Created attachment 1270361 [details]
Device Manager

Description of problem:
  The hotplugged virtio-blk-pci disk attached to a pci bridge disapears after hotplugging a virtio-scsi-pci device to another parallel pci bridge in Windows 10 guest.

Version-Release number of selected component (if applicable):
Host:
# rpm -q qemu-kvm-rhev
qemu-kvm-rhev-2.9.0-0.el7.patchwork201703291116.x86_64
# uname -r
3.10.0-635.el7.x86_64
Guest:
Windows 10 x64

How reproducible:
5/5

Steps to Reproduce:
1.Boot a guest with 8 pci-bridges:
/usr/libexec/qemu-kvm \
 -machine pc \
 -m 4096 \
 -smp 2,maxcpus=2,sockets=1,cores=2,threads=1 \
 -cpu SandyBridge,enforce \
 -rtc base=localtime,clock=host,driftfix=slew \
 -nodefaults \
 -device AC97 \
 -vga qxl \
 -chardev socket,id=seabioslog_log,path=/tmp/seabios-log,server,nowait \
 -device isa-debugcon,chardev=seabioslog_log,iobase=0x402 \
 -device usb-ehci,id=usb1 \
 -device usb-tablet,id=usb-tablet1 \
 -boot menu=on \
 -enable-kvm \
 -monitor stdio \
 -spice port=5900,disable-ticketing \
 -qmp tcp:0:9999,server,nowait \
 -drive file=/mnt/virtio-win-prewhql-0.1-135.iso,id=drive_cd,format=raw,if=none,cache=none,media=cdrom,readonly=on \
 -device ide-cd,drive=drive_cd,id=device_cd \
 -drive file=/mnt/win10-64-virtio.qcow2,format=qcow2,id=drive_sysdisk,if=none,cache=none,aio=native,werror=stop,rerror=stop \
 -device virtio-blk-pci,drive=drive_sysdisk,id=device_sysdisk,bootindex=0 \
 -device pci-bridge,id=bridge1,chassis_nr=1 \
 -device pci-bridge,id=bridge2,chassis_nr=2 \
 -device pci-bridge,id=bridge3,chassis_nr=3 \
 -device pci-bridge,id=bridge4,chassis_nr=4 \
 -device pci-bridge,id=bridge5,chassis_nr=5 \
 -device pci-bridge,id=bridge6,chassis_nr=6 \
 -device pci-bridge,id=bridge7,chassis_nr=7 \
 -device pci-bridge,id=bridge8,chassis_nr=8 \

2.Hotplug a virtio-blk-pci disk attached to bridge1:
{"execute":"__com.redhat_drive_add","arguments":{"file":"/mnt/blk5.qcow2","format":"qcow2","id":"drive_blk"}}
{"return":{}}
{"execute":"device_add","arguments":{"driver":"virtio-blk-pci","drive":"drive_blk","id":"device_blk","bus":"bridge1","addr":0}}
{"return":{}}

3.Hotplug a scsi disk attached to bridge2:
{"execute":"device_add","arguments":{"driver":"virtio-scsi-pci","id":"scsi1","bus":"bridge2","addr":1}}
{"return":{}}
{"execute":"__com.redhat_drive_add","arguments":{"file":"/mnt/scsi6.qcow2","format":"qcow2","id":"drive_scsi"}}
{"return":{}}
{"execute":"device_add","arguments":{"driver":"scsi-hd","drive":"drive_scsi","id":"device_scsi","bus":"scsi1.0"}}
{"return":{}}

Actual results:
The hotplugged virtio-blk-pci disk disappears after hotplugging virtio-scsi-pci device to bridge2.
{"execute":"device_add","arguments":{"driver":"virtio-scsi-pci","id":"scsi1","bus":"bridge2","addr":1}}

Expected results:
The hotplugged virtio-blk-pci disk should not be interfered by step 3.

Additional info:
1.Cannot be reproduced with qemu-kvm-rhev-2.8.0-6.el7.x86_64.

2.The screenshot of Device Manager is as attachment.

3.Cannot be reproduced with reverse hotplug order blew:
{"execute":"device_add","arguments":{"driver":"virtio-scsi-pci","id":"scsi1","bus":"bridge2","addr":1}}
{"return":{}}
{"execute":"__com.redhat_drive_add","arguments":{"file":"/mnt/scsi6.qcow2","format":"qcow2","id":"drive_scsi"}}
{"return":{}}
{"execute":"device_add","arguments":{"driver":"scsi-hd","drive":"drive_scsi","id":"device_scsi","bus":"scsi1.0"}}
{"return":{}}
{"execute":"__com.redhat_drive_add","arguments":{"file":"/mnt/blk5.qcow2","format":"qcow2","id":"drive_blk"}}
{"return":{}}
{"execute":"device_add","arguments":{"driver":"virtio-blk-pci","drive":"drive_blk","id":"device_blk","bus":"bridge1","addr":0}}
{"return":{}}