 Oct '16

31 Oct '16

hello, I am using libvirt 1.2.17 on CentOS 7.2 - kernel 3.10.0-327.13.1.el7.x86_64. The command guest-file-open failed to open file with error "Permission denied", the detail is as below: virsh qemu-agent-command instance-00000a9c '{"execute":"guest-file-open", "arguments":{"path":"/home/centos/test","mode":"r"}}' error: internal error: unable to execute QEMU agent command 'guest-file-open': failed to open file '/home/centos/test' (mode: 'r'): Permission denied In the guest, the file '/home/centos/test' exist and the access permissions is 777 as below: -rwxrwxrwx. 1 centos centos 18 Oct 27 11:16 test How can I fix it? Thanks very much!!! -mkliu28

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Re: [libvirt-users] Libvirt newer than 2.1.0 doesnt start up
by Rene Pasing 29 Oct '16

29 Oct '16

Hi all, thanks so far for your time and ideas. Please find the gdb output and also the debug-output of libvirt (as requested by Michal Privoznik and Laine Stump) here: https://paste.xinu.at/m-gPSHl/ On 10/19/2016 01:58 AM, Michal Privoznik wrote: > Those "Network is already in use by interface virbr1" error messages > worry me. Is the bridge active before you start libvirtd? If so we might > be losing netowrk state XML (or fail to parse it) and thus think network > is not started and because of autostart we try to start it again (which > fails). > [...] > Before you start libvirt, are there any files under > /var/run/libvirt/network/ ? If so, what's their content? Laine was already correct about that, this error message only appears when I manually try to restart libvirt after it already hung up. Maybe I should've made that more clear. Additionaly, no, there are no files in that directory, also I am pretty sure that I only got one instance of libvirt running According to the GDB log, the libvirt process is endlessly iterating over [1]. Any ideas what could be wrong? Thanks in advance Regards Rene [1] = https://github.com/libvirt/libvirt/blob/master/src/network/bridge_driver.c#…

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[libvirt-users] Failed to launch libvirt 1.2.7
by Marina Danial 25 Oct '16

25 Oct '16

Hello, I am currently working on Redhat 6 - Kernel 2.6.32-358.el6.x86_64. It has by default libvirt 0.10.2. I wanted version 1.2.7. So I downloaded this and libvirt-1.2.7.tar.gz and I followed the following steps: 1. ./configure (with its default settings) 2. make 3. make install Currently, the installation is in: /usr/local and the source tree is in /export/home/libvirt. I stopped the previously installed daemon so that the new one takes effect. I launched the daemon from /export/home/libvirt/daemon/libvirtd -d. However every time I launch the C++ code, this message appears: libvir: XML-RPC error : Failed to connect socket to '/var/run/libvirt/libvirt-sock': No such file or directory Failed to open connection to qemu:///system My questions are: 1. How can I launch the daemon from the source tree? It does not behave as it should when it is launched from /etc/init.d 2. How can any application e.g. virt-manager look at the new paths of the newly installed libvirt? 3. How can I get libvirt to work from the source tree as if it was originally installed in Redhat? Thanks Marina

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[libvirt-users] security BPC
by Michael Ströder 21 Oct '16

21 Oct '16

HI! Disclaimer: I'm a libvirt beginner using it for managing virtual machines based on qemu-kvm. Is there any documentation describing how to harden libvirt/qemu-kvm installations? Escpecially how to improve isolation of VMs: - secure time sync (with or without ntpd?) - random number generation - running VMs as different host OS users I do not need general OS hardening advice. Ciao, Michael.

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