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Caching qemu capabilities and KubeVirt
by Roman Mohr 13 Oct '22

13 Oct '22

Hi, I have a question regarding capability caching in the context of KubeVirt. Since we start in KubeVirt one libvirt instance per VM, libvirt has to re-discover on every VM start the qemu capabilities which leads to a 1-2s+ delay in startup. We already discover the features in a dedicated KubeVirt pod on each node. Therefore I tried to copy the capabilities over to see if that would work. It looks like in general it could work, but libvirt seems to detect a mismatch in the exposed KVM CPU ID in every pod. Therefore it invalidates the cache. The recreated capability cache looks esctly like the original one though ... The check responsible for the invalidation is this: ``` Outdated capabilities for '%s': host cpuid changed ``` So the KVM_GET_SUPPORTED_CPUID call seems to return slightly different values in different containers. After trying out the attached golang scripts in different containers, I could indeed see differences. I can however not really judge what the differences in these KVM function registers mean and I am curious if someone else knows. The files are attached too (as json for easy diffing). Best regards, Roman

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MemoryBacking options
by Simon Fairweather 10 Oct '22

10 Oct '22

Hi, Is there any documentation that states which options can be used together with each other. <domain> ... <memoryBacking> <hugepages> <page size="1" unit="G" nodeset="0-3,5"/> <page size="2" unit="M" nodeset="4"/> </hugepages> <nosharepages/> <locked/> <source type="file|anonymous|memfd"/> <access mode="shared|private"/> <allocation mode="immediate|ondemand" threads='8'/> <discard/> </memoryBacking> ... </domain>

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Re: Why host device disappear in libvirt doman xml?
by Michal Prívozník 29 Sep '22

29 Sep '22

[Once again, please keep the list on CC] On 9/29/22 04:59, 陈新隆 wrote: > Thanks for the detail explanation, it's very helpful. > > I guess : > 1. virsh dumpxml <domain> outputs the live xml(or active xml) Yes, if domain is running then it outputs the live XML, otherwise it outputs the inactive XML. For running domains you can use --inactive flag to get the inactive XML. > 2. virsh edit <domain> edits the inactive xml, so I should cold boot > domain to take effect Correct. Michal

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Re: Why host device disappear in libvirt doman xml?
by Michal Prívozník 28 Sep '22

