March 2020 - Users - libvirt List Archives

[libvirt-users] bridge / ubuntu / no arp reply
by François Chenais 15 Oct '26

15 Oct '26

Hello I'm trying to setup a bridged guest on an ubuntu 13.10 but it doesn't work. (Everything is ok with NAT) Network sniffing shows that arp replies don't come back to the guest. Test 1 ------ Guest : ping host_bridge_ip (ok) Test 2 ------ Guest: ping other_lan_host (KO) other_lan_host - receives arp who-is request - sends arp reply - arp -a shows the guest macaddr => Guest doesn't receive reply Test 3 ------ other_lan_host ping the Guest (KO) - arp -a shows "incomplete" addr - Guest receives nothing On Host ------- network tcpdump on bridge or vnet interfaces shows request but no reply ... Thanks in advance for help or ideas François

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[libvirt-users] [virtual interface] detach interface during boot succeed with no changes
by Yalan Zhang 08 Sep '22

08 Sep '22

Hi guys, when I detach an interface from vm during boot (vm boot not finished), it always fail. I'm not sure if there is an existing bug. I have confirmed with someone that for disk, there is similar behavior, if this is also acceptable? # virsh destroy rhel7.2; virsh start rhel7.2 ;sleep 2; virsh detach-interface rhel7.2 network 52:54:00:98:c4:a0; sleep 2; virsh dumpxml rhel7.2 |grep /interface -B9 Domain rhel7.2 destroyed Domain rhel7.2 started Interface detached successfully <address type='pci' domain='0x0000' bus='0x00' slot='0x06' function='0x0'/> </controller> <interface type='network'> <mac address='52:54:00:98:c4:a0'/> <source network='default' bridge='virbr0'/> <target dev='vnet0'/> <model type='rtl8139'/> <alias name='net0'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/> </interface> When I detach after the vm boot, expand the sleep time to 10, it will succeed. # virsh destroy rhel7.2; virsh start rhel7.2 ;sleep 10; virsh detach-interface rhel7.2 network 52:54:00:98:c4:a0; sleep 2; virsh dumpxml rhel7.2 |grep /interface -B9 Domain rhel7.2 destroyed Domain rhel7.2 started Interface detached successfully ------- Best Regards, Yalan Zhang IRC: yalzhang Internal phone: 8389413

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Set hostname of guest during installation time
by john doe 05 Nov '20

05 Nov '20

Hi, I would like to set the hostname when installing a guest, with the below command the hostname is not set to 'try06' in the guest: virt-install --name=try06 --graphic none --pxe --network bridge=virbr0 How can I set the hostname of the guest during installation time? I realy appriciate the support I'm getting in here, I'm fairly new to libvirt. -- John Doe

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[libvirt-users] Live migrate + change interface name
by Marc Roos 07 Oct '20

07 Oct '20

Is it possible to do a live migrate of a guest, having on the from host a source_device=eth2 and to host a source_dev=eth1?

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[libvirt-users] Add Virtlyst to the list of libvirt users
by Daniel Nicoletti 23 Sep '20

23 Sep '20

Hi, I've just released v1.0.0 of Virtlyst[1] a web tool to manage VMs using Qt/C++/Cutelyst https://dantti.wordpress.com/2018/04/19/announcing-virtlyst-a-web-interface… Thanks. 1 - https://github.com/cutelyst/Virtlyst -- Daniel Nicoletti KDE Developer - http://dantti.wordpress.com

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guest-fsfreeze-freeze freezes all mounted block devices
by Marc Roos 09 Aug '20

09 Aug '20

I wondered if anyone here can confirm that virsh qemu-agent-command domain '{"execute":"guest-fsfreeze-freeze"}' Freezes all mounted block devices filesystems. So if I use 4 block devices they are all frozen for snapshotting. Or just the root fs?

