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dns test
by NO SPAM 21 Jul '20

21 Jul '20

please ignore

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9p file sharing issue
by Johan 20 Jul '20

20 Jul '20

I've run into an issue with 9p file sharing that I suspect is a bug. I'm running some Debian ARM VMs (armhf Ubuntu guests on an aarch64 Debian stretch host in case that matters). I'm using direct kernel boot, so I'm also using 9p host file sharing so that kernel updates from within the guest would work. However, I've noticed that dpkg (the Debian/Ubuntu package manager) fails when writing into a /boot directory that's shared from the host via 9p. Some investigation reveals that this is because dpkg does an openat() call of the type openat(AT_FDCWD, "/boot/vmlinuz-4.15.0-111-generic-lpae.dpkg-new", O_WRONLY|O_CREAT|O_EXCL|O_LARGEFILE, 000); and that it's the 0 permissions mode (last parameter) that causes the call to fail with a "Permission denied" error. A simple test program that does the above openat() call but with another mode (say, 600) works just fine. Some further data: * QEMU runs as the unprivileged user libvirt-qemu (Debian default) * QEMU is version 2.8, libvirt version 3.0.0 * XML snippet for 9p setup: <filesystem type='mount' accessmode='squash'> <source dir='/host/path/boot-test9p'/> <target dir='boot_mount'/> <alias name='fs0'/> <address type='pci' domain='0x0000' bus='0x03' slot='0x01' function='0x0'/> </filesystem> * The 9p filesystem is mounted by this line in /etc/fstab on the guest: boot_mount /boot 9p rw,dirsync,_netdev,relatime,trans=virtio,version=9p2000.L 0 0 The essential problem seems to be that opening a file with a mode of 0 is not compatible with the "squash" 9p access mode. Is this expected? Thank you, Johan

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Unable to decode message length
by Valentin David 16 Jul '20

