Guests wont start with 15 pcie-root-port devices

[Brian Rak]

In 6.1, a guest with 15 empty pcie-root-port devices will not boot 
properly - it just hangs on "Guest has not initialized the display 
(yet).".  As soon as I remove the last pcie-root-port, the guest begins 
starting up normally.  My qemu command line:

/usr/libexec/qemu-kvm -name guest=xxx,debug-threads=on -S -object 
{"qom-type":"secret","id":"masterKey0","format":"raw","file":"/var/lib/libvirt/qemu/domain-29-xxx/master-key.aes"} 
-machine 
pc-q35-6.1,accel=kvm,usb=off,dump-guest-core=off,memory-backend=pc.ram 
-cpu Haswell-noTSX-IBRS -m 4096 -object 
{"qom-type":"memory-backend-ram","id":"pc.ram","size":4294967296} 
-overcommit mem-lock=off -smp 2,sockets=2,cores=1,threads=1 -uuid 
daf2c139-4991-4079-9b8a-b4c98fc675e0 -no-user-config -nodefaults 
-chardev socket,id=charmonitor,fd=31,server=on,wait=off -mon 
chardev=charmonitor,id=monitor,mode=control -rtc base=utc -no-shutdown 
-boot strict=on -device 
pcie-root-port,port=0x10,chassis=1,id=pci.1,bus=pcie.0,multifunction=on,addr=0x2 
-device 
pcie-root-port,port=0x11,chassis=2,id=pci.2,bus=pcie.0,addr=0x2.0x1 
-device 
pcie-root-port,port=0x12,chassis=3,id=pci.3,bus=pcie.0,addr=0x2.0x2 
-device 
pcie-root-port,port=0x13,chassis=4,id=pci.4,bus=pcie.0,addr=0x2.0x3 
-device 
pcie-root-port,port=0x14,chassis=5,id=pci.5,bus=pcie.0,addr=0x2.0x4 
-device 
pcie-root-port,port=0x15,chassis=6,id=pci.6,bus=pcie.0,addr=0x2.0x5 
-device 
pcie-root-port,port=0x16,chassis=7,id=pci.7,bus=pcie.0,addr=0x2.0x6 
-device 
pcie-root-port,port=0x17,chassis=8,id=pci.8,bus=pcie.0,addr=0x2.0x7 
-device 
pcie-root-port,port=0x18,chassis=9,id=pci.9,bus=pcie.0,multifunction=on,addr=0x3 
-device 
pcie-root-port,port=0x19,chassis=10,id=pci.10,bus=pcie.0,addr=0x3.0x1 
-device 
pcie-root-port,port=0x1a,chassis=11,id=pci.11,bus=pcie.0,addr=0x3.0x2 
-device 
pcie-root-port,port=0x1b,chassis=12,id=pci.12,bus=pcie.0,addr=0x3.0x3 
-device 
pcie-root-port,port=0x1c,chassis=13,id=pci.13,bus=pcie.0,addr=0x3.0x4 
-device 
pcie-root-port,port=0x1d,chassis=14,id=pci.14,bus=pcie.0,addr=0x3.0x5 
-device 
pcie-root-port,port=0x1e,chassis=15,id=pci.15,bus=pcie.0,addr=0x3.0x6 
-device qemu-xhci,id=usb,bus=pci.1,addr=0x0 -audiodev 
id=audio1,driver=none -vnc 
127.0.0.1:5410,websocket=41310,password=on,audiodev=audio1 -device 
cirrus-vga,id=video0,bus=pcie.0,addr=0x1 -device 
virtio-balloon-pci,id=balloon0,bus=pci.2,addr=0x0 -sandbox 
on,obsolete=deny,elevateprivileges=deny,spawn=deny,resourcecontrol=deny 
-msg timestamp=on

This same guest XML worked properly in 5.2, but I'm not sure if it broke 
in 6.0 or 6.1.  We're adding all these empty root ports so we can 
hotplug devices later without restarting the guest.  Any idea what went 
wrong here?