------- Comment From [email protected] 2025-03-31 05:29 EDT------- (In reply to comment #22) > Hi I'm seeing success in defining a virtio-mem-ccw device via `virsh edit`. > However I'm seeing failure when I try hotplugging a device. > > ``` > # virsh edit u25 > ... > # virsh start u25 > ... > # virsh dumpxml u2410 | grep virtio-mem -A10 > <memory model='virtio-mem'> > <target> > <size unit='KiB'>9437184</size> > <block unit='KiB'>2048</block> > <requested unit='KiB'>0</requested> > <current unit='KiB'>0</current> > <address base='0x80000000'/> > </target> > <alias name='virtiomem0'/> > <address type='ccw' cssid='0xfe' ssid='0x0' devno='0x0006'/> > </memory> > # cat ./virtio-mem.xml > <memory model='virtio-mem'> > <target> > <size unit='GiB'>9</size> > <block unit='MiB'>2</block> > <requested unit='KiB'>0</requested> > </target> > <address type='ccw'/> > </memory> > # virsh attach-device u25 $PWD/virtio-mem.xml > error: Failed to attach device from /var/lib/libvirt/images/virtio-mem.xml > error: internal error: unable to execute QEMU command 'device_add': > PCI-attached virtio based memory devices not supported > ``` > > Hotunplug succeeds however. > > ``` > # virsh dumpxml u2410 | grep virtio-mem -A10 > ./live-definition.xml > # virsh detach-device u2410 $PWD/live-definition.xml > Device detached successfully > ``` > > Additionally virtio-mem-pci does not work at all, logging the same error > message as above: `PCI-attached virtio based memory devices not supported`.
OK, It seems that libvirt ignores the address type and every virtio-mem device defaults to be a PCI device. That is a libvirt bug fixed upstream by: 9ef080d6d9 qemu_domain_address: fix CCW virtio-mem hotplug This leaves the QEMU error which does not allow to attache a PCI virtio-mem device. There must be patches missing in QEMU that prevent virtio-mem-pci devices to be attached on s390. Are these to commits included in qemu? commit d77ae821e8940bdb9d97ee688aaa949f45de1758 Author: David Hildenbrand <[email protected]> Date: Tue Jan 28 19:57:05 2025 +0100 s390x/s390-virtio-ccw: Support plugging PCI-based virtio memory devices Let's just wire it up, unlocking virtio-mem-pci support on s390x. While at it, drop the "return;" in s390_machine_device_unplug_request(), to make it look like the other handlers. Reviewed-by: Thomas Huth <[email protected]> Signed-off-by: David Hildenbrand <[email protected]> Message-ID: <[email protected]> Signed-off-by: Thomas Huth <[email protected]> commit 03248e714b0dc95f13221cfd4496cbdfa118e114 Author: David Hildenbrand <[email protected]> Date: Tue Jan 28 19:57:04 2025 +0100 virtio-mem-pci: Allow setting nvectors, so we can use MSI-X Let's do it similar as virtio-balloon-pci. With this change, we can use virtio-mem-pci on s390x, although plugging will still fail until properly wired up in the machine. No need to worry about transitional/non_transitional devices, because they don't exist for virtio-mem. Signed-off-by: David Hildenbrand <[email protected]> Reviewed-by: Thomas Huth <[email protected]> Message-ID: <[email protected]> Signed-off-by: Thomas Huth <[email protected]> -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/2097886 Title: [25.04 FEAT] [VS2027] KVM: Enable virtio-mem support - libvirt part To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu-z-systems/+bug/2097886/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
