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Memory locking limit and zero-copy migrations
by Milan Zamazal 20 Aug '22

20 Aug '22

Hi, do I read libvirt sources right that when <memtune> is not used in the libvirt domain then libvirt takes proper care about setting memory locking limits when zero-copy is requested for a migration? I also wonder whether there are any other situations where memory limits could be set by libvirt or QEMU automatically rather than having no memory limits? We had oVirt bugs in the past where certain VMs with VFIO devices couldn't be started due to extra requirements on the amount of locked memory and adding <hard_limit> to the domain apparently helped. Thanks, Milan

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Problem with a disk device of type 'volume'
by Frédéric Lespez 19 Aug '22

19 Aug '22

Hi, I need some help to debug a problem with libvirt and a disk device of type 'volume'. I have a VM failing to start with the following error : $ virsh -c qemu:///system start server error :Failed to start domain 'server' error :internal error: process exited while connecting to monitor: 2022-08-13T09:26:50.121259Z qemu-system-x86_64: -blockdev {"driver":"file","filename":"/mnt/images/debian-11-genericcloud-amd64.qcow2","node-name":"libvirt-3-storage","auto-read-only":true,"discard":"unmap"}: Could not open '/mnt/images/debian-11-genericcloud-amd64.qcow2': Permission denied I check the file access permission, but they are correct. I try to set everything to 777 or run qemu as root, but the problem persist. $ ll -d /mnt /mnt/images /mnt/images/* drwxr-xr-x 9 root root 4,0K 31 déc. 2021 /mnt drwxr-xr-x 2 root root 4,0K 13 août 11:31 /mnt/images -rw-r--r-- 1 libvirt-qemu libvirt-qemu 242M 13 août 11:31 /mnt/images/debian-11-genericcloud-amd64.qcow2 -rw-r--r-- 1 libvirt-qemu libvirt-qemu 366K 13 août 11:31 /mnt/images/server_cloudinit.iso -rw-r--r-- 1 libvirt-qemu libvirt-qemu 593M 13 août 11:59 /mnt/images/server_image.qcow2 After a lot of searching and testing, I found out that the disk device definition is linked to the source of the problem. The disk device is defined like this : <disk type="volume" device="disk"> <driver name="qemu" type="qcow2"/> <source pool="TERRAFORM" volume="server_image.qcow2"/> <target dev="vda" bus="virtio"/> <address type="pci" domain="0x0000" bus="0x00" slot="0x05" function="0x0"/> </disk> This image 'server_image.qcow2' use a backing file: $ qemu-img info /mnt/images/server_image.qcow2 --backing-chain image: /mnt/stockage_rapide/VMs/terraform/puppetdev_server_image.qcow2 file format: qcow2 virtual size: 6 GiB (6442450944 bytes) disk size: 475 MiB cluster_size: 65536 backing file: /mnt/images/debian-11-genericcloud-amd64.qcow2 backing file format: qcow2 Format specific information: compat: 0.10 compression type: zlib refcount bits: 16 image: /mnt/images/debian-11-genericcloud-amd64.qcow2 file format: qcow2 virtual size: 2 GiB (2147483648 bytes) disk size: 242 MiB cluster_size: 65536 Format specific information: compat: 1.1 compression type: zlib lazy refcounts: false refcount bits: 16 corrupt: false extended l2: false And here is the definition of the associated storage pool : <pool type="dir"> <name>TERRAFORM</name> <uuid>dae00836-db4d-49ba-9d32-1f0278055516</uuid> <capacity unit="bytes">155674652672</capacity> <allocation unit="bytes">74396299264</allocation> <available unit="bytes">81278353408</available> <source> </source> <target> <path>/mnt/images</path> <permissions> <mode>0755</mode> <owner>0</owner> <group>0</group> </permissions> </target> </pool> If I changed the disk device definition to this (and changing only that), the domain start and works fine (no permission problem !). <disk type="file" device="disk"> <driver name="qemu" type="qcow2"/> <source file="/mnt/images/server_image.qcow2"/> <target dev="vda" bus="virtio"/> <address type="pci" domain="0x0000" bus="0x00" slot="0x05" function="0x0"/> </disk> Could you help me find the reason why the domain doesn't work when the disk device is of type 'volume' ? Thanks in advance for your help. Regards, Fred Additional information: - Running this on Debian 11 with libvirt 8.0.0 (from backports) and qemu 7.0 (from backports). - Vanilla configuration of libvirt. I have just added my regular user to the libvirt group. - Problem exists even if AppArmor is disabled. PS: I want to use a disk device of type 'volume' because this domain is created by Terraform using the libvirt provider which use this kind of disk since it has some advantages. See the details here : https://github.com/dmacvicar/terraform-provider-libvirt/issues/126#issuecom…

