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Questions tagged [kvm-virtualization]

KVM (for Kernel-based Virtual Machine) is a full virtualization solution for Linux on x86 hardware containing virtualization extensions (Intel VT or AMD-V). It consists of a loadable kernel module, kvm.ko, that provides the core virtualization infrastructure and a processor specific module, kvm-intel.ko or kvm-amd.ko. KVM also requires a modified QEMU although work is underway to get the required changes upstream.

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Hiding physical hardware changes from VM guest

I'm running a Windows guest under Proxmox VE 8.2 (on Debian 12) and would like to hide information about the underlying physical hardware from the guest. Motivation I have paid full price for a ...
rohanc's user avatar
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Link-local IPv6 address unpingable through guest VM

We have multiple virtualizor based KVM VM provisioning hosts and none of the VMs can ping link-local IPv6 Addresses. To simplify: VM <--> VM Host: working VM <--> VM: not working VM <--&...
Ankesh Anand's user avatar
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1 answer
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libvirt port forwarding to guest: What changed with 10.4.0?

Network/Firewalls isn't my strong side, so there is the possibility that I'm making a very basic mistake. I need to access services running inside my qemu guest system from other devices in my network....
Gedi Nixan's user avatar
-1 votes
0 answers
47 views

Windows Server 2019 unexpected restart after CPU core increase

We recently moved our old Windows VMs from centos8 qemu/KVM to a new server with Alma Linux 9 running qemu/KVM. After moving the VM's, we increased our core count for the Windows VM to 64 cores from ...
snoopyr's user avatar
1 vote
1 answer
43 views

Solved - port-forwarding to KVM VM on Ubuntu

I,m configuring port forwarding to KVM VM on Ubuntu 22.04. I can connect to VM from outside of host server. But it failed from VM itself. my host's IP : 222.222.222.222 vm's IP : 192.168.122.201 ...
hwang's user avatar
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1 answer
49 views

How to VLAN tags for virtual machines with Open vSwitch, the internet is not connected

I installed the OVS package and created a bridge. When I connect the VM to that bridge, the internet works within the virtual machine. For example, I want to use VLAN tags like 100 and 200 within each ...
Zeee's user avatar
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1 vote
0 answers
22 views

KVM CPU Passthrough Frequencies

I am looking at a KVM server and client, and noticed something I don't really understand and I'm hoping someone can enlighten me/point me in the correct direction. cat /proc/cpuinfo shows - among ...
davidgo's user avatar
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internal error: failed to start qemu binary /usr/bin/qemu-system-x86_64 for probing : qemu-system-x86_64 : cannot create PID file

Cannot Start VM. observing following error internal error: failed to start qemu binary /usr/bin/qemu-system-x86_64 for probing : qemu-system-x86_64 : cannot create PID file
Venkateshwaran Thirugnanam's user avatar
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"No boot device" after migrate VM from XenServer to Promox

XenServer 8.2 Promox 8.2.2 My VM OS: Red Hat Enterprise Linux Server release 5.4 (Tikanga) After I export vm from XenServer then import to Promox, I can not start VM. It said: "No boot device&...
viet's user avatar
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Forward a single port to KVM Virtual Machine with Libvirt

I have a KVM that is currently running PBX software, and a OpenVPN server. I want to give a friend an IP Phone. I am connecting IP Phones to the OpenVPN Server so that they can communicate with the ...
chris chris's user avatar
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1 answer
144 views

TrueNAS Scale Installation on Proxmox Fails with "lsblk: CANT_FIND_vda3_OR_vdap3: not a block device" Error

I'm attempting to install TrueNAS Scale (24.04.0) in Proxmox (8.2.2), but the installation fails with the error message lsblk: CANT_FIND_vda3_OR_vdap3: not a block device. Below is the table of the ...
cyberquarks's user avatar
1 vote
1 answer
78 views

resolv.conf being stupid about local kvm domain

I'm trying to get DNS resolution to work for KVM/libvirt on a Debian 12 host with NM controlling the resolv.conf. My isolated KVM guest network is 10.10.10.0/24 and "hostname -d" of my ...
0xlivingbeef's user avatar
0 votes
1 answer
91 views

KVM Routed Bridge for Additional Subnet on Hetzner Using Netplan

I have a dedicated Ubuntu 22.04 server at Hetzner running KVM. I have assigned IP addresses from an additional subnet to guest VMs. I can reach the guest VMs via their public IP addresses as intended. ...
Kheldar Ambar's user avatar
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99 views

Arm cpu nested virtualization, How can I make VCPU start from EL2?