28 Sep '22

[Please, keep the list on CC for benefit of others] On 9/28/22 10:13, 陈新隆 wrote: > I'm using the `virsh dumpxml <domain name>` to check the xml. When I > first execute this command, there's two hostdev(GPU) in the xml, but > next time I execute the same command these two hostdev elements > disappeared. During this time, the vm didn't restart or stop. Also, > within the vm `lspci | grep -i nvidia` command did not print GPU infos. > > So I was wondering if there's a mechanism in libvirtd detach the hostdev > element without the vm stop or restart. This problem doesn't happen > often, so I am looking a way to reproduce it. > > Can you help me with these questions : > > 1. If I edit the xml manually then detached the hostdev elements from > xml by invoke libvirtd apis, will the vm apply it immediately without > stop or restart? Or I must restart the vm to apply the latest xml ? I'm not sure what you mean. Editing XML manually is different to using libvirt APIs to detach hostdevs. Here's how it works: 1) a domain is defined (say using virsh define file.xml), libvirt parses this XML, keeps it in a memory and stores it "somewhere" (it's under /etc/libvirt/qemu/ but we do not want users to hand edit those files manually as libvirt reads them only on libvirtd/virtqemud restart). This is called inactive XML, because it reflects the inactive state of domain. Sometimes it's also called config XML. 2) when the domain is started (e.g. virsh start), libvirt creates a copy of inactive XML, populates it with runtime information and saves it elsewhere (/run/libvirt/qemu/, but again, we do not want users to hand edit those files). This copy is referred to as live XML. 3) users can alter the live XML using APIs (e.g. to hotplug a device or hotunplug it). The inactive XML can be altered by providing altered XML and defining it again (here, domain name and UUID must match already existing domain). 4) upon domain shutoff, the live XML is thrown away, and finally 5) the inactive XML is never thrown away, until virsh undefine is called. Now, you can see that there's no real connection between live and inactive XMLs and changing one has no affect on the other, except when the domain is cold booted again. Live and inactive XMLs can vary wildly. Therefore, you can have inactive XML with two <hostdev/>-s, and active XML with no <hostdev> at all. NB, hotplug APIs can also be used to alter inactive XML (virsh attach-device --config / virsh detach-device --config / ...) or both at the same time (virsh attach-device --config --live / virsh attach-device --config --live / ...). And what you describe sounds as if those two <hostdev/>-s you saw at domain startup were hotunplugged. The fact that even 'lspci' ran from inside the domain can't find them only supports this theory. And no, libvirt never tries to bring inactive and live XMLs together. It has no intelligence built in to do that and we, developers, do not want such thing either. We might change something that user specifically wanted and I believe nobody likes those "smart" tools that get in your way. > 2. After a host device is hot-unplugged, will libvirtd aware of it then > remove the related `hostdev` element from xml ? Yes. I believe the reasoning is seen in the previous block of my reply. > > On Mon, Sep 26, 2022 at 10:10 PM Michal Prívozník <mprivozn(a)redhat.com > <mailto:mprivozn@redhat.com>> wrote: > > On 9/26/22 15:06, 陈新隆 wrote: > > > > <https://stackoverflow.com/posts/73854544/timeline > <https://stackoverflow.com/posts/73854544/timeline>> > > > > I'm using Kubevirt to manage my virtual machine instances. When I > using > > Kubevirt to create a vm(with two GPUs), kubevirt will generate a > libvirt > > guest domain xml for this vm which includes two GPUs, the domain > xml as > > follow : > > > > |<hostdev mode='subsystem' type='pci' managed='no'> <driver > > name='vfio'/> <source> <address domain='0x0000' bus='0x83' slot='0x00' > > function='0x0'/> </source> <alias name='ua-gpu-gpu0'/> <address > > type='pci' domain='0x0000' bus='0x06' slot='0x00' function='0x0'/> > > </hostdev> <hostdev mode='subsystem' type='pci' managed='no'> <driver > > name='vfio'/> <source> <address domain='0x0000' bus='0x84' slot='0x00' > > function='0x0'/> </source> <alias name='ua-gpu-gpu1'/> <address > > type='pci' domain='0x0000' bus='0x07' slot='0x00' function='0x0'/> > > </hostdev> | > > > > No one ever edit this domain xml, but these two |hostdev| element > > disappeared in the domain xml. During this time, I've run > > the |gpu_burn| command to do a stress test for these two GPUs. > > > > My question is : > > > > * when will libvirtd change the guest domain xml ? > > * why libvirtd delete these two |hostdev| from domain xml ? > > > > Libvirt does not remove anything from domain XML (except for the > elements it does not understand, but this is not the case). My suspicion > is that you're looking at live XML instead of inactive XML or vice > versa. Libvirt allows guests to be defined (i.e. libvirt manages their > inactive definition). However, a guest can be started with wildly > different configuration (e.g. without those two <hostdev/>-s). OR, they > might have been hot-unplugged. > > I still recommend reading this link: > This article can explain more details: > https://wiki.libvirt.org/page/VM_lifecycle > <https://wiki.libvirt.org/page/VM_lifecycle> Michal

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[Question] Should libvirt update live xml accordingly when guest mac is changed?
by Fangge Jin 26 Sep '22

