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consuming pre-created tap - with multiqueue
by Miguel Duarte de Mora Barroso 24 Sep '20

24 Sep '20

Hello, On KubeVirt, we are trying to pre-create a tap device, then instruct libvirt to consume it (via the type=ethernet , managed='no' attributes). It works as expected, **unless** when we create a multi-queue tap device. The difference when creating the tap device is that we set the multi-queue flag; libvirt throws the following error when consuming it: ``` LibvirtError(Code=38, Domain=0, Message='Unable to create tap device tap0: Invalid argument') ``` After digging a bit on the libvirt code (we're using libvirt 6.0.0), I see this on the logs (immediately before the error): {"component":"virt-launcher","level":"info","msg":"Enabling IFF_VNET_HDR","pos":"virNetDevProbeVnetHdr:190","subcomponent":"libvirt","thread":"33" ,"timestamp":"2020-09-22T10:34:29.335000Z"} I do not understand how it can try to set the VNET_HDR flag, since I have not set it when I created it, which, as per [0] should only happen when requested. Here's the tap device I'm creating: (output of `ip tuntap show`) - tap0: tap persist0x100 user 107 group 107 I'm confused by this, since on [1] it says that only one flag can be used (persist *or* vnet_hdr). Also, from my limited understanding, in order to open a pre-created tap device, it must be set to persistent. Am I right (in the sense that these flags cannot co-exist) ? If so, why would libvirt be setting the VNET_HDR flag on the tap device ? [0] - https://github.com/libvirt/libvirt/blob/v6.0.0/src/util/virnetdevtap.c#L261 [1] - https://github.com/libvirt/libvirt/blob/v6.0.0/src/util/virnetdevtap.c#L209

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Help on meson build
by Wei Wang 24 Sep '20

24 Sep '20

Hi folks, I'm trying to build libvirt using meson with the latest upstream libvirt, but the compilation fails: (followed on https://libvirt.org/compiling.html, not sure if any dependencies are missed) FAILED: src/util/libvirt_util.a.p/glibcompat.c.o .... In file included from ../src/util/glibcompat.c:19: ./config.h:1026:10: fatal error: config-post.h: No such file or directory FAILED: src/util/libvirt_util.a.p/virfirmware.c.o In file included from ../src/util/virarch.c:22: ./config.h:1026:10: fatal error: config-post.h: No such file or directory FAILED: src/util/libvirt_util.a.p/viraudit.c.o In file included from ../src/util/viraudit.c:22: ./config.h:1026:10: fatal error: config-post.h: No such file or directory Any help is appreciated. Thanks, Wei

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[libvirt-users] Add Virtlyst to the list of libvirt users
by Daniel Nicoletti 24 Sep '20

24 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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Fwd: can't define domain - error: cannot open /dev/null: Operation not permitted
by Lentes, Bernd 22 Sep '20

