January 2020 - Users - libvirt List Archives

[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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[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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[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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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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PCI/GPU Passthrough with xen
by Christoph 14 Feb '20

14 Feb '20

Hi All, it is possible to use pci/gpu passthrough with xen and libvirt? If yes, how is the syntax? Can I get an example? -- ------ Greetz

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Does Libvirt's json parser support single quoted string in qmp json string?
by Peter Luo 05 Feb '20

05 Feb '20

Hi All, I’m using qmp command via “virsh qemu-monitor-command” to perform block related jobs. And in my case, I execute block-commit to commit the changes in the top image to the base image which is encrypted. So in the base parameter, I need a json string which is single quoted to support the encryption parameters. However, the virsh is failed to parse the whole json qmp command. Attempt 1: Single quote without backflash, failed root@host:~# virsh qemu-monitor-command i-9wdfw2x8 "{\"execute\": \"block-commit\", \"arguments\": { \"device\": \"drive-virtio-disk2\", \"job-id\": \"job100\", \"base\":'json:{\"encrypt.key-secret\":\"vol-38973xjl.secret\",\"driver\":\"qcow2\",\"file\":{\"driver\":\"file\",\"filename\":\"/pitrix/data/container/vol-38973xjl.img\"}}', \"top\": \"/pitrix/data/container/vol-38973xjl_ss-2tw7v0mm.img\"}}" error: internal error: cannot parse json {"execute": "block-commit", "arguments": { "device": "drive-virtio-disk2", "job-id": "job100", "base":'json:{"encrypt.key-secret":"vol-38973xjl.secret","driver":"qcow2","file":{"driver":"file","filename":"/pitrix/data/container/vol-38973xjl.img"}}', "top": "/pitrix/data/container/vol-38973xjl_ss-2tw7v0mm.img"}}: lexical error: invalid char in json text. , "job-id": "job100", "base":'json:{"encrypt.key-secret":"vo (right here) ------^ Attempt 2: Single quote with backflash, failed root@host:~# virsh qemu-monitor-command i-9wdfw2x8 "{\"execute\": \"block-commit\", \"arguments\": { \"device\": \"drive-virtio-disk2\", \"job-id\": \"job100\", \"base\":\'json:{\"encrypt.key-secret\":\"vol-38973xjl.secret\",\"driver\":\"qcow2\",\"file\":{\"driver\":\"file\",\"filename\":\"/pitrix/data/container/vol-38973xjl.img\"}}\', \"top\": \"/pitrix/data/container/vol-38973xjl_ss-2tw7v0mm.img\"}}" error: internal error: cannot parse json {"execute": "block-commit", "arguments": { "device": "drive-virtio-disk2", "job-id": "job100", "base":\'json:{"encrypt.key-secret":"vol-38973xjl.secret","driver":"qcow2","file":{"driver":"file","filename":"/pitrix/data/container/vol-38973xjl.img"}}\', "top": "/pitrix/data/container/vol-38973xjl_ss-2tw7v0mm.img"}}: lexical error: invalid char in json text. , "job-id": "job100", "base":\'json:{"encrypt.key-secret":"v (right here) ------^ My libvirt version is 5.7.0, libyajl is 2.1.0. Thanks, Peter Luo

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Re: Does Libvirt's json parser support single quoted string in qmp json string?
by Peter Luo 31 Jan '20

