506 lines
12 KiB
C
506 lines
12 KiB
C
/*
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* virtio for kvm on s390
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*
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* Copyright IBM Corp. 2008
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License (version 2 only)
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* as published by the Free Software Foundation.
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*
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* Author(s): Christian Borntraeger <borntraeger@de.ibm.com>
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*/
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#include <linux/kernel_stat.h>
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#include <linux/init.h>
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#include <linux/bootmem.h>
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#include <linux/err.h>
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#include <linux/virtio.h>
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#include <linux/virtio_config.h>
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#include <linux/slab.h>
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#include <linux/virtio_console.h>
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#include <linux/interrupt.h>
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#include <linux/virtio_ring.h>
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#include <linux/export.h>
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#include <linux/pfn.h>
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#include <asm/io.h>
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#include <asm/kvm_para.h>
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#include <asm/kvm_virtio.h>
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#include <asm/sclp.h>
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#include <asm/setup.h>
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#include <asm/irq.h>
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#define VIRTIO_SUBCODE_64 0x0D00
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/*
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* The pointer to our (page) of device descriptions.
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*/
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static void *kvm_devices;
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static struct work_struct hotplug_work;
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struct kvm_device {
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struct virtio_device vdev;
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struct kvm_device_desc *desc;
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};
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#define to_kvmdev(vd) container_of(vd, struct kvm_device, vdev)
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/*
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* memory layout:
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* - kvm_device_descriptor
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* struct kvm_device_desc
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* - configuration
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* struct kvm_vqconfig
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* - feature bits
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* - config space
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*/
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static struct kvm_vqconfig *kvm_vq_config(const struct kvm_device_desc *desc)
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{
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return (struct kvm_vqconfig *)(desc + 1);
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}
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static u8 *kvm_vq_features(const struct kvm_device_desc *desc)
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{
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return (u8 *)(kvm_vq_config(desc) + desc->num_vq);
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}
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static u8 *kvm_vq_configspace(const struct kvm_device_desc *desc)
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{
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return kvm_vq_features(desc) + desc->feature_len * 2;
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}
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/*
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* The total size of the config page used by this device (incl. desc)
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*/
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static unsigned desc_size(const struct kvm_device_desc *desc)
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{
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return sizeof(*desc)
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+ desc->num_vq * sizeof(struct kvm_vqconfig)
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+ desc->feature_len * 2
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+ desc->config_len;
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}
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/* This gets the device's feature bits. */
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static u32 kvm_get_features(struct virtio_device *vdev)
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{
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unsigned int i;
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u32 features = 0;
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struct kvm_device_desc *desc = to_kvmdev(vdev)->desc;
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u8 *in_features = kvm_vq_features(desc);
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for (i = 0; i < min(desc->feature_len * 8, 32); i++)
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if (in_features[i / 8] & (1 << (i % 8)))
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features |= (1 << i);
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return features;
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}
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static void kvm_finalize_features(struct virtio_device *vdev)
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{
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unsigned int i, bits;
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struct kvm_device_desc *desc = to_kvmdev(vdev)->desc;
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/* Second half of bitmap is features we accept. */
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u8 *out_features = kvm_vq_features(desc) + desc->feature_len;
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/* Give virtio_ring a chance to accept features. */
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vring_transport_features(vdev);
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memset(out_features, 0, desc->feature_len);
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bits = min_t(unsigned, desc->feature_len, sizeof(vdev->features)) * 8;
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for (i = 0; i < bits; i++) {
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if (test_bit(i, vdev->features))
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out_features[i / 8] |= (1 << (i % 8));
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}
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}
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/*
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* Reading and writing elements in config space
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*/
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static void kvm_get(struct virtio_device *vdev, unsigned int offset,
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void *buf, unsigned len)
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{
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struct kvm_device_desc *desc = to_kvmdev(vdev)->desc;
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BUG_ON(offset + len > desc->config_len);
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memcpy(buf, kvm_vq_configspace(desc) + offset, len);
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}
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static void kvm_set(struct virtio_device *vdev, unsigned int offset,
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const void *buf, unsigned len)
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{
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struct kvm_device_desc *desc = to_kvmdev(vdev)->desc;
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BUG_ON(offset + len > desc->config_len);
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memcpy(kvm_vq_configspace(desc) + offset, buf, len);
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}
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/*
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* The operations to get and set the status word just access
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* the status field of the device descriptor. set_status will also
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* make a hypercall to the host, to tell about status changes
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*/
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static u8 kvm_get_status(struct virtio_device *vdev)
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{
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return to_kvmdev(vdev)->desc->status;
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}
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static void kvm_set_status(struct virtio_device *vdev, u8 status)
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{
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BUG_ON(!status);
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to_kvmdev(vdev)->desc->status = status;
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kvm_hypercall1(KVM_S390_VIRTIO_SET_STATUS,
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(unsigned long) to_kvmdev(vdev)->desc);
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}
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/*
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* To reset the device, we use the KVM_VIRTIO_RESET hypercall, using the
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* descriptor address. The Host will zero the status and all the
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* features.
