[PATCH v1 10/18] vfio/ccw: Create a CLOSE FSM event

Eric Farman
2022-06-02T17:20:12Z

Refactor the vfio_ccw_sch_quiesce() routine to extract the bit that
disables the subchannel and affects the FSM state. Use this to form
the basis of a CLOSE event that will mirror the OPEN event, and move
the subchannel back to NOT_OPER state.

A key difference with that mirroring is that while OPEN handles the
transition from NOT_OPER => STANDBY, the later probing of the mdev
handles the transition from STANDBY => IDLE. On the other hand,
the CLOSE event will move from one of the operating states {IDLE,
CP_PROCESSING, CP_PENDING} => NOT_OPER. That is, there is no stop
in a STANDBY state on the deconfigure path.

Add a call to cp_free() in this event, such that it is captured for
the various permutations of this event.

In the unlikely event that cio_disable_subchannel() returns -EBUSY,
the remaining logic of vfio_ccw_sch_quiesce() can still be used.

Signed-off-by: Eric Farman <farman@linux.ibm.com>
---
drivers/s390/cio/vfio_ccw_drv.c | 20 ++++++++------------
drivers/s390/cio/vfio_ccw_fsm.c | 26 ++++++++++++++++++++++++++
drivers/s390/cio/vfio_ccw_ops.c | 14 ++------------
drivers/s390/cio/vfio_ccw_private.h | 1 +
4 files changed, 37 insertions(+), 24 deletions(-)

diff --git a/drivers/s390/cio/vfio_ccw_drv.c b/drivers/s390/cio/vfio_ccw_drv.c
index 2d816dd01713..34995ad00332 100644
--- a/drivers/s390/cio/vfio_ccw_drv.c
+++ b/drivers/s390/cio/vfio_ccw_drv.c
@@ -44,13 +44,6 @@ int vfio_ccw_sch_quiesce(struct subchannel *sch)
if (!private)
return 0;

- spin_lock_irq(sch->lock);
- if (!sch->schib.pmcw.ena)
- goto out_unlock;
- ret = cio_disable_subchannel(sch);
- if (ret != -EBUSY)
- goto out_unlock;
-
iretry = 255;
do {

@@ -77,9 +70,7 @@ int vfio_ccw_sch_quiesce(struct subchannel *sch)
spin_lock_irq(sch->lock);
ret = cio_disable_subchannel(sch);
} while (ret == -EBUSY);
-out_unlock:
- private->state = VFIO_CCW_STATE_NOT_OPER;
- spin_unlock_irq(sch->lock);
+
return ret;
}

@@ -264,7 +255,7 @@ static void vfio_ccw_sch_remove(struct subchannel *sch)
if (!private)
return;

- vfio_ccw_sch_quiesce(sch);
+ vfio_ccw_fsm_event(private, VFIO_CCW_EVENT_CLOSE);
mdev_unregister_device(&sch->dev);

dev_set_drvdata(&sch->dev, NULL);
@@ -278,7 +269,12 @@ static void vfio_ccw_sch_remove(struct subchannel *sch)

static void vfio_ccw_sch_shutdown(struct subchannel *sch)
{
- vfio_ccw_sch_quiesce(sch);
+ struct vfio_ccw_private *private = dev_get_drvdata(&sch->dev);
+
+ if (!private)
+ return;
+
+ vfio_ccw_fsm_event(private, VFIO_CCW_EVENT_CLOSE);
}

/**
diff --git a/drivers/s390/cio/vfio_ccw_fsm.c b/drivers/s390/cio/vfio_ccw_fsm.c
index 25db8534ded0..926ae618c3fa 100644
--- a/drivers/s390/cio/vfio_ccw_fsm.c
+++ b/drivers/s390/cio/vfio_ccw_fsm.c
@@ -381,6 +381,27 @@ static void fsm_open(struct vfio_ccw_private *private,
spin_unlock_irq(sch->lock);
}

