1 files changed, 284 insertions, 0 deletions

diff --git a/drivers/s390/cio/vfio_ccw_drv.c b/drivers/s390/cio/vfio_ccw_drv.c
new file mode 100644
index 000000000..7a06cdff6
--- /dev/null
+++ b/drivers/s390/cio/vfio_ccw_drv.c
@@ -0,0 +1,284 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * VFIO based Physical Subchannel device driver
+ *
+ * Copyright IBM Corp. 2017
+ *
+ * Author(s): Dong Jia Shi <bjsdjshi@linux.vnet.ibm.com>
+ *            Xiao Feng Ren <renxiaof@linux.vnet.ibm.com>
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/device.h>
+#include <linux/slab.h>
+#include <linux/uuid.h>
+#include <linux/mdev.h>
+
+#include <asm/isc.h>
+
+#include "ioasm.h"
+#include "css.h"
+#include "vfio_ccw_private.h"
+
+struct workqueue_struct *vfio_ccw_work_q;
+struct kmem_cache *vfio_ccw_io_region;
+
+/*
+ * Helpers
+ */
+int vfio_ccw_sch_quiesce(struct subchannel *sch)
+{
+	struct vfio_ccw_private *private = dev_get_drvdata(&sch->dev);
+	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 {
+
+		ret = cio_cancel_halt_clear(sch, &iretry);
+
+		if (ret == -EIO) {
+			pr_err("vfio_ccw: could not quiesce subchannel 0.%x.%04x!\n",
+			       sch->schid.ssid, sch->schid.sch_no);
+			break;
+		}
+
+		/*
+		 * Flush all I/O and wait for
+		 * cancel/halt/clear completion.
+		 */
+		private->completion = &completion;
+		spin_unlock_irq(sch->lock);
+
+		if (ret == -EBUSY)
+			wait_for_completion_timeout(&completion, 3*HZ);
+
+		private->completion = NULL;
+		flush_workqueue(vfio_ccw_work_q);
+		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;
+}
+
+static void vfio_ccw_sch_io_todo(struct work_struct *work)
+{
+	struct vfio_ccw_private *private;
+	struct irb *irb;
+	bool is_final;
+
+	private = container_of(work, struct vfio_ccw_private, io_work);
+	irb = &private->irb;
+
+	is_final = !(scsw_actl(&irb->scsw) &
+		     (SCSW_ACTL_DEVACT | SCSW_ACTL_SCHACT));
+	if (scsw_is_solicited(&irb->scsw)) {
+		cp_update_scsw(&private->cp, &irb->scsw);
+		if (is_final)
+			cp_free(&private->cp);
+	}
+	memcpy(private->io_region->irb_area, irb, sizeof(*irb));
+
+	if (private->io_trigger)
+		eventfd_signal(private->io_trigger, 1);
+
+	if (private->mdev && is_final)
+		private->state = VFIO_CCW_STATE_IDLE;
+}
+
+/*
+ * Css driver callbacks
+ */
+static void vfio_ccw_sch_irq(struct subchannel *sch)
+{
+	struct vfio_ccw_private *private = dev_get_drvdata(&sch->dev);
+
+	inc_irq_stat(IRQIO_CIO);
+	vfio_ccw_fsm_event(private, VFIO_CCW_EVENT_INTERRUPT);
+}
+
+static int vfio_ccw_sch_probe(struct subchannel *sch)
+{
+	struct pmcw *pmcw = &sch->schib.pmcw;
+	struct vfio_ccw_private *private;
+	int ret;
+
+	if (pmcw->qf) {
+		dev_warn(&sch->dev, "vfio: ccw: does not support QDIO: %s\n",
+			 dev_name(&sch->dev));
+		return -ENODEV;
+	}
+
+	private = kzalloc(sizeof(*private), GFP_KERNEL | GFP_DMA);
+	if (!private)
+		return -ENOMEM;
+
+	private->io_region = kmem_cache_zalloc(vfio_ccw_io_region,
+					       GFP_KERNEL | GFP_DMA);
+	if (!private->io_region) {
+		kfree(private);
+		return -ENOMEM;
+	}
+
+	private->sch = 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);
+	if (ret)
+		goto out_free;
+
+	ret = vfio_ccw_mdev_reg(sch);
+	if (ret)
+		goto out_disable;
+
+	INIT_WORK(&private->io_work, vfio_ccw_sch_io_todo);
+	atomic_set(&private->avail, 1);
+	private->state = VFIO_CCW_STATE_STANDBY;
+
+	return 0;
+
+out_disable:
+	cio_disable_subchannel(sch);
+out_free:
+	dev_set_drvdata(&sch->dev, NULL);
+	kmem_cache_free(vfio_ccw_io_region, private->io_region);
+	kfree(private);
+	return ret;
+}
+
+static int vfio_ccw_sch_remove(struct subchannel *sch)
+{
+	struct vfio_ccw_private *private = dev_get_drvdata(&sch->dev);
+
+	vfio_ccw_sch_quiesce(sch);
+
+	vfio_ccw_mdev_unreg(sch);
+
+	dev_set_drvdata(&sch->dev, NULL);
+
+	kmem_cache_free(vfio_ccw_io_region, private->io_region);
+	kfree(private);
+
+	return 0;
+}
+
+static void vfio_ccw_sch_shutdown(struct subchannel *sch)
+{
+	vfio_ccw_sch_quiesce(sch);
+}
+
+/**
+ * vfio_ccw_sch_event - process subchannel event
+ * @sch: subchannel
+ * @process: non-zero if function is called in process context
+ *
+ * An unspecified event occurred for this subchannel. Adjust data according
+ * to the current operational state of the subchannel. Return zero when the
+ * event has been handled sufficiently or -EAGAIN when this function should
+ * be called again in process context.
