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Re: How to check tap device for sndbuf when I set sndbuf=0 in the interface xml
by Yalan Zhang 31 Oct '22

31 Oct '22

cc libvirt-users for more inputs Hi, I'm trying to find out how to check sndbuf for a tap device, could you please help to check it? In kernel 2.6.18, the tap device's default sndbuf is 1MB. There is a RFE bug[1] and patch[2] to introduce the option below in libvirt to adjust the sndbuf. <tune> <sndbuf>1600</sndbuf> </tune> It is said in the patch[2] that when we set sndbuf=0, we actually set it to 0xffffffff. How to check if it is set successfully? I have checked the below files, the value didn't change after I start a vm with sndbuf=0 # grep . /proc/sys/net/core/*mem_default /proc/sys/net/core/rmem_default:212992 /proc/sys/net/core/wmem_default:212992 And from the doc[3]: "The default value is set by the /proc/sys/net/core/wmem_default file and the maximum allowed value is set by the /proc/sys/net/core/wmem_max file." Current kernel 5.14.0-177.el9 has some updates about sndbuf: # cat /proc/sys/net/core/wmem_default 212992 # cat /proc/sys/net/core/wmem_max 212992 Thank you! [1] Bug 665293 <https://bugzilla.redhat.com/show_bug.cgi?id=665293> - RFE: Allow setting size of send buffer per TAP device in QEMU driver [2] https://listman.redhat.com/archives/libvir-list/2011-January/032763.html [3] https://man7.org/linux/man-pages/man7/socket.7.html Yalan

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Video device model set resolution does not work
by 陈新隆 31 Oct '22

31 Oct '22

Hi team, I've add a resolution sub-element to vga video device model, and the x attribute is 1920, y attribute is 1080. Dumped domain xml as follow : bash-4.4# virsh list > Authorization not available. Check if polkit service is running or see > debug message for more information. > Id Name State > ----------------------------------- > 1 proj1_vm-4uaz57bh running > bash-4.4# virsh dumpxml proj1_vm-4uaz57bh | grep -i -10 vga > Authorization not available. Check if polkit service is running or see > debug message for more information. > <alias name='input1'/> > </input> > <input type='keyboard' bus='ps2'> > <alias name='input2'/> > </input> > <graphics type='vnc' > socket='/var/run/kubevirt-private/dfe7d514-63f1-4e97-b642-f93109d5aa2f/virt-vnc'> > <listen type='socket' > socket='/var/run/kubevirt-private/dfe7d514-63f1-4e97-b642-f93109d5aa2f/virt-vnc'/> > </graphics> > <audio id='1' type='none'/> > <video> > <model type='vga' vram='65536' heads='1' primary='yes'> > <resolution x='1920' y='1080'/> > </model> > <alias name='video0'/> > <address type='pci' domain='0x0000' bus='0x00' slot='0x01' > function='0x0'/> > </video> > <memballoon model='virtio-non-transitional'> > <stats period='10'/> > <alias name='balloon0'/> > <address type='pci' domain='0x0000' bus='0x07' slot='0x00' > function='0x0'/> > </memballoon> It does work on my ubuntu guest, but it doesn't work on centos / windows guest. Is there any way to solve this problem ?

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Booting from USB device
by Simon Fairweather 28 Oct '22

28 Oct '22

I have a hooks file to hotplug a USB device at the prepare stage. Using OVMF version 2.6 this works fine, but using OVMF 2.7 the guest no longer boots from the USB device. Option 1) For it to work I have to set the boot order on the USB device and once the OVMF Shell appears I can reset it and it will find the USB device and boot. Option 2) Another setup which works if I remove all boot order settings from the guest and have a boot dev = 'fd' and this works every time.but I cannot add multiple entries. <os> <type arch='x86_64' machine='pc-q35-5.1'>hvm</type> <loader readonly='yes' type='pflash'>/usr/share/qemu/ovmf-x64/OVMF_CODE-pure-efi-tpm.fd</loader> <nvram>/etc/libvirt/qemu/nvram/b96bfc99-3612-0daa-9d8c-69e9d550d05a_VARS-pure-efi-tpm.fd</nvram> <boot dev='fd'/> <boot dev='hd'/> Any thoughts on how to get option 1) to working without having to do a reset.

