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cpuset.mems - Device or resource busy
by lejeczek 25 Jan '22

25 Jan '22

Hi guys On Centos 9 I get these in journal: ... libvirt version: 8.0.0, package: 1.el9 (builder(a)centos.org, 2022-01-14-15:00:06, ) hostname: dzien.mine.private Unable to write to '/sys/fs/cgroup/machine.slice/machine-qemu\x2d4\x2dubusrv2.scope/libvirt/cpuset.mems': Device or resource busy ... each time I do: -> virt-admin daemon-log-outputs There is more VMs running on the host but it's only these Ubuntu VMs Libvirt is not happy about. Any and all suggestions very appreciated. many thanks, L

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Best practices for retrying QEMU P2P migrations
by Raphael Norwitz 24 Jan '22

24 Jan '22

Heya, We’ve recently hit a number of failures on QEMU P2P live migrations which appear to be caused by transient networking disconnects at different points in the migration process. We would like to implement smarter retry logic in our control plane to ensure such issues don’t stall critical workflows. On the other hand, we cannot blindly retry every failed migration because doing so greatly lengthens the time to fail high level autmation when there is a real problem. Are there currently any generally understood best practices for retrying migrations from a control plane perspective? Ideally we would decide whether or not to retry based on error codes, but especially in the QEMU P2P migration path many generic codes are returned. For example, see [1] where we attempted to improve an error code for a likely retry-able set of failure cases. [1] https://listman.redhat.com/archives/libvir-list/2022-January/msg00217.html Thanks, Raphael

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What does the positional parameters of "virsh backup-begin" actually do?
by Ahmad Ismail 15 Jan '22

15 Jan '22

Normally when I backup a kvm machine I shutdown the machine then run: virsh list -all virsh shutdown Ubuntu18 virsh dumpxml Ubuntu18 > /MyBackup/Ubuntu18.xml cp /var/lib/libvirt/images/Ubuntu18.qcow2 /MyBackup/Ubuntu18.qcow2 However, I found a new sub-command. The help file says: % virsh backup-begin --help NAME backup-begin - Start a disk backup of a live domain SYNOPSIS backup-begin <domain> [--backupxml <string>] [--checkpointxml <string>] [--reuse-external] DESCRIPTION Use XML to start a full or incremental disk backup of a live domain, optionally creating a checkpoint OPTIONS [--domain] <string> domain name, id or uuid --backupxml <string> domain backup XML --checkpointxml <string> domain checkpoint XML --reuse-external reuse files provided by caller The problem with this help is, it is not clear enough. I understand that I should use virsh backup-begin vm1 to backup a live kvm machine. However, this command only create .qcow2 files. What about the .xml file. What does --backupxml , --checkpointxml & --reuse-external actually do? When should I use them?

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interface hotplug q35 machine type
by Miguel Duarte de Mora Barroso 13 Jan '22

13 Jan '22

Hello, I see that as part of libvirt's documentation [0] the q35 machine type will feature at most 1 hotplugged PCIe device - default - and users must prepare in advance according to their expectations of how many ifaces will be hotplugged: """ Slots on the pcie-root controller do not support hotplug, so the device will be hotplugged into the pcie-root-port controller. If you plan to hotplug more than a single PCI Express device, you should add a suitable number of pcie-root-port controllers when defining the guest: for example, add ```xml <controller type='pci' model='pcie-root'/> <controller type='pci' model='pcie-root-port'/> <controller type='pci' model='pcie-root-port'/> <controller type='pci' model='pcie-root-port'/> ``` if you expect to hotplug up to three PCI Express devices, either emulated or assigned from the host. """ Is there any alternative to this ? For our use case, I'm considering mimicking Openstack's implementation - [1] - and expose a knob that indicates what is the number of PCIe root ports to be used upon the domain definition. I wonder how open would the community be to having a machine type alias that would provide a "better" default - in the sense that it would have more root port controllers. [0] - https://libvirt.org/pci-hotplug.html#x86_64-q35 [1] - https://blueprints.launchpad.net/nova/+spec/configure-amount-of-pcie-ports