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*/
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static void kvm_reset(struct virtio_device *vdev)
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{
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kvm_hypercall1(KVM_S390_VIRTIO_RESET,
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(unsigned long) to_kvmdev(vdev)->desc);
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}
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/*
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* When the virtio_ring code wants to notify the Host, it calls us here and we
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* make a hypercall. We hand the address of the virtqueue so the Host
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* knows which virtqueue we're talking about.
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*/
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static bool kvm_notify(struct virtqueue *vq)
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{
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long rc;
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struct kvm_vqconfig *config = vq->priv;
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rc = kvm_hypercall1(KVM_S390_VIRTIO_NOTIFY, config->address);
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if (rc < 0)
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return false;
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return true;
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}
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/*
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* This routine finds the first virtqueue described in the configuration of
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* this device and sets it up.
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*/
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static struct virtqueue *kvm_find_vq(struct virtio_device *vdev,
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unsigned index,
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void (*callback)(struct virtqueue *vq),
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const char *name)
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{
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struct kvm_device *kdev = to_kvmdev(vdev);
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struct kvm_vqconfig *config;
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struct virtqueue *vq;
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int err;
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if (index >= kdev->desc->num_vq)
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return ERR_PTR(-ENOENT);
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if (!name)
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return NULL;
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config = kvm_vq_config(kdev->desc)+index;
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err = vmem_add_mapping(config->address,
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vring_size(config->num,
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KVM_S390_VIRTIO_RING_ALIGN));
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if (err)
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goto out;
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vq = vring_new_virtqueue(index, config->num, KVM_S390_VIRTIO_RING_ALIGN,
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vdev, true, (void *) config->address,
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kvm_notify, callback, name);
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if (!vq) {
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err = -ENOMEM;
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goto unmap;
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}
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/*
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* register a callback token
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* The host will sent this via the external interrupt parameter
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*/
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config->token = (u64) vq;
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vq->priv = config;
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return vq;
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unmap:
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vmem_remove_mapping(config->address,
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vring_size(config->num,
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KVM_S390_VIRTIO_RING_ALIGN));
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out:
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return ERR_PTR(err);
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}
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static void kvm_del_vq(struct virtqueue *vq)
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{
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struct kvm_vqconfig *config = vq->priv;
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vring_del_virtqueue(vq);
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vmem_remove_mapping(config->address,
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vring_size(config->num,
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KVM_S390_VIRTIO_RING_ALIGN));
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}
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static void kvm_del_vqs(struct virtio_device *vdev)
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{
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struct virtqueue *vq, *n;
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list_for_each_entry_safe(vq, n, &vdev->vqs, list)
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kvm_del_vq(vq);
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}
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static int kvm_find_vqs(struct virtio_device *vdev, unsigned nvqs,
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struct virtqueue *vqs[],
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vq_callback_t *callbacks[],
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const char *names[])
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{
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struct kvm_device *kdev = to_kvmdev(vdev);
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int i;
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/* We must have this many virtqueues. */
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if (nvqs > kdev->desc->num_vq)
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return -ENOENT;
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for (i = 0; i < nvqs; ++i) {
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vqs[i] = kvm_find_vq(vdev, i, callbacks[i], names[i]);
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if (IS_ERR(vqs[i]))
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goto error;
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}
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return 0;
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error:
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kvm_del_vqs(vdev);
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return PTR_ERR(vqs[i]);
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}
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static const char *kvm_bus_name(struct virtio_device *vdev)
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{
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return "";
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}
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/*
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* The config ops structure as defined by virtio config
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*/
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static const struct virtio_config_ops kvm_vq_configspace_ops = {
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.get_features = kvm_get_features,
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.finalize_features = kvm_finalize_features,
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.get = kvm_get,
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.set = kvm_set,
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.get_status = kvm_get_status,
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.set_status = kvm_set_status,
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.reset = kvm_reset,
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.find_vqs = kvm_find_vqs,
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.del_vqs = kvm_del_vqs,
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.bus_name = kvm_bus_name,
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};
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/*
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* The root device for the kvm virtio devices.
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* This makes them appear as /sys/devices/kvm_s390/0,1,2 not /sys/devices/0,1,2.
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*/
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static struct device *kvm_root;
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/*
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* adds a new device and register it with virtio
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* appropriate drivers are loaded by the device model
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*/
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static void add_kvm_device(struct kvm_device_desc *d, unsigned int offset)
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{
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struct kvm_device *kdev;
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kdev = kzalloc(sizeof(*kdev), GFP_KERNEL);
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if (!kdev) {
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printk(KERN_EMERG "Cannot allocate kvm dev %u type %u\n",
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offset, d->type);
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return;
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}
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kdev->vdev.dev.parent = kvm_root;
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kdev->vdev.id.device = d->type;
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kdev->vdev.config = &kvm_vq_configspace_ops;
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kdev->desc = d;
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if (register_virtio_device(&kdev->vdev) != 0) {
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printk(KERN_ERR "Failed to register kvm device %u type %u\n",
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offset, d->type);
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kfree(kdev);
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}
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}
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/*
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* scan_devices() simply iterates through the device page.