Recently I've been testing Arm architecture nested virtualization. Since I don't have actual Armv8.4 CPUs, I used QEMU-9.0.0-rc2 to simulate an Arm chip. According to the QEMU changelog, support for ...
jin's user avatar
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How can I give multiple KVM bridges access to Docker containers?

I'm running Docker CE 25 on Ubuntu Linux 22.04. I have numerous KVM VMs routing ip through bridges br25 and br50. All of these components reside on the same host. This issue has also been reproduced ...
me2017's user avatar
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1 answer
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kvm libvirt: Port Forwarding via nft not working

I use KVM to virtualize a Guest-Linux-Mint on my Host-Debian12. The Guest is obviously configured well with NAT: I can ssh into the Guest from the Host, I can reach the Internet from the Guest. But I ...
Sebastian's user avatar
9 votes
4 answers
2k views

What is the the purpose of using paravirtualization if there is a hardware assisted virtualization?

I am doing a research about QEMU/KVM and Firecracker/KVM. As far as I understood, both Firecracker and QEMU communicates with KVM to eventually benefit hardware assisted virtualization by changing CPU ...
panxl's user avatar
  • 93
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1 answer
48 views

Which piece of software touches network configuration files of a VM in a vagrant-libvirt setup with kvm/qemu?

Which element in a vagrant-libvirt-qemu/kvm-chain is responsible to actually configure the VM? Like editing the network configuration files. Wouldn't that totally depend on the details of the OS of ...
Robert Siemer's user avatar
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0 answers
70 views

kvm forward port from Host to guest VM bridge mode

I have a server Ubuntu 22.04 on cloud (VPS) with one external IP (public) address (19.162.31.26), and the internal IP (private) address (192.168.122.1). On that server I use libvirt (Virtual Machine ...
Mohammed haddadi's user avatar
0 votes
1 answer
390 views

Grub showing "attempt to read or write outside of disk 'hd0'" error when running in a proxmox VM

After installing a Debian 11 in a proxmox VM (with packer), grub would fail to boot into the newly created VM showing the error attempt to read or write outside of disk 'hd0'. When installing a VM ...
toydarian's user avatar
  • 140
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0 answers
647 views

Wireless-Bridge on a ubuntu 22.04 (netplan) for three QEMU VMs

I do have an apparently trivial, but it is rather an ambitious project. Wishing to run three ubuntu 22.04 VMs on my laptop, installing and configuring kubernetes for an initial learning phase with the ...
user1611183's user avatar
4 votes
1 answer
453 views

Effectiveness of sdmem on a VPS?

Does someone know if the sdmem program (part of the secure-delete tools) is effective on a VPS? I'd like to be sure I'm wiping certain private keys on a KVM VPS. I don't know why it would not be, I ...
stone.212's user avatar
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0 votes
1 answer
92 views

Linux Kernel and KVM

I am new to the concept of building your server and was reading about Hypervisors. I learnt that KVM is type 1 hypervisor and can be installed directly on the server without OS. But what confused me ...
ankshukla's user avatar
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0 answers
173 views

Create a Group RW-access for a KVM shared folder via virtiofs on Ubuntu Server 22

I have a folder /common on an Ubuntu Server 22 host which is RW accessible by all users in group users i.e. user alice (with uid 1000) is a member of users (with gid 12345) and has fuull RW access to /...
Cogicero's user avatar
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1 vote
1 answer
125 views

Qemu linux guest disconnected randomly

I have a mac m1 with an arm processor and I want to use Linux sometimes. For this I followed this guide and everything is working as expected and I have a working Linux guest. The only thing I added ...
amit's user avatar
  • 21
0 votes
1 answer
418 views

vlan on top of vlan-aware bridge: possible and how?

