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question about virtio related options: ats=on and iommu=on
by Yalan Zhang 09 Jan '23

09 Jan '23

Hi, I have a question about the virtio related options, could someone please help to confirm? In my understanding, the ats='on' should depend on the "iommu=on", but I'm not sure about it. Please check the details below. Thank you! Details: 1. set vm with intel iommu device, and enable iommu for virtio filesystem device: # virsh dumpxml rhel --xpath //iommu <iommu model="intel"> <driver intremap="on" caching_mode="on" iotlb="on"/> </iommu> Set iommu="on" ats="on" for virtio filesystem device: # virsh dumpxml rhel --xpath //filesystem <filesystem type="mount" accessmode="passthrough"> <driver type="virtiofs" queue="512" iommu="on" ats="on"/> <binary path="/usr/libexec/virtiofsd" xattr="on"> <cache mode="none"/> </binary> <source dir="/path1"/> <target dir="mount_tag1"/> <address type="pci" domain="0x0000" bus="0x04" slot="0x00" function="0x0"/> </filesystem> 2. failed to start the vm since "iommu_platform=true is not supported by the device" # virsh start rhel error: Failed to start domain 'rhel' error: internal error: qemu unexpectedly closed the monitor: 2023-01-09T03:48:03.198629Z qemu-kvm: -device {"driver":"vhost-user-fs-pci","iommu_platform":true,"ats":true,"id":"fs0","chardev":"chr-vu-fs0","queue-size":512,"tag":"mount_tag1","bus":"pci.4","addr":"0x0"}: iommu_platform=true is not supported by the device 3. update the xml to be with only ats="on", vm can start successfully, which is not expected. # virsh dumpxml rhel --xpath //filesystem <filesystem type="mount" accessmode="passthrough"> <driver type="virtiofs" queue="512" ats="on"/> <binary path="/usr/libexec/virtiofsd" xattr="on"> <cache mode="none"/> </binary> <source dir="/path1"/> <target dir="mount_tag1"/> <alias name="fs0"/> <address type="pci" domain="0x0000" bus="0x04" slot="0x00" function="0x0"/> </filesystem> the qemu cmd line: -chardev socket,id=chr-vu-fs0,path=/var/lib/libvirt/qemu/domain-5-rhel/fs0-fs.sock \ -device '{"driver":"vhost-user-fs-pci","ats":true,"id":"fs0","chardev":"chr-vu-fs0","queue-size":512,"tag":"mount_tag1","bus":"pci.4","addr":"0x0"}' Refer to libvirt.org: QEMU's virtio devices have some attributes related to the virtio transport under the driver element: The iommu attribute enables the use of emulated IOMMU by the device. The attribute ats controls the Address Translation Service support for PCIe devices. This is needed to make use of IOTLB support (see IOMMU devices). Possible values are on or off. In my understanding, the ats='on' should depend on the iommu='on', so if the device does not support iommu, it should not support ats, eigher. I'm not sure if the understanding is correct. Could someone please help to confirm it? Thank you! Yalan

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Public IPv6 Bridges
by André Malm 07 Jan '23

07 Jan '23

I'm having trouble getting IPv6 to work for my KVM/qemu guests. I have two bridges setup, one routed (external, non libvirt) bridge for public dedicated ipv4 + ipv6 which works for both protocols. Then I have a libvirt nat bridge (with the routed bridge as parent) with a nated ipv4 (that works) and I also want a public ipv6. I'm able to transmit udp packets out but I never get any response. Looking at tcpdump there are incoming neighbor solicitations that get unanswered and don't get forwarded to the guest. Do I need to set something special up for this to work? Ubuntu 22.04 / Libvirt 8.0.0 The routed bridge (pubBr) has ipv6 2001:x:x:7d8e:: - My nat bridge config below: <network> <name>natbr</name> <bridge name="natbr" /> <forward mode='nat' dev='pubBr'> <nat> <port start='8000' end='30000'/> </nat> </forward> <ip address="10.1.1.1" netmask="255.255.0.0"> <dhcp> <range start='10.1.1.2' end='10.1.1.255'/> </dhcp> </ip> <ip family="ipv6" address="2001:x:x:7d8e::1" prefix="64"> <dhcp> <host name="test" ip="2001:x:x:7d8e:a01:2ff::"/> </dhcp> </ip> </network> Thanks!