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[libvirt-users] Question about disabling UFO on guest
by Bao Nguyen 05 Aug '20

05 Aug '20

Hello everyone, I would like to ask a question regarding to disable UFO of virtio vNIC in my guest. I have read the document at https://libvirt.org/formatdomain.html *host* The csum, gso, tso4, tso6, ecn and ufo attributes with possible values on and off can be used to turn off host offloading options. By default, the supported offloads are enabled by QEMU. *Since 1.2.9 (QEMU only)* The mrg_rxbuf attribute can be used to control mergeable rx buffers on the host side. Possible values are on (default) and off. *Since 1.2.13 (QEMU only)* *guest* The csum, tso4, tso6, ecn and ufo attributes with possible values on and off can be used to turn off guest offloading options. By default, the supported offloads are enabl ed by QEMU. *Since 1.2.9 (QEMU only)* Then I disabled UFO on my vNIC on guest as the following configuration <devices> <interface type='network'> <source network='default'/> <target dev='vnet1'/> <model type='virtio'/> <driver name='vhost' txmode='iothread' ioeventfd='on' event_idx='off' queues='5' rx_queue_size='256' tx_queue_size='256'> *<host gso='off' ufo='off' />* *<guest ufo='off'/>* </driver> </interface> </devices> Then I reboot my node to get the change effect and it works. However, can I disable the UFO without touching the host OS? or it always has to disable on both host and guest like that? Thanks, Brs, Natsu

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Could you please help with questions about the net failover feature
by Yalan Zhang 09 Jul '20

09 Jul '20

Hi laine, I have leave some questions on IRC, but my VPN broken time after time. Please ignore the questions on IRC. In my understanding, the standby and primary hostdev interface may be in different subnet. I'm not sure whether it is correct. Could you please help to explain? Thank you in advance. For example, primary hostdev is connected to vf-pool with <pf='eth0'/>, while the standby is connected to NAT network with " forward dev='eth0'". The standby interface will get ip as 192.168.122.x, but after NAT, it will be in the same subnet of the vf. So after the VF is unplugged, the packet will still broadcast in the same subnet, and the vm will get the packet as the standby share the same mac. Right? Thank you! ------- Best Regards, Yalan Zhang IRC: yalzhang

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qemu hook: event for source host too
by Guy Godfroy 23 Jun '20

23 Jun '20

Hello, this is my first time posting on this mailing list. I wanted to suggest a addition to the qemu hook. I will explain it through my own use case. I use a shared LVM storage as a volume pool between my nodes. I use lvmlockd in sanlock mode to protect both LVM metadata corruption and concurrent volume mounting. When I run a VM on a node, I activate the desired LV with exclusive lock (lvchange -aey). When I stop the VM, I deactivate the LV, effectively releasing the exclusive lock (lvchange -an). When I migrate a VM (both live and offline), the LV has to be activated on both source and target nodes, so I have to use a shared lock (lvchange -asy). That's why I need a hook event on the source host too (as far as I know after my tests, the migration event is only triggered on the target host). Is such a feature a possibility? Thanks for your attention. Guy Godfroy

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Re: USB-hotplugging fails with "failed to load cgroup BPF prog: Operation not permitted" on cgroups v2
by Pavel Hrdina 13 May '20

