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Hugepages -- "Memory backend 'pc.ram' not found"
by Charles Polisher 21 Feb '22

21 Feb '22

Hello, After defining hugepages, as documented at https://libvirt.org/formatdomain.html#memory-backing , when I start the guest, I get a dialogue box that says: Error starting domain: internal error: qemu unexpectedly closed the monitor: 2022-02-20T01:10:36.520955Z qemu-system-x86_64: Memory backend 'pc.ram' not found Traceback (most recent call last): File "/usr/share/virt-manager/virtManager/asyncjob.py", line 65, in cb_wrapper callback(asyncjob, *args, **kwargs) File "/usr/share/virt-manager/virtManager/asyncjob.py", line 101, in tmpcb callback(*args, **kwargs) File "/usr/share/virt-manager/virtManager/object/libvirtobject.py", line 57, in newfn ret = fn(self, *args, **kwargs) File "/usr/share/virt-manager/virtManager/object/domain.py", line 1329, in startup self._backend.create() File "/usr/lib64/python3.9/site-packages/libvirt.py", line 1353, in create raise libvirtError('virDomainCreate() failed' After backing out changes, guest starts normally. I searched online for the error message, but found nothing useful. The hypervisor is running libvirtd (libvirt) 7.8.0 and QEMU emulator version 6.1.0, both build from source. I've got plenty of hugepages available. The domain's XML definition is attached. Any ideas where to look next? Thanks, -- Charles Polisher

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libvirt-python for alpine linux
by Tom Ammon 20 Feb '22

20 Feb '22

Hi everybody, Is there a libvirt-python package for alpine linux? I'm looking to containerize an app that uses libvirt-python, using alpine linux, but all I found that looked similar to libvirt-python was py-libvirt ( https://pkgs.alpinelinux.org/package/v3.3/main/x86/py-libvirt) and it looks pretty old. Tom -- ----------------------------------------------------------------------------- Tom Ammon M: (737) 400-9042 thomasammon(a)gmail.com -----------------------------------------------------------------------------

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SSH VM from outside, but not from host
by Wolf 16 Feb '22

16 Feb '22

Hi! 1) I have two network ports on my server. - eno1 has the IP: XX1.XX1.XX1.150 - bridge0 has the IP: XX2.XX2.XX2.100 and has the interface member: port eno2. eno2 is not set up with an IP address. 2) The host runs on IP: XX1.XX1.XX1.150 3) A VM uses the bridge: bridge0, and has the IP: XX2.XX2.XX2.100 I have a problem with this setup: I can ssh the VM on XX2.XX2.XX2.100 from outside, but from the host, XX1.XX1.XX1.150, I can't ssh the VM on XX2.XX2.XX2.100. Have I set up this wrong or is it something I can do to solve this? Thanks! Wolf

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Public IP on virtual machine network issue
by Marcin Groszek 15 Feb '22

15 Feb '22

I have been struggling with this for weeks and I was unable to find an answer on line. Perhaps someone here can help me. Oracle linux 8 running virtualization: hardware node has a public IP address on interface bridge0 and physical eno1 is a member of the bridge0 a virtual OS has interface bridged to lan and source is bridge0, Ip address of virtual OS is also a public from same class as the hardware node. I can route in and out of virtual, I can ping from hardware node to virtual and vice versa, so the routing works as it should, sort of. When I try tracepath or traceroute from outside to virtual I get !H on last hup same result when I try to do the same form hardware node to virtual I get !H Also, when I telnet (TCP) to a specific port on virtual where I have a daemon LISTENING OR NOT I get: No route to host. Same experiment works just fine for ssh port. Firewalld is not running, and I just have very basic iptables rules like allowing external address block to ssh to hardware node and to virtual dropping connections from all other sources This issue presented it self when I attempted to setup a galera node on virtual and ports 4567 is responding but 4568 and 4444 are not, but the daemons are running and I can clearly see lsoft showing "LISTENING" I capture the traffic and the tcp as well as udp are getting to the virtual. Is there a preconfigured netfiltering that I am not aware of? What am I missing? -- Best Regards: Marcin Groszek Business Voip Resource. http://www.voipplus.net

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libvirtd daemon missing in LFS
by Sai Kiran Kumar Reddy 15 Feb '22

15 Feb '22

Hi, I am Sai Kiran. I am trying to build libvirt from source on my Linux From Scratch(LFS) system. I have successfully installed libvirt and its dependencies. When I start virt-manager, there is a prompt in GUI saying that "libvirtd service is not installed". I also do not see any libvirtd in my system. I would like to install the libvirtd service(build from source). But I am not able to find the source code for it and also, I am not sure about the build process for the daemon. Could you please help me out here. Thanks in advance for your time and support. -- Regards, Sai Kiran.