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libvirt_connect_get_nic_models
by Simon Fairweather 02 Jan '23

02 Jan '23

Hi Can you confirm that I source get an array of these when running this api call, currently I just get a return of false root@computenode:/mnt/testpool# qemu -nic model=help Supported NIC models: e1000 e1000-82544gc e1000-82545em e1000e i82550 i82551 i82557a i82557b i82557c i82558a i82558b i82559a i82559b i82559c i82559er i82562 i82801 ne2k_pci pcnet rtl8139 tulip virtio-net-pci virtio-net-pci-non-transitional virtio-net-pci-transitional vmxnet3 function domain_get_nic_models($arch = 'x86_64') { $tmp = libvirt_connect_get_nic_models($this->conn, $arch) ; return ($tmp) ? $tmp : $this->_set_last_error(); }

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Snapshots of EFI VMs
by Simon Fairweather 30 Dec '22

30 Dec '22

Is there a timeline to fully support create/remove and revert for these VMs?

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how to add LD_PRELOAD in the xml
by Marc 30 Dec '22

30 Dec '22

How should I add LD_PRELOAD to domain xml. I guess within: <qemu:commandline> <qemu:arg value='env=LD_PRELOAD=/usr/lib64/libtcmalloc.so'/> </qemu:commandline> but this is generating syntax errors.

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Fwd: Need help
by Gk Gk 22 Dec '22

22 Dec '22

FYI.... ---------- Forwarded message --------- From: Gk Gk <ygk.kmr(a)gmail.com> Date: Wed, Dec 21, 2022 at 9:46 PM Subject: Re: Need help To: Daniel P. Berrangé <berrange(a)redhat.com> I have just created a new vm and rechecked the disk stats. This time around too, they seem to be different as shown below: >From libvirt python library: --- disk_name=sda read_req=10501,read_bytes=263819776,write_req=1933,write_bytes=82269184 --- So the write_bytes from above amounted to 78 MB approx. But from within the vm : --- root@sample2:~# iostat -p sda -h Linux 4.15.0-101-generic (sample2) 12/21/2022 _x86_64_ (1 CPU) avg-cpu: %user %nice %system %iowait %steal %idle 1.9% 0.0% 1.3% 0.4% 0.0% 96.4% Device tps kB_read/s kB_wrtn/s kB_read kB_wrtn sda 40.45 643.6k 21.2M 217.5M 7.2G sda1 40.04 637.6k 21.2M 215.5M 7.2G ---- 7.2 G is far from 78 MB. Am I doing wrong anywhere ? Btw, I did not reboot the new vm this time On Wed, Dec 21, 2022 at 9:30 PM Daniel P. Berrangé <berrange(a)redhat.com> wrote: > On Wed, Dec 21, 2022 at 09:26:14PM +0530, Gk Gk wrote: > > Thanks Daniel for the response. > > > > I am wondering what exactly is the difference in the process for a soft > and > > hard reboot in the context of a kvm guest ? Can you throw some light here > > please ? > > KVM will always do a soft reboot, where QEMU keeps running. > > > With regards, > Daniel > -- > |: https://berrange.com -o- > https://www.flickr.com/photos/dberrange :| > |: https://libvirt.org -o- > https://fstop138.berrange.com :| > |: https://entangle-photo.org -o- > https://www.instagram.com/dberrange :| > >

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Fwd: Need help
by Gk Gk 22 Dec '22

22 Dec '22

For larger reach....... ---------- Forwarded message --------- From: Gk Gk <ygk.kmr(a)gmail.com> Date: Thu, Dec 22, 2022 at 8:35 AM Subject: Re: Need help To: Daniel P. Berrangé <berrange(a)redhat.com> Hi Daniel, Did you get a chance to check this out ? Please let me know.... On Wednesday, December 21, 2022, Gk Gk <ygk.kmr(a)gmail.com> wrote: > I have just created a new vm and rechecked the disk stats. This time around too, they seem to be different as shown below: > From libvirt python library: > --- > disk_name=sda read_req=10501,read_bytes=263819776,write_req=1933,write_bytes=82269184 > --- > > So the write_bytes from above amounted to 78 MB approx. > But from within the vm : > --- > root@sample2:~# iostat -p sda -h > Linux 4.15.0-101-generic (sample2) 12/21/2022 _x86_64_ (1 CPU) > > avg-cpu: %user %nice %system %iowait %steal %idle > 1.9% 0.0% 1.3% 0.4% 0.0% 96.4% > > Device tps kB_read/s kB_wrtn/s kB_read kB_wrtn > sda > 40.45 643.6k 21.2M 217.5M 7.2G > sda1 > 40.04 637.6k 21.2M 215.5M 7.2G > ---- > 7.2 G is far from 78 MB. Am I doing wrong anywhere ? Btw, I did not reboot the new vm this time > > > > On Wed, Dec 21, 2022 at 9:30 PM Daniel P. Berrangé <berrange(a)redhat.com> wrote: >> >> On Wed, Dec 21, 2022 at 09:26:14PM +0530, Gk Gk wrote: >> > Thanks Daniel for the response. >> > >> > I am wondering what exactly is the difference in the process for a soft and >> > hard reboot in the context of a kvm guest ? Can you throw some light here >> > please ? >> >> KVM will always do a soft reboot, where QEMU keeps running. >> >> >> With regards, >> Daniel >> -- >> |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| >> |: https://libvirt.org -o- https://fstop138.berrange.com :| >> |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :| >> >