26 Sep '22

Hi I met an issue when testing trustGuestRxFilters: Attach a macvtap interface with trustGuestRxFilters=’yes’ to vm, then change interface mac address in vm. Should libvirt update interface mac in live vm xml accordingly? If not, vm network will be broken after managedsaving and restoring vm. BR, Fangge Jin Steps: 1. Start a vm 2. Attach a macvtap interface with trustGuestRxFilters=’yes’ to vm <interface type='direct' trustGuestRxFilters='yes'> <source dev='enp175s0v0' mode='passthrough'/> <target dev='macvtap0'/> <model type='virtio'/> <alias name='net1'/> </interface> 3. Check vm xml: # virsh dumpxml uefi --xpath //interface <interface type="direct" trustGuestRxFilters="yes"> <mac address="52:54:00:46:88:8b"/> <source dev="enp175s0v0" mode="passthrough"/> <target dev="macvtap2"/> <model type="virtio"/> <alias name="net0"/> <address type="pci" domain="0x0000" bus="0x01" slot="0x00" function="0x0"/> </interface> 4. Change interface mac in guest: # ip link set dev enp1s0 address 52:54:00:9d:a1:1e # ip a 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000 link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 inet 127.0.0.1/8 scope host lo valid_lft forever preferred_lft forever inet6 ::1/128 scope host valid_lft forever preferred_lft forever 4: enp1s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000 link/ether 52:54:00:9d:a1:1e brd ff:ff:ff:ff:ff:ff permaddr 52:54:00:46:88:8b inet 192.168.124.5/24 scope global enp1s0 valid_lft forever preferred_lft forever # ping 192.168.124.4 PING 192.168.124.4 (192.168.124.4) 56(84) bytes of data. 64 bytes from 192.168.124.4: icmp_seq=1 ttl=64 time=0.240 ms 64 bytes from 192.168.124.4: icmp_seq=2 ttl=64 time=0.138 ms --- 192.168.124.4 ping statistics --- 2 packets transmitted, 2 received, 0% packet loss, time 1001ms 5. Check vm xml: # virsh dumpxml uefi --xpath //interface <interface type="direct" trustGuestRxFilters="yes"> <mac address="52:54:00:46:88:8b"/> <source dev="enp175s0v0" mode="passthrough"/> <target dev="macvtap2"/> <model type="virtio"/> <alias name="net0"/> <address type="pci" domain="0x0000" bus="0x01" slot="0x00" function="0x0"/> </interface> 6. Check on host: 16: macvtap1@enp175s0v0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 500 link/ether 52:54:00:9d:a1:1e brd ff:ff:ff:ff:ff:ff inet6 fe80::5054:ff:fe46:888b/64 scope link valid_lft forever preferred_lft forever 7. Do managedsave and restore # virsh managedsave uefi Domain 'uefi' state saved by libvirt # virsh start uefi Domain 'uefi' started 8. Check vm network function: # ip a 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000 link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 inet 127.0.0.1/8 scope host lo valid_lft forever preferred_lft forever inet6 ::1/128 scope host valid_lft forever preferred_lft forever 4: enp1s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000 link/ether 52:54:00:9d:a1:1e brd ff:ff:ff:ff:ff:ff permaddr 52:54:00:46:88:8b inet 192.168.124.5/24 scope global enp1s0 valid_lft forever preferred_lft forever # ping 192.168.124.4 PING 192.168.124.4 (192.168.124.4) 56(84) bytes of data. --- 192.168.124.4 ping statistics --- 3 packets transmitted, 0 received, 100% packet loss, time 2036ms

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Why host device disappear in libvirt doman xml?
by 陈新隆 26 Sep '22

26 Sep '22

<https://stackoverflow.com/posts/73854544/timeline> I'm using Kubevirt to manage my virtual machine instances. When I using Kubevirt to create a vm(with two GPUs), kubevirt will generate a libvirt guest domain xml for this vm which includes two GPUs, the domain xml as follow : <hostdev mode='subsystem' type='pci' managed='no'> <driver name='vfio'/> <source> <address domain='0x0000' bus='0x83' slot='0x00' function='0x0'/> </source> <alias name='ua-gpu-gpu0'/> <address type='pci' domain='0x0000' bus='0x06' slot='0x00' function='0x0'/> </hostdev> <hostdev mode='subsystem' type='pci' managed='no'> <driver name='vfio'/> <source> <address domain='0x0000' bus='0x84' slot='0x00' function='0x0'/> </source> <alias name='ua-gpu-gpu1'/> <address type='pci' domain='0x0000' bus='0x07' slot='0x00' function='0x0'/> </hostdev> No one ever edit this domain xml, but these two hostdev element disappeared in the domain xml. During this time, I've run the gpu_burn command to do a stress test for these two GPUs. My question is : - when will libvirtd change the guest domain xml ? - why libvirtd delete these two hostdev from domain xml ?