22 Sep '20

> Von: "Lentes, Bernd" <bernd.lentes(a)helmholtz-muenchen.de> > Datum: 21. September 2020 um 18:38:48 MESZ > An: Martin Kletzander <mkletzan(a)redhat.com> > Betreff: Aw: can't define domain - error: cannot open /dev/null: Operation not permitted > > Hi Martin, > > after configuring the logging and a restart of the service the problem dissapeared !?! > > Bernd > > Bernd Lentes > > > Am 21.09.2020 um 10:02 schrieb Martin Kletzander <mkletzan(a)redhat.com>: > > > > On Sun, Sep 20, 2020 at 01:09:51PM +0200, Lentes, Bernd wrote: > >> Hi, > >> > > > > Hi, I'll start with the usual... > > > >> i have a two-node cluster running on SLES 12 with pacemaker. > >> The cluster refused to start the domains on one node. > >> So i took some of the domains out of the cluster and tried to start it manually. > >> This is what happened: > >> > >> virsh # define /mnt/share/vm_documents-oo.xml > >> error: Failed to define domain from /mnt/share/vm_documents-oo.xml > >> error: cannot open /dev/null: Operation not permitted > >> > >> Same with another domain. > >> > > > > What does the XML look like? What do the logs[0] say? > > > >> On the other node domains are defined and started without problems. > > > > Are the configs (libvirtd.conf and qemu.conf) the same on both nodes? > > > > Have a nice day, > > Martin > > > > [0] https://libvirt.org/kbase/debuglogs.html > > > >> Permissions on /dev and /dev/null are the same: > >> > >> ha-idg-1:/mnt/share # ll -d /dev > >> drwxr-xr-x 25 root root 5420 Sep 17 20:47 /dev > >> ha-idg-1:/mnt/share # ll /dev/null > >> crw-rw-rw- 1 root root 1, 3 Aug 24 14:39 /dev/null > >> > >> ha-idg-2:/mnt/share # ll -d /dev > >> drwxr-xr-x 25 root root 5340 Sep 9 10:31 /dev > >> ha-idg-2:/mnt/share # ll /dev/null > >> crw-rw-rw- 1 root root 1, 3 Aug 24 15:48 /dev/null > >> > >> ha-idg-1 is the one causing trouble. > >> Both systems SLES 12 SP4, same patchlevel. > >> livirt is: > >> ha-idg-1:/mnt/share # rpm -qa|grep -i libvirt > >> libvirt-daemon-driver-storage-iscsi-4.0.0-8.15.2.x86_64 > >> libvirt-libs-4.0.0-8.15.2.x86_64 > >> python-libvirt-python-4.0.0-2.34.x86_64 > >> libvirt-daemon-driver-nwfilter-4.0.0-8.15.2.x86_64 > >> libvirt-glib-1_0-0-0.2.1-1.2.x86_64 > >> typelib-1_0-LibvirtGLib-1_0-0.2.1-1.2.x86_64 > >> libvirt-admin-4.0.0-8.15.2.x86_64 > >> libvirt-daemon-driver-storage-4.0.0-8.15.2.x86_64 > >> libvirt-daemon-driver-storage-core-4.0.0-8.15.2.x86_64 > >> libvirt-daemon-driver-storage-scsi-4.0.0-8.15.2.x86_64 > >> libvirt-client-4.0.0-8.15.2.x86_64 > >> libvirt-daemon-driver-nodedev-4.0.0-8.15.2.x86_64 > >> libvirt-daemon-driver-storage-logical-4.0.0-8.15.2.x86_64 > >> libvirt-daemon-driver-qemu-4.0.0-8.15.2.x86_64 > >> libvirt-daemon-driver-secret-4.0.0-8.15.2.x86_64 > >> libvirt-daemon-driver-storage-rbd-4.0.0-8.15.2.x86_64 > >> libvirt-daemon-driver-interface-4.0.0-8.15.2.x86_64 > >> libvirt-daemon-4.0.0-8.15.2.x86_64 > >> libvirt-daemon-driver-network-4.0.0-8.15.2.x86_64 > >> libvirt-daemon-driver-storage-mpath-4.0.0-8.15.2.x86_64 > >> libvirt-daemon-qemu-4.0.0-8.15.2.x86_64 > >> libvirt-daemon-config-network-4.0.0-8.15.2.x86_64 > >> libvirt-daemon-driver-storage-disk-4.0.0-8.15.2.x86_64 > >> > >> Any ideas ? > >> Maybe a restart would help, but it's Linux, not Windows ... > >> I'd like to understand what's going wrong. > >> > >> Thanks. > >> > >> > >> Bernd > >> -- > >> > >> Bernd Lentes > >> Systemadministration > >> Institute for Metabolism and Cell Death (MCD) > >> Building 25 - office 122 > >> HelmholtzZentrum München > >> bernd.lentes(a)helmholtz-muenchen.de > >> phone: +49 89 3187 1241 > >> phone: +49 89 3187 3827 > >> fax: +49 89 3187 2294 > >> http://www.helmholtz-muenchen.de/mcd > >> > >> stay healthy > >> Helmholtz Zentrum MÃ¼nchen > >> > >> Helmholtz Zentrum MÃ¼nchen > >> > >> Helmholtz Zentrum Münche Helmholtz Zentrum Münche

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Fwd: can't define domain - error: cannot open /dev/null: Operation not permitted
by Lentes, Bernd 22 Sep '20

22 Sep '20

> Von: "Lentes, Bernd" <bernd.lentes(a)helmholtz-muenchen.de> > Datum: 21. September 2020 um 18:38:48 MESZ > An: Martin Kletzander <mkletzan(a)redhat.com> > Betreff: Aw: can't define domain - error: cannot open /dev/null: Operation not permitted > Helmholtz Zentrum M��nchen Helmholtz Zentrum M��nchen

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can't define domain - error: cannot open /dev/null: Operation not permitted
by Lentes, Bernd 21 Sep '20

