vfio: ccw: register vfio_ccw to the mediated device framework

To make vfio support subchannel devices, we need to leverage the
mediated device framework to create a mediated device for the
subchannel device.

This registers the subchannel device to the mediated device
framework during probe to enable mediated device creation.

Reviewed-by: Pierre Morel <pmorel@linux.vnet.ibm.com>
Signed-off-by: Dong Jia Shi <bjsdjshi@linux.vnet.ibm.com>
Message-Id: <20170317031743.40128-7-bjsdjshi@linux.vnet.ibm.com>
Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>

1 files changed, 147 insertions, 0 deletions

diff --git a/drivers/s390/cio/vfio_ccw_ops.c b/drivers/s390/cio/vfio_ccw_ops.c
new file mode 100644
index 000000000000..b8a2fed58f02
--- /dev/null
+++ b/drivers/s390/cio/vfio_ccw_ops.c
@@ -0,0 +1,147 @@
+/*
+ * Physical device callbacks for vfio_ccw
+ *
+ * Copyright IBM Corp. 2017
+ *
+ * Author(s): Dong Jia Shi <bjsdjshi@linux.vnet.ibm.com>
+ *            Xiao Feng Ren <renxiaof@linux.vnet.ibm.com>
+ */
+
+#include <linux/vfio.h>
+#include <linux/mdev.h>
+
+#include "vfio_ccw_private.h"
+
+static int vfio_ccw_mdev_notifier(struct notifier_block *nb,
+				  unsigned long action,
+				  void *data)
+{
+	struct vfio_ccw_private *private =
+		container_of(nb, struct vfio_ccw_private, nb);
+
+	if (!private)
+		return NOTIFY_STOP;
+
+	/*
+	 * TODO:
+	 * Vendor drivers MUST unpin pages in response to an
+	 * invalidation.
+	 */
+	if (action == VFIO_IOMMU_NOTIFY_DMA_UNMAP)
+		return NOTIFY_BAD;
+
+	return NOTIFY_DONE;
+}
+
+static ssize_t name_show(struct kobject *kobj, struct device *dev, char *buf)
+{
+	return sprintf(buf, "I/O subchannel (Non-QDIO)\n");
+}
+MDEV_TYPE_ATTR_RO(name);
+
+static ssize_t device_api_show(struct kobject *kobj, struct device *dev,
+			       char *buf)
+{
+	return sprintf(buf, "%s\n", VFIO_DEVICE_API_CCW_STRING);
+}
+MDEV_TYPE_ATTR_RO(device_api);
+
+static ssize_t available_instances_show(struct kobject *kobj,
+					struct device *dev, char *buf)
+{
+	struct vfio_ccw_private *private = dev_get_drvdata(dev);
+
+	return sprintf(buf, "%d\n", atomic_read(&private->avail));
+}
+MDEV_TYPE_ATTR_RO(available_instances);
+
+static struct attribute *mdev_types_attrs[] = {
+	&mdev_type_attr_name.attr,
+	&mdev_type_attr_device_api.attr,
+	&mdev_type_attr_available_instances.attr,
+	NULL,
+};
+
+static struct attribute_group mdev_type_group = {
+	.name  = "io",
+	.attrs = mdev_types_attrs,
+};
+
+struct attribute_group *mdev_type_groups[] = {
+	&mdev_type_group,
+	NULL,
+};
+
+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 (atomic_dec_if_positive(&private->avail) < 0)
+		return -EPERM;
+
+	private->mdev = mdev;
+
+	return 0;
+}
+
+static int vfio_ccw_mdev_remove(struct mdev_device *mdev)
+{
+	struct vfio_ccw_private *private;
+	struct subchannel *sch;
+	int ret;
+
+	private = dev_get_drvdata(mdev_parent_dev(mdev));
+	sch = private->sch;
+	ret = vfio_ccw_sch_quiesce(sch);
+	if (ret)
+		return ret;
+	ret = cio_enable_subchannel(sch, (u32)(unsigned long)sch);
+	if (ret)
+		return ret;
+
+	private->mdev = NULL;
+	atomic_inc(&private->avail);
+
+	return 0;
+}
+
+static int vfio_ccw_mdev_open(struct mdev_device *mdev)
+{
+	struct vfio_ccw_private *private =
+		dev_get_drvdata(mdev_parent_dev(mdev));
+	unsigned long events = VFIO_IOMMU_NOTIFY_DMA_UNMAP;
+
+	private->nb.notifier_call = vfio_ccw_mdev_notifier;
+
+	return vfio_register_notifier(mdev_dev(mdev), VFIO_IOMMU_NOTIFY,
+				      &events, &private->nb);
+}
+
+void vfio_ccw_mdev_release(struct mdev_device *mdev)
+{
+	struct vfio_ccw_private *private =
+		dev_get_drvdata(mdev_parent_dev(mdev));
+
+	vfio_unregister_notifier(mdev_dev(mdev), VFIO_IOMMU_NOTIFY,
+				 &private->nb);
+}
+
+static const struct mdev_parent_ops vfio_ccw_mdev_ops = {
+	.owner			= THIS_MODULE,
+	.supported_type_groups  = mdev_type_groups,
+	.create			= vfio_ccw_mdev_create,
+	.remove			= vfio_ccw_mdev_remove,
+	.open			= vfio_ccw_mdev_open,
+	.release		= vfio_ccw_mdev_release,
+};
+
+int vfio_ccw_mdev_reg(struct subchannel *sch)
+{
+	return mdev_register_device(&sch->dev, &vfio_ccw_mdev_ops);
+}
+
+void vfio_ccw_mdev_unreg(struct subchannel *sch)
+{
+	mdev_unregister_device(&sch->dev);
+}