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Backup KVM Guest VM in OVA or VMDK format
by Kaushal Shriyan 22 Sep '22

22 Sep '22

Hi, Is there a way to backup KVM Guest VM in kvmguestosimage.ova or kvmguestosimage.vmdk format as I am trying to restore it in AWS by referring to https://aws.amazon.com/ec2/vm-import/ article as per the below supported file format. [1] Open Virtualization Archive (OVA) [2] Virtual Machine Disk (VMDK) [3] Virtual Hard Disk (VHD/VHDX) [4] raw Also any method to take full and incremental backup of KVM Guest VM. Any help will be highly appreciated. I look forward to hearing from you. Thanks in Advance. Best Regards, Kaushal

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How can I check the history of all console logs starting from the first second of bootup
by Lucas Liu 22 Sep '22

22 Sep '22

Gratings: Recently, I got an error while installing a guest, the error message is this,: [image: image.png] Is there a method to get the full log? I have tried to use virt-install --console, or attach <log file="/var/log/libvirt/qemu/guestname-serial0.log" append="off"/> to get the full log, but they didn't work.

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Re: Help in porting smack related patches to meson build system
by Peter Krempa 20 Sep '22

20 Sep '22

On Mon, Sep 19, 2022 at 16:31:25 +0000, Vishal Gupta (vishagu2) wrote: > Hi Peter , Hi, I firstly want to ask you to avoid top-posting on technical mailing lists. > > > > Thanks for ur reply . > > > > Kirkstone is the latest release from Yocto foundation . details https://docs.yoctoproject.org/dev/migration-guides/migration-4.0.html > > > > Kirkstone support libvirt 8.10 https://layers.openembedded.org/layerindex/recipe/3052/ > > > > We are trying to port 2016 smack patch " https://listman.redhat.com/archives/libvir-list/2016-July/msg00456.html" for libvirt which is based on automake make file Okay so that is quite an old patch which was never finished and merged. > But above patch is incompatible with libvirt 8.10 .as libvirt 8.1 supports only meson > > > I was just wondering if above smack patch is already ported for meson based libvirt 8.10? > > We have issue in porting m4/virt-smack.m4 to meson.build file . virt-smack.m4 is define in 2016 smack patch No it is not ported. I want to warn you though that porting the build system part to meson will not be biggest of the problems. 1) The patch is more than 6 years old at this point There's quite a lot of change in libvirt during that time. Many helpers and internal APIs were refactored. The patch even once you port the build system will require *significant* rework to actually even compile. 2) libsmack (smack-utils) used by the new security module is not present in distros The library it requires doesn't seem to be adopted much: https://repology.org/project/smack-utils/versions Did you make sure that it's present in your environment? Additionally if you want to get the patch accepted upstream note that there were outstanding problems with the patch in the last version which is on the mailing list. I can see that there are definitely problems with coding style and the patch will need to be split to logical chunks as it's now just a big blob of code. Also given that the library is simply not present in distros it will require a justification why upstream should cary the patch. Carying code which is not compiled because of lack of dependencies is a burden to upstream and still can bitrot in the future. Even if you are not striving for upstreaming the patch, be prepared for more work than just porting the build system.

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Help in porting smack related patches to meson build system
by Akash Bhaskaran (akabhask) 19 Sep '22

19 Sep '22

Hi, We are trying to port some patches pertaining to files like Makefile.am ,configure.ac and .m4’s to libvirt kirkstone release. We see that latest kirskstone now uses meson build architecture. We have difficulties in porting the changes in the above-mentioned files to meson. Is there any script or reference you can provide for helping us port these files to meson? Thanks, Akash

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virt-manager alt-click passthrough?
by Alex 10 Sep '22

10 Sep '22

Hi, I'm using virt-manager to connect to a Windows 10 virtual machine, where I'm using photoshop. I need to send an alt-click key for some functions, but virt-manager is instead interpreting them. It isn't among the pre-configured options that can be sent. Is there a way to remap the alt key or alt-click combination so I can send it through to the virtual machine? I've also tried the RealVNC client/server trial, and I can't get that to connect at all. It does appear qemu/realvnc server is listening on 5900: tcp 0 0 127.0.0.1:5900 0.0.0.0:* LISTEN - qemu is also configured to listen (-spice port=5900,addr=127.0.0.1). I've also verified I can connect to port 5900 manually, so a Windows firewall is not the problem. Any ideas greatly appreciated.

