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// SPDX-License-Identifier: GPL-2.0
/*
* 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;
int ret;
sch = private->sch;
spin_lock_irqsave(sch->lock, flags);
private->state = VFIO_CCW_STATE_BUSY;
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;
ret = 0;
break;
case 1: /* Status pending */
case 2: /* Busy */
ret = -EBUSY;
break;
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))
ret = -ENODEV;
else
ret = sch->lpm ? -EACCES : -ENODEV;
break;
}
default:
ret = ccode;
}
spin_unlock_irqrestore(sch->lock, flags);
return ret;
}
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;
/* Don't try to build a cp if transport mode is specified. */
if (orb->tm.b) {
io_region->ret_code = -EOPNOTSUPP;
goto err_out;
}
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 = 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,
},
};
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