Description of problem:
can not see seabios GUI when boot with 240 "-device xio3130-downstream" via PCIe-switch.
Also test with 239 "-device xio3130-downstream", not hit this issue.

Version-Release number of selected component (if applicable):
qemu-kvm-rhev-2.3.0-22.el7.x86_64
kernel-3.10.0-313.el7.x86_64
seabios-bin-1.7.5-11.el7.noarch

How reproducible:
100%

Steps to Reproduce:
1. boot guest with 240 "-device xio3130-downstream"
# sh multi-pcie.sh 240
# cat multi-pcie.sh
#!/bin/sh

MACHINE=q35
SMP=4,cores=2,threads=2,sockets=1
MEM=4G
GUEST_IMG=/mnt/rhel7.2.qcow2_bak
IMG_FORMAT=qcow2

CLI="/usr/libexec/qemu-kvm -enable-kvm -M $MACHINE -smp $SMP -m $MEM -name vm1 -drive file=$GUEST_IMG,if=none,id=guest-img,format=$IMG_FORMAT,werror=stop,rerror=stop -device ide-hd,drive=guest-img,bus=ide.0,unit=0,id=os-disk,bootindex=1 -spice port=5932,disable-ticketing -vga qxl  -monitor stdio -qmp tcp:0:6666,server,nowait -boot menu=on -chardev file,path=/home/seabios.log,id=seabios -device isa-debugcon,chardev=seabios,iobase=0x402"

while [ ${i:=0} -lt ${1:-0} ]
do
    dstreamId=$((i))
    ustreamId=$((dstreamId/32))
    chassisId=$((dstreamId+1))
    blkDiskId=$((dstreamId))

    if [ $((dstreamId%32)) -eq 0 ]
    then
        CLI="$CLI -device ioh3420,bus=pcie.0,id=root.$ustreamId,slot=$ustreamId"
        CLI="$CLI -device x3130-upstream,bus=root.$ustreamId,id=upstream$ustreamId"
    fi

    CLI="$CLI -device xio3130-downstream,bus=upstream$ustreamId,id=downstream$dstreamId,chassis=$chassisId"
    i=$((i+1))
done

$CLI

2.
3.

Actual results:
Can not see seabios GUI via remoteview spice://$IP:$port
Using isa-debugcon debug, got the following messages:
SeaBIOS (version seabios-1.7.5-11.el7)
Running on QEMU (q35)
Running on KVM
RamSize: 0x80000000 [cmos]
Relocating init from 0x000e3f59 to 0x7ffb1cd0 (size 57960)
Found QEMU fw_cfg
RamBlock: addr 0x0000000000000000 len 0x0000000080000000 [e820]
RamBlock: addr 0x0000000100000000 len 0x0000000080000000 [e820]
Moving pm_base to 0x600
boot order:
1: /pci@i0cf8/pci8086,2922@1f,2/drive@0/disk@0
CPU Mhz=3396
=== PCI bus & bridge init ===
PCI: pci_bios_init_bus_rec bus = 0x0
PCI: pci_bios_init_bus_rec bdf = 0x18
PCI: primary bus = 0x0
PCI: secondary bus = 0xff -> 0x1
PCI: pci_bios_init_bus_rec bus = 0x1
PCI: pci_bios_init_bus_rec bdf = 0x100
PCI: primary bus = 0x0 -> 0x1
PCI: secondary bus = 0xff -> 0x2
PCI: pci_bios_init_bus_rec bus = 0x2
PCI: pci_bios_init_bus_rec bdf = 0x200
PCI: primary bus = 0x0 -> 0x2
PCI: secondary bus = 0xff -> 0x3
PCI: pci_bios_init_bus_rec bus = 0x3
PCI: subordinate bus = 0x0 -> 0x3
PCI: pci_bios_init_bus_rec bdf = 0x208
PCI: primary bus = 0x0 -> 0x2
PCI: secondary bus = 0xff -> 0x4
PCI: pci_bios_init_bus_rec bus = 0x4
PCI: subordinate bus = 0x0 -> 0x4
PCI: pci_bios_init_bus_rec bdf = 0x210
PCI: primary bus = 0x0 -> 0x2
PCI: secondary bus = 0xff -> 0x5
PCI: pci_bios_init_bus_rec bus = 0x5
PCI: subordinate bus = 0x0 -> 0x5
PCI: pci_bios_init_bus_rec bdf = 0x218
PCI: primary bus = 0x0 -> 0x2
PCI: secondary bus = 0xff -> 0x6
PCI: pci_bios_init_bus_rec bus = 0x6
PCI: subordinate bus = 0x0 -> 0x6
PCI: pci_bios_init_bus_rec bdf = 0x220
PCI: primary bus = 0x0 -> 0x2
PCI: secondary bus = 0xff -> 0x7
PCI: pci_bios_init_bus_rec bus = 0x7
PCI: subordinate bus = 0x0 -> 0x7
PCI: pci_bios_init_bus_rec bdf = 0x228
PCI: primary bus = 0x0 -> 0x2
PCI: secondary bus = 0xff -> 0x8
... ...

Expected results:
can see the seabio GUI and boot guest correctly.

Additional info: