KVM: s390: Add a channel I/O based virtio transport driver.

Add a driver for kvm guests that matches virtual ccw devices provided
by the host as virtio bridge devices.

These virtio-ccw devices use a special set of channel commands in order
to perform virtio functions.

Reviewed-by: Marcelo Tosatti <mtosatti@redhat.com>
Reviewed-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Gleb Natapov <gleb@redhat.com>

2 files changed, 854 insertions, 1 deletions

diff --git a/drivers/s390/kvm/Makefile b/drivers/s390/kvm/Makefile
index 0815690ac1e0..241891a57caf 100644
--- a/drivers/s390/kvm/Makefile
+++ b/drivers/s390/kvm/Makefile
@@ -6,4 +6,4 @@
 # it under the terms of the GNU General Public License (version 2 only)
 # as published by the Free Software Foundation.
 
-obj-$(CONFIG_S390_GUEST) += kvm_virtio.o
+obj-$(CONFIG_S390_GUEST) += kvm_virtio.o virtio_ccw.o
diff --git a/drivers/s390/kvm/virtio_ccw.c b/drivers/s390/kvm/virtio_ccw.c
new file mode 100644
index 000000000000..1a5aff31d752
--- /dev/null
+++ b/drivers/s390/kvm/virtio_ccw.c
@@ -0,0 +1,853 @@
+/*
+ * ccw based virtio transport
+ *
+ * Copyright IBM Corp. 2012
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License (version 2 only)
+ * as published by the Free Software Foundation.
+ *
+ *    Author(s): Cornelia Huck <cornelia.huck@de.ibm.com>
+ */
+
+#include <linux/kernel_stat.h>
+#include <linux/init.h>
+#include <linux/bootmem.h>
+#include <linux/err.h>
+#include <linux/virtio.h>
+#include <linux/virtio_config.h>
+#include <linux/slab.h>
+#include <linux/interrupt.h>
+#include <linux/virtio_ring.h>
+#include <linux/pfn.h>
+#include <linux/async.h>
+#include <linux/wait.h>
+#include <linux/list.h>
+#include <linux/bitops.h>
+#include <linux/module.h>
+#include <linux/io.h>
+#include <linux/kvm_para.h>
+#include <asm/setup.h>
+#include <asm/irq.h>
+#include <asm/cio.h>
+#include <asm/ccwdev.h>
+
+/*
+ * virtio related functions
+ */
+
+struct vq_config_block {
+        __u16 index;
+        __u16 num;
+} __packed;
+
+#define VIRTIO_CCW_CONFIG_SIZE 0x100
+/* same as PCI config space size, should be enough for all drivers */
+
+struct virtio_ccw_device {
+        struct virtio_device vdev;
+        __u8 status;
+        __u8 config[VIRTIO_CCW_CONFIG_SIZE];
+        struct ccw_device *cdev;
+        struct ccw1 *ccw;
+        __u32 area;
+        __u32 curr_io;
+        int err;
+        wait_queue_head_t wait_q;
+        spinlock_t lock;
+        struct list_head virtqueues;
+        unsigned long indicators;
+        unsigned long indicators2;
+        struct vq_config_block *config_block;
+};
+
+struct vq_info_block {
+        __u64 queue;
+        __u32 align;
+        __u16 index;
+        __u16 num;
+} __packed;
+
+struct virtio_feature_desc {
+        __u32 features;
+        __u8 index;
+} __packed;
+
+struct virtio_ccw_vq_info {
+        struct virtqueue *vq;
+        int num;
+        void *queue;
+        struct vq_info_block *info_block;
+        struct list_head node;
+};
+
+#define KVM_VIRTIO_CCW_RING_ALIGN 4096
+
+#define KVM_S390_VIRTIO_CCW_NOTIFY 3
+
+#define CCW_CMD_SET_VQ 0x13
+#define CCW_CMD_VDEV_RESET 0x33
+#define CCW_CMD_SET_IND 0x43
+#define CCW_CMD_SET_CONF_IND 0x53
+#define CCW_CMD_READ_FEAT 0x12
+#define CCW_CMD_WRITE_FEAT 0x11
+#define CCW_CMD_READ_CONF 0x22
+#define CCW_CMD_WRITE_CONF 0x21
+#define CCW_CMD_WRITE_STATUS 0x31
+#define CCW_CMD_READ_VQ_CONF 0x32
+
+#define VIRTIO_CCW_DOING_SET_VQ 0x00010000
+#define VIRTIO_CCW_DOING_RESET 0x00040000
+#define VIRTIO_CCW_DOING_READ_FEAT 0x00080000
+#define VIRTIO_CCW_DOING_WRITE_FEAT 0x00100000
+#define VIRTIO_CCW_DOING_READ_CONFIG 0x00200000
+#define VIRTIO_CCW_DOING_WRITE_CONFIG 0x00400000
+#define VIRTIO_CCW_DOING_WRITE_STATUS 0x00800000