31 Jan '20

Hi Peter Krempa, Thanks for your quick response, yes, I know since libvirt 5.8, the -blockdev is used for disk by default. However we have to maintain the old releases for the production environment for a while, so I still need use the old way to create the disk. >"base" argument must be a string. this means you need double quotes in >JSON ("). You also must properly escape any further JSON. > Do you mean the base argument need be formatted like below? \"base\":\"json:{\"encrypt.key-secret\":\"vol-38973xjl.secret\",\"driver\":\"qcow2\",\"file\":{\"driver\":\"file\",\"filename\":\"/pitrix/data/container/vol-38973xjl.img\"}}\" Please help me to point out where the examples are located? I did take a quick look at those test files, but no one seems to be matched with my case. Thanks, Peter Luo On 31/1/20, 6:52 PM, "Peter Krempa" <pkrempa(a)redhat.com> wrote: On Fri, Jan 31, 2020 at 18:38:33 +0800, Peter Luo wrote: > Hi All, > > > > I’m using qmp command via “virsh qemu-monitor-command” to perform block related jobs. > > And in my case, I execute block-commit to commit the changes in the top image to the base image which is encrypted. > > So in the base parameter, I need a json string which is single quoted to support the encryption parameters. > > However, the virsh is failed to parse the whole json qmp command. None of the above should be required with libvirt-5.10 and later when using qemu-4.2. Those two versions start using blockdev way of specifying images and encrypted images are supported. Please consider using libvirt-6.0 though as there are few fixes for blockdev. > > > > Attempt 1: Single quote without backflash, failed > > root@host:~# virsh qemu-monitor-command i-9wdfw2x8 "{\"execute\": \"block-commit\", \"arguments\": { \"device\": \"drive-virtio-disk2\", \"job-id\": \"job100\", \"base\":'json:{\"encrypt.key-secret\":\"vol-38973xjl.secret\",\"driver\":\"qcow2\",\"file\":{\"driver\":\"file\",\"filename\":\"/pitrix/data/container/vol-38973xjl.img\"}}', \"top\": \"/pitrix/data/container/vol-38973xjl_ss-2tw7v0mm.img\"}}" > > error: internal error: cannot parse json {"execute": "block-commit", "arguments": { "device": "drive-virtio-disk2", "job-id": "job100", "base":'json:{"encrypt.key-secret":"vol-38973xjl.secret","driver":"qcow2","file":{"driver":"file","filename":"/pitrix/data/container/vol-38973xjl.img"}}', "top": "/pitrix/data/container/vol-38973xjl_ss-2tw7v0mm.img"}}: lexical error: invalid char in json text. > > , "job-id": "job100", "base":'json:{"encrypt.key-secret":"vo "base" argument must be a string. this means you need double quotes in JSON ("). You also must properly escape any further JSON. Given that libvirt now supports the operation natively I'll refrain from elaborating on how to properly escape JSON to contain JSON strings, but there are few examples in the test suite. But please use the upstream supported way instead.

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Detecting of features of VMs
by Peter Krempa 29 Jan '20

29 Jan '20

Hi, I was asked by Nir and Eyal of the oVirt project on how to detect whether a certain feature is supported by libvirt. As I thought it might be better to document this publically rather than being lost in a private thread I'm posting this to libvirt-users. The specific question will be answered below. --- There are currently two interfaces which allow discovery of libvirts and in turn qemu's capabilities. Both return an XML which describes various aspects of the hosts or VMs capabilities. virConnectGetCapabilities(conn) https://libvirt.org/formatcaps.html The XML returned by this API describes mostly the host itself, the CPU, NUMA topology, security driver support, migration features but also describes guests architectures supported by the guest. In case of the qemu driver the guest section describes some of the aspects and configurations supported by the default qemu binary, the machine types and virtualization types it supports. Additionally the <features> section describes support for some long-existing features such as ACPI, APIC and disk snapshots. As these features are supported for a long time, it can be assumed that they are present (at least in case of the qemu driver) when the second API is present. Now while the virConnectGetCapabilities API provides mostly useful information about the host, the limitation of not being able to report information about specific qemu binaries or machine types lead to introduction. virConnectGetDomainCapabilities(conn, emulator_binary_path, architecture, machine_type, virt_type, flags) https://libvirt.org/formatdomaincaps.html The XML returned by this API describes the capabilities of an VM which would be started using the parameters given to the API (note that if the parameters are NULL a default is provided). The <os> subelement describes supported OS loader types and firmware binaries. <cpu> describes which CPU models are supported by the emulator and also the CPU which would be used if 'host-model' is selected as the CPU model. The <devices> section describes models and some properties of devices supported by the VM. The 'enum's reported in this XML map to supported values of some of the fields we report the possible configurations for. Note that these values are reported individually and all combinations aren't necessarily supported. The last section 'features' describes whether some high-level features supported by such a VM. The features themselves are described in the documentation above. Note that the entries into 'features' are added arbitrarily depending on whether a feature is deemed important enough to be exposed. So please feel free to report if anything is missing or it would be helpful if we reported any feature. --- Now specifically to the question: I was asked on when it's safe to pass VIR_DOMAIN_UNDEFINE_CHECKPOINTS_METADATA to virDomainUndefine. In this case it's safe to pass it if <features> contains the <backup> element regardless of the value of 'supported' attribute. I'll also mention this in the documentation of the domain caps XML.

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