Commit bbe37e4c authored by Dong Jia Shi's avatar Dong Jia Shi Committed by Cornelia Huck
Browse files

vfio: ccw: introduce a finite state machine 



The current implementation doesn't check if the subchannel is in a
proper device state when handling an event. Let's introduce
a finite state machine to manage the state/event change.

Signed-off-by: default avatarDong Jia Shi <bjsdjshi@linux.vnet.ibm.com>
Message-Id: <20170317031743.40128-14-bjsdjshi@linux.vnet.ibm.com>
Signed-off-by: default avatarCornelia Huck <cornelia.huck@de.ibm.com>
parent e5f84dba

drivers/s390/cio/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -18,5 +18,5 @@ obj-$(CONFIG_CCWGROUP) += ccwgroup.o 
qdio-objs := qdio_main.o qdio_thinint.o qdio_debug.o qdio_setup.o

obj-$(CONFIG_QDIO) += qdio.o



vfio_ccw-objs += vfio_ccw_drv.o vfio_ccw_cp.o vfio_ccw_ops.o

vfio_ccw-objs += vfio_ccw_drv.o vfio_ccw_cp.o vfio_ccw_ops.o vfio_ccw_fsm.o

obj-$(CONFIG_VFIO_CCW) += vfio_ccw.o

drivers/s390/cio/vfio_ccw_drv.c

+14 −102
Original line number Diff line number Diff line
@@ -60,54 +60,12 @@ int vfio_ccw_sch_quiesce(struct subchannel *sch) 


		ret = cio_disable_subchannel(sch);

	} while (ret == -EBUSY);



out_unlock:

	private->state = VFIO_CCW_STATE_NOT_OPER;

	spin_unlock_irq(sch->lock);

	return ret;

}



static int vfio_ccw_sch_io_helper(struct vfio_ccw_private *private)

{

	struct subchannel *sch;

	union orb *orb;

	int ccode;

	__u8 lpm;



	sch = private->sch;



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



	/* Issue "Start Subchannel" */

	ccode = ssch(sch->schid, orb);



	switch (ccode) {

	case 0:

		/*

		 * Initialize device status information

		 */

		sch->schib.scsw.cmd.actl |= SCSW_ACTL_START_PEND;

		return 0;

	case 1:		/* Status pending */

	case 2:		/* Busy */

		return -EBUSY;

	case 3:		/* Device/path not operational */

	{

		lpm = orb->cmd.lpm;

		if (lpm != 0)

			sch->lpm &= ~lpm;

		else

			sch->lpm = 0;



		if (cio_update_schib(sch))

			return -ENODEV;



		return sch->lpm ? -EACCES : -ENODEV;

	}

	default:

		return ccode;

	}

}



static void vfio_ccw_sch_io_todo(struct work_struct *work)

{

	struct vfio_ccw_private *private;
@@ -126,47 +84,9 @@ static void vfio_ccw_sch_io_todo(struct work_struct *work) 


	if (private->io_trigger)

		eventfd_signal(private->io_trigger, 1);

}



/* Deal with the ccw command request from the userspace. */

int vfio_ccw_sch_cmd_request(struct vfio_ccw_private *private)

{

	struct mdev_device *mdev = private->mdev;

	union orb *orb;

	union scsw *scsw = &private->scsw;

	struct ccw_io_region *io_region = &private->io_region;

	int ret;



	memcpy(scsw, io_region->scsw_area, sizeof(*scsw));



	if (scsw->cmd.fctl & SCSW_FCTL_START_FUNC) {

		orb = (union orb *)io_region->orb_area;



		ret = cp_init(&private->cp, mdev_dev(mdev), orb);

		if (ret)

			return ret;



		ret = cp_prefetch(&private->cp);

		if (ret) {

			cp_free(&private->cp);

			return ret;

		}



		/* Start channel program and wait for I/O interrupt. */

		ret = vfio_ccw_sch_io_helper(private);

		if (!ret)

			cp_free(&private->cp);

	} else if (scsw->cmd.fctl & SCSW_FCTL_HALT_FUNC) {

		/* XXX: Handle halt. */

		ret = -EOPNOTSUPP;

	} else if (scsw->cmd.fctl & SCSW_FCTL_CLEAR_FUNC) {

		/* XXX: Handle clear. */

		ret = -EOPNOTSUPP;

	} else {

		ret = -EOPNOTSUPP;

	}



	return ret;

	if (private->mdev)

		private->state = VFIO_CCW_STATE_IDLE;

}



/*
@@ -223,20 +143,9 @@ static struct attribute_group vfio_subchannel_attr_group = { 
static void vfio_ccw_sch_irq(struct subchannel *sch)