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* The type 0 is reserved to mean "end of devices".
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*/
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static void scan_devices(void)
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{
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unsigned int i;
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struct kvm_device_desc *d;
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for (i = 0; i < PAGE_SIZE; i += desc_size(d)) {
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d = kvm_devices + i;
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if (d->type == 0)
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break;
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add_kvm_device(d, i);
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}
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}
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/*
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* match for a kvm device with a specific desc pointer
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*/
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static int match_desc(struct device *dev, void *data)
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{
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struct virtio_device *vdev = dev_to_virtio(dev);
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struct kvm_device *kdev = to_kvmdev(vdev);
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return kdev->desc == data;
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}
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/*
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* hotplug_device tries to find changes in the device page.
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*/
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static void hotplug_devices(struct work_struct *dummy)
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{
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unsigned int i;
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struct kvm_device_desc *d;
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struct device *dev;
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for (i = 0; i < PAGE_SIZE; i += desc_size(d)) {
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d = kvm_devices + i;
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/* end of list */
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if (d->type == 0)
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break;
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/* device already exists */
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dev = device_find_child(kvm_root, d, match_desc);
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if (dev) {
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/* XXX check for hotplug remove */
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put_device(dev);
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continue;
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}
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/* new device */
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printk(KERN_INFO "Adding new virtio device %p\n", d);
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add_kvm_device(d, i);
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}
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}
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/*
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* we emulate the request_irq behaviour on top of s390 extints
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*/
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static void kvm_extint_handler(struct ext_code ext_code,
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unsigned int param32, unsigned long param64)
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{
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struct virtqueue *vq;
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u32 param;
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if ((ext_code.subcode & 0xff00) != VIRTIO_SUBCODE_64)
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return;
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inc_irq_stat(IRQEXT_VRT);
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/* The LSB might be overloaded, we have to mask it */
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vq = (struct virtqueue *)(param64 & ~1UL);
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/* We use ext_params to decide what this interrupt means */
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param = param32 & VIRTIO_PARAM_MASK;
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switch (param) {
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case VIRTIO_PARAM_CONFIG_CHANGED:
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virtio_config_changed(vq->vdev);
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break;
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case VIRTIO_PARAM_DEV_ADD:
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schedule_work(&hotplug_work);
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break;
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case VIRTIO_PARAM_VRING_INTERRUPT:
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default:
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vring_interrupt(0, vq);
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break;
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}
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}
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/*
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* For s390-virtio, we expect a page above main storage containing
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* the virtio configuration. Try to actually load from this area
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* in order to figure out if the host provides this page.
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*/
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static int __init test_devices_support(unsigned long addr)
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{
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int ret = -EIO;
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asm volatile(
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"0: lura 0,%1\n"
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"1: xgr %0,%0\n"
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"2:\n"
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EX_TABLE(0b,2b)
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EX_TABLE(1b,2b)
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: "+d" (ret)
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: "a" (addr)
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: "0", "cc");
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return ret;
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}
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/*
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* Init function for virtio
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* devices are in a single page above top of "normal" + standby mem
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*/
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static int __init kvm_devices_init(void)
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{
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int rc;
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unsigned long total_memory_size = sclp_get_rzm() * sclp_get_rnmax();
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if (!MACHINE_IS_KVM)
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return -ENODEV;
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if (test_devices_support(total_memory_size) < 0)
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return -ENODEV;
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rc = vmem_add_mapping(total_memory_size, PAGE_SIZE);
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if (rc)
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return rc;
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kvm_devices = (void *) total_memory_size;
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kvm_root = root_device_register("kvm_s390");
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if (IS_ERR(kvm_root)) {
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rc = PTR_ERR(kvm_root);
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printk(KERN_ERR "Could not register kvm_s390 root device");
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vmem_remove_mapping(total_memory_size, PAGE_SIZE);
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return rc;
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}
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INIT_WORK(&hotplug_work, hotplug_devices);
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irq_subclass_register(IRQ_SUBCLASS_SERVICE_SIGNAL);
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register_external_irq(EXT_IRQ_CP_SERVICE, kvm_extint_handler);
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scan_devices();
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return 0;
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}
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/* code for early console output with virtio_console */
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static __init int early_put_chars(u32 vtermno, const char *buf, int count)
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{
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char scratch[17];
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unsigned int len = count;
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if (len > sizeof(scratch) - 1)
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len = sizeof(scratch) - 1;
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scratch[len] = '\0';
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memcpy(scratch, buf, len);
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kvm_hypercall1(KVM_S390_VIRTIO_NOTIFY, __pa(scratch));
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return len;
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}
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static int __init s390_virtio_console_init(void)
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{
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if (sclp_has_vt220() || sclp_has_linemode())
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return -ENODEV;
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return virtio_cons_early_init(early_put_chars);
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}
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console_initcall(s390_virtio_console_init);
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/*
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* We do this after core stuff, but before the drivers.
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*/
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postcore_initcall(kvm_devices_init);
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