[libvirt-users] [virtual interface] detach interface during boot succeed with no changes
Hi guys, when I detach an interface from vm during boot (vm boot not finished), it always fail. I'm not sure if there is an existing bug. I have confirmed with someone that for disk, there is similar behavior, if this is also acceptable? # virsh destroy rhel7.2; virsh start rhel7.2 ;sleep 2; virsh detach-interface rhel7.2 network 52:54:00:98:c4:a0; sleep 2; virsh dumpxml rhel7.2 |grep /interface -B9 Domain rhel7.2 destroyed Domain rhel7.2 started Interface detached successfully <address type='pci' domain='0x0000' bus='0x00' slot='0x06' function='0x0'/> </controller> <interface type='network'> <mac address='52:54:00:98:c4:a0'/> <source network='default' bridge='virbr0'/> <target dev='vnet0'/> <model type='rtl8139'/> <alias name='net0'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/> </interface> When I detach after the vm boot, expand the sleep time to 10, it will succeed. # virsh destroy rhel7.2; virsh start rhel7.2 ;sleep 10; virsh detach-interface rhel7.2 network 52:54:00:98:c4:a0; sleep 2; virsh dumpxml rhel7.2 |grep /interface -B9 Domain rhel7.2 destroyed Domain rhel7.2 started Interface detached successfully ------- Best Regards, Yalan Zhang IRC: yalzhang Internal phone: 8389413
On 09/04/2017 03:37 AM, Yalan Zhang wrote:
Hi guys,
when I detach an interface from vm during boot (vm boot not finished), it always fail. I'm not sure if there is an existing bug. I have confirmed with someone that for disk, there is similar behavior, if this is also acceptable?
unplugging a PCI device properly requires cooperation from the guest OS. If the guest OS isn't running yet, the unplug won't complete, so qemu (and libvirt) still show the device as plugged into the guest. virsh reports success on the unplug because unplugging a device is done asynchronously - the "success" means "libvirt successfully told qemu to unplug the device, qemu has told the virtual machine to unplug the device, and is waiting for acknowledgment from the virtual machine that the guest has completed removal". At some later time the guest OS may complete its part of the unplug; when that happens, qemu will get a notification and will send an event to libvirt - at that time the device will be removed from libvirt's list of devices. tl;dr - this is all expected.
# virsh destroy rhel7.2; virsh start rhel7.2 ;sleep 2; virsh detach-interface rhel7.2 network 52:54:00:98:c4:a0; sleep 2; virsh dumpxml rhel7.2 |grep /interface -B9 Domain rhel7.2 destroyed
Domain rhel7.2 started
Interface detached successfully
<address type='pci' domain='0x0000' bus='0x00' slot='0x06' function='0x0'/> </controller> <interface type='network'> <mac address='52:54:00:98:c4:a0'/> <source network='default' bridge='virbr0'/> <target dev='vnet0'/> <model type='rtl8139'/> <alias name='net0'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/> </interface>
When I detach after the vm boot, expand the sleep time to 10, it will succeed.
# virsh destroy rhel7.2; virsh start rhel7.2 ;sleep 10; virsh detach-interface rhel7.2 network 52:54:00:98:c4:a0; sleep 2; virsh dumpxml rhel7.2 |grep /interface -B9 Domain rhel7.2 destroyed
Domain rhel7.2 started
Interface detached successfully
------- Best Regards, Yalan Zhang IRC: yalzhang Internal phone: 8389413
_______________________________________________ libvirt-users mailing list libvirt-users@redhat.com https://www.redhat.com/mailman/listinfo/libvirt-users
Hi Laine, As for the hot-unplug behavior, I have one more question about it, could you please help to confirm? unplugging a PCI device properly requires cooperation from the guest OS.
If the guest OS isn't running yet, the unplug won't complete, so qemu (and libvirt) still show the device as plugged into the guest.
virsh reports success on the unplug because unplugging a device is done asynchronously - the "success" means "libvirt successfully told qemu to unplug the device, qemu has told the virtual machine to unplug the device, and is waiting for acknowledgment from the virtual machine that the guest has completed removal". At some later time the guest OS may complete its part of the unplug; when that happens, qemu will get a notification and will send an event to libvirt - at that time the device will be removed from libvirt's list of devices.
tl;dr - this is all expected.
The question is that, when I unplug it during boot, the virsh cmd will succeed but the interface still exists, which is expected. After the vm boot successfully, the guest OS will *not* complete this removal. When I tried to detach it again, it reported that the device was in the process of unplugging. Is this acceptable? # virsh detach-interface rhel_new network 52:54:00:36:a8:d4 Interface detached successfully # virsh domiflist rhel_new Interface Type Source Model MAC ------------------------------------------------------------- vnet4 network default virtio 52:54:00:36:a8:d4 # virsh detach-interface rhel_new network 52:54:00:36:a8:d4 error: Failed to detach interface error: internal error: unable to execute QEMU command 'device_del': Device net0 is already in the process of unplug Thank you! Yalan On Thu, Sep 14, 2017 at 12:48 AM Laine Stump <laine@laine.org> wrote:
On 09/04/2017 03:37 AM, Yalan Zhang wrote:
Hi guys,
when I detach an interface from vm during boot (vm boot not finished), it always fail. I'm not sure if there is an existing bug. I have confirmed with someone that for disk, there is similar behavior, if this is also acceptable?
unplugging a PCI device properly requires cooperation from the guest OS. If the guest OS isn't running yet, the unplug won't complete, so qemu (and libvirt) still show the device as plugged into the guest.
virsh reports success on the unplug because unplugging a device is done asynchronously - the "success" means "libvirt successfully told qemu to unplug the device, qemu has told the virtual machine to unplug the device, and is waiting for acknowledgment from the virtual machine that the guest has completed removal". At some later time the guest OS may complete its part of the unplug; when that happens, qemu will get a notification and will send an event to libvirt - at that time the device will be removed from libvirt's list of devices.
tl;dr - this is all expected.
