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Command line equivalent for cpu pinning
by Gianluca Cecchi 28 Jun '24

28 Jun '24

Hello, on my Fedora 39 with libvirt 9.7.0-3.fc39 qemu-kvm 8.1.3-5.fc39 kernel 6.8.11-200.fc39.x86_64 I'm testing cpu pinning The hw is a Nuc with 13th Gen Intel(R) Core(TM) i7-1360P If I pass from this in my guest xml: <vcpu placement='static'>4</vcpu> <cpu mode='host-passthrough' check='none' migratable='on'> <topology sockets='1' dies='1' cores='4' threads='1'/> </cpu> to this: <vcpu placement='static'>4</vcpu> <cputune> <vcpupin vcpu='0' cpuset='0'/> <vcpupin vcpu='1' cpuset='2'/> <vcpupin vcpu='2' cpuset='4'/> <vcpupin vcpu='3' cpuset='6'/> </cputune> <cpu mode='host-passthrough' check='none' migratable='on'> <topology sockets='1' dies='1' cores='4' threads='1'/> </cpu> It seems to me that the generated command line of the qemu-system-x88_64 process doesn't change. As if the cputune options were not considered What should I see as different? Actually it seems it is indeed honored, because if I run stress-ng in the VM in the second scenario and top command in the host, I see only pcpu 0,2,4,6 going up with the load. Instead the first scenario keeps several different cpus alternating in the load. The real question could be: if I want to reproduce from the command line the cputune options, how can I do it? Is it only a cpuset wrapper used for the qemu-system-x86_64 process to place it in a cpuset control group? I see for the pid of the process $ sudo cat /proc/340215/cgroup 0::/machine.slice/machine-qemu\x2d8\x2dc7anstgt.scope/libvirt/emulator and $ sudo systemd-cgls /machine.slice CGroup /machine.slice: └─machine-qemu\x2d8\x2dc7anstgt.scope … └─libvirt ├─340215 /usr/bin/qemu-system-x86_64.... ├─vcpu1 ├─vcpu2 ├─vcpu0 ├─emulator └─vcpu3 What could be an easy command to replicate from the command line what virsh does? Thanks in advance Gianluca

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cpu vmx migration issue
by d tbsky 25 Jun '24

25 Jun '24

Hi: I update our RHEL9 system to RHEL 9.4, which brings libvirt 10.0. I try to calculate the cpu baseline for our two-node cluster with command "virsh domcapabilities" then "virsh hypervisor-cpu-baseline --migratable". the result has many cpu features begin with "vmx". the test cluster has cpu "intel E3-1280 V3" and "intel I3-9100F". when I try live migrate vm, it failed and told me "guest CPU doesn't match specification: missing features: vmx-apicv-register,vmx-apicv-vid,vmx-posted-intr". at another cluster with cpu " Intel i5-2520M" and "Intel i7-9750H" the migration works fine for the calculated cpu result. although there are still many "vmx" cpu features in the result. if I delete all these vmx features, then migration works fine for both cluster, like old days. I wonder what's the benefit to expose these vmx features to guest if I don't do any nested virtualization. is it ok the drop all these vmx cpu features for a guest? thanks a lot for help!

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unable to start a nested vm due to iommu_group issue
by daggs 22 Jun '24

22 Jun '24

Greetings, I'm working on a new os for my server which runs 2 vms. I'm using nested vms to work on it so I won't take down the server. the new os is alpine 3.20, qemu is 9.0.1, libvirt is 10.3.0. I have a device I want to pass to one of the guests, here is the iommu group layout: IOMMU Group 18 00:1f.0 ISA bridge [0601]: Intel Corporation 82801IB (ICH9) LPC Interface Controller [8086:2918] (rev 02) IOMMU Group 18 00:1f.2 SATA controller [0106]: Intel Corporation 82801IR/IO/IH (ICH9R/DO/DH) 6 port SATA Controller [AHCI mode] [8086:2922] (rev 02) IOMMU Group 18 00:1f.3 SMBus [0c05]: Intel Corporation 82801I (ICH9 Family) SMBus Controller [8086:2930] (rev 02) IOMMU Group 18 00:1f.4 Audio device [0403]: Intel Corporation 82801I (ICH9 Family) HD Audio Controller [8086:293e] (rev 03) the device in question is 00:1f.4: utils-server:/home/igor# lspci -s 00:1f.4 -nnv 00:1f.4 Audio device [0403]: Intel Corporation 82801I (ICH9 Family) HD Audio Controller [8086:293e] (rev 03) Subsystem: Red Hat, Inc. QEMU Virtual Machine [1af4:1100] Flags: bus master, fast devsel, latency 0, IRQ 10, IOMMU group 18 Memory at e1080000 (32-bit, non-prefetchable) [size=16K] Capabilities: [60] MSI: Enable- Count=1/1 Maskable- 64bit+ Kernel driver in use: vfio-pci to achieve that, I've compiled the kernel with acs patch and defined it in the kernel cmdline: BOOT_IMAGE=/boot/vmlinuz-lts root=UUID=44299ace-27c6-4047-8cbd-bbffcc0a65f0 ro modules=sd-mod,usb-storage,ext4 quiet rootfstype=ext4 iommu=pt intel_iommu=on pcie_acs_override=id:8086:293e,8086:10c9 I see in dmesg, acs is enabled, see: # dmesg | grep "ACS overrides" [ 0.000000] Warning: PCIe ACS overrides enabled; This may allow non-IOMMU protected peer-to-peer DMA the xml file can be found at https://bpa.st/FARQ. when I try to start the vm, I get this: # virsh start streamer error: Failed to start domain 'streamer' error: internal error: QEMU unexpectedly closed the monitor (vm='streamer'): 2024-06-21T08:39:17.959476Z qemu-system-x86_64: -device {"driver":"vfio-pci","host":"0000:00:1f.4","id":"hostdev0","bus":"pcie.0","addr":"0x1f.0x5"}: vfio 0000:00:1f.4: group 18 is not viable Please ensure all devices within the iommu_group are bound to their vfio bus driver any ideas what am I missing? is it possible this cannot work within a vm? Thanks, Dagg