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DMARC & similar @admins
by lejeczek 12 Jan '22

12 Jan '22

Hi guys My memory fools me? - I remembered this list had DMAR+other_bits sorted, so users like myself, on Yahoo, did not loose their own emails. regards, L

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'migrate' says it worked but in reality it did not - centOS 9
by lejeczek 11 Jan '22

11 Jan '22

Hi guys. I have a peculiar situation where between boxes: C->A -> $ virsh migrate --unsafe --live c8kubermaster1 qemu+ssh://10.1.1.99/system -> $ echo $? 0 but above does _not_ happen, instead!! VM was stopped in started, but _not_ migrated LIVE A->C -> $ virsh migrate --unsafe --live c8kubermaster1 qemu+ssh://10.1.1.100/system -> $ echo $? 0 indeed VM migrates live. box A & C have virtually identical OS stack, HW difference is: C = Ryzen 5 5600G A = Ryzen 5 3600 domain XML snippet where I think it matters: ... </metadata> <memory unit='GiB'>4</memory> <currentMemory unit='GiB'>4</currentMemory> <vcpu placement='static'>2</vcpu> <resource> <partition>/machine</partition> </resource> <os> <type arch='x86_64' machine='pc-i440fx-rhel7.6.0'>hvm</type> <boot dev='hd'/> </os> <features> <acpi/> <apic/> </features> <cpu mode='custom' match='exact' check='full'> <model fallback='forbid'>EPYC-IBPB</model> <feature policy='require' name='ibpb'/> <feature policy='require' name='ssbd'/> <feature policy='require' name='virt-ssbd'/> <feature policy='disable' name='monitor'/> <feature policy='require' name='x2apic'/> <feature policy='require' name='hypervisor'/> <feature policy='disable' name='svm'/> <feature policy='require' name='topoext'/> </cpu> <clock offset='utc'> <timer name='rtc' tickpolicy='catchup'/> <timer name='pit' tickpolicy='delay'/> <timer name='hpet' present='no'/> </clock> <on_poweroff>destroy</on_poweroff> <on_reboot>restart</on_reboot> <on_crash>destroy</on_crash> <pm> <suspend-to-mem enabled='no'/> <suspend-to-disk enabled='no'/> </pm> <devices> <emulator>/usr/libexec/qemu-kvm</emulator> <disk type='file' device='disk'> ... Initially I submitted a BZ against 'PCS' but continued to filled with it and I find 'libvirt' might be the culprit(also?) here. There is not much in logs, certainly nothing (with default verbosity) in virtqemud.service Is it that VM gets migrated but then is restarted on 'migrate_to' host? if so then why? How to start troubleshooting such 'monstrosity'? - all suggestions appreciated. many thanks, L.

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by FRANK, Michael 11 Jan '22

11 Jan '22

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error during host deploy
by Dana Elfassy 11 Jan '22

11 Jan '22

Hi, While running a test case of adding hosts on ovirt system tests there was a failure while the following command was executed: vdsm-tool configure --force On libvirtd log I found this error: 2021-12-17 00:11:41.753+0000: 28031: error : virNetTLSContextNew:732 : Unable to generate diffie-hellman parameters: Error in public key generation. How would you suggest to debug this failure? attaching libvirtd & journalctl logs libvirt version: 7.10.0, package: 1.module_el8.6.0+1046+bd8eec5e Thanks, Dana The error from host deploy log: "2021-12-17 01":"11":"45 CET - fatal":[ ost-basic-suite-master-host-0 ]:"FAILED! =>"{ "changed":true, "cmd":[ "vdsm-tool", "configure", "--force" ], "delta":"0:00:06.908971", "end":"2021-12-17 01:11:42.815057", "msg":"non-zero return code", "rc":1, "start":"2021-12-17 01:11:35.906086", "stderr":"Error: ServiceOperationError: _systemctlStart failed\nb'Job for libvirtd.service failed because a fatal signal was delivered causing the control process to dump core.\\nSee \"systemctl status libvirtd.service\" and \"journalctl -xe\" for details.\\n' ", "stderr_lines":[ "Error: ServiceOperationError: _systemctlStart failed", "b'Job for libvirtd.service failed because a fatal signal was delivered causing the control process to dump core.\\nSee \"systemctl status libvirtd.service\" and \"journalctl -xe\" for details.\\n' " ], "stdout":"\nChecking configuration status...\n\nlvm is configured for vdsm\nCurrent revision of multipath.conf detected, preserving\nlibvirt is already configured for vdsm\nSUCCESS: ssl configured to true. No conflicts\nsanlock is configured for vdsm\nManaged volume database is already configured\n\nRunning configure...\nReconfiguration of libvirt is done.\nReconfiguration of passwd is done.", "stdout_lines":[ "", "Checking configuration status...", "", "lvm is configured for vdsm", "Current revision of multipath.conf detected, preserving", "libvirt is already configured for vdsm", "SUCCESS: ssl configured to true. No conflicts", "sanlock is configured for vdsm", "Managed volume database is already configured", "", "Running configure...", "Reconfiguration of libvirt is done.", "Reconfiguration of passwd is done." ] }