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failed to load seccomp syscall filter in kernel: Operation canceled
by Jiatong Shen 28 Oct '22

28 Oct '22

Hello community, I am operating an openstack cluster where applications (libvirt/nova etc) are running using containers. The compute node's arch is aarch64 (phytium 2500), when there are virtual machines around 60 or 70, I failed to boot new virtual machines and faced with following error message, error: internal error: qemu unexpectedly closed the monitor: 2022-10-24T06:23:54.545685Z qemu-system-aarch64: -sandbox on,obsolete=deny,elevateprivileges=deny,spawn=deny,resourcecontrol=deny: failed to load seccomp syscall filter in kernel: Operation canceled Interestingly, if I virsh stop one virtual machine, I am able to boot another. Besides, I managed to manually boot a virtual machine without any issue. So my question is what could be the potential cause of this behavior and how can I deal with it? Thank you very much in advance for the help. -- Best Regards, Jiatong Shen

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Virtual Networking
by Armin Lepir 26 Oct '22

26 Oct '22

Hi I am using libvrt for the first time. Im building a KVM for multiple Virtual OS instances. The problem i have is with your official documentation for Virtual Networking. https://wiki.libvirt.org/page/VirtualNetworking The following is wrong: The default mode is BRIDGE + NAT. Optional mode is ROUTING. It should be: The default mode is ROUTING + NAT. Optional mode is BRIDGE. As far as i know a bridge operates on the Layer2. IP and NAT operate on the Layer3. NAT can not operate on the L2. Please tell me that im wrong and explain how am i wrong. Best Regards

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Re: MemoryBacking options
by Michal Prívozník 24 Oct '22

24 Oct '22

[Once again, I ask you to keep the list on the CC. In gmail's web UI it's the 'Reply to all' button]. On 10/22/22 11:19, Simon Fairweather wrote: > Is there a way to limit the shared memory allocated via Libvirt to > memory backing? > Yes, there is. On the top level there's /domain/memoryBacking [1] that serves as the default value for the guest. Then, under /domain/cpu/numa/cell [2] individual guest NUMA nodes are configured and each can have @memAccess attribute which overrides the top level setting (=memoryBacking). And finally, under /domain/devices/memory [3] individual RAM modules can be configured, and each one can have @access attribute which overrides both top level AND guest NUMA node setting. For instance: <domain> <maxMemory slots='16' unit='GiB'>8</maxMemory> <memory unit='GiB'>5</memory> <memoryBacking> <access mode='private'/> </memoryBacking> ... <cpu> <numa> <cell id='0' memory='2' unit='GiB' memAccess='shared'/> <cell id='1' memory='2' unit='GiB' /> </numa> </cpu> ... <devices> <memory model='dimm' access='private'> <target> <size unit='GiB'>1</size> <node>0</node> </target> </memory> </device> </domain> Here, the guest NUMA node 0 is going to be shared, except for DIMM module attached to it (which is going to be private) and NUMA node 1 is going to be private again. Michal 1: https://libvirt.org/formatdomain.html#memory-backing 2: https://libvirt.org/formatdomain.html#cpu-model-and-topology 3: https://libvirt.org/formatdomain.html#memory-devices > > > On Mon, Oct 17, 2022 at 9:06 AM Michal Prívozník <mprivozn(a)redhat.com > <mailto:mprivozn@redhat.com>> wrote: > > [please keep the list on CC for benefit of the community] > On 10/16/22 09:58, Simon Fairweather wrote: > > Thanks Michal, Are there any known issues with Memory Backing. We have > > QEMU 7.1 and libvirt 8.7. > > > > If just Memory Backing is set the VM Freezes after a couple of > hours and > > the allocated CPUs show 100% on the host. > > > > Seems to happen more on AMD Platforms than Intel. > > > > Please advise on any info you need, likely this is a QEMU issue. > > > > <memoryBacking> > > <source type='memfd'/> > > <access mode='shared'/> > > </memoryBacking> > > Agreed, this smells like QEMU issue. There's nothing obviously wrong > with this snipped. I have a VM with just that and run it just fine. > Although, I run it for couple of hours max. > > Michal >

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Cannot create vm with machine type raspi2b
by Niccolò Belli 22 Oct '22

22 Oct '22

Hi, I'm trying to use virt-manager to create a Raspberry Pi 2 virtual machine on my Talos 2 ppc64le workstation. In virt-manager I click on "New", then "Manual install", architecture "arm" and machine type "raspi2b". Next I set either "Generic or unknown OS" or "Debian 11" as operating system, I keep the default 1024 memory and 1 cpu and then I disable storage for this virtual machine (because I want to use an existing image with direct kernel boot, see https://raspi.debian.net/tested-images/) I check "Customize configuration before install" and I click "Finish". Unfortunately I get the following error: Error starting installation: Did not find any UEFI binary path for arch 'armv7l' So I've decided to start from scratch and select "virt" as machine type instead of "raspi2b" and change it back later. With "virt" I manage to reach the configuration overview before the installation begins. At this point I have three options for Firmware: Default UEFI UEFI armv7l:/usr/share/qemu/edk2-arm-code.fd UEFI is the default and if I change the machine type to raspi2b I still have the same three options (/usr/share/qemu/edk2-arm-code.fd does indeed exist in my file system). Unfortunately clicking on "Begin Installation" leads me to yet another error: Unable to complete install: 'internal error: Required option 'modelName' is not set for PCI controller with index '1', model 'pcie-root-port' and modelName 'none'' If I change the machine type back to "virt" I don't get any error. I'm using app-emulation/qemu 7.1.0, app-emulation/libvirt-8.8.0 and virt-manager-4.1.0 on Gentoo Linux ppc64le with a 4K page size kernel. Thanks, Niccolo' Belli