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librbd encryption and guest XML
by melanie witt 18 Jun '24

18 Jun '24

Hi, I have been trying to use the librbd engine to run a guest from an encrypted RBD image and am running into some problems. What I would like to do is: 1. Start from an unencrypted raw image with an OS 2. Make an encrypted clone of that image 3. Boot a guest from the encrypted clone image What I have tried so far (simplified): 1. Make a clone of the unencrypted image rbd clone images/unencrypted@snap images/encryptedclone 2. Format the clone image with encryption rbd encryption format images/encryptedclone luks1 passphrase.bin 3. Create guest XML with the encrypted clone [...] <disk type="network" device="disk"> <driver type="raw" cache="writeback"/> <source protocol="rbd" name="images/encryptedclone"> <host name="127.0.0.1" port="6789"/> <encryption format="luks" engine="librbd"> <secret type="passphrase" uuid="secretuuid"/> </encryption> </source> <auth username="cinder"> <secret type="ceph" uuid="othersecretuuid"/> </auth> <target dev="vda" bus="virtio"/> </disk> [...] and virDomainCreateWithFlags() with the XML. I don't get any errors from libvirt (no errors about loading encryption) but this configuration does not seem to work, the guest won't boot. If anyone can give me a hint what I'm doing wrong, I would appreciate it. Cheers, -melwitt

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brew services start libvirt failed to start libvirt on MacOS Sonoma
by absiplant＠gmail.com 17 Jun '24

17 Jun '24

Hello, I am hoping someone can point me in the right direction regarding issues I have starting up libvirt services on MacOS Sonoma. I am running: macOS Sonoma 14.5 llibvirt: stable 10.4.0 (bottled) qemu: stable 9.0.1 (bottled) I have the following entries in libvirt.conf: listen_tls = 0 listen_tcp = 1 listen_addr = "0.0.0.0" unix_sock_group = "libvirt" unix_sock_ro_perms = "0777" unix_sock_rw_perms = "0770" unix_sock_admin_perms = "0700" unix_sock_dir = "/opt/homebrew/var/run/libvirt" auth_unix_ro = "none" auth_unix_rw = "none" auth_tls = "none" tls_no_sanity_certificate = 1 tls_no_verify_certificate = 1 log_filters="1:qemu 1:libvirt 4:object 4:json 2:event 1:util" log_outputs="1:file:/opt/homebrew/var/log/libvirt/libvirtd.log" I added ```firewalld = 0``` and ```irewall_backend = "none"```. These made no difference, I have since removed both. Snippets of the log in debug mode indicate a usable firewall backend cannot be found, is there a way to resolve this on macOS? 8617315328: debug : virSystemdNotifyStartup:648 : Skipping systemd notify, not requested 6105182208: debug : virThreadJobSet:97 : Thread 6105182208 is now running job daemon-init 6105182208: warning : virProcessGetStartTime:1205 : Process start time of pid 10814 not available on this platform 6105182208: debug : virGDBusIsServiceEnabled:386 : Service org.freedesktop.login1 is unavailable 6105182208: debug : virStateInitialize:663 : Running global init for Remote state driver 6105182208: debug : virStateInitialize:670 : State init result 1 (mandatory=0) 6105182208: debug : virStateInitialize:663 : Running global init for bridge state driver 6105182208: error : virNetworkLoadDriverConfig:147 : internal error: could not find a usable firewall backend 6105182208: debug : virStateInitialize:670 : State init result -1 (mandatory=0) 6105182208: error : virStateInitialize:674 : Initialisation of bridge state driver failed: internal error: could not find a usable firewall backend 6105182208: error : daemonRunStateInit:617 : Driver state initialisation failed 6105182208: debug : virThreadJobClear:122 : Thread 6105182208 finished job daemon-init with ret=0 Thanks.