21 Sep '20

Hi, i have a two-node cluster running on SLES 12 with pacemaker. The cluster refused to start the domains on one node. So i took some of the domains out of the cluster and tried to start it manually. This is what happened: virsh # define /mnt/share/vm_documents-oo.xml error: Failed to define domain from /mnt/share/vm_documents-oo.xml error: cannot open /dev/null: Operation not permitted Same with another domain. On the other node domains are defined and started without problems. Permissions on /dev and /dev/null are the same: ha-idg-1:/mnt/share # ll -d /dev drwxr-xr-x 25 root root 5420 Sep 17 20:47 /dev ha-idg-1:/mnt/share # ll /dev/null crw-rw-rw- 1 root root 1, 3 Aug 24 14:39 /dev/null ha-idg-2:/mnt/share # ll -d /dev drwxr-xr-x 25 root root 5340 Sep 9 10:31 /dev ha-idg-2:/mnt/share # ll /dev/null crw-rw-rw- 1 root root 1, 3 Aug 24 15:48 /dev/null ha-idg-1 is the one causing trouble. Both systems SLES 12 SP4, same patchlevel. livirt is: ha-idg-1:/mnt/share # rpm -qa|grep -i libvirt libvirt-daemon-driver-storage-iscsi-4.0.0-8.15.2.x86_64 libvirt-libs-4.0.0-8.15.2.x86_64 python-libvirt-python-4.0.0-2.34.x86_64 libvirt-daemon-driver-nwfilter-4.0.0-8.15.2.x86_64 libvirt-glib-1_0-0-0.2.1-1.2.x86_64 typelib-1_0-LibvirtGLib-1_0-0.2.1-1.2.x86_64 libvirt-admin-4.0.0-8.15.2.x86_64 libvirt-daemon-driver-storage-4.0.0-8.15.2.x86_64 libvirt-daemon-driver-storage-core-4.0.0-8.15.2.x86_64 libvirt-daemon-driver-storage-scsi-4.0.0-8.15.2.x86_64 libvirt-client-4.0.0-8.15.2.x86_64 libvirt-daemon-driver-nodedev-4.0.0-8.15.2.x86_64 libvirt-daemon-driver-storage-logical-4.0.0-8.15.2.x86_64 libvirt-daemon-driver-qemu-4.0.0-8.15.2.x86_64 libvirt-daemon-driver-secret-4.0.0-8.15.2.x86_64 libvirt-daemon-driver-storage-rbd-4.0.0-8.15.2.x86_64 libvirt-daemon-driver-interface-4.0.0-8.15.2.x86_64 libvirt-daemon-4.0.0-8.15.2.x86_64 libvirt-daemon-driver-network-4.0.0-8.15.2.x86_64 libvirt-daemon-driver-storage-mpath-4.0.0-8.15.2.x86_64 libvirt-daemon-qemu-4.0.0-8.15.2.x86_64 libvirt-daemon-config-network-4.0.0-8.15.2.x86_64 libvirt-daemon-driver-storage-disk-4.0.0-8.15.2.x86_64 Any ideas ? Maybe a restart would help, but it's Linux, not Windows ... I'd like to understand what's going wrong. Thanks. Bernd -- Bernd Lentes Systemadministration Institute for Metabolism and Cell Death (MCD) Building 25 - office 122 HelmholtzZentrum München bernd.lentes(a)helmholtz-muenchen.de phone: +49 89 3187 1241 phone: +49 89 3187 3827 fax: +49 89 3187 2294 http://www.helmholtz-muenchen.de/mcd stay healthy Helmholtz Zentrum MÃ¼nchen Helmholtz Zentrum MÃ¼nchen

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redirecting guest serial to file on the host
by daggs 21 Sep '20

21 Sep '20

Greetings, I have a vm to which I can access using virsh console vm1/ I'd like in addition to be able to dump the serial of the vm in to a file on the host. I've found this https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/6/ht… but it seems that the first second example which might be suited to what I need doesn't work as I get an empty file: here are my serial config for the vm: <serial type='pty'> <source path='/dev/pts/2'/> <target type='isa-serial' port='0'> <model name='isa-serial'/> </target> <alias name='serial0'/> </serial> <serial type='file'> <source path='/var/log/router-serial.log'/> <target type='isa-serial' port='0'> <model name='isa-serial'/> </target> <alias name='serial1'/> </serial> <console type='pty' tty='/dev/pts/2'> <source path='/dev/pts/2'/> <target type='serial' port='0'/> <alias name='serial0'/> </console> what might be wrong in the above? Dagg.

