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authorDong Jia Shi <bjsdjshi@linux.vnet.ibm.com>2017-03-17 04:17:40 +0100
committerCornelia Huck <cornelia.huck@de.ibm.com>2017-03-31 12:55:11 +0200
commitbbe37e4cb89702aa78e0f44618c5af7f9aaa33f6 (patch)
tree46269ef030a61c19f629701e53678e0311b2d2c7 /drivers/s390/cio/vfio_ccw_fsm.c
parente5f84dbaea59b4f712dac428c337528b70e1c533 (diff)
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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>
Diffstat (limited to 'drivers/s390/cio/vfio_ccw_fsm.c')
-rw-r--r--drivers/s390/cio/vfio_ccw_fsm.c207
1 files changed, 207 insertions, 0 deletions
diff --git a/drivers/s390/cio/vfio_ccw_fsm.c b/drivers/s390/cio/vfio_ccw_fsm.c
new file mode 100644
index 000000000000..55b6cc55758e
--- /dev/null
+++ b/drivers/s390/cio/vfio_ccw_fsm.c
@@ -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,
+ },
+};