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Diffstat (limited to 'results/classifier/accel-gemma3:12b/vmm/1577')
| -rw-r--r-- | results/classifier/accel-gemma3:12b/vmm/1577 | 85 |
1 files changed, 85 insertions, 0 deletions
diff --git a/results/classifier/accel-gemma3:12b/vmm/1577 b/results/classifier/accel-gemma3:12b/vmm/1577 new file mode 100644 index 000000000..5bad61870 --- /dev/null +++ b/results/classifier/accel-gemma3:12b/vmm/1577 @@ -0,0 +1,85 @@ + +device_del return is already in the process of unplug frequently +Description of problem: +recently we update qemu 6.1.1 to qemu 7.1.0, and run into an issue with the following error: + +command '{ "execute": "device_del", "arguments": { "id": "virtio-diskX" } }' for VM "id" failed ({ "return": {"class": "GenericError", "desc": "Device virtio-diskX is already in the process of unplug"} }). + +The issue is reproducible. With a few seconds delay before hot-unplug, hot-unplug just works fine. + +After a few digging, we found that the commit 9323f892b39 may incur the issue. +------------------ + failover: fix unplug pending detection + + Failover needs to detect the end of the PCI unplug to start migration + after the VFIO card has been unplugged. + + To do that, a flag is set in pcie_cap_slot_unplug_request_cb() and reset in + pcie_unplug_device(). + + But since + 17858a169508 ("hw/acpi/ich9: Set ACPI PCI hot-plug as default on Q35") + we have switched to ACPI unplug and these functions are not called anymore + and the flag not set. So failover migration is not able to detect if card + is really unplugged and acts as it's done as soon as it's started. So it + doesn't wait the end of the unplug to start the migration. We don't see any + problem when we test that because ACPI unplug is faster than PCIe native + hotplug and when the migration really starts the unplug operation is + already done. + + See c000a9bd06ea ("pci: mark device having guest unplug request pending") + a99c4da9fc2a ("pci: mark devices partially unplugged") + + Signed-off-by: Laurent Vivier <lvivier@redhat.com> + Reviewed-by: Ani Sinha <ani@anisinha.ca> + Message-Id: <20211118133225.324937-4-lvivier@redhat.com> + Reviewed-by: Michael S. Tsirkin <mst@redhat.com> + Signed-off-by: Michael S. Tsirkin <mst@redhat.com> +------------------ +The purpose is for detecting the end of the PCI device hot-unplug. However, we feel the error confusing. How is it possible that a disk "is already in the process of unplug" during the first hot-unplug attempt? So far as I know, the issue was also encountered by libvirt, but they simply ignored it: + + https://bugzilla.redhat.com/show_bug.cgi?id=1878659 + +Hence, a question is: should we have the line below in acpi_pcihp_device_unplug_request_cb()? + + pdev->qdev.pending_deleted_event = true; + +It would be great if you as the author could give us a few hints. + +Thank you very much for your reply! + +Sincerely, + +Yu Zhang @ Compute Platform IONOS + + +The issue is reproducible in our own stack, which is not quite easy to describe in a few command lines. We simplified it a bit by a script instead. Although it's not able to reproduce, it could be somewhat helpful to understand the issue. + +``` +#!/bin/bash + +HOME=~ +QEMU=$HOME/qemu/bin/qemu-system-x86_64 +DISK1=$HOME/img/disk1.qcow2 +DISK4=$HOME/img/disk4.qcow2 +DISK5=$HOME/img/disk5.qcow2 + +$QEMU \ + -cpu host -enable-kvm -m 2048 -smp 2 \ + -object iothread,id=iothread1 \ + -drive file=$DISK1,if=none,id=drive-virtio-disk1,format=qcow2,snapshot=off,discard=on,cache=none \ + -device virtio-blk-pci,bus=pci.0,addr=0x4,drive=drive-virtio-disk1,iothread=iothread1,num-queues=1,discard=on,id=virtio-disk1 \ + -object iothread,id=iothread4 \ + -drive file=$DISK4,if=none,id=drive-virtio-disk4,format=qcow2,snapshot=off,discard=on,cache=none \ + -device virtio-blk-pci,bus=pci.0,addr=0x5,drive=drive-virtio-disk4,iothread=iothread4,num-queues=1,discard=on,id=virtio-disk4 \ + -object iothread,id=iothread5 \ + -drive file=$DISK5,if=none,id=drive-virtio-disk5,format=qcow2,snapshot=off,discard=on,cache=none \ + -device virtio-blk-pci,bus=pci.0,addr=0x6,drive=drive-virtio-disk5,iothread=iothread5,num-queues=1,discard=on,id=virtio-disk5 \ + -qmp unix:./qmp-sock,server,nowait & + +sleep 5 + +echo '{"execute":"qmp_capabilities"}{"execute": "device_del","arguments": { "id": "virtio-disk5"}}{"execute": "query-block"}' | nc -U -w 1 ./qmp-sock +echo '{"execute":"qmp_capabilities"}{"execute": "device_del","arguments": { "id": "virtio-disk5"}}{"execute": "query-block"}' | nc -U -w 1 ./qmp-sock``` +Additional information: +Possible workaround: https://lore.kernel.org/qemu-devel/20230403131833-mutt-send-email-mst@kernel.org/T/#t |