{

	struct vfio_ccw_private *private = dev_get_drvdata(&sch->dev);

	struct irb *irb;



	inc_irq_stat(IRQIO_CIO);



	if (!private)

		return;



	irb = this_cpu_ptr(&cio_irb);

	memcpy(&private->irb, irb, sizeof(*irb));



	queue_work(vfio_ccw_work_q, &private->io_work);



	if (private->completion)

		complete(private->completion);

	vfio_ccw_fsm_event(private, VFIO_CCW_EVENT_INTERRUPT);

}



static int vfio_ccw_sch_probe(struct subchannel *sch)
@@ -258,6 +167,7 @@ static int vfio_ccw_sch_probe(struct subchannel *sch) 
	dev_set_drvdata(&sch->dev, private);



	spin_lock_irq(sch->lock);

	private->state = VFIO_CCW_STATE_NOT_OPER;

	sch->isc = VFIO_CCW_ISC;

	ret = cio_enable_subchannel(sch, (u32)(unsigned long)sch);

	spin_unlock_irq(sch->lock);
@@ -274,6 +184,7 @@ static int vfio_ccw_sch_probe(struct subchannel *sch) 


	INIT_WORK(&private->io_work, vfio_ccw_sch_io_todo);

	atomic_set(&private->avail, 1);

	private->state = VFIO_CCW_STATE_STANDBY;



	return 0;
@@ -321,6 +232,7 @@ static void vfio_ccw_sch_shutdown(struct subchannel *sch) 
 */

static int vfio_ccw_sch_event(struct subchannel *sch, int process)

{

	struct vfio_ccw_private *private = dev_get_drvdata(&sch->dev);

	unsigned long flags;



	spin_lock_irqsave(sch->lock, flags);
@@ -331,16 +243,16 @@ static int vfio_ccw_sch_event(struct subchannel *sch, int process) 
		goto out_unlock;



	if (cio_update_schib(sch)) {

		/* Not operational. */

		css_sched_sch_todo(sch, SCH_TODO_UNREG);



		/*

		 * TODO:

		 * Probably we should send the machine check to the guest.

		 */

		vfio_ccw_fsm_event(private, VFIO_CCW_EVENT_NOT_OPER);

		goto out_unlock;

	}



	private = dev_get_drvdata(&sch->dev);

	if (private->state == VFIO_CCW_STATE_NOT_OPER) {

		private->state = private->mdev ? VFIO_CCW_STATE_IDLE :

				 VFIO_CCW_STATE_STANDBY;

	}



out_unlock:

	spin_unlock_irqrestore(sch->lock, flags);

drivers/s390/cio/vfio_ccw_fsm.c

0 → 100644
+207 −0
Original line number Diff line number Diff line 
/*

 * Finite state machine for vfio-ccw device handling

 *

 * Copyright IBM Corp. 2017

 *

 * Author(s): Dong Jia Shi <bjsdjshi@linux.vnet.ibm.com>

 */



#include <linux/vfio.h>

#include <linux/mdev.h>



#include "ioasm.h"

#include "vfio_ccw_private.h"



static int fsm_io_helper(struct vfio_ccw_private *private)

{

	struct subchannel *sch;

	union orb *orb;

	int ccode;

	__u8 lpm;

	unsigned long flags;



	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);



	/* Issue "Start Subchannel" */

	ccode = ssch(sch->schid, orb);



	switch (ccode) {

	case 0:

		/*

		 * Initialize device status information

		 */

		sch->schib.scsw.cmd.actl |= SCSW_ACTL_START_PEND;

		return 0;

	case 1:		/* Status pending */

	case 2:		/* Busy */

		return -EBUSY;

	case 3:		/* Device/path not operational */

	{

		lpm = orb->cmd.lpm;

		if (lpm != 0)

			sch->lpm &= ~lpm;

		else

			sch->lpm = 0;



		if (cio_update_schib(sch))

			return -ENODEV;



		return sch->lpm ? -EACCES : -ENODEV;

	}

	default:

		return ccode;

	}

}



static void fsm_notoper(struct vfio_ccw_private *private,

			enum vfio_ccw_event event)

{

	struct subchannel *sch = private->sch;



	/*

	 * TODO:

	 * Probably we should send the machine check to the guest.

	 */

	css_sched_sch_todo(sch, SCH_TODO_UNREG);

	private->state = VFIO_CCW_STATE_NOT_OPER;

}



/*

 * No operation action.