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KVM/QEMU Memory Ballooning
by Sprencz, Pal Csongor (GE Healthcare) 18 Sep '20

18 Sep '20

Dear libvirt community, My name is Csongor Sprencz from the GE Healthcare. I contacting you regarding some questions about the memory ballooning mechanism of the KVM/QEMU system. I hope that I contact the right forum to get answer to my question In short we have a ScientificLinux7 base host OS system, on top of that I would want to run a KVM/QEMU virtual machine. The kvm version is used on the host OS is the following. qemu-kvm-common-1.5.3-173.el7_8.1.x86_64 libvirt-daemon-driver-qemu-4.5.0-23.el7_7.6.x86_64 qemu-kvm-1.5.3-173.el7_8.1.x86_64 The guest Linux OS is Suse. The VM cfg does contain the mem balloon device configuration. Inside of the VM we have a Kubernetes. The host system has 64GB, the VM has maxmemory and currentmemory set to 32GB. I would like to ask you, how we can test that the memory ballooning mechanism works? Does it works on this version or not. What I see on the host level, if I put under stress the host with a hugh memory allocation, in that case the VM resident memory size it is decreasing, but it not decrease so much as it is expected, and it started to swap out to host swap disk. The VM on idle state it has 32GB total memory and 21GB free memory. And what I see the RSS size of the qemu is decresing with 5-6GB. Do you have any procedure, how it can be tested? Or there is any log where I can see that the memory ballooning is started to work? Regards, Csongor

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network config not working on newer libvirt
by daggs 16 Sep '20

16 Sep '20

Greetings, up until a year ago, I was running a server with Debian 10 (stable) on it with the latest versions of libvirt, qemu and kernel 4.19.x Debian 10 had to offer (both libvirt and qemu versions were really old). the network config was simple, one of the vm acted as a router and provided the ip for both the host and the vm. I've recently switched distro and now I'm running latest stable libvirt, qemu and kernel 5.4.x I've tried to reinstate the network config on the new distro but I cannot get ip via dhcp for the second vm. if I assign manual ip and gateway, I have access to the outside world. here are the relevant dumps: network on the router vm: <interface type='network'> <mac address='52:54:00:53:1c:6b'/> <source network='default'/> <target dev='virtsw0-vm1'/> <model type='virtio'/> <address type='pci' domain='0x0000' bus='0x21' slot='0x01' function='0x0'/> </interface> the other vm <interface type='network'> <mac address='52:54:00:5a:4c:8c'/> <source network='default'/> <target dev='virtsw0-vm2'/> <model type='virtio'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/> </interface> and finally: <network connections='2'> <name>default</name> <uuid>61bc1a72-bd02-408a-b88e-dec696742c20</uuid> <bridge name='virtsw0' stp='on' delay='0'/> <mac address='52:54:00:6b:1b:92'/> </network> as it is possible I'm missing a kernel config, here is the output of lsmod: vfio_pci 49152 6 vfio_virqfd 16384 1 vfio_pci vfio_iommu_type1 32768 2 vfio 28672 16 vfio_iommu_type1,vfio_pci ip6table_nat 16384 1 iptable_nat 16384 1 ebtables 24576 0 bridge 143360 0 stp 16384 1 bridge llc 16384 2 bridge,stp cfg80211 647168 0 x86_pkg_temp_thermal 20480 0 kvm_intel 237568 8 vhost_net 24576 3 vhost 36864 1 vhost_net tap 24576 1 vhost_net kvm 663552 1 kvm_intel tun 53248 8 vhost_net r8152 73728 0 nct6775 57344 0 mei_me 32768 0 hwmon_vid 20480 1 nct6775 irqbypass 16384 22 vfio_pci,kvm mii 16384 1 r8152 mei 77824 1 mei_me coretemp 16384 0 efivarfs 16384 1 and the .config at https://dpaste.com/9ZUCBDE9R any ideas how to fix it? Thanks, Dagg.

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Question about reduced memory by balloon driver (QEMU specific?)
by Henry lol 16 Sep '20

16 Sep '20

Hi guys, When a guest's memory is dynamically reduced with setMemory API (and "balloon" QMP API), I'm wondering whether the virtio-balloon driver in the guest is consuming such reduced memory. If so, how can I see that the memory virtio-balloon is consuming? and is it possible the virtio-balloon has such a huge memory even though it's a kernel module?? Thanks,

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