+#define VIRTIO_CCW_DOING_SET_IND 0x01000000
+#define VIRTIO_CCW_DOING_READ_VQ_CONF 0x02000000
+#define VIRTIO_CCW_DOING_SET_CONF_IND 0x04000000
+#define VIRTIO_CCW_INTPARM_MASK 0xffff0000
+
+static struct virtio_ccw_device *to_vc_device(struct virtio_device *vdev)
+{
+        return container_of(vdev, struct virtio_ccw_device, vdev);
+}
+
+static int doing_io(struct virtio_ccw_device *vcdev, __u32 flag)
+{
+        unsigned long flags;
+        __u32 ret;
+
+        spin_lock_irqsave(get_ccwdev_lock(vcdev->cdev), flags);
+        if (vcdev->err)
+                ret = 0;
+        else
+                ret = vcdev->curr_io & flag;
+        spin_unlock_irqrestore(get_ccwdev_lock(vcdev->cdev), flags);
+        return ret;
+}
+
+static int ccw_io_helper(struct virtio_ccw_device *vcdev, __u32 intparm)
+{
+        int ret;
+        unsigned long flags;
+        int flag = intparm & VIRTIO_CCW_INTPARM_MASK;
+
+        spin_lock_irqsave(get_ccwdev_lock(vcdev->cdev), flags);
+        ret = ccw_device_start(vcdev->cdev, vcdev->ccw, intparm, 0, 0);
+        if (!ret)
+                vcdev->curr_io |= flag;
+        spin_unlock_irqrestore(get_ccwdev_lock(vcdev->cdev), flags);
+        wait_event(vcdev->wait_q, doing_io(vcdev, flag) == 0);
+        return ret ? ret : vcdev->err;
+}
+
+static inline long do_kvm_notify(struct subchannel_id schid,
+                                 unsigned long queue_index)
+{
+        register unsigned long __nr asm("1") = KVM_S390_VIRTIO_CCW_NOTIFY;
+        register struct subchannel_id __schid asm("2") = schid;
+        register unsigned long __index asm("3") = queue_index;
+        register long __rc asm("2");
+
+        asm volatile ("diag 2,4,0x500\n"
+                      : "=d" (__rc) : "d" (__nr), "d" (__schid), "d" (__index)
+                      : "memory", "cc");
+        return __rc;
+}
+
+static void virtio_ccw_kvm_notify(struct virtqueue *vq)
+{
+        struct virtio_ccw_vq_info *info = vq->priv;
+        struct virtio_ccw_device *vcdev;
+        struct subchannel_id schid;
+
+        vcdev = to_vc_device(info->vq->vdev);
+        ccw_device_get_schid(vcdev->cdev, &schid);
+        do_kvm_notify(schid, virtqueue_get_queue_index(vq));
+}
+
+static int virtio_ccw_read_vq_conf(struct virtio_ccw_device *vcdev, int index)
+{
+        vcdev->config_block->index = index;
+        vcdev->ccw->cmd_code = CCW_CMD_READ_VQ_CONF;
+        vcdev->ccw->flags = 0;
+        vcdev->ccw->count = sizeof(struct vq_config_block);
+        vcdev->ccw->cda = (__u32)(unsigned long)(vcdev->config_block);
+        ccw_io_helper(vcdev, VIRTIO_CCW_DOING_READ_VQ_CONF);
+        return vcdev->config_block->num;
+}
+
+static void virtio_ccw_del_vq(struct virtqueue *vq)
+{
+        struct virtio_ccw_device *vcdev = to_vc_device(vq->vdev);
+        struct virtio_ccw_vq_info *info = vq->priv;
+        unsigned long flags;
+        unsigned long size;
+        int ret;
+        unsigned int index = virtqueue_get_queue_index(vq);
+
+        /* Remove from our list. */
+        spin_lock_irqsave(&vcdev->lock, flags);
+        list_del(&info->node);
+        spin_unlock_irqrestore(&vcdev->lock, flags);
+
+        /* Release from host. */
+        info->info_block->queue = 0;
+        info->info_block->align = 0;
+        info->info_block->index = index;
+        info->info_block->num = 0;
+        vcdev->ccw->cmd_code = CCW_CMD_SET_VQ;
+        vcdev->ccw->flags = 0;
+        vcdev->ccw->count = sizeof(*info->info_block);
+        vcdev->ccw->cda = (__u32)(unsigned long)(info->info_block);
+        ret = ccw_io_helper(vcdev, VIRTIO_CCW_DOING_SET_VQ | index);
+        /*
+         * -ENODEV isn't considered an error: The device is gone anyway.
