When we call ssch, an interrupt might already be pending once we return from the START SUBCHANNEL instruction. Therefore we need to make sure interrupts are disabled while holding the subchannel lock until after we're done with our processing.

Cc: stable@vger.kernel.org #v4.12+ Reviewed-by: Dong Jia Shi bjsdjshi@linux.ibm.com Acked-by: Halil Pasic pasic@linux.vnet.ibm.com Acked-by: Pierre Morel pmorel@linux.vnet.ibm.com Signed-off-by: Cornelia Huck cohuck@redhat.com --- drivers/s390/cio/vfio_ccw_fsm.c | 19 ++++++++++++------- 1 file changed, 12 insertions(+), 7 deletions(-)

diff --git a/drivers/s390/cio/vfio_ccw_fsm.c b/drivers/s390/cio/vfio_ccw_fsm.c index ff6963ad6e39..3c800642134e 100644 --- a/drivers/s390/cio/vfio_ccw_fsm.c +++ b/drivers/s390/cio/vfio_ccw_fsm.c @@ -20,12 +20,12 @@ static int fsm_io_helper(struct vfio_ccw_private *private) int ccode; __u8 lpm; unsigned long flags; + int ret;

sch = private->sch;

spin_lock_irqsave(sch->lock, flags); private->state = VFIO_CCW_STATE_BUSY; - spin_unlock_irqrestore(sch->lock, flags);

orb = cp_get_orb(&private->cp, (u32)(addr_t)sch, sch->lpm);

@@ -38,10 +38,12 @@ static int fsm_io_helper(struct vfio_ccw_private *private) * Initialize device status information */ sch->schib.scsw.cmd.actl |= SCSW_ACTL_START_PEND; - return 0; + ret = 0; + break; case 1: /* Status pending */ case 2: /* Busy */ - return -EBUSY; + ret = -EBUSY; + break; case 3: /* Device/path not operational */ { lpm = orb->cmd.lpm; @@ -51,13 +53,16 @@ static int fsm_io_helper(struct vfio_ccw_private *private) sch->lpm = 0;

if (cio_update_schib(sch)) - return -ENODEV; - - return sch->lpm ? -EACCES : -ENODEV; + ret = -ENODEV; + else + ret = sch->lpm ? -EACCES : -ENODEV; + break; } default: - return ccode; + ret = ccode; } + spin_unlock_irqrestore(sch->lock, flags); + return ret; }

static void fsm_notoper(struct vfio_ccw_private *private,