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How to merge incremental backups generated with virsh backup-begin?
by Jorge Luiz Correa 19 Oct '22

19 Oct '22

I'm trying to create incremental backups that I could restore when necessary. All backups are being generated fine but I couldn't find a way to recreate an image using all or some of the backup files. For example, my domain is called jammy and is running. jammy-backup.xml: <domainbackup> <incremental></incremental> </domainbackup> jammy-checkpoint.xml <domaincheckpoint> <disks> <disk name="vda" checkpoint="bitmap"/> </disks> </domaincheckpoint> ~# virsh backup-begin jammy jammy-backup.xml jammy-checkpoint.xml * This command with these files generates backup file in /var/lib/libvirt/images appending the checkpoint timestamp in file name (jammy.qcow2 -> jammy.qcow2.TIMESTAMP). ~# virsh checkpoint-list jammy Name Creation Time ----------------------------------------- 1666006874 2022-10-17 08:41:14 -0300 ~# ls -lh /var/lib/libvirt/images -rw-r--r-- 1 libvirt-qemu kvm 2,6G out 18 14:38 jammy.qcow2 -rw------- 1 root root 1,5G out 17 08:41 jammy.qcow2.1666006874 If I create a new domain using jammy.qcow2.1666006874 as disk, everything works good. Then, I've created some incremental backups. jammy-backup.xml: <domainbackup> <incremental>1666006874</incremental> </domainbackup> ~# virsh backup-begin jammy jammy-backup.xml jammy-checkpoint.xml ~# ls -lh /var/lib/libvirt/images -rw-r--r-- 1 libvirt-qemu kvm 2,6G out 18 14:38 jammy.qcow2 -rw------- 1 root root 1,5G out 17 08:41 jammy.qcow2.1666006874 -rw------- 1 root root 247M out 17 14:42 jammy.qcow2.1666010735 At this point, if I need to restore the backup with checkpoint 1666010735, how can I create a new image using jammy.qcow2.1666010735 and jammy.qcow2.1666006874? I would like to merge the incremental backup jammy.qcow2.1666010735 into the full backup jammy.qcow2.1666006874, to get a new image so I can create a new domain using it as disk. Am I doing it the right way? Ubuntu 22.04 LTS KVM libvirt 8.0.0-1ubuntu7.1 qemu 1:6.2+dfsg-2ubuntu6.4 Thank you! -- Jorge Luiz Corrêa Embrapa Agricultura Digital echo "CkpvcmdlIEx1aXogQ29ycmVhCkFu YWxpc3RhIGRlIFJlZGVzIGUgU2VndXJhbm NhCkVtYnJhcGEgQWdyaWN1bHR1cmEgRGln aXRhbCAtIE5USQpBdi4gQW5kcmUgVG9zZW xsbywgMjA5IChCYXJhbyBHZXJhbGRvKQpD RVAgMTMwODMtODg2IC0gQ2FtcGluYXMsIF NQClRlbGVmb25lOiAoMTkpIDMyMTEtNTg4 Mgpqb3JnZS5sLmNvcnJlYUBlbWJyYXBhLm JyCgo="|base64 -d -- __________________________ Aviso de confidencialidade Esta mensagem da Empresa Brasileira de Pesquisa Agropecuaria (Embrapa), empresa publica federal regida pelo disposto na Lei Federal no. 5.851, de 7 de dezembro de 1972, e enviada exclusivamente a seu destinatario e pode conter informacoes confidenciais, protegidas por sigilo profissional. Sua utilizacao desautorizada e ilegal e sujeita o infrator as penas da lei. Se voce a recebeu indevidamente, queira, por gentileza, reenvia-la ao emitente, esclarecendo o equivoco. Confidentiality note This message from Empresa Brasileira de Pesquisa Agropecuaria (Embrapa), a government company established under Brazilian law (5.851/72), is directed exclusively to its addressee and may contain confidential data, protected under professional secrecy rules. Its unauthorized use is illegal and may subject the transgressor to the law's penalties. If you are not the addressee, please send it back, elucidating the failure.