# virsh destroy rhel7.2; virsh start rhel7.2 ;sleep 2; virsh detach-interface rhel7.2 network 52:54:00:98:c4:a0; sleep 2; virsh dumpxml rhel7.2 |grep /interface -B9 Domain rhel7.2 destroyed
Domain rhel7.2 started
Interface detached successfully
<address type='pci' domain='0x0000' bus='0x00' slot='0x06' function='0x0'/> </controller> <interface type='network'> <mac address='52:54:00:98:c4:a0'/> <source network='default' bridge='virbr0'/> <target dev='vnet0'/> <model type='rtl8139'/> <alias name='net0'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/> </interface>
When I detach after the vm boot, expand the sleep time to 10, it will
succeed.
# virsh destroy rhel7.2; virsh start rhel7.2 ;sleep 10; virsh detach-interface rhel7.2 network 52:54:00:98:c4:a0; sleep 2; virsh dumpxml rhel7.2 |grep /interface -B9 Domain rhel7.2 destroyed
Domain rhel7.2 started
Interface detached successfully
------- Best Regards, Yalan Zhang IRC: yalzhang Internal phone: 8389413
_______________________________________________ libvirt-users mailing list libvirt-users@redhat.com https://www.redhat.com/mailman/listinfo/libvirt-users
On Thu, Sep 08, 2022 at 15:16:56 +0800, Yalan Zhang wrote:
Hi Laine,
As for the hot-unplug behavior, I have one more question about it, could you please help to confirm?
unplugging a PCI device properly requires cooperation from the guest OS.
If the guest OS isn't running yet, the unplug won't complete, so qemu (and libvirt) still show the device as plugged into the guest.
virsh reports success on the unplug because unplugging a device is done asynchronously - the "success" means "libvirt successfully told qemu to unplug the device, qemu has told the virtual machine to unplug the device, and is waiting for acknowledgment from the virtual machine that the guest has completed removal". At some later time the guest OS may complete its part of the unplug; when that happens, qemu will get a notification and will send an event to libvirt - at that time the device will be removed from libvirt's list of devices.
tl;dr - this is all expected.
The question is that, when I unplug it during boot, the virsh cmd will succeed but the interface still exists, which is expected. After the vm boot successfully, the guest OS will *not* complete this removal. When I tried to detach it again, it reported that the device was in the process of unplugging. Is this acceptable?
# virsh detach-interface rhel_new network 52:54:00:36:a8:d4 Interface detached successfully # virsh domiflist rhel_new Interface Type Source Model MAC ------------------------------------------------------------- vnet4 network default virtio 52:54:00:36:a8:d4
# virsh detach-interface rhel_new network 52:54:00:36:a8:d4 error: Failed to detach interface error: internal error: unable to execute QEMU command 'device_del': Device net0 is already in the process of unplug
The same problem was already reported for disks: https://bugzilla.redhat.com/show_bug.cgi?id=2087047 https://gitlab.com/libvirt/libvirt/-/issues/309 The main problem is that qemu doesn't re-send the request to unplug the device and rather reprots an eroror. At the same time the guest OS doesn't notice it any more, so the unplug can't be finished until the VM is rebooted.
Hi Peter, Thank you for pointing that out, I will track the issue on that bug instead. Yalan On Thu, Sep 8, 2022 at 3:58 PM Peter Krempa <pkrempa@redhat.com> wrote:
On Thu, Sep 08, 2022 at 15:16:56 +0800, Yalan Zhang wrote:
Hi Laine,
As for the hot-unplug behavior, I have one more question about it, could you please help to confirm?
unplugging a PCI device properly requires cooperation from the guest OS.
If the guest OS isn't running yet, the unplug won't complete, so qemu (and libvirt) still show the device as plugged into the guest.
virsh reports success on the unplug because unplugging a device is done asynchronously - the "success" means "libvirt successfully told qemu to unplug the device, qemu has told the virtual machine to unplug the device, and is waiting for acknowledgment from the virtual machine that the guest has completed removal". At some later time the guest OS may complete its part of the unplug; when that happens, qemu will get a notification and will send an event to libvirt - at that time the device will be removed from libvirt's list of devices.
tl;dr - this is all expected.
The question is that, when I unplug it during boot, the virsh cmd will succeed but the interface still exists, which is expected. After the vm boot successfully, the guest OS will *not* complete this removal. When I tried to detach it again, it reported that the device was in the process of unplugging. Is this acceptable?
# virsh detach-interface rhel_new network 52:54:00:36:a8:d4 Interface detached successfully # virsh domiflist rhel_new Interface Type Source Model MAC ------------------------------------------------------------- vnet4 network default virtio 52:54:00:36:a8:d4
# virsh detach-interface rhel_new network 52:54:00:36:a8:d4 error: Failed to detach interface error: internal error: unable to execute QEMU command 'device_del': Device net0 is already in the process of unplug
The same problem was already reported for disks:
https://bugzilla.redhat.com/show_bug.cgi?id=2087047
https://gitlab.com/libvirt/libvirt/-/issues/309
The main problem is that qemu doesn't re-send the request to unplug the device and rather reprots an eroror. At the same time the guest OS doesn't notice it any more, so the unplug can't be finished until the VM is rebooted.
participants (3)
-
Laine Stump -
Peter Krempa -
Yalan Zhang