16 Jul '20

Hello all, I have been trying to get libvirtd to work but when I connect to it with virsh, I get "error : virNetMessageDecodeLength:131 : Unable to decode message length" This happens with libvirt 6.1.0, libtirpc 1.2.6, rpcsvc-proto 1.4.1. I have tried with other versions, but I still get the same error. If anybody has any tip on what to try next, that would be helpful. Thank you in advance. Here is the debug log of libvirtd when I try to connect with virsh: 2020-07-14 16:29:58.220+0000: 5352: info : virEventGLibHandleDispatch:116 : EVENT_GLIB_DISPATCH_HANDLE: watch=2 events=1 cb=0x7f7b55b86c50 opaque=0x556fbcf8b8a0 2020-07-14 16:29:58.220+0000: 5352: info : virObjectNew:250 : OBJECT_NEW: obj=0x556fbcf8d770 classname=virNetSocket 2020-07-14 16:29:58.220+0000: 5352: info : virNetSocketNew:278 : RPC_SOCKET_NEW: sock=0x556fbcf8d770 fd=18 errfd=-1 pid=0 localAddr=127.0.0.1;0, remoteAddr=127.0.0.1;0 2020-07-14 16:29:58.220+0000: 5352: info : virObjectNew:250 : OBJECT_NEW: obj=0x556fbcf8da50 classname=virNetServerClient 2020-07-14 16:29:58.220+0000: 5352: info : virObjectRef:385 : OBJECT_REF: obj=0x556fbcf8d770 2020-07-14 16:29:58.220+0000: 5352: info : virEventGLibTimeoutAdd:341 : EVENT_GLIB_ADD_TIMEOUT: timer=1 interval=-1 cb=0x7f7b55b8d490 opaque=0x556fbcf8da50 ff=(nil) 2020-07-14 16:29:58.220+0000: 5352: info : virNetServerClientNewInternal:421 : RPC_SERVER_CLIENT_NEW: client=0x556fbcf8da50 sock=0x556fbcf8d770 2020-07-14 16:29:58.220+0000: 5352: info : virObjectRef:385 : OBJECT_REF: obj=0x556fbcf8da50 2020-07-14 16:29:58.220+0000: 5352: info : virObjectRef:385 : OBJECT_REF: obj=0x556fbcf8d770 2020-07-14 16:29:58.220+0000: 5352: info : virEventGLibHandleAdd:160 : EVENT_GLIB_ADD_HANDLE: watch=11 fd=18 events=1 cb=0x7f7b55b86c50 opaque=0x556fbcf8d770 ff=0x7f7b55b86c00 2020-07-14 16:29:58.220+0000: 5352: info : virObjectRef:385 : OBJECT_REF: obj=0x556fbcf8da50 2020-07-14 16:29:58.220+0000: 5352: info : virNetServerCheckLimits:280 : Re-enabling services 2020-07-14 16:29:58.220+0000: 5352: info : virEventGLibHandleUpdate:194 : EVENT_GLIB_UPDATE_HANDLE: watch=2 events=1 2020-07-14 16:29:58.220+0000: 5352: info : virObjectNew:250 : OBJECT_NEW: obj=0x556fbcf8e330 classname=virKeepAlive 2020-07-14 16:29:58.220+0000: 5352: info : virKeepAliveNew:208 : RPC_KEEPALIVE_NEW: ka=0x556fbcf8e330 client=0x556fbcf8da50 2020-07-14 16:29:58.220+0000: 5352: info : virObjectRef:385 : OBJECT_REF: obj=0x556fbcf8da50 2020-07-14 16:29:58.220+0000: 5352: info : virObjectUnref:347 : OBJECT_UNREF: obj=0x556fbcf8da50 2020-07-14 16:29:58.220+0000: 5352: info : virObjectUnref:347 : OBJECT_UNREF: obj=0x556fbcf8d770 2020-07-14 16:29:58.220+0000: 5352: info : virEventGLibHandleDispatch:116 : EVENT_GLIB_DISPATCH_HANDLE: watch=11 events=1 cb=0x7f7b55b86c50 opaque=0x556fbcf8d770 2020-07-14 16:29:58.220+0000: 5352: error : virNetMessageDecodeLength:131 : Unable to decode message length 2020-07-14 16:29:58.220+0000: 5352: info : virKeepAliveStop:300 : RPC_KEEPALIVE_STOP: ka=0x556fbcf8e330 client=0x556fbcf8da50 2020-07-14 16:29:58.221+0000: 5352: info : virObjectRef:385 : OBJECT_REF: obj=0x556fbcf8da50 2020-07-14 16:29:58.221+0000: 5352: info : virObjectUnref:347 : OBJECT_UNREF: obj=0x556fbcf8e330 2020-07-14 16:29:58.221+0000: 5352: info : virObjectUnref:349 : OBJECT_DISPOSE: obj=0x556fbcf8e330 2020-07-14 16:29:58.221+0000: 5352: info : virKeepAliveDispose:221 : RPC_KEEPALIVE_DISPOSE: ka=0x556fbcf8e330 2020-07-14 16:29:58.221+0000: 5352: info : virObjectUnref:347 : OBJECT_UNREF: obj=0x556fbcf8da50 2020-07-14 16:29:58.221+0000: 5352: info : virObjectUnref:347 : OBJECT_UNREF: obj=0x556fbcf8da50 2020-07-14 16:29:58.221+0000: 5352: info : virObjectRef:385 : OBJECT_REF: obj=0x556fbcf8da50 2020-07-14 16:29:58.221+0000: 5352: info : virObjectUnref:347 : OBJECT_UNREF: obj=0x556fbcf8da50 2020-07-14 16:29:58.221+0000: 5352: info : virEventGLibHandleRemove:261 : EVENT_GLIB_REMOVE_HANDLE: watch=11 2020-07-14 16:29:58.221+0000: 5352: info : virObjectUnref:347 : OBJECT_UNREF: obj=0x556fbcf8d770 2020-07-14 16:29:58.221+0000: 5352: info : virNetServerCheckLimits:280 : Re-enabling services 2020-07-14 16:29:58.221+0000: 5352: info : virEventGLibHandleUpdate:194 : EVENT_GLIB_UPDATE_HANDLE: watch=2 events=1 2020-07-14 16:29:58.221+0000: 5352: info : virObjectUnref:347 : OBJECT_UNREF: obj=0x556fbcf8da50 2020-07-14 16:29:58.221+0000: 5352: info : virEventGLibHandleRemoveIdle:242 : EVENT_GLIB_REMOVE_HANDLE_IDLE: watch=11 ff=0x7f7b55b86c00 opaque=0x556fbcf8d770 2020-07-14 16:29:58.221+0000: 5352: info : virObjectUnref:347 : OBJECT_UNREF: obj=0x556fbcf8da50 2020-07-14 16:29:58.221+0000: 5352: info : virObjectUnref:349 : OBJECT_DISPOSE: obj=0x556fbcf8da50 2020-07-14 16:29:58.221+0000: 5352: info : virNetServerClientDispose:976 : RPC_SERVER_CLIENT_DISPOSE: client=0x556fbcf8da50 2020-07-14 16:29:58.221+0000: 5352: info : virEventGLibTimeoutRemove:437 : EVENT_GLIB_REMOVE_TIMEOUT: timer=1 2020-07-14 16:29:58.221+0000: 5352: info : virObjectUnref:347 : OBJECT_UNREF: obj=0x556fbcf8d770 2020-07-14 16:29:58.221+0000: 5352: info : virObjectUnref:349 : OBJECT_DISPOSE: obj=0x556fbcf8d770 2020-07-14 16:29:58.221+0000: 5352: info : virNetSocketDispose:1332 : RPC_SOCKET_DISPOSE: sock=0x556fbcf8d770 2020-07-14 16:29:58.221+0000: 5352: info : virEventGLibTimeoutRemoveIdle:417 : EVENT_GLIB_REMOVE_TIMEOUT_IDLE: timer=1 ff=(nil) opaque=0x556fbcf8da50