 */

static void fsm_nop(struct vfio_ccw_private *private,

		    enum vfio_ccw_event event)

{

}



static void fsm_io_error(struct vfio_ccw_private *private,

			 enum vfio_ccw_event event)

{

	pr_err("vfio-ccw: FSM: I/O request from state:%d\n", private->state);

	private->io_region.ret_code = -EIO;

}



static void fsm_io_busy(struct vfio_ccw_private *private,

			enum vfio_ccw_event event)

{

	private->io_region.ret_code = -EBUSY;

}



static void fsm_disabled_irq(struct vfio_ccw_private *private,

			     enum vfio_ccw_event event)

{

	struct subchannel *sch = private->sch;



	/*

	 * An interrupt in a disabled state means a previous disable was not

	 * successful - should not happen, but we try to disable again.

	 */

	cio_disable_subchannel(sch);

}



/*

 * Deal with the ccw command request from the userspace.

 */

static void fsm_io_request(struct vfio_ccw_private *private,

			   enum vfio_ccw_event event)

{

	union orb *orb;

	union scsw *scsw = &private->scsw;

	struct ccw_io_region *io_region = &private->io_region;

	struct mdev_device *mdev = private->mdev;



	private->state = VFIO_CCW_STATE_BOXED;



	memcpy(scsw, io_region->scsw_area, sizeof(*scsw));



	if (scsw->cmd.fctl & SCSW_FCTL_START_FUNC) {

		orb = (union orb *)io_region->orb_area;



		io_region->ret_code = cp_init(&private->cp, mdev_dev(mdev),

					      orb);

		if (io_region->ret_code)

			goto err_out;



		io_region->ret_code = cp_prefetch(&private->cp);

		if (io_region->ret_code) {

			cp_free(&private->cp);

			goto err_out;

		}



		/* Start channel program and wait for I/O interrupt. */

		io_region->ret_code = fsm_io_helper(private);

		if (io_region->ret_code) {

			cp_free(&private->cp);

			goto err_out;

		}

		return;

	} else if (scsw->cmd.fctl & SCSW_FCTL_HALT_FUNC) {

		/* XXX: Handle halt. */

		io_region->ret_code = -EOPNOTSUPP;

		goto err_out;

	} else if (scsw->cmd.fctl & SCSW_FCTL_CLEAR_FUNC) {

		/* XXX: Handle clear. */

		io_region->ret_code = -EOPNOTSUPP;

		goto err_out;

	}



err_out:

	private->state = VFIO_CCW_STATE_IDLE;

}



/*

 * Got an interrupt for a normal io (state busy).

 */

static void fsm_irq(struct vfio_ccw_private *private,

		    enum vfio_ccw_event event)

{

	struct irb *irb;



	if (!private)

		return;



	irb = this_cpu_ptr(&cio_irb);

	memcpy(&private->irb, irb, sizeof(*irb));



	queue_work(vfio_ccw_work_q, &private->io_work);



	if (private->completion)

		complete(private->completion);

}



/*

 * Device statemachine

 */

fsm_func_t *vfio_ccw_jumptable[NR_VFIO_CCW_STATES][NR_VFIO_CCW_EVENTS] = {

	[VFIO_CCW_STATE_NOT_OPER] = {

		[VFIO_CCW_EVENT_NOT_OPER]	= fsm_nop,

		[VFIO_CCW_EVENT_IO_REQ]		= fsm_io_error,

		[VFIO_CCW_EVENT_INTERRUPT]	= fsm_disabled_irq,

	},

	[VFIO_CCW_STATE_STANDBY] = {

		[VFIO_CCW_EVENT_NOT_OPER]	= fsm_notoper,

		[VFIO_CCW_EVENT_IO_REQ]		= fsm_io_error,

		[VFIO_CCW_EVENT_INTERRUPT]	= fsm_irq,

	},

	[VFIO_CCW_STATE_IDLE] = {

		[VFIO_CCW_EVENT_NOT_OPER]	= fsm_notoper,

		[VFIO_CCW_EVENT_IO_REQ]		= fsm_io_request,

		[VFIO_CCW_EVENT_INTERRUPT]	= fsm_irq,

	},

	[VFIO_CCW_STATE_BOXED] = {

		[VFIO_CCW_EVENT_NOT_OPER]	= fsm_notoper,

		[VFIO_CCW_EVENT_IO_REQ]		= fsm_io_busy,

		[VFIO_CCW_EVENT_INTERRUPT]	= fsm_irq,

	},

	[VFIO_CCW_STATE_BUSY] = {

		[VFIO_CCW_EVENT_NOT_OPER]	= fsm_notoper,

		[VFIO_CCW_EVENT_IO_REQ]		= fsm_io_busy,

		[VFIO_CCW_EVENT_INTERRUPT]	= fsm_irq,

	},

};

drivers/s390/cio/vfio_ccw_ops.c

+25 −3
Original line number Diff line number Diff line
@@ -35,7 +35,11 @@ static int vfio_ccw_mdev_reset(struct mdev_device *mdev) 
	if (ret)

		return ret;



	return cio_enable_subchannel(sch, (u32)(unsigned long)sch);

	ret = cio_enable_subchannel(sch, (u32)(unsigned long)sch);

	if (!ret)

		private->state = VFIO_CCW_STATE_IDLE;



	return ret;