+         * This may happen on device detach.
+         */
+        if (ret && (ret != -ENODEV))
+                dev_warn(&vq->vdev->dev, "Error %d while deleting queue %d",
+                         ret, index);
+
+        vring_del_virtqueue(vq);
+        size = PAGE_ALIGN(vring_size(info->num, KVM_VIRTIO_CCW_RING_ALIGN));
+        free_pages_exact(info->queue, size);
+        kfree(info->info_block);
+        kfree(info);
+}
+
+static void virtio_ccw_del_vqs(struct virtio_device *vdev)
+{
+        struct virtqueue *vq, *n;
+
+        list_for_each_entry_safe(vq, n, &vdev->vqs, list)
+                virtio_ccw_del_vq(vq);
+}
+
+static struct virtqueue *virtio_ccw_setup_vq(struct virtio_device *vdev,
+                                             int i, vq_callback_t *callback,
+                                             const char *name)
+{
+        struct virtio_ccw_device *vcdev = to_vc_device(vdev);
+        int err;
+        struct virtqueue *vq;
+        struct virtio_ccw_vq_info *info;
+        unsigned long size;
+        unsigned long flags;
+
+        /* Allocate queue. */
+        info = kzalloc(sizeof(struct virtio_ccw_vq_info), GFP_KERNEL);
+        if (!info) {
+                dev_warn(&vcdev->cdev->dev, "no info\n");
+                err = -ENOMEM;
+                goto out_err;
+        }
+        info->info_block = kzalloc(sizeof(*info->info_block),
+                                   GFP_DMA | GFP_KERNEL);
+        if (!info->info_block) {
+                dev_warn(&vcdev->cdev->dev, "no info block\n");
+                err = -ENOMEM;
+                goto out_err;
+        }
+        info->num = virtio_ccw_read_vq_conf(vcdev, i);
+        size = PAGE_ALIGN(vring_size(info->num, KVM_VIRTIO_CCW_RING_ALIGN));
+        info->queue = alloc_pages_exact(size, GFP_KERNEL | __GFP_ZERO);
+        if (info->queue == NULL) {
+                dev_warn(&vcdev->cdev->dev, "no queue\n");
+                err = -ENOMEM;
+                goto out_err;
+        }
+
+        vq = vring_new_virtqueue(i, info->num, KVM_VIRTIO_CCW_RING_ALIGN, vdev,
+                                 true, info->queue, virtio_ccw_kvm_notify,
+                                 callback, name);
+        if (!vq) {
+                /* For now, we fail if we can't get the requested size. */
+                dev_warn(&vcdev->cdev->dev, "no vq\n");
+                err = -ENOMEM;
+                free_pages_exact(info->queue, size);
+                goto out_err;
+        }
+        info->vq = vq;
+        vq->priv = info;
+
+        /* Register it with the host. */
+        info->info_block->queue = (__u64)info->queue;
+        info->info_block->align = KVM_VIRTIO_CCW_RING_ALIGN;
+        info->info_block->index = i;
+        info->info_block->num = info->num;
+        vcdev->ccw->cmd_code = CCW_CMD_SET_VQ;
+        vcdev->ccw->flags = 0;
+        vcdev->ccw->count = sizeof(*info->info_block);
+        vcdev->ccw->cda = (__u32)(unsigned long)(info->info_block);
+        err = ccw_io_helper(vcdev, VIRTIO_CCW_DOING_SET_VQ | i);
+        if (err) {
+                dev_warn(&vcdev->cdev->dev, "SET_VQ failed\n");
+                free_pages_exact(info->queue, size);
+                info->vq = NULL;
+                vq->priv = NULL;
+                goto out_err;
+        }
+
+        /* Save it to our list. */
+        spin_lock_irqsave(&vcdev->lock, flags);
+        list_add(&info->node, &vcdev->virtqueues);
+        spin_unlock_irqrestore(&vcdev->lock, flags);
+
+        return vq;
+
+out_err:
+        if (info)
+                kfree(info->info_block);
+        kfree(info);
