Re: [Qemu-devel] [PATCH] cpus: Fix event order on resume of stopped guest

[Kevin Wolf <kwolf@redhat.com>]

Am 23.04.2018 um 10:45 hat Markus Armbruster geschrieben:
> When resume of a stopped guest immediately runs into block device
> errors, the BLOCK_IO_ERROR event is sent before the RESUME event.
> 
> Reproducer:
> 
> 1. Create a scratch image
>    $ dd if=/dev/zero of=scratch.img bs=1M count=100
> 
>    Size doesn't actually matter.
> 
> 2. Prepare blkdebug configuration:
> 
>    $ cat >blkdebug.conf <<EOF
>    [inject-error]
>    event = "write_aio"
>    errno = "5"
>    EOF
> 
>    Note that errno 5 is EIO.
> 
> 3. Run a guest with an additional scratch disk, i.e. with additional
>    arguments
>    -drive if=none,id=scratch-drive,format=raw,werror=stop,file=blkdebug:blkdebug.conf:scratch.img
>    -device virtio-blk-pci,id=scratch,drive=scratch-drive
> 
>    The blkdebug part makes all writes to the scratch drive fail with
>    EIO.  The werror=stop pauses the guest on write errors.
> 
> 4. Connect to the QMP socket e.g. like this:
>    $ socat UNIX:/your/qmp/socket READLINE,history=$HOME/.qmp_history,prompt='QMP> '
> 
>    Issue QMP command 'qmp_capabilities':
>    QMP> { "execute": "qmp_capabilities" }
> 
> 5. Boot the guest.
> 
> 6. In the guest, write to the scratch disk, e.g. like this:
> 
>    # dd if=/dev/zero of=/dev/vdb count=1
> 
>    Do double-check the device specified with of= is actually the
>    scratch device!
> 
> 7. Issue QMP command 'cont':
>    QMP> { "execute": "cont" }
> 
> After step 6, I get a BLOCK_IO_ERROR event followed by a STOP event.  Good.
> 
> After step 7, I get BLOCK_IO_ERROR, then RESUME, then STOP.  Not so
> good; I'd expect RESUME, then BLOCK_IO_ERROR, then STOP.

Do you want to rephrase this in the form of a script for qemu-iotests?

I suppose the 'dd' line can be replaced by a 'qemu-io' monitor command.

Kevin