13 May '20

On Mon, Jan 20, 2020 at 09:00:15PM +0100, Pol Van Aubel wrote: > Hi, > > Quoting Pavel Hrdina (2020-01-20 14:29:36) > > On Sat, Jan 18, 2020 at 11:17:11PM +0100, Pol Van Aubel wrote: > > > Hi all, > > > > > > I've disabled cgroups v1 on my system with the kernel boot option > > > "systemd.unified_cgroup_hierarchy=1". Since doing so, USB hotplugging > > > fails to work, seemingly due to a permissions problem with BPF. Please > > > note that the technique I'm going to describe worked just fine for > > > hotplugging USB devices to running domains until this change. > > > Attaching / detaching USB devices when the domain is down still works as > > > expected. > > > > > > I get the same error when attaching a device in virt-manager, as I do > > > when running the following command: > > > > > > sudo virsh attach-device wenger /dev/stdin --persistent <<END > > > <hostdev mode='subsystem' type='usb' managed='yes'> > > > <source startupPolicy='optional'> > > > <vendor id='0x046d' /> > > > <product id='0xc215' /> > > > </source> > > > </hostdev> > > > END > > > > > > This returns > > > error: Failed to attach device from /dev/stdin > > > error: failed to load cgroup BPF prog: Operation not permitted > > > > > > > > > virt-manager returns basically the same error, but for completeness' > > > sake, here it is: > > > > > > failed to load cgroup BPF prog: Operation not permitted > > > > > > Traceback (most recent call last): > > > File "/usr/share/virt-manager/virtManager/addhardware.py", line 1327, in _add_device > > > self.vm.attach_device(dev) > > > File "/usr/share/virt-manager/virtManager/object/domain.py", line 920, in attach_device > > > self._backend.attachDevice(devxml) > > > File "/usr/lib/python3.8/site-packages/libvirt.py", line 590, in attachDevice > > > if ret == -1: raise libvirtError ('virDomainAttachDevice() failed', dom=self) > > > libvirt.libvirtError: failed to load cgroup BPF prog: Operation not permitted > > > > > > > > > Now, libvirtd is running as root, so I don't understand why any > > > operation on BPF programs is not permitted. I've dug into libvirt's code > > > a bit to see what is throwing this error and it boils down to > > > <https://github.com/libvirt/libvirt/blob/7d608469621a3fda72dff2a89308e68cc9f…> > > > and > > > <https://github.com/libvirt/libvirt/blob/02bf7cc68bfc76242f02d23e73cad36618f…> > > > but I have no clue what that syscall is doing, so that's where my > > > debugging capability basically ends. > > > > > > Maybe this is something as simple as setting the right ACL somewhere. I > > > haven't touched /etc/libvirt/qemu.conf except for setting nvram. There > > > *is* something about cgroup_device_acl there but afaict that's for > > > cgroups v1, when there was still a device cgroup controller. Any help > > > would be greatly appreciated. > > > > > > > > > Domain log files: > > > Upon execution of the above commands, nothing gets added to the domain > > > log in /var/log/qemu/wenger.log, so I've decided they're likely > > > irrelevant to the issue. Please ask for any additional info required. > > > > > > > > > System information: > > > Arch Linux, (normal) kernel 5.4.11 > > > libvirt 5.10.0 > > > qemu 4.2.0, using KVM. > > > Host system is x86_64 on an intel 5820k. > > > Guest system is probably irrelevant, but is Windows 10 on the same. > > > > > > > > > Possibly relevant kernel build options: > > > $ zgrep BPF /proc/config.gz > > > [22:55:52]: zgrep BPF /proc/config.gz > > > > > > CONFIG_CGROUP_BPF=y > > > CONFIG_BPF=y > > > CONFIG_BPF_SYSCALL=y > > > CONFIG_BPF_JIT_ALWAYS_ON=y > > > CONFIG_IPV6_SEG6_BPF=y > > > CONFIG_NETFILTER_XT_MATCH_BPF=m > > > # CONFIG_BPFILTER is not set > > > CONFIG_NET_CLS_BPF=m > > > CONFIG_NET_ACT_BPF=m > > > CONFIG_BPF_JIT=y > > > CONFIG_BPF_STREAM_PARSER=y > > > CONFIG_LWTUNNEL_BPF=y > > > CONFIG_HAVE_EBPF_JIT=y > > > CONFIG_BPF_EVENTS=y > > > # CONFIG_BPF_KPROBE_OVERRIDE is not set > > > # CONFIG_TEST_BPF is not set > > > > Hi > > > > I've installed clean archlinux to try this out and it works as expected, > > I'm able to attach USB device into a VM. > > > > My system env is mostly the same as yours except for kernel version: > > > > kernel 5.4.13 > > libvirt 5.10.0 > > qemu 4.2.0, using KVM. > > > > Please enable libvirt debug logs [1] and share the output with us. > > I've updated to 5.4.13 and created a barebones VM without storage to > reproduce the behaviour. libvirtd debug logs are attached. There appear > to be two BPF failures of the same BPF program (?). The first is on line > 23209, which appears to be part of machine startup, and which I don't > actually notice. The second one is where I manually add the USB device, > on line 30599. > > Thanks, Thanks for the logs, but it did not help to figure out where the issue is. I was hoping to see some error output from the syscall but the line that should contain it is empty: 2020-01-20 19:47:15.589+0000: 8579: debug : virBPFLoadProg:78 : Can you please check system logs and output of dmesg? I've managed to run into this article [1] that explains that even if you have all permissions and no SELinux you can still be blocked by something called kernel_lockdown and it should appear in dmesg. Pavel [1] <https://gehrcke.de/2019/09/running-an-ebpf-program-may-require-lifting-the-…>

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