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回复： Failed in using LD_PRELOAD to hook mmap system call in qemu(through libvirt)
by Xiong。 07 Jan '22

07 Jan '22

On Thu, Jan 06, 2022 at 07:44:25PM +0800, Xiong。 wrote: > Dear sir: >     I want to hook mmap system call in qemu, and I use > libvirt to passthrough the environment argument like this: >  <qemu:commandline> >    <qemu:env name='LD_PRELOAD' value='/glibcHookMMAP.so'/> >  </qemu:commandline> > But it failed. I can hardly find out what is the matter! > The log in libvirt like this:ERROR: ld.so: object > '/glibcHookMMAP.so' from LD_PRELOAD cannot be preloaded > (cannot open shared object file): ignored.    Firstly, > I think it's the problem of authority. But the file > glibcHookMMAP.so has been done with command `chmod 777`. > My environment is as follows: Ubuntu 18.04.2 Linux > 5.4.0-92 libvirt 4.0.0 qemu 2.11.1 On Thu, Jan 06, 2022 at 09:47:25PM +0800, Daniel P. Berrangé。 wrote: > Aside from normal file permissions, the other likely problem on Ubuntu > will be AppArmor policy. It likely won't allow QEMU to load files from > the / directory - if you put your .so in /usr/local/lib it might > work. On Thu, Jan 07, 2022 at 09:27:25AM +0800, Xiong。 wrote: > I have a try, but it does not work and makes the same warning: > ld.so: object '/usr/local/lib/glibcHookMMAP.so' from LD_PRELOAD cannot be preloaded (cannot open shared object file): ignored. > However, I use qemu command directly and it works. Command is like this: > sudo LD_PRELOAD=/usr/local/lib/glibcHookMMAP.so qemu-system-x86_64 -enable-kvm ...(other args). > After that, I get print information with my hook program. And I think the problem is in passing the environment args in libvirt. Sorry, I find out what's the matter. The AppArmor policy limits the libvirt, and modifing configuration works. Thank you for your advise!

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Failed in using LD_PRELOAD to hook mmap system call in qemu(through libvirt)
by Xiong。 07 Jan '22

07 Jan '22

Dear sir:      I want to hook mmap system call in qemu, and I use libvirt to passthrough the environment argument like this:<qemu:commandline> <qemu:env name='LD_PRELOAD' value='/glibcHookMMAP.so'/> </qemu:commandline>    But it failed. I can hardly find out what is the matter! The log in libvirt like this:ERROR: ld.so: object '/glibcHookMMAP.so' from LD_PRELOAD cannot be preloaded (cannot open shared object file): ignored.    Firstly, I think it's the problem of authority. But the file glibcHookMMAP.so has been done with command `chmod 777`.    My environment is as follows: Ubuntu 18.04.2 Linux 5.4.0-92 libvirt 4.0.0 qemu 2.11.1     Look forward to your feedbacks.     Sincerely yours

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