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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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CPU features/flags - host vs. guest (Libvirt/QEMU/KVM)
by kAja Ziegler 07 Sep '22

07 Sep '22

Hello, does anyone know of any list/table (ideally as up-to-date as possible) with individual CPU features/flags for x86_64 (preferably Intel), which would state: - description of individual features/flags - dependencies between individual features/flags - e.g. avx on xsave - what features/flags are checked on the hypervisor (host), but are not propagated to the guest - e.g. acpi, ds, monitor, pbe, tm, etc. - some are masked/disabled [(not) supported] by Libvirt, others by KVM/QEMU - what features/flags active for/in the guest limit certain virtualization behavior/options such as live migration - e.g. invtsc, xsaves - so far I only found https://github.com/libvirt/libvirt/blob/master/src/cpu_map/x86_features.xml - features with migratable='no' I would like to tweak the CPU configuration for the virtual servers ie. choose the basic CPU model and turn on/off the necessary or appropriate features/flags while maintaining the possibility of live migration. But I miss the above-mentioned contexts, because not all the mentioned features within the cpu element in the VM definition (domains in Libvirt) are then visible inside the VM in /proc/cpuinfo. Of course, I know about other related commands, registers, etc. like "virsh capabilities|cpu-baseline|cpu-compare", MSR, fixes in CPU microcode, host-model or host-passthrough CPU... but I'm still not sure about setting the match, check and fallback attributes and the resulting behavior of Libvirt and QEMU/KVM. Many thanks in advance for any response K. Ziegler

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Libvirtd slower over time
by André Malm 29 Aug '22

29 Aug '22

Hello, I have some issues with libvirtd getting slow over time. After a fresh reboot (or systemctl restart libvirtd) virsh list / virt-install is fast, as expected, but after a couple of months uptime they both take a significantly longer time. Virsh list takes around 3 seconds (from 0.04s on a fresh reboot) and virt-install takes over a minute (from around a second). Running strace on virsh list it seems to get stuck in a loop on this: poll([{fd=5<socket:[173169773]>, events=POLLOUT}, {fd=6<anon_inode:[eventfd]>, events=POLLIN}], 2, -1) = 2 ([{fd=5, revents=POLLOUT}, {fd=6, revents=POLLIN}]) While restarting libvirtd fixes it a restart takes around 1 minute where ebtables rules etc are recreated and it does interrupt the service. What could cause this? How would I troubleshoot this? I'm running Ubuntu 22.04 / libvirt 8.0.0 with 70 active VM’s on a 16/32 core machine with 256GB of ram, CPU is below 50% usage at all times, memory below 50% usage and swap 0% usage. Thanks, André

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Libvirt web application
by Callie Martin 25 Aug '22

25 Aug '22

Hello, We received the following message on Red Hat's Twitter account. Can anyone on this list confirm if libvirt-users(a)redhat.com is 1) active and 2) the right contact information for this user to reach out to? [image: image.png] Thanks, -- Callie Martin She / Her / Hers Manager, Social Media Red Hat <https://www.redhat.com/> 100 E. Davie St. Raleigh, NC calmarti(a)redhat.com M: 919-630-7721 | T: 919-890-8011 @RedHat <https://twitter.com/redhat> Red Hat <https://www.linkedin.com/company/red-hat> Red Hat <https://www.facebook.com/RedHatInc> <https://red.ht/sig>

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NUMA node - Memory Only
by Jin Huang 22 Aug '22

22 Aug '22

Hi, libvirt-users How could I set up a memory-only and no-cpu NUMA node for the qemu-VM with the XML file? Seems each NUMA cell has to be bundled with some specific cpuids. If I write the element like this, it is wrong. <cpu mode='host-passthrough'> <numa> <cell id='0' cpus='0-3' memory='16' unit='GiB'/> <cell id='1' cpus='*null*' memory='16' unit='GiB'/> </numa> </cpu> Also if I ignore the cpus item, it is not acceptable for the virsh command. The reason I want the memory-only node is that I want to set up multiple memory tiers for the VM, just like https://stevescargall.com/2022/06/10/using-linux-kernel-memory-tiering/ Thank You Best Jin Huang