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Need help
by Gk Gk 21 Dec '22

21 Dec '22

Hi All, I am trying to get guest VM's disk statistics using a libvirt python library as follows: --- raw_xml = domain.XMLDesc(0) for disk in doc.getElementsByTagName('disk'): disk_data = disk.getElementsByTagName('target') --- The above code is yielding the following stats for two disks inside the VM: -- disk_name=sda read_req=34137,read_bytes=445358592,write_req=2405970,write_bytes=24943391744 disk_name=sdb read_req=34357,read_bytes=450754048,write_req=2405984,write_bytes=24943465472 --- The write_bytes divided by 1024 yields 24358853 kB. But when I compare the above statistics from the iostat data shown from inside the VM, I see a stark difference between the two results as shown below: --- root@sample:~# iostat Linux 4.15.0-101-generic (sample) 12/21/2022 _x86_64_ (1 CPU) avg-cpu: %user %nice %system %iowait %steal %idle 0.27 0.00 0.03 0.02 0.01 99.68 Device tps kB_read/s kB_wrtn/s kB_read kB_wrtn sda 0.24 0.04 11.87 400052 121844120 sdb 0.00 0.00 1.19 5269 12223752 ---- Why is there a huge difference in the number of bytes read and written for the two disks as reported by libvirt ? Please explain. Thanks Kumar

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[Question] Which qcow2 options could be inherited to snapshot/blockcopy?
by Meina Li 20 Dec '22

20 Dec '22

Hi, I'm trying to find out which qcow2 options could be inherited to snapshot/blockcopy and then test them. >From https://github.com/qemu/qemu/blob/master/qapi/block-core.json#L4720 we can know all the qcow2 options. As far as I know, size, cluster_size and extended-l2 have already been implemented. So I'm curious that: 1) What are the current status and future plans of other options? Like compat option. 2) Also whether the vol-clone can cover all options? Thank you very much. And please help to correct me if I have something wrong. Best Regards, Meina Li

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Failed to connect socket to '/var/run/libvirt/virtnetworkd-sock': No such file or directory
by 陈新隆 20 Dec '22

20 Dec '22

Hi team, i'm trying to hotplug an interface to guest, after execute the command below I got an error : ``` virsh attach-interface --domain 1 --type network --source net1 --model virtio-non-transitional --target /sys/devices/virtual/net/net1/tap603053 --mac ac:de:48:77:a2:32 --config --live error: Failed to attach interface error: Failed to connect socket to '/var/run/libvirt/virtnetworkd-sock': No such file or directory ``` According to https://libvirt.org/daemons.html there's two arch of daemon which is "monolithic" and "modular" , so I was wondering if I connect to the monolithic daemon (libvirtd) to attach the interface should works. Then I execute the command below : ``` bash-4.4# virsh -c qemu:///system?socket=/var/run/libvirt/libvirt-sock attach-interface --domain 1 --type network --source net1 --model virtio-non-transitional --target /sys/devices/virtual/net/net1/tap603053 --mac ac:de:48:77:a2:32 --config --live Authorization not available. Check if polkit service is running or see debug message for more information. error: Failed to attach interface error: Failed to connect socket to '/var/run/libvirt/virtnetworkd-sock': No such file or directory ``` Still, I got the same error. My question is : 1. How should I hotplug/unplug an interface without virtnetworkd ? 2. Am I right about the guess of "If I use monolithic daemon then I can hotplug/unplug an interface without virtnetworkd ?

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