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.
Fixes: 7d3ce5ab9430 ("virtio/s390: support READ_STATUS command for virtio-ccw")
Reviewed-by: Halil Pasic <email@example.com>
Signed-off-by: Cornelia Huck <firstname.lastname@example.org>
1 file changed