+        return ERR_PTR(err);
+}
+
+static int virtio_ccw_find_vqs(struct virtio_device *vdev, unsigned nvqs,
+                               struct virtqueue *vqs[],
+                               vq_callback_t *callbacks[],
+                               const char *names[])
+{
+        struct virtio_ccw_device *vcdev = to_vc_device(vdev);
+        unsigned long *indicatorp = NULL;
+        int ret, i;
+
+        for (i = 0; i < nvqs; ++i) {
+                vqs[i] = virtio_ccw_setup_vq(vdev, i, callbacks[i], names[i]);
+                if (IS_ERR(vqs[i])) {
+                        ret = PTR_ERR(vqs[i]);
+                        vqs[i] = NULL;
+                        goto out;
+                }
+        }
+        ret = -ENOMEM;
+        /* We need a data area under 2G to communicate. */
+        indicatorp = kmalloc(sizeof(&vcdev->indicators), GFP_DMA | GFP_KERNEL);
+        if (!indicatorp)
+                goto out;
+        *indicatorp = (unsigned long) &vcdev->indicators;
+        /* Register queue indicators with host. */
+        vcdev->indicators = 0;
+        vcdev->ccw->cmd_code = CCW_CMD_SET_IND;
+        vcdev->ccw->flags = 0;
+        vcdev->ccw->count = sizeof(vcdev->indicators);
+        vcdev->ccw->cda = (__u32)(unsigned long) indicatorp;
+        ret = ccw_io_helper(vcdev, VIRTIO_CCW_DOING_SET_IND);
+        if (ret)
+                goto out;
+        /* Register indicators2 with host for config changes */
+        *indicatorp = (unsigned long) &vcdev->indicators2;
+        vcdev->indicators2 = 0;
+        vcdev->ccw->cmd_code = CCW_CMD_SET_CONF_IND;
+        vcdev->ccw->flags = 0;
+        vcdev->ccw->count = sizeof(vcdev->indicators2);
+        vcdev->ccw->cda = (__u32)(unsigned long) indicatorp;
+        ret = ccw_io_helper(vcdev, VIRTIO_CCW_DOING_SET_CONF_IND);
+        if (ret)
+                goto out;
+
+        kfree(indicatorp);
+        return 0;
+out:
+        kfree(indicatorp);
+        virtio_ccw_del_vqs(vdev);
+        return ret;
+}
+
+static void virtio_ccw_reset(struct virtio_device *vdev)
+{
+        struct virtio_ccw_device *vcdev = to_vc_device(vdev);
+
+        /* Zero status bits. */
+        vcdev->status = 0;
+
+        /* Send a reset ccw on device. */
+        vcdev->ccw->cmd_code = CCW_CMD_VDEV_RESET;
+        vcdev->ccw->flags = 0;
+        vcdev->ccw->count = 0;
+        vcdev->ccw->cda = 0;
+        ccw_io_helper(vcdev, VIRTIO_CCW_DOING_RESET);
+}
+
+static u32 virtio_ccw_get_features(struct virtio_device *vdev)
+{
+        struct virtio_ccw_device *vcdev = to_vc_device(vdev);
+        struct virtio_feature_desc features;
+        int ret;
+
+        /* Read the feature bits from the host. */
+        /* TODO: Features > 32 bits */
+        features.index = 0;
+        vcdev->ccw->cmd_code = CCW_CMD_READ_FEAT;
+        vcdev->ccw->flags = 0;
+        vcdev->ccw->count = sizeof(features);
+        vcdev->ccw->cda = vcdev->area;
+        ret = ccw_io_helper(vcdev, VIRTIO_CCW_DOING_READ_FEAT);
+        if (ret)
+                return 0;
+
+        memcpy(&features, (void *)(unsigned long)vcdev->area,
+               sizeof(features));
+        return le32_to_cpu(features.features);
+}
+
+static void virtio_ccw_finalize_features(struct virtio_device *vdev)
+{
+        struct virtio_ccw_device *vcdev = to_vc_device(vdev);
+        struct virtio_feature_desc features;
+        int i;
+
+        /* Give virtio_ring a chance to accept features. */
+        vring_transport_features(vdev);
+
+        for (i = 0; i < sizeof(*vdev->features) / sizeof(features.features);
+             i++) {