+static void fsm_close(struct vfio_ccw_private *private,
+ enum vfio_ccw_event event)
+{
+ struct subchannel *sch = private->sch;
+ int ret;
+
+ spin_lock_irq(sch->lock);
+
+ if (!sch->schib.pmcw.ena)
+ goto out_unlock;
+
+ ret = cio_disable_subchannel(sch);
+ if (ret == -EBUSY)
+ vfio_ccw_sch_quiesce(sch);
+
+out_unlock:
+ private->state = VFIO_CCW_STATE_NOT_OPER;
+ spin_unlock_irq(sch->lock);
+ cp_free(&private->cp);
+}
+
/*
* Device statemachine
*/
@@ -391,6 +412,7 @@ fsm_func_t *vfio_ccw_jumptable[NR_VFIO_CCW_STATES][NR_VFIO_CCW_EVENTS] = {
[VFIO_CCW_EVENT_ASYNC_REQ] = fsm_async_error,
[VFIO_CCW_EVENT_INTERRUPT] = fsm_disabled_irq,
[VFIO_CCW_EVENT_OPEN] = fsm_open,
+ [VFIO_CCW_EVENT_CLOSE] = fsm_nop,
},
[VFIO_CCW_STATE_STANDBY] = {
[VFIO_CCW_EVENT_NOT_OPER] = fsm_notoper,
@@ -398,6 +420,7 @@ fsm_func_t *vfio_ccw_jumptable[NR_VFIO_CCW_STATES][NR_VFIO_CCW_EVENTS] = {
[VFIO_CCW_EVENT_ASYNC_REQ] = fsm_async_error,
[VFIO_CCW_EVENT_INTERRUPT] = fsm_irq,
[VFIO_CCW_EVENT_OPEN] = fsm_nop,
+ [VFIO_CCW_EVENT_CLOSE] = fsm_notoper,
},
[VFIO_CCW_STATE_IDLE] = {
[VFIO_CCW_EVENT_NOT_OPER] = fsm_notoper,
@@ -405,6 +428,7 @@ fsm_func_t *vfio_ccw_jumptable[NR_VFIO_CCW_STATES][NR_VFIO_CCW_EVENTS] = {
[VFIO_CCW_EVENT_ASYNC_REQ] = fsm_async_request,
[VFIO_CCW_EVENT_INTERRUPT] = fsm_irq,
[VFIO_CCW_EVENT_OPEN] = fsm_notoper,
+ [VFIO_CCW_EVENT_CLOSE] = fsm_close,
},
[VFIO_CCW_STATE_CP_PROCESSING] = {
[VFIO_CCW_EVENT_NOT_OPER] = fsm_notoper,
@@ -412,6 +436,7 @@ fsm_func_t *vfio_ccw_jumptable[NR_VFIO_CCW_STATES][NR_VFIO_CCW_EVENTS] = {
[VFIO_CCW_EVENT_ASYNC_REQ] = fsm_async_retry,
[VFIO_CCW_EVENT_INTERRUPT] = fsm_irq,
[VFIO_CCW_EVENT_OPEN] = fsm_notoper,
+ [VFIO_CCW_EVENT_CLOSE] = fsm_close,
},
[VFIO_CCW_STATE_CP_PENDING] = {
[VFIO_CCW_EVENT_NOT_OPER] = fsm_notoper,
@@ -419,5 +444,6 @@ fsm_func_t *vfio_ccw_jumptable[NR_VFIO_CCW_STATES][NR_VFIO_CCW_EVENTS] = {
[VFIO_CCW_EVENT_ASYNC_REQ] = fsm_async_request,
[VFIO_CCW_EVENT_INTERRUPT] = fsm_irq,
[VFIO_CCW_EVENT_OPEN] = fsm_notoper,
+ [VFIO_CCW_EVENT_CLOSE] = fsm_close,
},
};
diff --git a/drivers/s390/cio/vfio_ccw_ops.c b/drivers/s390/cio/vfio_ccw_ops.c
index 9e5c184eab89..38c715da61c6 100644
--- a/drivers/s390/cio/vfio_ccw_ops.c
+++ b/drivers/s390/cio/vfio_ccw_ops.c
@@ -33,9 +33,7 @@ static int vfio_ccw_mdev_reset(struct vfio_ccw_private *private)
* There are still a lot more instructions need to be handled. We
* should come back here later.
*/
- ret = vfio_ccw_sch_quiesce(sch);
- if (ret)
- return ret;
+ vfio_ccw_fsm_event(private, VFIO_CCW_EVENT_CLOSE);

ret = cio_enable_subchannel(sch, (u32)(unsigned long)sch);
if (!ret)
@@ -64,7 +62,6 @@ static int vfio_ccw_mdev_notifier(struct notifier_block *nb,
if (vfio_ccw_mdev_reset(private))
return NOTIFY_BAD;

- cp_free(&private->cp);
return NOTIFY_OK;
}

@@ -163,15 +160,9 @@ static void vfio_ccw_mdev_remove(struct mdev_device *mdev)
dev_set_drvdata(&mdev->dev, NULL);
vfio_unregister_group_dev(&private->vdev);

- if ((private->state != VFIO_CCW_STATE_NOT_OPER) &&
- (private->state != VFIO_CCW_STATE_STANDBY)) {
- if (!vfio_ccw_sch_quiesce(private->sch))
- private->state = VFIO_CCW_STATE_STANDBY;
- /* The state will be NOT_OPER on error. */
- }
+ vfio_ccw_fsm_event(private, VFIO_CCW_EVENT_CLOSE);

vfio_uninit_group_dev(&private->vdev);
- cp_free(&private->cp);
atomic_inc(&private->avail);
}

@@ -222,7 +213,6 @@ static void vfio_ccw_mdev_close_device(struct vfio_device *vdev)
/* The state will be NOT_OPER on error. */
}

- cp_free(&private->cp);
vfio_ccw_unregister_dev_regions(private);
vfio_unregister_notifier(vdev->dev, VFIO_IOMMU_NOTIFY, &private->nb);
}
diff --git a/drivers/s390/cio/vfio_ccw_private.h b/drivers/s390/cio/vfio_ccw_private.h
index d7ba6846e5c5..02a4a5edd00c 100644
--- a/drivers/s390/cio/vfio_ccw_private.h
+++ b/drivers/s390/cio/vfio_ccw_private.h
@@ -144,6 +144,7 @@ enum vfio_ccw_event {
VFIO_CCW_EVENT_INTERRUPT,
VFIO_CCW_EVENT_ASYNC_REQ,
VFIO_CCW_EVENT_OPEN,
+ VFIO_CCW_EVENT_CLOSE,
/* last element! */
NR_VFIO_CCW_EVENTS
};
--
2.32.0