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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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Networking KVM virtual machines to VLAN interface on host

I have a VLAN interface (enp98s0f0.4000) set up on my KVM host, which is a Hetzner dedicated server. The VLAN is set up to route through a Hetzner vSwitch, and I can ping out to Cloud instances ...
emberdex's user avatar
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KVM - Reduce Storage Size of QCOW2 File To Specific Size

I want to reduce the storage size of the VM's running on a Linux 8 physical machine from 2 TB to 400 GB. The actual size of VM's is around 100 GB. But the space we give it as allocated size is too big ...
rndm_acct1's user avatar
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network does not work for VM after a while, only resolves after changing MAC

I have installed pfSense as a KVM guest in a Debian 11 host using libvirt. The host has two interfaces. One is attached to the VM using macVLAN driver, and serves as pfSense's WAN interface. The other ...
Mustafa Mohiuodin's user avatar
1 vote
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Machine type issue when migrating KVM VMs with live snapshots from Debian to Ubuntu

I'm trying to migrate around 40 KVM VMs (containing a few hundred live snapshots mostly used for automated testing on Windows) from a Ubuntu 22 server to a Debian 11 server. The machine type of most ...
John Salazar's user avatar
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Cloud-init in kvm guests (Debian and Centos) not setting interface settings

Im trying to use cloud-init to setup kvm guests (currently Debian 11 and CentOS Stream 8), and I am looking for help in correcting the meta-data and user-data files. Everything else seems to work, but ...
Unpossible's user avatar
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How to make KVM guest configs persistent across reboots/shutdown

I create a KVM Guest VM (virsh define a.xml, virsh start a.xml). Guest uses pre-configured/pre-made QCOW2 disk image, which represents a virtual router (Arista vEOS). Host is Redhat 9.1. Guest is ...
Mo Fatty's user avatar
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Connect (create ethernet link) between two VMs using their assigned SR-IOV Virtual Functions (VFs)

I have two KVM virtual machines created on RHEL9. I partitioned an SR-IOV-capable Physical NIC such that I was able to get Virtual NICs (Virtual Functions) from it. For each VM, I assigned it a VF. ...
Mo Fatty's user avatar
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ebtables is causing packet loss

I am using AlmaLinux 8 on a dedicated server and hosting VPSes using KVM. Applying ebtables rules on those VPSes is causing packet loss issue. Bridge chain: v1001, entries: 1, policy: DROP -p IPv4 -s ...
Jevin Gala's user avatar
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104 views

QEMU SMP options

I'm trying to understand the QEMU smp option. Currently I have set it to: smp 4 As far as I understand that should create 4 vCPU (with 1 core and 1 thread I suppose). Would it be better for ...
Maestro's user avatar
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How do I route ALL VM (qemu-kvm, libvirt) traffic through proxy running in Host?

Host: Ubuntu 20.04 Proxy Client and Server: V2ray Proxy Client connecting to Server and is available in the host on 127.0.0.110808 for Socks and 127.0.0.1:10809 for http. VMs: Multiple vms running ...
Malvo's user avatar
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Determine QEMU KVM overhead?

My guest OS shows about 5 percent CPU usage, but my host machine shows the QEMU process taking about 25 percent. I'm trying to understand where this difference comes from, as I am using KVM ...
Maestro's user avatar
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QEMU load average vs cpu count

When I configure more CPU cores, the load average in my Guest OS as shown by top also increases linearly. I'm trying to understand why this happens, because I expected either the opposite or at least ...
Maestro's user avatar
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2 votes
1 answer
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Dynamic CPU allocation/scaling in QEMU KVM

How can I dynamically allocate/scale CPU resources to my QEMU VM according to the workload of the VM? Would this require a script? Is it even possible to change CPU allocation at runtime? I have a ...
Aarav Prasad's user avatar
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Remove "lspci" devices from guest VM - possibilities and limitations

Prerequesites: some RedHat KVM hypevisor and Ubuntu server as guest. So, I'm worryng about virtual pci devices, connected to my Linux VM (on VPS) by default. One of them is VGA device which lets ...
agiAWjoa0za's user avatar
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KVM with public IP for a VM

I'm looking to build a VM using KVM/qemu in my dedicated server and assign to it one of the 2 Ip addresses I got assigned for my dedi. However, following this guide https://medium.com/techtalk-blog/...
Archer Sterling's user avatar
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in Cuckoo sandbox how to setup simple gloabal routing using KVM as my guest machine?

im using kvm because the malware im analyzing has virtualbox detection. ive gotten cuckoo working with virtualbox im having trouble with the kvm one. I'm using ubuntu 18.04 as the main host. ive tried ...
George Cardoso's user avatar
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vm machines cannot ping each other via bridge network [duplicate]

I created vhost1 and vhost2 by using virt-manager which run on a Ubuntu server 22.04 The Host and VMS connected via a bridge network. So here's the thing: The ping working fine between Host and VMS, ...
mdzz's user avatar
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-1 votes
3 answers
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Use cloud server's network to serve local server's content