+                int highbits = i % 2 ? 32 : 0;
+                features.index = i;
+                features.features = cpu_to_le32(vdev->features[i / 2]
+                                                >> highbits);
+                memcpy((void *)(unsigned long)vcdev->area, &features,
+                       sizeof(features));
+                /* Write the feature bits to the host. */
+                vcdev->ccw->cmd_code = CCW_CMD_WRITE_FEAT;
+                vcdev->ccw->flags = 0;
+                vcdev->ccw->count = sizeof(features);
+                vcdev->ccw->cda = vcdev->area;
+                ccw_io_helper(vcdev, VIRTIO_CCW_DOING_WRITE_FEAT);
+        }
+}
+
+static void virtio_ccw_get_config(struct virtio_device *vdev,
+                                  unsigned int offset, void *buf, unsigned len)
+{
+        struct virtio_ccw_device *vcdev = to_vc_device(vdev);
+        int ret;
+
+        /* Read the config area from the host. */
+        vcdev->ccw->cmd_code = CCW_CMD_READ_CONF;
+        vcdev->ccw->flags = 0;
+        vcdev->ccw->count = offset + len;
+        vcdev->ccw->cda = vcdev->area;
+        ret = ccw_io_helper(vcdev, VIRTIO_CCW_DOING_READ_CONFIG);
+        if (ret)
+                return;
+
+        memcpy(vcdev->config, (void *)(unsigned long)vcdev->area,
+               sizeof(vcdev->config));
+        memcpy(buf, &vcdev->config[offset], len);
+}
+
+static void virtio_ccw_set_config(struct virtio_device *vdev,
+                                  unsigned int offset, const void *buf,
+                                  unsigned len)
+{
+        struct virtio_ccw_device *vcdev = to_vc_device(vdev);
+
+        memcpy(&vcdev->config[offset], buf, len);
+        /* Write the config area to the host. */
+        memcpy((void *)(unsigned long)vcdev->area, vcdev->config,
+               sizeof(vcdev->config));
+        vcdev->ccw->cmd_code = CCW_CMD_WRITE_CONF;
+        vcdev->ccw->flags = 0;
+        vcdev->ccw->count = offset + len;
+        vcdev->ccw->cda = vcdev->area;
+        ccw_io_helper(vcdev, VIRTIO_CCW_DOING_WRITE_CONFIG);
+}
+
+static u8 virtio_ccw_get_status(struct virtio_device *vdev)
+{
+        struct virtio_ccw_device *vcdev = to_vc_device(vdev);
+
+        return vcdev->status;
+}
+
+static void virtio_ccw_set_status(struct virtio_device *vdev, u8 status)
+{
+        struct virtio_ccw_device *vcdev = to_vc_device(vdev);
+
+        /* Write the status to the host. */
+        vcdev->status = status;
+        memcpy((void *)(unsigned long)vcdev->area, &status, sizeof(status));
+        vcdev->ccw->cmd_code = CCW_CMD_WRITE_STATUS;
+        vcdev->ccw->flags = 0;
+        vcdev->ccw->count = sizeof(status);
+        vcdev->ccw->cda = vcdev->area;
+        ccw_io_helper(vcdev, VIRTIO_CCW_DOING_WRITE_STATUS);
+}
+
+static struct virtio_config_ops virtio_ccw_config_ops = {
+        .get_features = virtio_ccw_get_features,
+        .finalize_features = virtio_ccw_finalize_features,
+        .get = virtio_ccw_get_config,
+        .set = virtio_ccw_set_config,
+        .get_status = virtio_ccw_get_status,
+        .set_status = virtio_ccw_set_status,
+        .reset = virtio_ccw_reset,
+        .find_vqs = virtio_ccw_find_vqs,
+        .del_vqs = virtio_ccw_del_vqs,
+};
+
+
+/*
+ * ccw bus driver related functions
+ */
+
+static void virtio_ccw_release_dev(struct device *_d)
+{
+        struct virtio_device *dev = container_of(_d, struct virtio_device,
+                                                 dev);
+        struct virtio_ccw_device *vcdev = to_vc_device(dev);
+
+        kfree((void *)(unsigned long)vcdev->area);
