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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: Dong Jia Shi <bjsdjshi@linux.vnet.ibm.com>
Message-Id: <20170317031743.40128-14-bjsdjshi@linux.vnet.ibm.com>
Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
This commit is contained in:
Dong Jia Shi 2017-03-17 04:17:40 +01:00 committed by Cornelia Huck
parent e5f84dbaea
commit bbe37e4cb8
5 changed files with 287 additions and 107 deletions
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2
drivers/s390/cio/Makefile
View File

@ -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

116
drivers/s390/cio/vfio_ccw_drv.c
View File

@ -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);

207
drivers/s390/cio/vfio_ccw_fsm.c Normal file
View File

@ -0,0 +1,207 @@
/*
* 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,
},
};

28
drivers/s390/cio/vfio_ccw_ops.c
View File

@ -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;
}

41
drivers/s390/cio/vfio_ccw_private.h
View File

@ -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