I'm currently working on configuring an opensuse host as a KVM hypervisor. I have a physical interface as slave for a bridge. I'm going to make this bridge interface vlan-aware and handle the VLAN-...
aquilares's user avatar
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0 answers
236 views

How do I remove cloud-init backing image from my VM?

I am moving a VM from Ubuntu 22.04.3 LTS KVM host to a RHEL 8.9 Ootpa KVM host. When I try to start the VM on the destination (RHEL) host I see, error: Cannot access backing file '/var/iso/jammy-...
mr.zog's user avatar
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1 answer
313 views

What is the correct KVM VM vCPU config in cockpit for proper load balance on physical CPUs

I have dual CPU server. I want to run some VMs on top of it. While configuring VMs thru cockpit (on redhat 8.0). I cam across this screen: I just want to allocate 8 cores with 4 on each physical CPU. ...
rajeev's user avatar
  • 101
1 vote
1 answer
133 views

Set Maximum cpu qemu/libvirt almalinux

I want ask to increase supported CPU core on qemu kvm. When I creating new VM I see error like below error: internal error: QEMU unexpectedly closed the monitor (vm='ID'): qemu-system-x86_64: -accel ...
Hendra Setyawan's user avatar
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0 answers
94 views

High CPU load by KVM VM

VMs are hosting Java and they seem to be using high sy% CPU on the server. Is there a way to limit it via Libvirt ? Other VMs not using Java in them are not using that much sy% on the server. I ...
Jevin Gala's user avatar
0 votes
0 answers
253 views

Libvirt shared storage pool

I have what I hope is a quick question. I'm running: CENTOS 9 KVM/QEMU Pacemaker, DLM, lvmlockd, fence_scsi I have a simple two node KVM cluster where I've set up a LVM logical volume on a attached ...
JDW52's user avatar
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0 votes
0 answers
113 views

Docker performance issue with nested Ubuntu KVM

I have an issue with docker performance in a nested Ubuntu VM. Here's the setup: OpenStack Infrastructure My Workstation (A) My Project Host (B) My Project VM (C) Version info: OS: Ubuntu 22.04 ...
Martin's user avatar
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4 votes
1 answer
421 views

How to sucessfully import an .ova vm exported from ovirt/kvm (Red Hat OS)?

So, I was given an .ova file. This is exported from a server using a combination of KVM/QEMU and ovirt technologie - the server runs RedHat and I want to import this .ova file into vmware or ...
oolnux's user avatar
  • 41
1 vote
1 answer
480 views

Cannot access deb.debian.org from VM after port forwarding using /etc/libvirt/hooks/qemu

Setup On host server with Debian Bookworm I created two VM-s (pserver 192.168.122.227 and pagent-1 192.168.122.126) via cockpit (kvm). Both of them are running Debian Bullseye. I am using default ...
Matija Sirk's user avatar
0 votes
0 answers
57 views

is there a way to hot plug all functions of a pcie device instead of just function 0?

It is often that we have pcie devices for example GPUs. That has multiple functions. I can statically assign all the functions to a domain by editing the XML. However, I would like to be about detach/...
Wang's user avatar
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0 votes
0 answers
165 views

Ubuntu 22.04.3: error when exec virsh sysinfo command: unsupported configuration: Host SMBIOS information is not available

I installed KVM on Ubuntu 22.04.3 Desktop on Lenovo ThinkSystem SR550. My command I used to install KVM was: sudo apt update sudo apt upgrade sudo apt install qemu-kvm libvirt-daemon-system libvirt-...
Bonavadeur's user avatar
1 vote
0 answers
149 views

KVM VM obtaining duplicate IP address for strange MAC address

I have a ubuntu KVM host on which Ubuntu virtual machine is created in virt-manager. The VM is obtaining 2 different IP's from DHCP server which is running on Windows Server. 1st IP address lease ...
Myk's user avatar
  • 11
0 votes
0 answers
98 views

KVM Virt network setting to be on the same network as the host?