+        kfree(vcdev->config_block);
+        kfree(vcdev->ccw);
+        kfree(vcdev);
+}
+
+static int irb_is_error(struct irb *irb)
+{
+        if (scsw_cstat(&irb->scsw) != 0)
+                return 1;
+        if (scsw_dstat(&irb->scsw) & ~(DEV_STAT_CHN_END | DEV_STAT_DEV_END))
+                return 1;
+        if (scsw_cc(&irb->scsw) != 0)
+                return 1;
+        return 0;
+}
+
+static struct virtqueue *virtio_ccw_vq_by_ind(struct virtio_ccw_device *vcdev,
+                                              int index)
+{
+        struct virtio_ccw_vq_info *info;
+        unsigned long flags;
+        struct virtqueue *vq;
+
+        vq = NULL;
+        spin_lock_irqsave(&vcdev->lock, flags);
+        list_for_each_entry(info, &vcdev->virtqueues, node) {
+                if (virtqueue_get_queue_index(info->vq) == index) {
+                        vq = info->vq;
+                        break;
+                }
+        }
+        spin_unlock_irqrestore(&vcdev->lock, flags);
+        return vq;
+}
+
+static void virtio_ccw_int_handler(struct ccw_device *cdev,
+                                   unsigned long intparm,
+                                   struct irb *irb)
+{
+        __u32 activity = intparm & VIRTIO_CCW_INTPARM_MASK;
+        struct virtio_ccw_device *vcdev = dev_get_drvdata(&cdev->dev);
+        int i;
+        struct virtqueue *vq;
+        struct virtio_driver *drv;
+
+        /* Check if it's a notification from the host. */
+        if ((intparm == 0) &&
+            (scsw_stctl(&irb->scsw) ==
+             (SCSW_STCTL_ALERT_STATUS | SCSW_STCTL_STATUS_PEND))) {
+                /* OK */
+        }
+        if (irb_is_error(irb))
+                vcdev->err = -EIO; /* XXX - use real error */
+        if (vcdev->curr_io & activity) {
+                switch (activity) {
+                case VIRTIO_CCW_DOING_READ_FEAT:
+                case VIRTIO_CCW_DOING_WRITE_FEAT:
+                case VIRTIO_CCW_DOING_READ_CONFIG:
+                case VIRTIO_CCW_DOING_WRITE_CONFIG:
+                case VIRTIO_CCW_DOING_WRITE_STATUS:
+                case VIRTIO_CCW_DOING_SET_VQ:
+                case VIRTIO_CCW_DOING_SET_IND:
+                case VIRTIO_CCW_DOING_SET_CONF_IND:
+                case VIRTIO_CCW_DOING_RESET:
+                case VIRTIO_CCW_DOING_READ_VQ_CONF:
+                        vcdev->curr_io &= ~activity;
+                        wake_up(&vcdev->wait_q);
+                        break;
+                default:
+                        /* don't know what to do... */
+                        dev_warn(&cdev->dev, "Suspicious activity '%08x'\n",
+                                 activity);
+                        WARN_ON(1);
+                        break;
+                }
+        }
+        for_each_set_bit(i, &vcdev->indicators,
+                         sizeof(vcdev->indicators) * BITS_PER_BYTE) {
+                /* The bit clear must happen before the vring kick. */
+                clear_bit(i, &vcdev->indicators);
+                barrier();
+                vq = virtio_ccw_vq_by_ind(vcdev, i);
+                vring_interrupt(0, vq);
+        }
+        if (test_bit(0, &vcdev->indicators2)) {
+                drv = container_of(vcdev->vdev.dev.driver,
+                                   struct virtio_driver, driver);
+
+                if (drv && drv->config_changed)
+                        drv->config_changed(&vcdev->vdev);
+                clear_bit(0, &vcdev->indicators2);
+        }
+}
+
+/*
+ * We usually want to autoonline all devices, but give the admin
+ * a way to exempt devices from this.
