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

["Philippe Mathieu-Daudé" <philmd@linaro.org>]

Hi Fiona,

On 9/12/25 13:15, Fiona Ebner wrote:
> 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.

Thanks for the report. Commits reverted.

> 
> 
> 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
> 
>