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libvirt-guests on Redhat
by Joe Muller 06 Jan '25

06 Jan '25

Hello, Per libvirt and Redhat (up to RHEL7) documentation, the libvirt-guests daemon should be enabled to ensure that guest VMs are properly shutdown/suspended if the KVM host is shutdown/rebooted. I understand that in addition to other changes, Redhat moved from the 'monolithic' libvirtd service model to the 'modular' multiple service model. Out of the box, the systemd libvirt-guests.service is disabled, and testing shows that the associated qemu-kvm processes for virtual machines are simply killed as the various virt* services are stopped as part of the systemd shutdown target. Did Redhat just decide to fork libvirt and do their own thing, or there some equivalent way to get the same clean shutdown behavior which libvirt-guests used to provide? Relevant documentation: --- https://libvirt.org/daemons.html https://docs.redhat.com/en/documentation/red_hat_enterprise_linux/9/html/co… -- Joe Muller System Administrator Sonic.

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Best practice to manage network
by linux＠hklb.ch 03 Jan '25

03 Jan '25

Hi, First, sorry if the topic has already been discussed recently (the only thread I found related to my problem was created in 2010..) I have a hypervisor with KVM and LXC installed on a Debian 12, and I'm using libvirt to create my VM. All my networks are defined in my /etc/network/interfaces.d/* (I'm using openvswitch with specific options, such as port mirroring/patch/...) , and I'm configuring the network on my VM XML definition like this : <interface type='bridge'> <mac address='52:54:00:ab:c3:d3'/> <source bridge='prod'/> <vlan> <tag id='55'/> </vlan> <virtualport type='openvswitch'> <parameters interfaceid='331d973c-0c5b-4d3c-b2ad-590f908e680d'/> </virtualport> <target dev='vnet180'/> <model type='virtio'/> <mtu size='9216'/> <alias name='net1'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x05' function='0x0'/> </interface> It is working perfectly, until I'm restarting my network (using ifreload, ifup, systemctl network restart, ...) - all my VM come unreachable... To make it work again, I also need to restart libvirtd Is it still expected to have this behavior ? What would be a better way to configure the network ? Thanks in advance Lucas

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kernel panic when hotswapping nvidia gpu via gpu passthrough in a windows vm
by 5zj1zxgr＠anonaddy.me 31 Dec '24

31 Dec '24

This may be more issue with nvidia drivers, but just wanted to check if anyone tried to perform gpu passthrough with an nvidia gpu that is used as a secondary gpu on a nvidia "prime" laptop - laptop with both an integrated intel iGPU and a secondary nvidia dGPU. I was able SOMETIMES to perform GPU passthrough successfully with a VM, but SOMETIMES it led to kernel panics. It usually happens when virtual machine shuts down and nvidia dGPU is returned to the host. Dec 30 14:29:53 host kernel: ACPI Error: Needed [Integer/String/Buffer], found [Reference] 00000000f0ed5a9d (20240827/exresop-388) Dec 30 14:29:53 host kernel: ACPI Error: AE_AML_OPERAND_TYPE, While resolving operands for [And] (20240827/dswexec-433) Dec 30 14:29:53 host kernel: ACPI Error: Aborting method \_SB.PCI0.LPCB.EC0._Q20 due to previous error (AE_AML_OPERAND_TYPE) (20240827/psparse-529) Dec 30 14:29:56 host kernel: ACPI Error: Needed [Integer/String/Buffer], found [Reference] 0000000059be91f0 (20240827/exresop-388) Dec 30 14:29:56 host kernel: ACPI Error: AE_AML_OPERAND_TYPE, While resolving operands for [And] (20240827/dswexec-433) Dec 30 14:29:56 host kernel: ACPI Error: Aborting method \_SB.PCI0.LPCB.EC0._Q20 due to previous error (AE_AML_OPERAND_TYPE) (20240827/psparse-529) Any advice would be really appreciated.

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Re: Features from Capabilities
by Simon Fairweather 24 Dec '24

24 Dec '24

For HyperV looks like I can build a list from the schema, but for CPU options would I use the xml in /usr/share/libvirt/cpu

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Features from Capabilities
by Simon Fairweather 22 Dec '24

22 Dec '24

HI, Is there any documentation or somewhere I can look at features that could be selected? I have started to create an extract from capabilities and domcapabilities to provide a list I can use for selection. Example these are the following entries I have selected to allow running of Hyperv in Server 2019 <features> <acpi/> <apic/> <hyperv mode='custom'> <relaxed state='on'/> <vapic state='on'/> <spinlocks state='on' retries='8191'/> <vendor_id state='on' value='none'/> </hyperv> </features> <cpu mode='custom' match='strict' check='none'> <model fallback='forbid'>Skylake-Client-IBRS</model> <topology sockets='1' dies='1' clusters='1' cores='4' threads='1'/> </cpu> <clock offset='localtime'> <timer name='hpet' present='no'/> <timer name='hypervclock' present='no'/> </clock> But looking to find a list of options that would be valid to be specified. Regards Simon.