+ */
+#define __DEV_WORDS ((__MAX_SUBCHANNEL + (8*sizeof(long) - 1)) / \
+                     (8*sizeof(long)))
+static unsigned long devs_no_auto[__MAX_SSID + 1][__DEV_WORDS];
+
+static char *no_auto = "";
+
+module_param(no_auto, charp, 0444);
+MODULE_PARM_DESC(no_auto, "list of ccw bus id ranges not to be auto-onlined");
+
+static int virtio_ccw_check_autoonline(struct ccw_device *cdev)
+{
+        struct ccw_dev_id id;
+
+        ccw_device_get_id(cdev, &id);
+        if (test_bit(id.devno, devs_no_auto[id.ssid]))
+                return 0;
+        return 1;
+}
+
+static void virtio_ccw_auto_online(void *data, async_cookie_t cookie)
+{
+        struct ccw_device *cdev = data;
+        int ret;
+
+        ret = ccw_device_set_online(cdev);
+        if (ret)
+                dev_warn(&cdev->dev, "Failed to set online: %d\n", ret);
+}
+
+static int virtio_ccw_probe(struct ccw_device *cdev)
+{
+        cdev->handler = virtio_ccw_int_handler;
+
+        if (virtio_ccw_check_autoonline(cdev))
+                async_schedule(virtio_ccw_auto_online, cdev);
+        return 0;
+}
+
+static void virtio_ccw_remove(struct ccw_device *cdev)
+{
+        struct virtio_ccw_device *vcdev = dev_get_drvdata(&cdev->dev);
+
+        if (cdev->online) {
+                unregister_virtio_device(&vcdev->vdev);
+                dev_set_drvdata(&cdev->dev, NULL);
+        }
+        cdev->handler = NULL;
+}
+
+static int virtio_ccw_offline(struct ccw_device *cdev)
+{
+        struct virtio_ccw_device *vcdev = dev_get_drvdata(&cdev->dev);
+
+        unregister_virtio_device(&vcdev->vdev);
+        dev_set_drvdata(&cdev->dev, NULL);
+        return 0;
+}
+
+
+/* Area needs to be big enough to fit status, features or configuration. */
+#define VIRTIO_AREA_SIZE VIRTIO_CCW_CONFIG_SIZE /* biggest possible use */
+
+static int virtio_ccw_online(struct ccw_device *cdev)
+{
+        int ret;
+        struct virtio_ccw_device *vcdev;
+
+        vcdev = kzalloc(sizeof(*vcdev), GFP_KERNEL);
+        if (!vcdev) {
+                dev_warn(&cdev->dev, "Could not get memory for virtio\n");
+                ret = -ENOMEM;
+                goto out_free;
+        }
+        vcdev->area = (__u32)(unsigned long)kzalloc(VIRTIO_AREA_SIZE,
+                                                    GFP_DMA | GFP_KERNEL);
+        if (!vcdev->area) {
+                dev_warn(&cdev->dev, "Cound not get memory for virtio\n");
+                ret = -ENOMEM;
+                goto out_free;
+        }
+        vcdev->config_block = kzalloc(sizeof(*vcdev->config_block),
+                                   GFP_DMA | GFP_KERNEL);
+        if (!vcdev->config_block) {
+                ret = -ENOMEM;
+                goto out_free;
+        }
+        vcdev->ccw = kzalloc(sizeof(*vcdev->ccw), GFP_DMA | GFP_KERNEL);
+        if (!vcdev->ccw) {
+                ret = -ENOMEM;
+                goto out_free;
+        }
+
+        vcdev->vdev.dev.parent = &cdev->dev;
+        vcdev->vdev.dev.release = virtio_ccw_release_dev;
+        vcdev->vdev.config = &virtio_ccw_config_ops;
+        vcdev->cdev = cdev;
+        init_waitqueue_head(&vcdev->wait_q);
+        INIT_LIST_HEAD(&vcdev->virtqueues);
+        spin_lock_init(&vcdev->lock);
+
+        dev_set_drvdata(&cdev->dev, vcdev);
+        vcdev->vdev.id.vendor = cdev->id.cu_type;
+        vcdev->vdev.id.device = cdev->id.cu_model;
+        ret = register_virtio_device(&vcdev->vdev);
+        if (ret) {
+                dev_warn(&cdev->dev, "Failed to register virtio device: %d\n",
+                         ret);
+                goto out_put;
+        }
+        return 0;
+out_put:
+        dev_set_drvdata(&cdev->dev, NULL);
+        put_device(&vcdev->vdev.dev);
+        return ret;
+out_free:
+        if (vcdev) {
+                kfree((void *)(unsigned long)vcdev->area);
+                kfree(vcdev->config_block);
+                kfree(vcdev->ccw);