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Memory locking limit and zero-copy migrations
by Milan Zamazal 19 Aug '22

19 Aug '22

Hi, do I read libvirt sources right that when <memtune> is not used in the libvirt domain then libvirt takes proper care about setting memory locking limits when zero-copy is requested for a migration? I also wonder whether there are any other situations where memory limits could be set by libvirt or QEMU automatically rather than having no memory limits? We had oVirt bugs in the past where certain VMs with VFIO devices couldn't be started due to extra requirements on the amount of locked memory and adding <hard_limit> to the domain apparently helped. Thanks, Milan

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Problem with a disk device of type 'volume'
by Frédéric Lespez 18 Aug '22

18 Aug '22

Hi, I need some help to debug a problem with libvirt and a disk device of type 'volume'. I have a VM failing to start with the following error : $ virsh -c qemu:///system start server error :Failed to start domain 'server' error :internal error: process exited while connecting to monitor: 2022-08-13T09:26:50.121259Z qemu-system-x86_64: -blockdev {"driver":"file","filename":"/mnt/images/debian-11-genericcloud-amd64.qcow2","node-name":"libvirt-3-storage","auto-read-only":true,"discard":"unmap"}: Could not open '/mnt/images/debian-11-genericcloud-amd64.qcow2': Permission denied I check the file access permission, but they are correct. I try to set everything to 777 or run qemu as root, but the problem persist. $ ll -d /mnt /mnt/images /mnt/images/* drwxr-xr-x 9 root root 4,0K 31 déc. 2021 /mnt drwxr-xr-x 2 root root 4,0K 13 août 11:31 /mnt/images -rw-r--r-- 1 libvirt-qemu libvirt-qemu 242M 13 août 11:31 /mnt/images/debian-11-genericcloud-amd64.qcow2 -rw-r--r-- 1 libvirt-qemu libvirt-qemu 366K 13 août 11:31 /mnt/images/server_cloudinit.iso -rw-r--r-- 1 libvirt-qemu libvirt-qemu 593M 13 août 11:59 /mnt/images/server_image.qcow2 After a lot of searching and testing, I found out that the disk device definition is linked to the source of the problem. The disk device is defined like this : <disk type="volume" device="disk"> <driver name="qemu" type="qcow2"/> <source pool="TERRAFORM" volume="server_image.qcow2"/> <target dev="vda" bus="virtio"/> <address type="pci" domain="0x0000" bus="0x00" slot="0x05" function="0x0"/> </disk> This image 'server_image.qcow2' use a backing file: $ qemu-img info /mnt/images/server_image.qcow2 --backing-chain image: /mnt/stockage_rapide/VMs/terraform/puppetdev_server_image.qcow2 file format: qcow2 virtual size: 6 GiB (6442450944 bytes) disk size: 475 MiB cluster_size: 65536 backing file: /mnt/images/debian-11-genericcloud-amd64.qcow2 backing file format: qcow2 Format specific information: compat: 0.10 compression type: zlib refcount bits: 16 image: /mnt/images/debian-11-genericcloud-amd64.qcow2 file format: qcow2 virtual size: 2 GiB (2147483648 bytes) disk size: 242 MiB cluster_size: 65536 Format specific information: compat: 1.1 compression type: zlib lazy refcounts: false refcount bits: 16 corrupt: false extended l2: false And here is the definition of the associated storage pool : <pool type="dir"> <name>TERRAFORM</name> <uuid>dae00836-db4d-49ba-9d32-1f0278055516</uuid> <capacity unit="bytes">155674652672</capacity> <allocation unit="bytes">74396299264</allocation> <available unit="bytes">81278353408</available> <source> </source> <target> <path>/mnt/images</path> <permissions> <mode>0755</mode> <owner>0</owner> <group>0</group> </permissions> </target> </pool> If I changed the disk device definition to this (and changing only that), the domain start and works fine (no permission problem !). <disk type="file" device="disk"> <driver name="qemu" type="qcow2"/> <source file="/mnt/images/server_image.qcow2"/> <target dev="vda" bus="virtio"/> <address type="pci" domain="0x0000" bus="0x00" slot="0x05" function="0x0"/> </disk> Could you help me find the reason why the domain doesn't work when the disk device is of type 'volume' ? Thanks in advance for your help. Regards, Fred Additional information: - Running this on Debian 11 with libvirt 8.0.0 (from backports) and qemu 7.0 (from backports). - Vanilla configuration of libvirt. I have just added my regular user to the libvirt group. - Problem exists even if AppArmor is disabled. PS: I want to use a disk device of type 'volume' because this domain is created by Terraform using the libvirt provider which use this kind of disk since it has some advantages. See the details here : https://github.com/dmacvicar/terraform-provider-libvirt/issues/126#issuecom…