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Overriding qemu.conf libvirt-qemu user per-domain
by Pascal Proulx 21 Dec '24

21 Dec '24

Hello, How can I override the libvirt-qemu user defined in /etc/libvirt/qemu.conf using a per-domain (virtual machine) override using the domain XML definitions? I can find qemu arg overrides but not this and I may have missed it. Thank you

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List of valid arch's for virt-install
by Jeffrey Walton 14 Dec '24

14 Dec '24

Hi Everyone, I'm converting about 150 Virtual Box vm's to QEMU/KVM using `qemu-img convert` followed by a `virt-install`. The vm's are a mix of amd64, i686 and mx32, and they will run on a amd64 machine. I want to use the `virt-install --arch` option during the conversion. The man page for virt-install [1] does not list valid arch's. (I can't find a page for virt-install at libvirt.org) Where can I find the list of valid arch's for virt-install? A related question is, if I also specify `--cpu host` to ensure the host cpu's ISA's are available to the vm, then will that conflict with the `--arch arch` option? Thanks in advance. [1] https://manpages.org/virt-install

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Running libvirt without dnsmasq
by procmem＠riseup.net 10 Dec '24

10 Dec '24

Hi, we are trying to document a way for our users to run libvirt without dnsmasq to reduce attack surface on the host. We are aware that the default network uses it but plan to disable that and use our own custom configured networks instead. Uninstalling dnsmasq causes libvirt to refuse to start even if the default network is no longer running. Is this possible or is this something that needs code changes upstream?

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linux guests can ping websites but cannot browse the internet while Windows guest has no issues, using 'default' nat forwarding
by persev＠guysmail.com 06 Dec '24

06 Dec '24

Hello. I had been using linux and Windows guests with QEMU KVM for a long time with no issues on LinuxMint 21.2. Then one day all the linux guests could not connect to the internet effectively. (I guess, an apt upgrade has some responsibility here, not sure). Then I installed LinuxMint 22, hoping to get an overall upgrade. Setup a Debian 12 KVM guest anew but noticed the same issues. I can ping websites from inside the VM and there are no packet loss. But other than that, the VM seemingly cannot connect to the internet. `ping wikipedia.org` works flawless but `curl` results in the following: $ curl -v 'wikipedia.org' Trying 103.102.166.224:80... Trying [<IPv6 address>]:80... Immediate connect failed for [<IPv6 address>]:80... Network is unreachable doing an apt update also results in Network unreachable. Also, Firefox cannot load websites. So it appears the guest vm can only resolve dns names and nothing else. Surprisingly, I have a Windows guest that has no internet issue at all; websites load fine in Edge. My Android Virtual Device (which uses qemu) works fine too. What might be the problem here? Am I missing some configuration in the host? Any help is appreciated. What other info can I post here to help identify the problem? $ uname -a Linux hp 6.8.0-49-generic #49-Ubuntu SMP PREEMPT_DYNAMIC Mon Nov 4 02:06:24 UTC 2024 x86_64 x86_64 x86_64 GNU/Linux $ virsh net-dumpxml default <network connections='1'> <name>default</name> <uuid>...</uuid> <forward mode='nat'> <nat> <port start='1024' end='65535'/> </nat> </forward> <bridge name='virbr0' stp='on' delay='0'/> <mac address='52:54:00:44:e6:c0'/> <ip address='192.168.122.1' netmask='255.255.255.0'> <dhcp> <range start='192.168.122.2' end='192.168.122.254'/> </dhcp> </ip> </network> The network tag from xml config for this debian12 VM is <interface type="network"> <mac address="52:54:00:79:b8:39"/> <source network="default" portid="c2529d6f-088f-4b5d-8829-625d494213e5" bridge="virbr0"/> <target dev="vnet0"/> <model type="virtio"/> <alias name="net0"/> <address type="pci" domain="0x0000" bus="0x02" slot="0x00" function="0x0"/> </interface> From inside the guest $ ip a 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000 link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 inet 127.0.0.1/8 scope host lo valid_lft forever preferred_lft forever inet6 ::1/128 scope host noprefixroute valid_lft forever preferred_lft forever 2: enp2s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000 link/ether 52:54:00:79:b8:39 brd ff:ff:ff:ff:ff:ff inet 192.168.122.65/24 brd 192.168.122.255 scope global dynamic noprefixroute enp2s0 valid_lft 2549sec preferred_lft 2549sec inet6 fe80::b96d:f09b:80d1:b1ae/64 scope link noprefixroute valid_lft forever preferred_lft forever

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Re: Set permissions and ownership of disk image created by vol-upload
by Martin Kletzander 27 Nov '24

27 Nov '24

On Tue, Nov 19, 2024 at 07:01:39PM +0000, Andrew Martin wrote: >Hello, > >I am using libvirt 8.0 on Ubuntu 22.04 and would like to utilize the vol-upload >command to upload a disk image: >https://www.libvirt.org/manpages/virsh.html#vol-upload > >I am using the "directory" storage pool type: >https://libvirt.org/storage.html#directory-pool > >However, when uploading the disk image, it gets written with octal permissions >0600 and owner root:root. Ideally I'd like this file to be owned by >libvirt-qemu:libvirt-qemu with permissions 0660 so that the group can read it. > >I've tried the following, none of which seem to alter the owner or permissions: > >- change the umask in the libvirtd systemd unit >- edit the user, group, and dynamic_ownership settings in /etc/libvirt/qemu.conf >- run "virsh pool-edit default" and change the <mode>, <owner>, or <group> tags > >How can I configure libvirtd to create these uploaded files with the desired >permissions and ownership? > Use virsh vol-create <pool> <volume.xml> where the volume xml looks something like this (adjust to your liking): <volume> <name>perms.img</name> <capacity unit='M'>100</capacity> <target> <path>/var/lib/libvirt/images/perms.img</path> <format type='raw'/> <permissions> <mode>0755</mode> <owner>77</owner> <group>77</group> </permissions> </target> </volume> And then use virsh vol-upload to populate the volume with what you want. That ought to be enough. HTH, Martin >Thanks, > >Andrew

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