Re: mips system emulation failure with virtio

[Alex Bennée]

Richard Purdie <richard.purdie@linuxfoundation.org> writes:

> With qemu 8.1.0 we see boot hangs fox x86-64 targets. 
>
> These are fixed by 0d58c660689f6da1e3feff8a997014003d928b3b (softmmu:
> Use async_run_on_cpu in tcg_commit) but if I add that commit, mips and
> mips64 break, hanging at boot unable to find a rootfs. 

(Widen CC list)

>
> We use virtio for network and disk and both of those change in the
> bootlog from messages like:
>
> [    1.726118] virtio-pci 0000:00:13.0: enabling device (0000 -> 0003)
> [    1.728864] virtio-pci 0000:00:14.0: enabling device (0000 -> 0003)
> [    1.729948] virtio-pci 0000:00:15.0: enabling device (0000 -> 0003)
> ...
> [    2.162148] virtio_blk virtio2: 1/0/0 default/read/poll queues
> [    2.168311] virtio_blk virtio2: [vda] 1184242 512-byte logical 
>
> to:
>
> [    1.777051] virtio-pci 0000:00:13.0: enabling device (0000 -> 0003)
> [    1.779822] virtio-pci 0000:00:14.0: enabling device (0000 -> 0003)
> [    1.780926] virtio-pci 0000:00:15.0: enabling device (0000 -> 0003)
> ...
> [    1.894852] virtio_rng: probe of virtio1 failed with error -28
> ...
> [    2.063553] virtio_blk virtio2: 1/0/0 default/read/poll queues
> [    2.064260] virtio_blk: probe of virtio2 failed with error -28
> [    2.069080] virtio_net: probe of virtio0 failed with error -28
>
>
> i.e. the virtio drivers no longer work.

Interesting, as you say this seems to be VirtIO specific as the baseline
tests (using IDE) work fine:

  ➜  ./tests/venv/bin/avocado run 
./tests/avocado/tuxrun_baselines.py:test_mips64
  JOB ID     : 71f3e3b7080164b78ef1c8c1bb6bc880932d8c9b
  JOB LOG    : 
/home/alex/avocado/job-results/job-2023-09-05T15.01-71f3e3b/job.log
   (1/2) ./tests/avocado/tuxrun_baselines.py:TuxRunBaselineTest.test_mips64: 
PASS (12.19 s)
   (2/2) ./tests/avocado/tuxrun_baselines.py:TuxRunBaselineTest.test_mips64el: 
PASS (11.78 s)
  RESULTS    : PASS 2 | ERROR 0 | FAIL 0 | SKIP 0 | WARN 0 | INTERRUPT 0 | 
CANCEL 0
  JOB TIME   : 24.79 s

> I tested with current qemu master
> (17780edd81d27fcfdb7a802efc870a99788bd2fc) and mips is still broken
> there.
>
> Is this issue known about?

Could you raise a bug at:

  https://gitlab.com/qemu-project/qemu/-/issues

I'm curious why MIPS VirtIO is affected but nothing else is...

>
> Cheers,
>
> Richard


-- 
Alex Bennée
Virtualisation Tech Lead @ Linaro