linux/drivers/s390
Cornelia Huck 182f709c5c virtio/s390: implement virtio-ccw revision 2 correctly
CCW_CMD_READ_STATUS was introduced with revision 2 of virtio-ccw,
and drivers should only rely on it being implemented when they
negotiated at least that revision with the device.

However, virtio_ccw_get_status() issued READ_STATUS for any
device operating at least at revision 1. If the device accepts
READ_STATUS regardless of the negotiated revision (which some
implementations like QEMU do, even though the spec currently does
not allow it), everything works as intended. While a device
rejecting the command should also be handled gracefully, we will
not be able to see any changes the device makes to the status,
such as setting NEEDS_RESET or setting the status to zero after
a completed reset.

We negotiated the revision to at most 1, as we never bumped the
maximum revision; let's do that now and properly send READ_STATUS
only if we are operating at least at revision 2.

Cc: stable@vger.kernel.org
Fixes: 7d3ce5ab94 ("virtio/s390: support READ_STATUS command for virtio-ccw")
Reviewed-by: Halil Pasic <pasic@linux.ibm.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Link: https://lore.kernel.org/r/20210216110645.1087321-1-cohuck@redhat.com
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
2021-02-24 00:31:23 +01:00
..
block for-5.12/block-2021-02-17 2021-02-21 11:02:48 -08:00
char s390 updates for the 5.12 merge window 2021-02-21 13:40:06 -08:00
cio s390/qdio: remove 'merge_pending' mechanism 2021-02-13 17:17:55 +01:00
crypto s390 updates for the 5.12 merge window 2021-02-21 13:40:06 -08:00
net s390 updates for the 5.12 merge window 2021-02-21 13:40:06 -08:00
scsi SCSI misc on 20201216 2020-12-16 13:34:31 -08:00
virtio virtio/s390: implement virtio-ccw revision 2 correctly 2021-02-24 00:31:23 +01:00
Makefile s390: remove pointless drivers-y in drivers/s390/Makefile 2019-09-16 13:21:51 +02:00