Re: getting the console output for s390 cdrom-test?

[Thomas Huth <thuth@redhat.com>]

On 08/02/2021 11.27, Peter Maydell wrote:
> On Thu, 4 Feb 2021 at 16:08, Thomas Huth <thuth@redhat.com> wrote:
>>
>> On 22/01/2021 21.32, Peter Maydell wrote:
>>> Hi; I've been looking at why the s390 cdrom test has an intermittent
>>> failure on my aarch64 box. Looking at some TCG debug log output
>>> I think what is happening is that sometimes execution diverges from
>>> a successful run inside virtio_scsi_setup() and we end up failing
>>> a vs_assert(), which triggers a "Guest crashed on cpu 0: disabled-wait"
>>> which then makes the qtest hang until its timeout.
>>>
>>> I think that vs_assert() ought to be printing some information
>>> to the console about which assert fails when it happens, but
>>> how do I need to tweak the qtest to get it to capture this
>>> console log somewhere?
>>
>>    Hi!
>>
>> Sorry for the late reply ... did you get any further with this already?
> 
> No, I've been mostly working on other stuff. Thanks for the instructions
> on how to capture stdio. This is what a success looks like:
> 
> LOADPARM=[        ]
> Using virtio-scsi.
> Warning: Could not locate a usable virtio-scsi device
> Using virtio-blk.
> Using guessed DASD geometry.
> Using ECKD scheme (block size  4096), CDL
> No zIPL section in IPL2 record.
> zIPL load failed.
> Using virtio-blk.
> ISO boot image size verified
> 
> And this is a failure:
> 
> LOADPARM=[        ]
> Using virtio-scsi.
> target: 0x0000000000000094
> 
> ! SCSI cannot report LUNs: response VS RESP=09 !

Looks like the SCSI controller returned VIRTIO_SCSI_S_FAILURE instead of the 
expected VIRTIO_SCSI_S_BAD_TARGET here (see virtio_scsi_locate_device() in 
pc-bios/s390-ccw/virtio-scsi.c).

The question is: How could that happen? If I get hw/scsi/virtio-scsi.c 
right, this is only set by virtio_scsi_fail_cmd_req(), i.e. it only happens 
if virtio_scsi_parse_req() returned -ENOTSUP ... which indicates that there 
was something wrong with the VirtIOSCSIReq request?

Could you maybe try to add some debug printfs to virtio_scsi_parse_req() in 
hw/scsi/virtio-scsi.c and/or to scsi_report_luns() / vs_run() in 
pc-bios/s390-ccw/virtio-scsi.c to see whether there is something obviously 
wrong in the request?

  Thomas