+ */
+static int vfio_ccw_sch_event(struct subchannel *sch, int process)
+{
+	struct vfio_ccw_private *private = dev_get_drvdata(&sch->dev);
+	unsigned long flags;
+	int rc = -EAGAIN;
+
+	spin_lock_irqsave(sch->lock, flags);
+	if (!device_is_registered(&sch->dev))
+		goto out_unlock;
+
+	if (work_pending(&sch->todo_work))
+		goto out_unlock;
+
+	if (cio_update_schib(sch)) {
+		vfio_ccw_fsm_event(private, VFIO_CCW_EVENT_NOT_OPER);
+		rc = 0;
+		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;
+	}
+	rc = 0;
+
+out_unlock:
+	spin_unlock_irqrestore(sch->lock, flags);
+
+	return rc;
+}
+
+static struct css_device_id vfio_ccw_sch_ids[] = {
+	{ .match_flags = 0x1, .type = SUBCHANNEL_TYPE_IO, },
+	{ /* end of list */ },
+};
+MODULE_DEVICE_TABLE(css, vfio_ccw_sch_ids);
+
+static struct css_driver vfio_ccw_sch_driver = {
+	.drv = {
+		.name = "vfio_ccw",
+		.owner = THIS_MODULE,
+	},
+	.subchannel_type = vfio_ccw_sch_ids,
+	.irq = vfio_ccw_sch_irq,
+	.probe = vfio_ccw_sch_probe,
+	.remove = vfio_ccw_sch_remove,
+	.shutdown = vfio_ccw_sch_shutdown,
+	.sch_event = vfio_ccw_sch_event,
+};
+
+static int __init vfio_ccw_sch_init(void)
+{
+	int ret;
+
+	vfio_ccw_work_q = create_singlethread_workqueue("vfio-ccw");
+	if (!vfio_ccw_work_q)
+		return -ENOMEM;
+
+	vfio_ccw_io_region = kmem_cache_create_usercopy("vfio_ccw_io_region",
+					sizeof(struct ccw_io_region), 0,
+					SLAB_ACCOUNT, 0,
+					sizeof(struct ccw_io_region), NULL);
+	if (!vfio_ccw_io_region) {
+		destroy_workqueue(vfio_ccw_work_q);
+		return -ENOMEM;
+	}
+
+	isc_register(VFIO_CCW_ISC);
+	ret = css_driver_register(&vfio_ccw_sch_driver);
+	if (ret) {
+		isc_unregister(VFIO_CCW_ISC);
+		kmem_cache_destroy(vfio_ccw_io_region);
+		destroy_workqueue(vfio_ccw_work_q);
+	}
+
+	return ret;
+}
+
+static void __exit vfio_ccw_sch_exit(void)
+{
+	css_driver_unregister(&vfio_ccw_sch_driver);
+	isc_unregister(VFIO_CCW_ISC);
+	kmem_cache_destroy(vfio_ccw_io_region);
+	destroy_workqueue(vfio_ccw_work_q);
+}
+module_init(vfio_ccw_sch_init);
+module_exit(vfio_ccw_sch_exit);
+
+MODULE_LICENSE("GPL v2");