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- /*
- * VFIO-KVM bridge pseudo device
- *
- * Copyright (C) 2013 Red Hat, Inc. All rights reserved.
- * Author: Alex Williamson <alex.williamson@redhat.com>
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation.
- */
- #include <linux/errno.h>
- #include <linux/file.h>
- #include <linux/kvm_host.h>
- #include <linux/list.h>
- #include <linux/module.h>
- #include <linux/mutex.h>
- #include <linux/slab.h>
- #include <linux/uaccess.h>
- #include <linux/vfio.h>
- struct kvm_vfio_group {
- struct list_head node;
- struct vfio_group *vfio_group;
- };
- struct kvm_vfio {
- struct list_head group_list;
- struct mutex lock;
- bool noncoherent;
- };
- static struct vfio_group *kvm_vfio_group_get_external_user(struct file *filep)
- {
- struct vfio_group *vfio_group;
- struct vfio_group *(*fn)(struct file *);
- fn = symbol_get(vfio_group_get_external_user);
- if (!fn)
- return ERR_PTR(-EINVAL);
- vfio_group = fn(filep);
- symbol_put(vfio_group_get_external_user);
- return vfio_group;
- }
- static void kvm_vfio_group_put_external_user(struct vfio_group *vfio_group)
- {
- void (*fn)(struct vfio_group *);
- fn = symbol_get(vfio_group_put_external_user);
- if (!fn)
- return;
- fn(vfio_group);
- symbol_put(vfio_group_put_external_user);
- }
- /*
- * Groups can use the same or different IOMMU domains. If the same then
- * adding a new group may change the coherency of groups we've previously
- * been told about. We don't want to care about any of that so we retest
- * each group and bail as soon as we find one that's noncoherent. This
- * means we only ever [un]register_noncoherent_dma once for the whole device.
- */
- static void kvm_vfio_update_coherency(struct kvm_device *dev)
- {
- struct kvm_vfio *kv = dev->private;
- bool noncoherent = false;
- struct kvm_vfio_group *kvg;
- mutex_lock(&kv->lock);
- list_for_each_entry(kvg, &kv->group_list, node) {
- /*
- * TODO: We need an interface to check the coherency of
- * the IOMMU domain this group is using. For now, assume
- * it's always noncoherent.
- */
- noncoherent = true;
- break;
- }
- if (noncoherent != kv->noncoherent) {
- kv->noncoherent = noncoherent;
- if (kv->noncoherent)
- kvm_arch_register_noncoherent_dma(dev->kvm);
- else
- kvm_arch_unregister_noncoherent_dma(dev->kvm);
- }
- mutex_unlock(&kv->lock);
- }
- static int kvm_vfio_set_group(struct kvm_device *dev, long attr, u64 arg)
- {
- struct kvm_vfio *kv = dev->private;
- struct vfio_group *vfio_group;
- struct kvm_vfio_group *kvg;
- void __user *argp = (void __user *)arg;
- struct fd f;
- int32_t fd;
- int ret;
- switch (attr) {
- case KVM_DEV_VFIO_GROUP_ADD:
- if (get_user(fd, (int32_t __user *)argp))
- return -EFAULT;
- f = fdget(fd);
- if (!f.file)
- return -EBADF;
- vfio_group = kvm_vfio_group_get_external_user(f.file);
- fdput(f);
- if (IS_ERR(vfio_group))
- return PTR_ERR(vfio_group);
- mutex_lock(&kv->lock);
- list_for_each_entry(kvg, &kv->group_list, node) {
- if (kvg->vfio_group == vfio_group) {
- mutex_unlock(&kv->lock);
- kvm_vfio_group_put_external_user(vfio_group);
- return -EEXIST;
- }
- }
- kvg = kzalloc(sizeof(*kvg), GFP_KERNEL);
- if (!kvg) {
- mutex_unlock(&kv->lock);
- kvm_vfio_group_put_external_user(vfio_group);
- return -ENOMEM;
- }
- list_add_tail(&kvg->node, &kv->group_list);
- kvg->vfio_group = vfio_group;
- mutex_unlock(&kv->lock);
- kvm_vfio_update_coherency(dev);
- return 0;
- case KVM_DEV_VFIO_GROUP_DEL:
- if (get_user(fd, (int32_t __user *)argp))
- return -EFAULT;
- f = fdget(fd);
- if (!f.file)
- return -EBADF;
- vfio_group = kvm_vfio_group_get_external_user(f.file);
- fdput(f);
- if (IS_ERR(vfio_group))
- return PTR_ERR(vfio_group);
- ret = -ENOENT;
- mutex_lock(&kv->lock);
- list_for_each_entry(kvg, &kv->group_list, node) {
- if (kvg->vfio_group != vfio_group)
- continue;
- list_del(&kvg->node);
- kvm_vfio_group_put_external_user(kvg->vfio_group);
- kfree(kvg);
- ret = 0;
- break;
- }
- mutex_unlock(&kv->lock);
- kvm_vfio_group_put_external_user(vfio_group);
- kvm_vfio_update_coherency(dev);
- return ret;
- }
- return -ENXIO;
- }
- static int kvm_vfio_set_attr(struct kvm_device *dev,
- struct kvm_device_attr *attr)
- {
- switch (attr->group) {
- case KVM_DEV_VFIO_GROUP:
- return kvm_vfio_set_group(dev, attr->attr, attr->addr);
- }
- return -ENXIO;
- }
- static int kvm_vfio_has_attr(struct kvm_device *dev,
- struct kvm_device_attr *attr)
- {
- switch (attr->group) {
- case KVM_DEV_VFIO_GROUP:
- switch (attr->attr) {
- case KVM_DEV_VFIO_GROUP_ADD:
- case KVM_DEV_VFIO_GROUP_DEL:
- return 0;
- }
- break;
- }
- return -ENXIO;
- }
- static void kvm_vfio_destroy(struct kvm_device *dev)
- {
- struct kvm_vfio *kv = dev->private;
- struct kvm_vfio_group *kvg, *tmp;
- list_for_each_entry_safe(kvg, tmp, &kv->group_list, node) {
- kvm_vfio_group_put_external_user(kvg->vfio_group);
- list_del(&kvg->node);
- kfree(kvg);
- }
- kvm_vfio_update_coherency(dev);
- kfree(kv);
- kfree(dev); /* alloc by kvm_ioctl_create_device, free by .destroy */
- }
- static int kvm_vfio_create(struct kvm_device *dev, u32 type)
- {
- struct kvm_device *tmp;
- struct kvm_vfio *kv;
- /* Only one VFIO "device" per VM */
- list_for_each_entry(tmp, &dev->kvm->devices, vm_node)
- if (tmp->ops == &kvm_vfio_ops)
- return -EBUSY;
- kv = kzalloc(sizeof(*kv), GFP_KERNEL);
- if (!kv)
- return -ENOMEM;
- INIT_LIST_HEAD(&kv->group_list);
- mutex_init(&kv->lock);
- dev->private = kv;
- return 0;
- }
- struct kvm_device_ops kvm_vfio_ops = {
- .name = "kvm-vfio",
- .create = kvm_vfio_create,
- .destroy = kvm_vfio_destroy,
- .set_attr = kvm_vfio_set_attr,
- .has_attr = kvm_vfio_has_attr,
- };
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