2 3

SELinux labels change in libvirt
by Ram Lavi 16 Jul '20

16 Jul '20

Hello all, tl;dr, can you point me to the point in the libvirt repo where it's trying to change a tap-device's SELinux label? I am trying to create a tap device with libvirt on a super-privileged container, and then use it on another, unprivileged container with libvirt. User wise, I know I need the super-privileged container to open the tap device with the user of the unprivileged one - that I already did and it's not the issue. But I have a problem when I open the tap device in the non-privileged container: the tap device currently has the spc_t label since the tun_socket inherited the selinux context from the super-privileged container who creates it. then libvirt is trying to change the SELinux labels, and since it's not privileged then it fails. But I didn't find where and how libvirt is trying to change the tap device's label. Can you point me to that specific code on libvirt? Ram Lavi Senior Software Engineer Red Hat Israel <https://www.redhat.com/> Yerushalaim Road 34, Ra'anana ralavi(a)redhat.com IM: ralavi @RedHat <https://twitter.com/redhat> Red Hat <https://www.linkedin.com/company/red-hat> Red Hat <https://www.facebook.com/RedHatInc> <https://www.redhat.com/>

2 5

Help with external snapshots as backups
by Alex Regan 14 Jul '20

14 Jul '20

Hi, I have a win10 guest on a fedora32 system and have some questions as I explore using external snapshots as a form of backup in case of a Windows failure (as in, it won't boot or is completely irrecoverable) as well as revision control (to be able to rollback changes after a failed app install, etc). The first hit on Google for external snapshots involves a RHEL7 document that talks about how it's not officially supported. The current RHEL8 docs don't include any references to snapshots. The fedora docs I've found are many years old - I'm just not sure if they're still applicable. Where can I find the current docs for fedora32? - If I've already created a live internal snapshot, can I then create an external safely? Are all changes currently being written to this internal snapshot now? - Can external snapshots be used for backup? Perhaps there are predefined steps for doing this that I can follow? This is the procedure I'm currently using. I've made a backup of the original image - can I now just continue to backup the snapshots in the eventuality of a crash, then use this original image backup and the snapshots to restore it? I suppose I would also periodically merge the snapshots back into the a single snapshot to ease the process? # virsh snapshot-create-as --domain dave-win10a win10a-state01 --diskspec vda,file=/var/lib/libvirt/images/vm_snapshots/disk-overlay.qcow2,snapshot=external --memspec file=/var/lib/libvirt/images/vm_snapshots/mem-overlay.qcow2,snapshot=external --atomic Domain snapshot win10a-state01 created # ls -lh vm_snapshots/ total 3.3G -rw------- 1 qemu qemu 196K Jul 11 12:32 disk-overlay.qcow2 -rw------- 1 root root 3.3G Jul 11 12:32 mem-overlay.qcow2 Thanks, Alex

2 1

Emulated TPM devices and snapshots of running VMs
by Milan Zamazal 09 Jul '20

09 Jul '20

Hi, I would like to clarify how to make snapshots of running VMs with emulated TPM devices. As far as I understand QEMU documentation, it's possible to make snapshots of running VMs with TPM, but it's important to retain the state of swtpm. Does libvirt assist with that in any way or is it completely user's responsibility? libvirt pauses the VM internally when making a snapshot, which should be the right moment to copy the swtpm data, but the user doesn't have control over it. Is there a way to make a copy of swtpm data that is guaranteed to be consistent with the snapshot? Thank you, Milan

2 5

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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Why wireless interface cannot be attached to a Linux host bridge?
by ryotaro kobayashi 08 Jul '20

08 Jul '20

Hello, everyone. I'm from japan and using machine translation, so I apologize if it's hard to read. I am currently trying to build a virtual environment using Ubuntu and kvm. However, I found out from the following page that the virtual machine cannot use the bridge network because I am using a wireless network. https://wiki.libvirt.org/page/Networking I am having trouble with this because my PC is using a wireless LAN. On that page it says "wireless interfaces cannot be attached to a Linux host bridge", I Can you tell me why this is so? Is it a limitation of the NIC driver for the wireless LAN? Or is it a limitation of libvirt? Best regards.

6 9

Testing DKIM signatures
by dberrange＠yahoo.com 02 Jul '20

02 Jul '20

Please ignore this test message

2 1

Asking for suggestion and questions regarding the workings/internals of Libvirt
by Shashwat shagun 01 Jul '20

01 Jul '20

I am building a multi-tenant json REST API for managing KVM VMs but don't know if libvirt transactions are going to be fast enough to be invoked directly? or do i need a job queue? Does libvirtd already have a job queue that is used when handling time-consuming tasks like creating domain and such? If yes then what about tasks such as volUpload or download? Shashwat. shashwatshagun2581(a)gmail.com

1 0