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qemu+ssh connections to a remote libvirt fail as ssh banner configured
by Yalan Zhang 14 Feb '22

14 Feb '22

Hi there, I have a system configured with ssh login banner like as below: # cat ~/.bashrc ... echo "=================================================================================" echo "====== This machine is occupied by xxx for testing now. If you are about to use it, contact xxx first ======" echo "=================================================================================" It works as expected that whenever someone logs into this system by ssh, he/she will see this warning message. But it seems such settings will impact a virsh client connection with ssh, when I try to connect the libvirt daemon on this system, it will error out : # virsh -c qemu+ssh://${my_host}/system list --all root@${my_host}'s password: error: failed to connect to the hypervisor error: packet 1027423545 bytes received from server too large, want 33554432 I have searched and found some related explanations[1], and [2] says "The virsh man page doesn't mention ssh, so it sounds like the file /usr/share/doc/libvirt-doc/remote.html shipped with libvirt-doc could use a patch mentioning this." But I can not find anything about this currently on file:///usr/share/doc/libvirt-docs/html/remote.html. Could we have this documented for reference with all the possibilities? Thank you! [1] https://bugs.launchpad.net/ubuntu/+source/libvirt/+bug/868753/comments/17 [2] https://bugs.launchpad.net/ubuntu/+source/libvirt/+bug/868753/comments/14 ------- Best Regards, Yalan Zhang IRC: yalzhang

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NVMe drive PCI passthrough and suprise hotplug
by Kalra, Ashish 07 Feb '22

07 Feb '22

[AMD Official Use Only] Hi, I am using Fedora 33, with the following KVM, qemu and libvirt versions: QEMU 5.1.0 libvirt 6.6.0 KVM 5.14.18 We have done pass-through of a PCIe NVMe device to the guest running on FC33 using either virt-manager or virsh and then we do the hot-unplug of the device while it is attached to the guest. The device is no longer seen on the guest hardware device list on virt-manager and then we hotplug the device again and we are able to use it on the Host, but when we try to re-attach it to the guest, we get the following error message: Requested operation is not valid, PCI device 0000:c4::00.0 is in use by driver QEMU, Domain fedora 33. So somehow libvirt still thinks the hot-unplugged device is attached. Tracing the flow of hot un-plug event from guest to host : ->Guest pcie hotplug support detected the NVMe driver unplug (from guest kernel logs): pciehp: Slot (0-6): Attention button pressed pciehp: Slot (0-6): Powering off due to to button press. -> Also looks like the guest notified Host/KVM (from host kernel logs): pcieport: 0000:c4:0000.0: pciehp: Slot (208): Card not present -> Correspondingly, vfio-pci module notified Qemu : vfio-pci: 0000:c4:0000.0: Relaying device request to user (#0) -> Then the un-plugged device reset is done. vfio-pci: vfio_bar_restore: reset recovery - restoring BARs pci 0000:c4:00.0: Removing from iommu group 105. -> Next tried to verify if libvirt detected the DELETED_DRIVE event from qemu. Running SystemTap script to capture events between qemu and libvirt : stap examples/systemtap/qemu-monitor.stp When the NVMe drive is attached to VM the following log output is seen from SystemTap: execute "device-add", driver: "vfio-pci", host: "0000:c4:00.0", id: "hostdev0", bus: "pci.7", addr: "0". When we hot-unplug the NVMe drive, the following log output is seen from SystemTap: event: DEVICE_DELETED, device: "hostdev0", path: "/machine/peripheral/hostdev0". So it looks like that qemu sent the "DEVICE_DELTED" event to libvirt, but libvirt has still not removed the attached device from its bookeeping list. I understand there is already a thread from 20202, discussing a similar issue : https://www.spinics.net/linux/fedora/libvirt-users/msg12590.html But I am not sure if there is any fix/support added for this recently. Looking for any feedback related to above and PCI device passthrough and hotplug support. Thanks, Ashish

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udmabuf error with libvirt + QEMU
by M, Shivakumar 01 Feb '22