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Libvirt virsh : Error starting network, cannot execute binary /usr/sbin/iptables
by Pascal 17 Aug '22

17 Aug '22

Hi, I am a bit lost and hope someone can help me. I am running Debian bookworm (testing) with last updates. $ sudo apt policy libvirt-daemon libvirt-daemon: Installé : 8.5.0-1 Candidat : 8.5.0-1 Table de version : *** 8.5.0-1 100 100 /var/lib/dpkg/status I am unable to start default network , and get an error related to iptables : $ sudo virsh net-start default erreur :Impossible de démarrer le réseau default erreur :internal error: Failed to apply firewall rules /usr/sbin/iptables -w --table filter --list-rules: libvirt: erreur : cannot execute binary /usr/sbin/iptables: Aucun fichier ou dossier de ce type Sorry for the french, it says "impossible to start default network" and "no such file or folder" at the end. It is true I removed iptables because I want to use only nftables (I removed both ufw and iptables packages (apt remove), and enabled the nftables service before error raises). Before this, all was fine, but when I enabled nftables, all VMs disapeared from virt-manager). I uninstalled KVM related packages and reinstalled, still the same. I also installed back iptables, but strangely I still get the same error, although binary /usr/sbin/iptables is there. I tried many things with no luck, restarted libvirtd service, recreated the network, etc... Has anyone some idea about what is happening here ? is there some incompatibility with nftables (firewalld service is disabled) and libvirt ? Thank you, Pascal

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libvirt can't setup simple bridged network?
by Ian Pilcher 15 Aug '22

15 Aug '22

I feel like I'm taking crazy pills! I'm reading the libvirt network XML format documentation[1], and I can't figure out how to create a simple bridged network - no NAT, no routing, no OVS, no macvtap, etc. I.e., just a Linux bridge with a single physical interface attached. None of the 3 scenarios listed for <forward mode='bridge'> describe the simple setup that I'm trying to create, so it looks like I'll need to create the bridge separately. (It's not hard to do, it just seems like such a weird gap the in the functionality.) [1] https://libvirt.org/formatnetwork.html -- ======================================================================== Google Where SkyNet meets Idiocracy ========================================================================

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New functionality in virt-install
by O'Reilly, Michael 09 Aug '22

09 Aug '22

Hi libvirt-users, I've been tracking the progress of this patch https://listman.redhat.com/archives/libvir-list/2022-August/233328.html to enable SGX support in libvirt. My question is this. Who is responsible for ensuring that new functionality like SGX is also supported by virt-install? Is it part of the commit process to ensure virt-install can use the new functionality in libvirt, or is it up to the virt-manager community to track changes. And maybe this is a question for the virt-tools-list(a)redhat.com list also? Some guidance would be appreciated. Regards Michael OR -------------------------------------------------------------- Intel Research and Development Ireland Limited Registered in Ireland Registered Office: Collinstown Industrial Park, Leixlip, County Kildare Registered Number: 308263 This e-mail and any attachments may contain confidential material for the sole use of the intended recipient(s). Any review or distribution by others is strictly prohibited. If you are not the intended recipient, please contact the sender and delete all copies.

