Re: [PULL 03/23] hw/net/virtio-net: make VirtIONet.vlans an array instead of a pointer

[Fiona Ebner <f.ebner@proxmox.com>]

Hi,

Am 28.10.25 um 11:19 AM schrieb Philippe Mathieu-Daudé:
> From: Michael Tokarev <mjt@tls.msk.ru>
> 
> This field is a fixed-size buffer (number of elements is MAX_VLAN,
> known at build time).  There's no need to allocate it dynamically,
> it can be made an integral part of VirtIONet structure.
> 
> This field is the only user of VMSTATE_BUFFER_POINTER_UNSAFE() macro.
> 
> Reviewed-by: Akihiko Odaki <odaki@rsg.ci.i.u-tokyo.ac.jp>
> Tested-by: Lei Yang <leiyang@redhat.com>
> Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
> Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
> Message-ID: <20251023135316.31128-2-mjt@tls.msk.ru>
> Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>

unfortunately, after this commit, loading a VM state taken with v10.1.2
or older doesn't work anymore:

> qemu-system-x86_64: Missing section footer for 0000:00:13.0/virtio-net
> qemu-system-x86_64: Section footer error, section_id: 41

Reproducer below [0].


Reverting

> 58341158d0 migration/vmstate: remove VMSTATE_BUFFER_POINTER_UNSAFE macro
> 3a9cd2a4a1 hw/net/virtio-net: make VirtIONet.vlans an array instead of a pointer

in current master makes it work again.


I'm also seeing the following when a guest is actually running:

> kvm: VQ 1 size 0x100 < last_avail_idx 0x9 - used_idx 0x3e30
> kvm: load of migration failed: Operation not permitted: error while loading state for instance 0x0 of device '0000:00:13.0/virtio-net': Failed to load element of type virtio for virtio: -1

and here too a revert of the two commits seems to help :)


Best Regards,
Fiona


[0]:

> [I] root@pve9a1 ~# cat snapshot-virtio-net.sh
> #!/bin/bash
> rm /tmp/disk.qcow2
> args="
>   -netdev type=tap,id=net1,ifname=tap104i1,script=/usr/libexec/qemu-server/pve-bridge,downscript=/usr/libexec/qemu-server/pve-bridgedown,vhost=on
>   -device virtio-net-pci,mac=BC:24:11:32:3C:69,netdev=net1,bus=pci.0,addr=0x13,id=net1
>   -machine type=pc-i440fx-10.1
> "
> $1/qemu-img create -f qcow2 /tmp/disk.qcow2 1G
> $1/qemu-system-x86_64 --qmp stdio --blockdev qcow2,node-name=node0,file.driver=file,file.filename=/tmp/disk.qcow2 $args <<EOF
> {"execute": "qmp_capabilities"}
> {"execute": "snapshot-save", "arguments": { "job-id": "save0", "tag": "snap", "vmstate": "node0", "devices": ["node0"] } }
> {"execute": "quit"}
> EOF
> $2/qemu-system-x86_64 --qmp stdio --blockdev qcow2,node-name=node0,file.driver=file,file.filename=/tmp/disk.qcow2 $args -loadvm snap