[Bug 1856834] Re: PCI broken in qemu ppc e500 in v2.12.0 and other versions

[Andrej Krutak]

Not even reverting the patch worked for me, and it's still broken on
qemu 5.1.

For example:

~/OSS/qemu/ppc-softmmu/qemu-system-ppc -machine mpc8544ds -nographic
-cpu e500mc -serial mon:stdio -kernel zImage -initrd rootfs.ird -append
'console=ttyS0,115200' -device e1000,netdev=main -netdev
hubport,hubid=0,id=main -net tap,ifname=tap0 -device virtio-balloon-pci
-device virtio-rng-pci  -device virtio-blk-pci-transitional,drive=drive0
-drive file=disk,if=none,id=drive0,format=raw

causes the linux kernel to freeze after probing the virtio_blk device:

virtio_rng: probe of virtio1 failed with error -22
virtio_blk virtio2: [vda] 131072 512-byte logical blocks (67.1 MB/64.0 MiB)

Not specifying the virtio-blk-pci device makes the system boot, but
still all but the first (e1000) PCI devices seem to not probe.

It seems I can trace this behavior at least to version 2.4.1, probably
even sooner (can't make my linux boot on those, so I'm unsure...).

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https://bugs.launchpad.net/bugs/1856834

Title:
  PCI broken in qemu ppc e500 in v2.12.0 and other versions

Status in QEMU:
  New

Bug description:
  The same qemu -M mpc... command that works on qemu-system-ppc version
  2.8.0 freezes guest on bootup and shows error for qemu-system-ppc
  version 4.2.0release and 4.19dirtygit:

  qemu-system-ppc: virtio-blk failed to set guest notifier (-24), ensure -accel 
kvm is set.
  qemu-system-ppc: virtio_bus_start_ioeventfd: failed. Fallback to userspace 
(slower).

  ends/freezes at:
  nbd: registered device at major 43
   vda:

  I'm using -drive file=/home/me/rawimage.dd,if=virtio and works fine in
  version 2.8.0 installed with apt-get install (Ubuntu 17.04) and also
  with 2.8.0 official release from git/github that I compiled/built
  myself. But both of the newer releases fail on the same exact machine
  same config.

  I also noticed that qemu-2.8.0 was fine with mtd but the newer ones I tried 
weren't, ie gave
  qemu-system-ppc: -drive if=mtd: machine type does not support 
if=mtd,bus=0,unit=0
  (but I removed -drive if=mtd since wasn't using it anyway)

  I also tried on windows but I think virtio doesn't work on windows
  hosts at all? On windows host it fails the same way, even version 2.12
  as well as 4.1.10...

  used:
  ./configure --prefix=/opt/... --enable-fdt --enable-kvm --enable-debug

  (basically all steps the same on same exact system same config, yet
  2.8.0 works fine whether apt-get installed or built from source while
  the others I built, 4.19/4.2.0 or 2.12/4.1.10(win) don't.)

  In case newer qemu versions act weird on various kernels, I did try with both 
vmlinuz-4.10.0-19-generic and vmlinuz-4.13.12-041312-generic (I didn't compile 
them but I can provide config-..files. This is on Ubuntu 17.04 x86_64 host 
emulating e500v2 cpm guest, ie -M mpc... GUEST kernel 2.6.32.44 which is why I 
can't use -M ppce500 instead..)
  tx
       ecs

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