01 Feb '22

Hi, We are seeing an issue with udambuf, where it says "open /dev/udmabuf: No such file or directory " even if the device exits. This issue particularly we are seeing with libvirt. When we run the QEMU args on the command line, everything works as expected. It seems to be some permission issue when we use the Libvirt, please help us on resolving this. [cid:image001.png@01D817A5.0151F260] Libvirt Version: 6.0.0 Host: Ubuntu 21.04 QEMU commands: qemu-system-x86_64 \ -enable-kvm \ -smp cores=4,threads=2,sockets=1 \ -m 4096 \ -name win-vm-0 \ -cpu host \ -drive id=windows_drive,if=virtio,file=/win10_enterprise.qcow2,format=qcow2,cache=none \ -device vfio-pci,host=0000:00:02.2 \ -device e1000,netdev=net0,mac=00:a1:00:00:00:10 \ -netdev user,id=net0,ipv6=off,hostfwd=tcp::1111-:22,hostfwd=tcp::3389-:3389 \ -monitor tcp:127.0.0.1:11111,server,nowait \ -rtc base=localtime \ -usb \ -device usb-tablet \ -device usb-kbd \ -device usb-mouse \ -device virtio-vga,blob=true \ -display gtk,gl=on \ -object memory-backend-memfd,id=mem1,hugetlb=off,size=4096M \ -machine memory-backend=mem1 Libvirt XML: <?xml version="1.0"?> <domain xmlns:qemu=http://libvirt.org/schemas/domain/qemu/1.0 type="kvm"> <name>win-vm-0</name> <memory unit="KiB">4194304</memory> <currentMemory unit="KiB">4194304</currentMemory> <memoryBacking supported="yes"> <source type="memfd"/> </memoryBacking> <vcpu>6</vcpu> <os> <type arch="x86_64" machine="pc">hvm</type> <boot dev="hd"/> <boot dev="cdrom"/> </os> <features> <acpi/> <apic/> <hyperv> <relaxed state="on"/> <vapic state="on"/> <spinlocks state="on" retries="8191"/> </hyperv> <vmport state="off"/> </features> <cpu mode="host-model"> <model fallback="forbid"/> </cpu> <clock offset="utc"> </clock> <on_poweroff>destroy</on_poweroff> <on_reboot>restart</on_reboot> <on_crash>destroy</on_crash> <devices> <emulator>/usr/bin/qemu-system-x86_64</emulator> <disk type="file" device="disk"> <driver name="qemu" type="qcow2"/> <source file="/win10_enterprise.qcow2" index="1"/> <backingStore/> <target dev="sda" bus="sata"/> <alias name="sata0-0-0"/> <address type="drive" controller="0" bus="0" target="0" unit="0"/> </disk> <interface type="bridge"> <source bridge="br0"/> <model type="virtio"/> </interface> <serial type="pty"> <target port="0"/> <target type="serial" port="0"> </target> <alias name="serial0"/> </serial> <console type="pty"> <target type="serial" port="0"/> <alias name="serial0"/> </console> <hostdev mode="subsystem" type="pci" managed="yes"> <driver name="vfio"/> <source> <address domain="0x0000" bus="0x00" slot="0x02" function="0x02"/> </source> </hostdev> </devices> <qemu:commandline> <qemu:arg value="-device"/> <qemu:arg value="virtio-vga,blob=true"/> <qemu:arg value="-display"/> <qemu:arg value="gtk,gl=on"/> <qemu:env name="DISPLAY" value=":1.0"/> </qemu:commandline> </domain> Thanks, Shiv

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frequent network collapse possibly due to bridging
by Hakan E. Duran 30 Jan '22

30 Jan '22

Hi, I would like some help to troubleshoot the problem I have been having lately with my VM host, which contains 5 VMs, one of which is for pi-hole, unbound services. It has been a relatively common occurrence in the last few weeks for me to find that the host machine has lost its network when I get back home from work. Restoring the VM/VMs do not fix the problem, the host needs to be restarted for a fix, otherwise there is both loss of name resolution, as well as an internet connection; I cannot ping even IPs such as 8.8.8.8. Since I use the pi-hole VM as the DNS server for my LAN, this means that my whole LAN gets disconnected from internet, until the host machine is rebooted. The host machine has a little complicated network setup: the two gigabit connections are bonded and bridged to the VMs; however this set up has been serving me so well for several years now. The problem, on the other hand, appeared a few weeks ago. This doesn't happen every day but often enough to be annoying and disruptive for my family. My question is, how can I troubleshoot this problem and figure out whether it is truly due to network bridging somehow collapsing or not? I tried to find some log files but all I could find were the /var/log/libvirt/qemu/$VM files, and the particular log file for the pi-hole VM reported the following lines; however, I am not sure if they are associated with a real crash or just due to shutting down and restarting the host (please excuse the word-wrapping): char device redirected to /dev/pts/2 (label charserial0) qxl_send_events: spice-server bug: guest stopped, ignoring 2022-01-20T23:41:17.012445Z qemu-system-x86_64: terminating on signal 15 from pid 1 (/sbin/init) 2022-01-20 23:41:17.716+0000: shutting down, reason=crashed 2022-01-20 23:42:46.059+0000: starting up libvirt version: 7.10.0, qemu version: 6.2.0, kernel: 5.10.89-1-MANJARO, hostname: -redacted- Please excuse my ignorance but is there a way to restart the networking without rebooting the host machine? This will not solve my problem since I won't be able to reach to the host remotely if the networking is down. The real solution would be preventing these network crashes and the first step in that would be effective troubleshooting in my opinion. Any input/guidance will be greatly appreciated. I can provide more info about my host/VM(s) if the above is not adequate. Thanks, Hakan Duran

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Backend memory object creation - query
by M, Shivakumar 27 Jan '22

27 Jan '22

Hello, For our use-case with Libvirt we want to create the Memory backend object , Expected QEMU args would be -object memory-backend-memfd,id=mem1,size=4096M Request you to please help us to specify this arg in the libvirt XML. Thanks, Shiv

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