+        }
+        kfree(vcdev);
+        return ret;
+}
+
+static int virtio_ccw_cio_notify(struct ccw_device *cdev, int event)
+{
+        /* TODO: Check whether we need special handling here. */
+        return 0;
+}
+
+static struct ccw_device_id virtio_ids[] = {
+        { CCW_DEVICE(0x3832, 0) },
+        {},
+};
+MODULE_DEVICE_TABLE(ccw, virtio_ids);
+
+static struct ccw_driver virtio_ccw_driver = {
+        .driver = {
+                .owner = THIS_MODULE,
+                .name = "virtio_ccw",
+        },
+        .ids = virtio_ids,
+        .probe = virtio_ccw_probe,
+        .remove = virtio_ccw_remove,
+        .set_offline = virtio_ccw_offline,
+        .set_online = virtio_ccw_online,
+        .notify = virtio_ccw_cio_notify,
+        .int_class = IOINT_VIR,
+};
+
+static int __init pure_hex(char **cp, unsigned int *val, int min_digit,
+                           int max_digit, int max_val)
+{
+        int diff;
+
+        diff = 0;
+        *val = 0;
+
+        while (diff <= max_digit) {
+                int value = hex_to_bin(**cp);
+
+                if (value < 0)
+                        break;
+                *val = *val * 16 + value;
+                (*cp)++;
+                diff++;
+        }
+
+        if ((diff < min_digit) || (diff > max_digit) || (*val > max_val))
+                return 1;
+
+        return 0;
+}
+
+static int __init parse_busid(char *str, unsigned int *cssid,
+                              unsigned int *ssid, unsigned int *devno)
+{
+        char *str_work;
+        int rc, ret;
+
+        rc = 1;
+
+        if (*str == '\0')
+                goto out;
+
+        str_work = str;
+        ret = pure_hex(&str_work, cssid, 1, 2, __MAX_CSSID);
+        if (ret || (str_work[0] != '.'))
+                goto out;
+        str_work++;
+        ret = pure_hex(&str_work, ssid, 1, 1, __MAX_SSID);
+        if (ret || (str_work[0] != '.'))
+                goto out;
+        str_work++;
+        ret = pure_hex(&str_work, devno, 4, 4, __MAX_SUBCHANNEL);
+        if (ret || (str_work[0] != '\0'))
+                goto out;
+
+        rc = 0;
+out:
+        return rc;
+}
+
+static void __init no_auto_parse(void)
+{
+        unsigned int from_cssid, to_cssid, from_ssid, to_ssid, from, to;
+        char *parm, *str;
+        int rc;
+
+        str = no_auto;
+        while ((parm = strsep(&str, ","))) {
+                rc = parse_busid(strsep(&parm, "-"), &from_cssid,
+                                 &from_ssid, &from);
+                if (rc)
+                        continue;
+                if (parm != NULL) {
+                        rc = parse_busid(parm, &to_cssid,
+                                         &to_ssid, &to);
+                        if ((from_ssid > to_ssid) ||
+                            ((from_ssid == to_ssid) && (from > to)))
+                                rc = -EINVAL;
+                } else {
+                        to_cssid = from_cssid;
+                        to_ssid = from_ssid;
+                        to = from;
+                }
+                if (rc)
+                        continue;
+                while ((from_ssid < to_ssid) ||
+                       ((from_ssid == to_ssid) && (from <= to))) {
+                        set_bit(from, devs_no_auto[from_ssid]);
+                        from++;
+                        if (from > __MAX_SUBCHANNEL) {
+                                from_ssid++;
+                                from = 0;
+                        }
+                }
+        }
+}
+
+static int __init virtio_ccw_init(void)
+{
+        /* parse no_auto string before we do anything further */
+        no_auto_parse();
+        return ccw_driver_register(&virtio_ccw_driver);
+}
+module_init(virtio_ccw_init);
+
+static void __exit virtio_ccw_exit(void)
+{
+        ccw_driver_unregister(&virtio_ccw_driver);
+}
+module_exit(virtio_ccw_exit);