}



static int vfio_ccw_mdev_notifier(struct notifier_block *nb,
@@ -112,10 +116,14 @@ static int vfio_ccw_mdev_create(struct kobject *kobj, struct mdev_device *mdev) 
	struct vfio_ccw_private *private =

		dev_get_drvdata(mdev_parent_dev(mdev));



	if (private->state == VFIO_CCW_STATE_NOT_OPER)

		return -ENODEV;



	if (atomic_dec_if_positive(&private->avail) < 0)

		return -EPERM;



	private->mdev = mdev;

	private->state = VFIO_CCW_STATE_IDLE;



	return 0;

}
@@ -126,10 +134,20 @@ static int vfio_ccw_mdev_remove(struct mdev_device *mdev) 
		dev_get_drvdata(mdev_parent_dev(mdev));

	int ret;



	if (!private)

		goto out;



	if ((private->state == VFIO_CCW_STATE_NOT_OPER) ||

	    (private->state == VFIO_CCW_STATE_STANDBY))

		goto out;



	ret = vfio_ccw_mdev_reset(mdev);

	if (ret)

		return ret;



	private->state = VFIO_CCW_STATE_STANDBY;



out:

	private->mdev = NULL;

	atomic_inc(&private->avail);
@@ -193,14 +211,18 @@ static ssize_t vfio_ccw_mdev_write(struct mdev_device *mdev, 
	private = dev_get_drvdata(mdev_parent_dev(mdev));

	if (!private)

		return -ENODEV;

	if (private->state != VFIO_CCW_STATE_IDLE)

		return -EACCES;



	region = &private->io_region;

	if (copy_from_user((void *)region + *ppos, buf, count))

		return -EFAULT;



	region->ret_code = vfio_ccw_sch_cmd_request(private);

	if (region->ret_code != 0)

	vfio_ccw_fsm_event(private, VFIO_CCW_EVENT_IO_REQ);

	if (region->ret_code != 0) {

		private->state = VFIO_CCW_STATE_IDLE;

		return region->ret_code;

	}



	return count;

}

drivers/s390/cio/vfio_ccw_private.h

+40 −1
Original line number Diff line number Diff line
@@ -21,6 +21,7 @@ 
/**

 * struct vfio_ccw_private

 * @sch: pointer to the subchannel

 * @state: internal state of the device

 * @completion: synchronization helper of the I/O completion

 * @avail: available for creating a mediated device

 * @mdev: pointer to the mediated device
@@ -34,6 +35,7 @@ 
 */

struct vfio_ccw_private {

	struct subchannel	*sch;

	int			state;

	struct completion	*completion;

	atomic_t		avail;

	struct mdev_device	*mdev;
@@ -52,6 +54,43 @@ extern int vfio_ccw_mdev_reg(struct subchannel *sch); 
extern void vfio_ccw_mdev_unreg(struct subchannel *sch);



extern int vfio_ccw_sch_quiesce(struct subchannel *sch);

extern int vfio_ccw_sch_cmd_request(struct vfio_ccw_private *private);



/*

 * States of the device statemachine.

 */

enum vfio_ccw_state {

	VFIO_CCW_STATE_NOT_OPER,

	VFIO_CCW_STATE_STANDBY,

	VFIO_CCW_STATE_IDLE,

	VFIO_CCW_STATE_BOXED,

	VFIO_CCW_STATE_BUSY,

	/* last element! */

	NR_VFIO_CCW_STATES

};



/*

 * Asynchronous events of the device statemachine.

 */

enum vfio_ccw_event {

	VFIO_CCW_EVENT_NOT_OPER,

	VFIO_CCW_EVENT_IO_REQ,

	VFIO_CCW_EVENT_INTERRUPT,

	/* last element! */

	NR_VFIO_CCW_EVENTS

};



/*

 * Action called through jumptable.

 */

typedef void (fsm_func_t)(struct vfio_ccw_private *, enum vfio_ccw_event);

extern fsm_func_t *vfio_ccw_jumptable[NR_VFIO_CCW_STATES][NR_VFIO_CCW_EVENTS];



static inline void vfio_ccw_fsm_event(struct vfio_ccw_private *private,

				     int event)

{

	vfio_ccw_jumptable[private->state][event](private, event);

}



extern struct workqueue_struct *vfio_ccw_work_q;



#endif

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