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Can RHEL7 VM run remote commands to Fedora36 host?
by Carol Bouchard 01 Aug '22

01 Aug '22

I have a Fedora36 laptop which hosts VMs with RHEL7 using libvirt. One of the RHEL7 VMs, runs remote commands (as root) to 'start' another VM by way of my laptop. In other words, the following command is run: virsh --connect 'qemu+ssh://192.168.120.1/system' start beaker-test-vm1.beaker If I run non-remote version of the command on the laptop, it is successful. For example, virsh --connect qemu:///system start beaker-test-vm1.beaker <-- Successful on laptop. If I do a query like the following *(notice socket use)*, it is successful. virsh -d0 --connect 'qemu+ssh://192.168.120.1/system?*socket*=/var/run/libvirt/libvirt-sock-ro' domstate beaker-test-vm1.beaker Without socket, I get the following error: *error: failed to connect to the hypervisor* *error: End of file while reading data: Ncat: No such file or directory.: Input/output error* This does not work for 'start' because I believe this is a read-only socket since I see the error: error: Failed to start domain beaker-test-vm1.beaker error: operation forbidden: read only access prevents virDomainCreate When I look at my laptop, there is no /var/run/libvirt/libvirt-sock. So.....I've been wondering whether RHEL7 virsh/libvirt is compatible with Fedora36. Is there a work-around? I can't change the distros on my laptop or VMs. Carol

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Can RHEL7 VM run remote libvirt commands to Fedora36 host?
by Carol Bouchard 01 Aug '22

01 Aug '22

I have a test environment that use to work but no longer does. My laptop is Fedora36 (libvirt version 8.1.0.2) while the VMs it spawns are RHEL7 (max libvirt version is 4.5.0). The source of my problem seems to be that RHEL7 libvirt needs rw socket /var/run/libvirt/libvirt-sock which no longer exists in fedora36. The following is successful from RHEL7 VM to laptop: virsh -d0 --connect 'qemu+ssh://192.168.120.1/system?*socket*=/var/run/libvirt/libvirt-sock-ro' domstate beaker-test-vm1.beaker If I change the action from domstate to start, it fails on error: Failed to start domain beaker-test-vm1.beaker error: operation forbidden: read only access prevents virDomainCreate which made me realize ro stands for read-only; however, there is no libvirt-sock. I tried some of the other socket files without success. Is there a work-around? Carol

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how to get vm uptime through libvirt api
by Jiatong Shen 26 Jul '22

26 Jul '22

Hello community, I would like to know if there is an api to get a virtual machine's uptime. Thank you in advance for the help. -- Best Regards, Jiatong Shen

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Eject CD ROM medium fails with 'Tray of device is not open'
by liang chaojun 25 Jul '22

25 Jul '22

Hi Guys, I have hit an issue on testing against our testbed, It's failed to eject cdrom media after reboot from installed the guest OS. The reproduce step: 1. Attach a block device with a ISO media and start install VM from ISO. 2. <disk type='block' device='cdrom'> <driver name='qemu' type='raw'/> <source dev='/dev/disk/by-id/pbdx-vol-cfe60dca-c271-491b-be3c-11fa8d7625a4' index='6'/> <backingStore/> <target dev='hda' bus='ide' tray='open'/> <readonly/> <alias name='ide0-0-0'/> <address type='drive' controller='0' bus='0' target='0' unit='0'/> </disk> 3. After installed the OS and reboot from system disk successful. 4. Then I want to eject CDROM through update device with the xml like below or using virsh tool 'virsh change-media iso_test hda --eject' 5. All those will failed at "internal error: unable to execute QEMU command 'blockdev-remove-medium': Tray of device 'ide0-0-0' is not open" <disk type='block' device='cdrom'> <driver name='qemu' type='raw'/> <backingStore/> <target dev='hda' bus='ide' tray='open'/> <readonly/> <alias name='ide0-0-0'/> <address type='drive' controller='0' bus='0' target='0' unit='0'/> </disk> block info looks like below: virsh qemu-monitor-command iso_test --hmp info block setlocale: No such file or directory libvirt-6-format: /dev/disk/by-id/pbdx-vol-cfe60dca-c271-491b-be3c-11fa8d7625a4 (raw, read-only) Attached to: ide0-0-0 Removable device: locked, tray closed Cache mode: writeback Reproduce envrionment: Operating system: rhat8.4 Architecture:x86 kernel version:4.18.0-305 libvirt version:v7.9.0(private build) Hypervisor and version:QEMU 5.1.0(private build) Is there any workaround? Any comments are appreciated. Thanks!

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