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Libvirt virsh : Error starting network, cannot execute binary /usr/sbin/iptables
by Pascal 17 Aug '22

17 Aug '22

Hi, I am a bit lost and hope someone can help me. I am running Debian bookworm (testing) with last updates. $ sudo apt policy libvirt-daemon libvirt-daemon: Installé : 8.5.0-1 Candidat : 8.5.0-1 Table de version : *** 8.5.0-1 100 100 /var/lib/dpkg/status I am unable to start default network , and get an error related to iptables : $ sudo virsh net-start default erreur :Impossible de démarrer le réseau default erreur :internal error: Failed to apply firewall rules /usr/sbin/iptables -w --table filter --list-rules: libvirt: erreur : cannot execute binary /usr/sbin/iptables: Aucun fichier ou dossier de ce type Sorry for the french, it says "impossible to start default network" and "no such file or folder" at the end. It is true I removed iptables because I want to use only nftables (I removed both ufw and iptables packages (apt remove), and enabled the nftables service before error raises). Before this, all was fine, but when I enabled nftables, all VMs disapeared from virt-manager). I uninstalled KVM related packages and reinstalled, still the same. I also installed back iptables, but strangely I still get the same error, although binary /usr/sbin/iptables is there. I tried many things with no luck, restarted libvirtd service, recreated the network, etc... Has anyone some idea about what is happening here ? is there some incompatibility with nftables (firewalld service is disabled) and libvirt ? Thank you, Pascal

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libvirt can't setup simple bridged network?
by Ian Pilcher 16 Aug '22

16 Aug '22

I feel like I'm taking crazy pills! I'm reading the libvirt network XML format documentation[1], and I can't figure out how to create a simple bridged network - no NAT, no routing, no OVS, no macvtap, etc. I.e., just a Linux bridge with a single physical interface attached. None of the 3 scenarios listed for <forward mode='bridge'> describe the simple setup that I'm trying to create, so it looks like I'll need to create the bridge separately. (It's not hard to do, it just seems like such a weird gap the in the functionality.) [1] https://libvirt.org/formatnetwork.html -- ======================================================================== Google Where SkyNet meets Idiocracy ========================================================================

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New functionality in virt-install
by O'Reilly, Michael 09 Aug '22

09 Aug '22

Hi libvirt-users, I've been tracking the progress of this patch https://listman.redhat.com/archives/libvir-list/2022-August/233328.html to enable SGX support in libvirt. My question is this. Who is responsible for ensuring that new functionality like SGX is also supported by virt-install? Is it part of the commit process to ensure virt-install can use the new functionality in libvirt, or is it up to the virt-manager community to track changes. And maybe this is a question for the virt-tools-list(a)redhat.com list also? Some guidance would be appreciated. Regards Michael OR -------------------------------------------------------------- Intel Research and Development Ireland Limited Registered in Ireland Registered Office: Collinstown Industrial Park, Leixlip, County Kildare Registered Number: 308263 This e-mail and any attachments may contain confidential material for the sole use of the intended recipient(s). Any review or distribution by others is strictly prohibited. If you are not the intended recipient, please contact the sender and delete all copies.

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Can RHEL7 VM run remote commands to Fedora36 host?
by Carol Bouchard 02 Aug '22

