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Fix permission /dev/kvm

Posted by udienz on February 03, 2015 · 2 mins read

Problem ini sangat umum ketika kita memasang qemu-kvm, contohnya ketika akan melakukan pembuatan mesin virtual dengan cara berikut:

/usr/bin/qemu-system-x86_64 -netdev user,id=user.0,hostfwd=tcp::3213-:22 -device virtio-net,netdev=user.0 -drive file=output-qemu/packer-qemu.qcow2,if=virtio,cache=writeback -boot once=d -name packer-qemu -machine type=pc,accel=kvm -cdrom packer_cache/ubuntu.iso -m 512M -vnc 0.0.0.0:47
Could not access KVM kernel module: Permission denied

Atau error seperti berikut

2015 /02/03 18:33:37 packer-builder-qemu: 2015/02/03 18:33:37 Qemu stderr: Could not access KVM kernel module: Permission denied
2015/02/03 18:33:37 packer-builder-qemu: 2015/02/03 18:33:37 Qemu stderr: failed to initialize KVM: Permission denied
2015/02/03 18:33:37 ui error: ==> qemu: Error launching VM: Qemu failed to start. Please run with logs to get more info.
2015/02/03 18:33:37 ui: ==> qemu: Deleting output directory...
==> qemu: Error launching VM: Qemu failed to start. Please run with logs to get more info.
2015/02/03 18:33:37 ui error: Build 'qemu' errored: Build was halted.
2015/02/03 18:33:37 Builds completed. Waiting on interrupt barrier...

Hal ini dikarenakan ACL pada berkas /dev/kvm yang belum memasukkan user kita, contohnya:

sudo getfacl /dev/kvm
getfacl: Removing leading '/' from absolute path names
# file: dev/kvm
# owner: root
# group: kvm
user::rw-
group::rw-
other::---

Seharusnya pada kolom user ada user kita :(. Untuk mengatasinya kita perlu melakukan modifikasi ACL pada berkas /dev/kvm dengan cara:

sudo setfacl -m user:$USER:rw- /dev/kvm

contoh jika user adalah udienz:

sudo setfacl -m user:udienz:rw- /dev/kvm
sudo getfacl /dev/kvm
getfacl: Removing leading '/' from absolute path names
# file: dev/kvm
# owner: root
# group: kvm
user::rw-
user:udienz:rw-
group::rw-
mask::rw-
other::---

Silakan dicoba

Referensi:

  1. https://bbs.archlinux.org/viewtopic.php?id=69454

  2. http://ubuntuforums.org/showthread.php?t=1976606

  3. http://forums.debian.net/viewtopic.php?f=10&t=111711&sid=e550c9b1d0a8bec4ff430ec9f3858569&start=15

  4. http://stevedowe.me/2014/09/fix-permissions-error-with-kvm-virtual-machine-on-debian.html