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vfio usage in a vm
by daggs 14 Jun '24

14 Jun '24

Greetings, I wanted to know if it is possible to attach a virtual nic (shows up as 02:01.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL-8100/8101L/8139 PCI Fast Ethernet Adapter (rev 20)) to the vfio module, when I modprobe it I get this error: [ 854.624668] vfio-pci: probe of 0000:02:01.0 failed with error -22 Thanks, Dagg

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Statically Defining a Network
by richard.schmitt＠starlab.io 13 Jun '24

13 Jun '24

We install libvirt in a AlmaLinux 9 Kickstart file. The version of libvirt we are using is 10.0.0. What we'd like to do is to statically define a network in the kickstart file without having to run `virsh net-define`. In other words, we had hoped that by installing a <network>.xml file in /usr/share/libvirt/networks, that that network would be recognized by libvirt the first time the system is booted. This does not appear to be the case. Is there a way to statically define libvirt networks without needing to run 'virsh net-define'? Thanks

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Re: Guests: Unable to get IP address
by Michal Prívozník 11 Jun '24

11 Jun '24

Please keep the list on CC so that others can benefit from the conversation too. On 5/21/24 14:34, Arun Mani J wrote: > Thanks for the reply! > > I recreated the NAT network using the guide from https://wiki.libvirt.org/Networking.html. > > The configuration now reads as: > <network> > <name>default</name> > <uuid>33376669-6292-44c9-b26b-9d2ee69826a7</uuid> > <forward mode="nat"> > <nat> > <port start="1024" end="65535"/> > </nat> > </forward> > <bridge name="virbr0" stp="on" delay="0"/> > <mac address="52:54:00:78:76:0f"/> > <ip address="192.168.122.1" netmask="255.255.255.0"> > <dhcp> > <range start="192.168.122.2" end="192.168.122.254"/> > </dhcp> > </ip> > </network> > > There is a dhcp section but still I'm not able to get my guest working. > > I have dnsmasq-base package installed in my host. However I'm not sure how to see if that is running. Like I opened Systems Monitor and can't find any process with that name. > > So may be that's the problem? Well, have you restarted the network? You need the 'virsh net-destroy default && virsh net-start default' combo to restart it. After that you should see dnsmasq process, e.g. via 'ps axf | grep dnsmasq'. Michal

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TLS live migrations and cgroups (cpuset)
by Giovanni Tirloni 30 May '24

30 May '24

Hello, I have got a situation where a live migration (TLS) is failing because the virtual machine has the following configuration: <vcpu placement='static' cpuset='0-1,3,5,7-47,49,51,53,55-95'>2</vcpu> This is in place because the host is shared with some other application with strict requirements and so the `machine.slice` was limited to these CPUs. During a live migration, libvirtd (running as root) seems to spawn a new rpc-libvirtd process with the same uid/gid defined in qemu.conf (non-root). It then fails to write to `cpuset.cpus`: virNetClientProgramDispatchError:172 : Unable to write to '/sys/fs/cgroup/cpuset/machine.slice/machine-qemu\x2d80\x2dinstance\x2d0000007c.scope/libvirt/emulator/cpuset.cpus': Permission denied Here are the running processes during the live migration: UID PID GID PPID CMD root 2639801 0 2639361 /usr/sbin/libvirtd --listen 12345 3033179 109 2638878 /usr/sbin/libvirtd --listen 12345 3033179 109 2638878 [rpc-libvirtd] (processes with uid=12345 are spawned during the migration. gid=109 is `kvm`) Changing group membership and file permissions has no effect because the file/directory permissions in machine.slice are not inherited inside the machine scope (a workaround was setting regular files as 664 and making the non-root UID of rpc-libvirtd be a member of the root group). I did not try to change the user/group in qemu.conf for fear of breaking other parts of the system or sabotaging security (e.g. by setting it to root/root for qemu-system-x86_64). The systemd scope for the machine has "Delegate=yes" so systemd expects the manager process to fully own the cgroups configuration. So looking at libvirtd, I cannot find a configuration setting that would either change the UID/GID of that rpc-libvirtd process or how to tweak the cgroups file permissions. Any insights? Environment: * Ubuntu 22.04 x86_64 * systemd 249.11 * libvirt 8.0.0

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How can I create a VM in virt-manager that can access the internet through the host but can't even see the host or other devices on the LAN?
by imthenachoman＠gmail.com 23 May '24

23 May '24

I want to be able to create multiple VMs for testing purposes -- questionable websites, files that could be infected with a virus, etc. I want to make sure these VMs should be able to access the internet (through the host) but they should not be able to access the host or any other device on the LAN. I tried `NAT` mode but that let's me access the host and other devices on the LAN. I tried `Isolated` mode but that doesn't give me internet access. I don't want to run a second VM and route traffic through it. I want to avoid creating FW rules on the host or VMs because I'll be creating and destroying VMs all the time. And I think I need to use some kind of NAT because I don't want my router to know/see the VMs as clients. What do I need to do?

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