02 Aug '22

I have a Fedora36 laptop which hosts VMs with RHEL7 using libvirt. One of the RHEL7 VMs, runs remote commands (as root) to 'start' another VM by way of my laptop. In other words, the following command is run: virsh --connect 'qemu+ssh://192.168.120.1/system' start beaker-test-vm1.beaker If I run non-remote version of the command on the laptop, it is successful. For example, virsh --connect qemu:///system start beaker-test-vm1.beaker <-- Successful on laptop. If I do a query like the following *(notice socket use)*, it is successful. virsh -d0 --connect 'qemu+ssh://192.168.120.1/system?*socket*=/var/run/libvirt/libvirt-sock-ro' domstate beaker-test-vm1.beaker Without socket, I get the following error: *error: failed to connect to the hypervisor* *error: End of file while reading data: Ncat: No such file or directory.: Input/output error* This does not work for 'start' because I believe this is a read-only socket since I see the error: error: Failed to start domain beaker-test-vm1.beaker error: operation forbidden: read only access prevents virDomainCreate When I look at my laptop, there is no /var/run/libvirt/libvirt-sock. So.....I've been wondering whether RHEL7 virsh/libvirt is compatible with Fedora36. Is there a work-around? I can't change the distros on my laptop or VMs. Carol

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Can RHEL7 VM run remote libvirt commands to Fedora36 host?
by Carol Bouchard 02 Aug '22

02 Aug '22

I have a test environment that use to work but no longer does. My laptop is Fedora36 (libvirt version 8.1.0.2) while the VMs it spawns are RHEL7 (max libvirt version is 4.5.0). The source of my problem seems to be that RHEL7 libvirt needs rw socket /var/run/libvirt/libvirt-sock which no longer exists in fedora36. The following is successful from RHEL7 VM to laptop: virsh -d0 --connect 'qemu+ssh://192.168.120.1/system?*socket*=/var/run/libvirt/libvirt-sock-ro' domstate beaker-test-vm1.beaker If I change the action from domstate to start, it fails on error: Failed to start domain beaker-test-vm1.beaker error: operation forbidden: read only access prevents virDomainCreate which made me realize ro stands for read-only; however, there is no libvirt-sock. I tried some of the other socket files without success. Is there a work-around? Carol

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how to get vm uptime through libvirt api
by Jiatong Shen 26 Jul '22

26 Jul '22

Hello community, I would like to know if there is an api to get a virtual machine's uptime. Thank you in advance for the help. -- Best Regards, Jiatong Shen

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Eject CD ROM medium fails with 'Tray of device is not open'
by liang chaojun 25 Jul '22

25 Jul '22

Hi Guys, I have hit an issue on testing against our testbed, It's failed to eject cdrom media after reboot from installed the guest OS. The reproduce step: 1. Attach a block device with a ISO media and start install VM from ISO. 2. <disk type='block' device='cdrom'> <driver name='qemu' type='raw'/> <source dev='/dev/disk/by-id/pbdx-vol-cfe60dca-c271-491b-be3c-11fa8d7625a4' index='6'/> <backingStore/> <target dev='hda' bus='ide' tray='open'/> <readonly/> <alias name='ide0-0-0'/> <address type='drive' controller='0' bus='0' target='0' unit='0'/> </disk> 3. After installed the OS and reboot from system disk successful. 4. Then I want to eject CDROM through update device with the xml like below or using virsh tool 'virsh change-media iso_test hda --eject' 5. All those will failed at "internal error: unable to execute QEMU command 'blockdev-remove-medium': Tray of device 'ide0-0-0' is not open" <disk type='block' device='cdrom'> <driver name='qemu' type='raw'/> <backingStore/> <target dev='hda' bus='ide' tray='open'/> <readonly/> <alias name='ide0-0-0'/> <address type='drive' controller='0' bus='0' target='0' unit='0'/> </disk> block info looks like below: virsh qemu-monitor-command iso_test --hmp info block setlocale: No such file or directory libvirt-6-format: /dev/disk/by-id/pbdx-vol-cfe60dca-c271-491b-be3c-11fa8d7625a4 (raw, read-only) Attached to: ide0-0-0 Removable device: locked, tray closed Cache mode: writeback Reproduce envrionment: Operating system: rhat8.4 Architecture:x86 kernel version:4.18.0-305 libvirt version:v7.9.0(private build) Hypervisor and version:QEMU 5.1.0(private build) Is there any workaround? Any comments are appreciated. Thanks!

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NetworkD or NetworkManager. Does it matter?
by Mnecraftchest1 24 Jul '22

24 Jul '22

Hello there. I am in the process of building an Arch Linux install for a virtualization server for my home lab, and I am trying to decide what networking system I should use. The two I am considering are SystemD-NetworkD, and NetworkManager. Looking along the lines of support from libvirt, would I be better off with one or the other, or does it not matter which one I use?

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