Re: [PATCH v3 09/11] vfio/ccw: Create a CLOSE FSM event

Matthew Rosato <mjrosato@xxxxxxxxxxxxx> · Tue, 5 Jul 2022 15:29:19 -0400

On 6/30/22 4:36 PM, Eric Farman wrote:
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@xxxxxxxxxxxxx>

Reviewed-by: Matthew Rosato <mjrosato@xxxxxxxxxxxxx>

---
  drivers/s390/cio/vfio_ccw_drv.c     | 17 +++++------------
  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, 34 insertions(+), 24 deletions(-)

diff --git a/drivers/s390/cio/vfio_ccw_drv.c b/drivers/s390/cio/vfio_ccw_drv.c
index 7d9189640da3..f98c9915e73d 100644
--- a/drivers/s390/cio/vfio_ccw_drv.c
+++ b/drivers/s390/cio/vfio_ccw_drv.c
@@ -41,13 +41,6 @@ int vfio_ccw_sch_quiesce(struct subchannel *sch)
  	DECLARE_COMPLETION_ONSTACK(completion);
  	int iretry, ret = 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 {
  
@@ -74,9 +67,7 @@ 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;
  }
  
@@ -256,7 +247,7 @@ static void vfio_ccw_sch_remove(struct subchannel *sch)
  {
  	struct vfio_ccw_private *private = dev_get_drvdata(&sch->dev);
  
-	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);
@@ -270,7 +261,9 @@ 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);
+
+	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 2811b2040490..89eb3feffa41 100644
--- a/drivers/s390/cio/vfio_ccw_fsm.c
+++ b/drivers/s390/cio/vfio_ccw_fsm.c
@@ -384,6 +384,27 @@ 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
   */
@@ -394,6 +415,7 @@ 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,
@@ -401,6 +423,7 @@ 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_notoper,
+		[VFIO_CCW_EVENT_CLOSE]		= fsm_close,
  	},
  	[VFIO_CCW_STATE_IDLE] = {
  		[VFIO_CCW_EVENT_NOT_OPER]	= fsm_notoper,
@@ -408,6 +431,7 @@ 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,
@@ -415,6 +439,7 @@ 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,
@@ -422,5 +447,6 @@ 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 a7ea9358e461..fc5b83187bd9 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;
  	}
  
@@ -159,15 +156,9 @@ static void vfio_ccw_mdev_remove(struct mdev_device *mdev)
  
  	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);
  }
  
@@ -217,7 +208,6 @@ 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, VFIO_IOMMU_NOTIFY, &private->nb);
  }
diff --git a/drivers/s390/cio/vfio_ccw_private.h b/drivers/s390/cio/vfio_ccw_private.h
index 8dff1699a7d9..435d401b8fb9 100644
--- a/drivers/s390/cio/vfio_ccw_private.h
+++ b/drivers/s390/cio/vfio_ccw_private.h
@@ -143,6 +143,7 @@ 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
  };