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Re: MemoryBacking options
by Michal Prívozník 17 Oct '22

17 Oct '22

[please keep the list on CC for benefit of the community] On 10/16/22 09:58, Simon Fairweather wrote: > Thanks Michal, Are there any known issues with Memory Backing. We have > QEMU 7.1 and libvirt 8.7. > > If just Memory Backing is set the VM Freezes after a couple of hours and > the allocated CPUs show 100% on the host. > > Seems to happen more on AMD Platforms than Intel. > > Please advise on any info you need, likely this is a QEMU issue. > > <memoryBacking> > <source type='memfd'/> > <access mode='shared'/> > </memoryBacking> Agreed, this smells like QEMU issue. There's nothing obviously wrong with this snipped. I have a VM with just that and run it just fine. Although, I run it for couple of hours max. Michal

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Qeustion about how to use domsetlaunchsecstate command correctly.
by 贺培轩 14 Oct '22

14 Oct '22

Hello, I'm new to libvirt. I have tried to launch a sev vm with secret injection recently, and I found the command domsetlaunchsecstate is what I need. But I had some problem to make it work. Here is what I did to use this command. 1. run command: virsh create sev-guest.xml 2. create secret header file and secret file. 3. run command: virsh domsetlaunchsecstate sev-guest-1 --secrethdr <hdr-filename> --secret <secret-filename> . But it will report this error: SEV: not in correct state. I think it is because the vm is not in a paused state. So how can I launch a sev vm which is in a paused state? How should I revise my xml file? The sev-guest.xml I use is as follows: <domain type="kvm"> <name>sev-guest-1</name> <uuid>d50a4205-40e0-4482-b0dc-f26bb4a1a9ff</uuid> <metadata> <libosinfo:libosinfo xmlns:libosinfo=" http://libosinfo.org/xmlns/libvirt/domain/1.0"> <libosinfo:os id="http://ubuntu.com/ubuntu/16.04"/> </libosinfo:libosinfo> </metadata> <memory>4194304</memory> <currentMemory>4194304</currentMemory> <memtune> <hard_limit>4563402</hard_limit> </memtune> <vcpu>32</vcpu> <cpu mode='custom' match='exact' check='partial'> <model fallback='forbid'>EPYC</model> </cpu> <os> <type arch="x86_64" machine="q35">hvm</type> <loader readonly="yes" type="pflash">/data01/OVMF.fd</loader> <nvram template="/data01/OVMF.fd">/var/lib/libvirt/qemu/nvram/sev-guest-1_VARS.fd</nvram> <boot dev="hd"/> </os> <features> <acpi/> <apic/> </features> <clock offset="utc"> <timer name="rtc" tickpolicy="catchup"/> <timer name="pit" tickpolicy="delay"/> <timer name="hpet" present="no"/> </clock> <pm> <suspend-to-mem enabled="no"/> <suspend-to-disk enabled="no"/> </pm> <devices> <emulator>/usr/local/bin/qemu-system-x86_64</emulator> <disk type="file" device="disk"> <driver name="qemu" type="qcow2"/> <source file="/data01/AMDSEV/sev-guest-1.qcow2"/> <target dev="sda" bus="scsi"/> </disk> <controller type="scsi" index="0" model="virtio-scsi"> <driver iommu="on"/> </controller> <controller type="virtio-serial" index="0"> <driver iommu="on"/> </controller> <controller type="usb" index="0" model="ich9-ehci1"/> <controller type="usb" index="0" model="ich9-uhci1"> <master startport="0"/> </controller> <controller type="usb" index="0" model="ich9-uhci2"> <master startport="2"/> </controller> <controller type="usb" index="0" model="ich9-uhci3"> <master startport="4"/> </controller> <controller type='pci' index='1' model='pcie-root-port'> <model name='pcie-root-port'/> <target chassis='1' port='0x8'/> <alias name='pci.1'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x0' multifunction='on'/> </controller> <controller type='pci' index='2' model='pcie-root-port'> <model name='pcie-root-port'/> <target chassis='2' port='0x9'/> <alias name='pci.2'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x1'/> </controller> <controller type='pci' index='3' model='pcie-root-port'> <model name='pcie-root-port'/> <target chassis='3' port='0xa'/> <alias name='pci.3'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x2'/> </controller> <controller type='pci' index='4' model='pcie-root-port'> <model name='pcie-root-port'/> <target chassis='4' port='0xb'/> <alias name='pci.4'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x3'/> </controller> <console type="pty"/> <input type="tablet" bus="usb"/> <graphics type="vnc" port="-1" listen="127.0.0.1"/> <video> <model type="vga"/> <address type='pci' slot='0x07'/> </video> <memballoon model="virtio"> <driver iommu="on"/> </memballoon> </devices> <launchSecurity type="sev"> <cbitpos>51</cbitpos> <reducedPhysBits>1</reducedPhysBits> <policy>0x05</policy> <dhCert>XXXXXXXXX</dhCert> <session>XXXXXXXXXXXXXXXXx</session> </launchSecurity> </domain> Thank you in advance, Peixuan

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