As described in here How to Install KVM on Ubuntu 22.04 Step-by-Step I've done a series of commands: $ sudo vi /etc/netplan/01-netcfg.yaml network: ethernets: enp0s3: dhcp4: false ...
丶 Limeー来夢 丶's user avatar
0 votes
0 answers
215 views

How to set default disk image format in Cockpit/QEMU

I create my virtual machines on Debian 12 with Linux Cockpit 287-1 which uses QEMU/KVM for virtualization. If I create a VM, the default disk format is always in RAW-format. However, due to some ...
Drudge's user avatar
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0 answers
37 views

KVM iptables VM connect using host IP

I have three VMs on a host: Hardware Host: 192.168.0.220 VM-1: 192.168.122.10 VM-2: 192.168.122.11 VM-3: 192.168.122.12 I can connect from one VM to the other using the VM's IP address (e.g....
user1873584's user avatar
5 votes
0 answers
6k views

How do I convert a VMDK disk to QCOW2 using qemu-img without inflating the disk?

I'm converting some VMs from vSphere to KVM/QEMU but each time it inflates the thin provisioned disk. Before converting the image from vmdk to qcow2, first I export OVAs or OVFs from vSphere to make ...
Vita's user avatar
  • 263
1 vote
0 answers
193 views

KVM virt-install issue

I want to run arch linux as guest but after virt-install screen is stuck at console Escape character is ^] (Ctrl + ]).However VMs install by virt-manager are working fine and console is also working ...
Black_Bird's user avatar
3 votes
1 answer
207 views

Mmio stale data patched on hypervisor but vulnerable inside kvm guest

My hypervisor tells me that Mmio stale data is patched: Vulnerability Mmio stale data: Mitigation; Clear CPU buffers; SMT disabled But when I check inside my kvm running linux 6.1.0-12-amd64, I ...
user9503's user avatar
0 votes
0 answers
198 views

Performance problems when running Wireguard between Linux virtual machines. Same config on physical hosts works fine

I’m running into performance problems with Wireguard tunnels running between two virtual machines on the same hypervisor (running under Qemu/KVM) and I would greatly appreciate any insights/advice ...
Tulkas's user avatar
  • 1
0 votes
1 answer
4k views

KVM: qemu-system-x86_64: cannot set up guest memory 'pc.ram': Cannot allocate memory

When trying to start a VM (1GB allocated) I have run into memory allocation issue even though I have more than enough memory on the system (16GB): error: Failed to start domain exampleVM error: ...
LetMeSOThat4U's user avatar
1 vote
1 answer
207 views

Filter packets with iptables on a tap interface

I'm trying to write firewall rules to prevent a guest machine from accessing the internet. The server (Ubuntu server 22.0, using KVM) has a physical connection (enp34s0), which is connected to the ...
Amit's user avatar
  • 11
2 votes
1 answer
148 views

Libvirtd TCP port 16514 queries

I have a server that is running libvirtd. I just checked libvirtd ports and see below output. I wondered Why port 16514 PID is always 1 and why tcp6 is handling ipv4 with multi connections. Can anyone ...
Rama's user avatar
  • 87
1 vote
3 answers
433 views

In cloud, is it possible to access guest VM from host machine?

In KVM, it is possible to access the guest machine from the host machine. For example, you can SSH to the host machine and then access the guest VM by virsh console vm_name. Is that possible in cloud? ...
Noob_Guy's user avatar
  • 111
1 vote
1 answer
562 views

Memory ballooning doesn't try to reclaim page cache

I have a host running Proxmox with some VMs on it. Due to some unpredictability with the memory usage of some applications, and wanting to give some VMs (like a DB) memory for the page cache when ...
user avatar
1 vote
1 answer
1k views

Changing KVM VM listening on 5901 to some other port

OK this is rather silly, but real problem. vncserver keeps binding on 5902 port. That is because qemu is listening on 5900 and 5901: % netstat -lntup Active Internet connections (only servers) Proto ...
LetMeSOThat4U's user avatar

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