Snapshot created with 6.2.0 cannot be loaded with 7.0.0-rc1

Host environment

• Operating system: Proxmox VE 7.1 (but using upstream QEMU builds throughout this report)
• OS/kernel version: Linux pve701 5.13.19-6-pve #1 SMP PVE 5.13.19-14 (Thu, 10 Mar 2022 16:24:52 +0100) x86_64 GNU/Linux
• Architecture: x86
• QEMU flavor: qemu-system-x86_64
• QEMU version: QEMU emulator version 6.2.91 (v7.0.0-rc1)
• QEMU command line when creating the snapshot:

  ./qemu-system-x86_64 -chardev 'socket,id=qmp,path=/var/run/qemu-server/140.qmp,server=on,wait=off' -mon 'chardev=qmp,mode=control' -pidfile /var/run/qemu-server/140.pid -m 512 -device 'virtio-scsi-pci,id=scsihw0,bus=pci.0,addr=0x5' -drive 'file=/var/lib/vz/images/140/vm-140-disk-0.qcow2,if=none,id=drive-scsi0,format=qcow2,node-name=scsi0' -device 'scsi-hd,bus=scsihw0.0,channel=0,scsi-id=0,lun=0,drive=drive-scsi0,id=scsi0' -machine 'type=pc-i440fx-6.2'

• QEMU command line when loading the snapshot:

  ./qemu-system-x86_64 -chardev 'socket,id=qmp,path=/var/run/qemu-server/140.qmp,server=on,wait=off' -mon 'chardev=qmp,mode=control' -pidfile /var/run/qemu-server/140.pid -m 512 -device 'virtio-scsi-pci,id=scsihw0,bus=pci.0,addr=0x5' -drive 'file=/var/lib/vz/images/140/vm-140-disk-0.qcow2,if=none,id=drive-scsi0,format=qcow2,node-name=scsi0' -device 'scsi-hd,bus=scsihw0.0,channel=0,scsi-id=0,lun=0,drive=drive-scsi0,id=scsi0' -machine 'type=pc-i440fx-6.2' -loadvm takenwith620

Description of problem

Loading the snapshot will fail with:

qemu-system-x86_64: Missing section footer for 0000:00:01.3/piix4_pm
qemu-system-x86_64: Error -22 while loading VM state

Steps to reproduce

1. Start VM with 6.2.0.
2. Create a snapshot takenwith620 with snapshot-save QMP command.
3. Stop VM and try to load snapshot with v7.0.0-rc1.

Additional information

Bisecting led to 5ead62185d ("memory: Make memory_region_is_mapped() succeed when mapped via an alias"), but reverting that alone wasn't enough, so I continued and got to 7c0fa8dff8 ("pcie: Add support for Single Root I/O Virtualization (SR/IOV)"). Only reverting both seems to fix the issue.