Re: [qemu-s390x] [PATCH for-2.11] pc-bios/s390-ccw: Fix problem with invalid virtio-scsi LUN when rebooting

[Christian Borntraeger]

Thomas,

does this patch help as well?

diff --git a/pc-bios/s390-ccw/Makefile b/pc-bios/s390-ccw/Makefile
index 6d0c2ee..2687590 100644
--- a/pc-bios/s390-ccw/Makefile
+++ b/pc-bios/s390-ccw/Makefile
@@ -12,7 +12,7 @@ $(call set-vpath, $(SRC_PATH)/pc-bios/s390-ccw)
 OBJECTS = start.o main.o bootmap.o sclp.o virtio.o virtio-scsi.o 
virtio-blkdev.o
 QEMU_CFLAGS := $(filter -W%, $(QEMU_CFLAGS))
 QEMU_CFLAGS += -ffreestanding -fno-delete-null-pointer-checks -msoft-float
-QEMU_CFLAGS += -march=z900 -fPIE -fno-strict-aliasing
+QEMU_CFLAGS += -march=z900 -fPIE -fno-strict-aliasing 
-fno-zero-initialized-in-bss
 QEMU_CFLAGS += $(call cc-option, $(QEMU_CFLAGS), -fno-stack-protector)
 LDFLAGS += -Wl,-pie -nostdlib
 



On 11/17/2017 07:45 PM, Christian Borntraeger wrote:
> 
> 
> On 11/17/2017 07:10 PM, Thomas Huth wrote:
>> When rebooting a guest that has a virtio-scsi disk, the s390-ccw
>> bios sometimes bails out with an error message like this:
>>
>> ! SCSI cannot report LUNs: STATUS=02 RSPN=70 KEY=05 CODE=25 QLFR=00, sure !
>>
>> Enabling the scsi_req* tracing in QEMU shows that the ccw bios is
>> trying to execute the REPORT LUNS SCSI command with a LUN != 0, and
>> this causes the SCSI command to fail.
>> Looks like we neither clear the BSS of the s390-ccw bios during reboot,
>> nor do we explicitly set the default_scsi_device.lun value to 0, so
>> this variable can contain random values from the OS after the reboot.
>> By setting this variable explicitly to 0, the problem is fixed and
>> the reboots always succeed.
>>
>> Buglink: https://bugzilla.redhat.com/show_bug.cgi?id=1514352
>> Signed-off-by: Thomas Huth <address@hidden>
> 
> Acked-by: Christian Borntraeger <address@hidden>
> 
> We had these things multile times in the past. The QEMU elf loader does not
> zero the BSS (it just loads the load section).  Hmm, what about letting the 
> BIOS zero its bss itself. IIRC the kernel does the same thing. I will have a
> look into that for 2.12.
> 
> PS: Please do not forget to rebuild the bios
>> ---
>>  pc-bios/s390-ccw/virtio-scsi.c | 3 ++-
>>  1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/pc-bios/s390-ccw/virtio-scsi.c b/pc-bios/s390-ccw/virtio-scsi.c
>> index c92f5d3..4fe4b9d 100644
>> --- a/pc-bios/s390-ccw/virtio-scsi.c
>> +++ b/pc-bios/s390-ccw/virtio-scsi.c
>> @@ -223,7 +223,8 @@ static void virtio_scsi_locate_device(VDev *vdev)
>>
>>      for (target = 0; target <= vdev->config.scsi.max_target; target++) {
>>          sdev->channel = channel;
>> -        sdev->target = target; /* sdev->lun will be 0 here */
>> +        sdev->target = target;
>> +        sdev->lun = 0;          /* LUN has to be 0 for REPORT LUNS */
>>          if (!scsi_report_luns(vdev, data, sizeof(data))) {
>>              if (resp.response == VIRTIO_SCSI_S_BAD_TARGET) {
>>                  continue;
>>
> 
>