device virtio-net-device hangs machine type microvm with qemu 9+

[Emile iMil Heitor]

Hi,

I'm using the microvm machine type this way:

qemu-system-x86_64 -M microvm,x-option-roms=off,rtc=on,acpi=off,pic=off,accel=kvm -cpu 
host,+invtsc -kernel netbsd-SMOL -append "console=com root=ld0a -z" -global 
virtio-mmio.force-legacy=false -device virtio-blk-device,drive=hdc3d5b19b0,share-rw=on 
-drive if=none,file=bozohttpd-amd64.img,format=raw,id=hdc3d5b19b0 -device 
virtio-net-device,netdev=netc3d5b19b0 -netdev user,id=netc3d5b19b0,hostfwd=::4280-:80 
-display none -serial mon:stdio -pidfile qemu-bozohttpd.pid

This worked well with qemu < 9, but with qemu 9+ it hangs at start
and outputs nothing.
strace(1) output:

ppoll([{fd=4, events=POLLIN}, {fd=6, events=POLLIN}, {fd=8, events=POLLIN}, {fd=9, events=POLLIN}], 4, {tv_sec=0, tv_nsec=26809377}, 
NULL, 8) = 0 (Timeout)
ppoll([{fd=4, events=POLLIN}, {fd=6, events=POLLIN}, {fd=8, events=POLLIN}, {fd=9, events=POLLIN}], 4, {tv_sec=0, tv_nsec=26809377}, 
NULL, 8) = 0 (Timeout)
ppoll([{fd=4, events=POLLIN}, {fd=6, events=POLLIN}, {fd=8, events=POLLIN}, {fd=9, events=POLLIN}], 4, {tv_sec=0, tv_nsec=26809377}, 
NULL, 8) = 0 (Timeout)
ppoll([{fd=4, events=POLLIN}, {fd=6, events=POLLIN}, {fd=8, events=POLLIN}, {fd=9, events=POLLIN}], 4, {tv_sec=0, tv_nsec=26809377}, 
NULL, 8) = 0 (Timeout)
ppoll([{fd=4, events=POLLIN}, {fd=6, events=POLLIN}, {fd=8, events=POLLIN}, {fd=9, events=POLLIN}], 4, {tv_sec=0, tv_nsec=26809377}, 
NULL, 8) = 0 (Timeout)
[continues]

Without -device virtio-net-device, the vm boots with no issues.
FWIW I also tried with a Linux kernel and the behaviour is the same.

I reproduced this with qemu 9.0.0, 9.1.1 and current.
It boots as expected in 8.2.7.

build:
$ ./configure --disable-docs --target-list=x86_64-softmmu --enable-debug 
--enable-slirp --enable-virtfs

Any hint?

Thanks,

------------------------------------------------------------------------
Emile `iMil' Heitor <imil@{home.imil.net,NetBSD.org}> | https://imil.net