I am trying to build a web application for a local community. I'd like to host a postgres database, a SSR frontend server, a REST backend server. The internet and electricity are pretty cheap here and ...
berinaniesh's user avatar
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network-latency/ping degradation over time correlated with memory fragmentation

There is an Online Charging System (OCS) which handles Diameter Ro and Gy traffic. The OCS receives CCR Diameter messages and answers with CCA Diameter messages. And this response time - latency - ...
Neighbour's user avatar
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virtual pfSense setup with virtual interfaces

I am running a linux Desktop, for virtualization I am using QEMU/KVM. In order to properly test my ansible Scripts I would like to create a virtual lab environment on my Desktop, that behaves like the ...
philipp's user avatar
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Unable to install a VM in KVM: Error: Unable to destroy domain

I am runnging ubuntu server and I am unable to launch virtual machines, Initially it said permission denied but now it is also saying error: Failed to destroy domain 'esxi03' error: Requested ...
christian Martin's user avatar
1 vote
1 answer
154 views

How to use more then 2GB of ram when using running a nested BIOS VM using KVM

I have a Linux host running Debian 11 and on that host, I have a Ubuntu 22.04 VM. Inside that VM I want to run a Windows 10 VM using nested virtualization. The ubuntu VM is booted using EFI and nested ...
nezu's user avatar
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Occasional packet loss between bridge interfaces

I have two virtualization servers based on libvirt and KVM. And sometimes I see packages get lost on one particular virtual machine. After restarting the virtualization host this problem is solved, ...
akashavkin's user avatar
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51 views

Can I use OpenStack Rocky with a neoverse-n1?

Situation: For now, I'm stuck on OpenStack Rocky on Ubuntu 18.04.6 and I have some beefy Neoverse-n1 hardware (aarch64, 64-core, 1TB memory) to integrate. Can I accomplish this with on my current OS ...
jimbob's user avatar
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1 vote
0 answers
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Virtualized Centos 7 on Ubuntu host: very slow I/O

I run a Centos 7 virtualized in Ubuntu 20.04. There is a huge I/O performance drop in the VM compared to the host. The host has plenty of RAM. Host: * MB/s = 1,000,000 bytes/s * KB = 1000 bytes, KiB = ...
Laurent's user avatar
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1 vote
1 answer
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Three virtio-blk devices crashing Windows 10 VM

If three virtio-blk devices are added VM is crashing in the middle of the Windows 10 boot. The attached blockdev has no influence. VM is working fine using two virtio-blk. qemu-system-x86_64 \ ... -...
Jonas's user avatar
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1 answer
166 views

Ping to/from KVM QEMU VM running in another network namespace

I cannot ping to the default network namespace from a KVM QEMU VM running in a separate network namespace. Here is my setup: ip netns add test-ns # Creating veth ip link add if-in-ns type veth peer ...
jak kaj's user avatar
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How to create a shared Disk with the image stored on Host in KVM?

I am currently trying to setup a disk, using the raw img format on the host, which is then shared between multiple guest VMs (which are running Alpine Linux), using the libvirt / KVM virtualization ...
Apoorv Pal's user avatar
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106 views

Attach two network interfaces in a KVM guest to two VLANs in a physical switch through a single-interface host

I have installed a Debian-based VM with two network interfaces, one with one public IP and another with one private IP. I can access public gateway IP and beyond from the public interface (native/...
Antonio López's user avatar
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Why are pci-devices passed as node and not by the parent

I was wondering why in every pci / gpu passthrought tutorial devices are passed by each node. Consider the following +- pci_0000_40_03_1 | | | +- pci_0000_41_00_0 | | | +- ...
Basur's user avatar
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1 vote
1 answer
99 views

How to read qemu fw_cfg value in windows guest?

Unable to find information about how to read -fw_cfg value in windows guest with the help of this: https://github.com/virtio-win/kvm-guest-drivers-windows/tree/master/fwcfg Related question: https://...
Jonas's user avatar
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0 answers
43 views

How to add two interfaces to KVM VM acting like a loopback

I have KVM machine with network interface (say eth0) attached to virbr0, I use it to ssh into the vm. I would like to add two more ethernet interfaces (say eth1 and eth2) and "bridge it on the ...
stan's user avatar
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1 vote
0 answers
77 views

libvirt virsh not using a predefined target while attaching interface

I am trying to automate the process of creating a Guest VM. I am using uvt-kvm to create the VM. I am also taking a network type as a parameter. This can be either nat or macvtap. Now in the script I ...
akarX_123's user avatar
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443 views

QEMU Shared folder between Linux host and windows 10 Guest

I installed samba then I used the following command: qemu-system-x86_64 -drive file=Windows.img,format=qcow2,if=virtio -nic user,id=nic0,smb=/home/aarav/Downloads After starting up the VM, I opened ...
Aarav Prasad's user avatar
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0 answers
32 views

How to convert virtual machine images to bootable OS installation?

