/* * 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, };