I have a virtual machine installed in QEMU. I want to migrate this machine and use it as base machine. Query I have is that it is possible, and if yes will simple converting .img to .iso and burning ...
Ayush Gupta's user avatar
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0 answers
96 views

Unable to access Internet from user-defined docker bridge network hosted on KVM

I am running Docker from a KVM: Docker --- (hosted on) ----> KVM Guest ---- (hosted on) ----> KVM host I created a docker bridge network with the following command: docker create test user@...
Lifu Huang's user avatar
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0 answers
19 views

Is it possible to use the IO priority from a KVM guest on the host?

When I use KVM with libvirt and virtio block devices, does it propagate IO priority in some way? If the guest starts a process with ioidle priority, I want it to run only if the host is also in ioidle ...
allo's user avatar
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1 answer
43 views

KVM guest low network speed

I have a KVM guest VM running RHEL 8.7 (12vCPU, 24GB RAM) and a hypervisor with 10Gb NICs. I'm getting weird results when using iperf3 on my guest machine as a client and a TrueNAS server as a server. ...
chetzz's user avatar
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0 votes
0 answers
44 views

qemu virtual machines slow during RAID5 check

Operating system: CentOS 7.9 (on both host and guests) Host specs: CPU - AMD EPYC 7502P 32-Core Processor RAM - 250 GB (only 22G used by all VMs) Disk - Four Samsung SSD 870 QVO 4TB, grouped in a ...
William Seligman's user avatar
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0 answers
119 views

QEMU boot with no progress for quite long after using the -enable-kvm option

I just wanna start a vm based on x86_64 via qemu, everything goes as expected(e.g. showing the console and login part) when I run the command below qemu-system-x86_64 \ -nographic \ -smp 4 \ -kernel ~/...
DESPERATE's user avatar
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0 answers
67 views

Physical/Bridge and KVM ports shows up even after unplugged the cable!

We have Debian 10, it has two physical interfaces which we bridge to KVM. The issue I have is, when I shutdown the port from my virtual operating system or I disconnect the cable the birdge and ...
Himanshu Dua's user avatar
1 vote
0 answers
31 views

KVM : What is the Maximum Number of Physical CPU and Physical Core KVM Can Support on a Single HOST

I am new here so this is my first day with a very confusing Quistion so please help me to understand it Properly. Expert Advise Required My Quastion is : I have a dell PowerEDGE Server With Intel ...
Tech Donkeey's user avatar
3 votes
2 answers
372 views

slow performance on ssd when using kvm to launch vm's

On my host hardware I have 1G's speed on my vm I create using kvm it drops to around 20MB's My host is running ubuntu 22.04 LTS How can I optimise this? I am using file based VM's. I created disk ...
shorif2000's user avatar
0 votes
1 answer
602 views

Routing KVM VM traffic over wireguard from host OS

I'm trying to setup a Wireguard tunnel on my host OS and route all network traffic from a specific KVM VM over this Wireguard VPN. My KVM VMs are setup using bridged networking. The interface name on ...
user3749382's user avatar
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0 answers
155 views

How to connect to VM from another computer in the local network

I have a host system (running Debian 11) where I installed a virtual machine (Ubuntu 22.04) using KVM. I can ssh between host and VM using their IPs (192.168.122.1 and 192.168.122.230). I also can ssh ...
Matias Irazoqui's user avatar
1 vote
1 answer
192 views

Migration disabled: vhost-user backend lacks VHOST_USER_PROTOCOL_F_LOG_SHMFD feature

I tried this command on the host. virsh snapshot-create-as --domain test_vm_back --name "snapshot-before-install-package" --description "snapshot test" As you know, this is just a ...
Constantin Hong's user avatar
0 votes
1 answer
180 views

libvirt live storage migration but keep vm on same host

Is libvirt capable of doing a live storage migration but keep the VM on the same host? I have two NFS Network filesystem pools on one host. I would like to live migrate the underlying qcow2 disk files ...
eKKiM's user avatar
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0 answers
732 views

Error starting domain: unsupported configuration: host doesn't support passthrough of host PCI devices - fedora 37

I added the section in the xml file of the VM win10 and I got the following error: Error starting domain: unsupported configuration: host doesn't support passthrough of host PCI devices when trying to ...
jeanix46's user avatar
0 votes
1 answer
124 views

Windows asking me to sign in with a company email?

Windows is asking me to sign in with my company's email, problem is I don't have one and nor is the company related to me whatsoever. I am trying to run Windows LTSC on QEMU. What gives?
Aarav Prasad's user avatar
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0 answers
73 views

"Welcome to Intellek" when trying to install Windows LTSC 2021 in Qemu [duplicate]

On the "Account" stage, it says "Welcome to Intellek" and prompts me to enter my email for Intellek. I do not know what that is, a search reveals it is some company? I downloaded ...
Aarav Prasad's user avatar

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