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![Paolo Bonzini](/assets/img/avatar_default.png)
If there are no assigned devices, the guest PAT are not providing any useful information and can be overridden to writeback; VMX always does this because it has the "IPAT" bit in its extended page table entries, but SVM does not have anything similar. Hook into VFIO and legacy device assignment so that they provide this information to KVM. Reviewed-by: Alex Williamson <alex.williamson@redhat.com> Tested-by: Joerg Roedel <jroedel@suse.de> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
295 lines
6.1 KiB
C
295 lines
6.1 KiB
C
/*
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* VFIO-KVM bridge pseudo device
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*
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* Copyright (C) 2013 Red Hat, Inc. All rights reserved.
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* Author: Alex Williamson <alex.williamson@redhat.com>
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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 as
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* published by the Free Software Foundation.
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*/
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#include <linux/errno.h>
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#include <linux/file.h>
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#include <linux/kvm_host.h>
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#include <linux/list.h>
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#include <linux/module.h>
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#include <linux/mutex.h>
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#include <linux/slab.h>
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#include <linux/uaccess.h>
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#include <linux/vfio.h>
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#include "vfio.h"
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struct kvm_vfio_group {
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struct list_head node;
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struct vfio_group *vfio_group;
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};
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struct kvm_vfio {
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struct list_head group_list;
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struct mutex lock;
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bool noncoherent;
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};
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static struct vfio_group *kvm_vfio_group_get_external_user(struct file *filep)
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{
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struct vfio_group *vfio_group;
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struct vfio_group *(*fn)(struct file *);
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fn = symbol_get(vfio_group_get_external_user);
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if (!fn)
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return ERR_PTR(-EINVAL);
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vfio_group = fn(filep);
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symbol_put(vfio_group_get_external_user);
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return vfio_group;
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}
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static void kvm_vfio_group_put_external_user(struct vfio_group *vfio_group)
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{
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void (*fn)(struct vfio_group *);
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fn = symbol_get(vfio_group_put_external_user);
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if (!fn)
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return;
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fn(vfio_group);
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symbol_put(vfio_group_put_external_user);
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}
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static bool kvm_vfio_group_is_coherent(struct vfio_group *vfio_group)
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{
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long (*fn)(struct vfio_group *, unsigned long);
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long ret;
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fn = symbol_get(vfio_external_check_extension);
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if (!fn)
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return false;
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ret = fn(vfio_group, VFIO_DMA_CC_IOMMU);
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symbol_put(vfio_external_check_extension);
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return ret > 0;
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}
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/*
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* Groups can use the same or different IOMMU domains. If the same then
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* adding a new group may change the coherency of groups we've previously
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* been told about. We don't want to care about any of that so we retest
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* each group and bail as soon as we find one that's noncoherent. This
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* means we only ever [un]register_noncoherent_dma once for the whole device.
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*/
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static void kvm_vfio_update_coherency(struct kvm_device *dev)
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{
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struct kvm_vfio *kv = dev->private;
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bool noncoherent = false;
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struct kvm_vfio_group *kvg;
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mutex_lock(&kv->lock);
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list_for_each_entry(kvg, &kv->group_list, node) {
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if (!kvm_vfio_group_is_coherent(kvg->vfio_group)) {
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noncoherent = true;
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break;
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}
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}
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if (noncoherent != kv->noncoherent) {
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kv->noncoherent = noncoherent;
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if (kv->noncoherent)
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kvm_arch_register_noncoherent_dma(dev->kvm);
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else
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kvm_arch_unregister_noncoherent_dma(dev->kvm);
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}
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mutex_unlock(&kv->lock);
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}
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static int kvm_vfio_set_group(struct kvm_device *dev, long attr, u64 arg)
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{
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struct kvm_vfio *kv = dev->private;
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struct vfio_group *vfio_group;
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struct kvm_vfio_group *kvg;
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int32_t __user *argp = (int32_t __user *)(unsigned long)arg;
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struct fd f;
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int32_t fd;
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int ret;
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switch (attr) {
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case KVM_DEV_VFIO_GROUP_ADD:
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if (get_user(fd, argp))
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return -EFAULT;
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f = fdget(fd);
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if (!f.file)
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return -EBADF;
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vfio_group = kvm_vfio_group_get_external_user(f.file);
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fdput(f);
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if (IS_ERR(vfio_group))
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return PTR_ERR(vfio_group);
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mutex_lock(&kv->lock);
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list_for_each_entry(kvg, &kv->group_list, node) {
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if (kvg->vfio_group == vfio_group) {
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mutex_unlock(&kv->lock);
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kvm_vfio_group_put_external_user(vfio_group);
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return -EEXIST;
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}
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}
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kvg = kzalloc(sizeof(*kvg), GFP_KERNEL);
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if (!kvg) {
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mutex_unlock(&kv->lock);
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kvm_vfio_group_put_external_user(vfio_group);
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return -ENOMEM;
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}
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list_add_tail(&kvg->node, &kv->group_list);
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kvg->vfio_group = vfio_group;
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kvm_arch_start_assignment(dev->kvm);
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mutex_unlock(&kv->lock);
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kvm_vfio_update_coherency(dev);
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return 0;
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case KVM_DEV_VFIO_GROUP_DEL:
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if (get_user(fd, argp))
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return -EFAULT;
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f = fdget(fd);
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if (!f.file)
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return -EBADF;
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vfio_group = kvm_vfio_group_get_external_user(f.file);
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fdput(f);
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if (IS_ERR(vfio_group))
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return PTR_ERR(vfio_group);
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ret = -ENOENT;
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mutex_lock(&kv->lock);
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list_for_each_entry(kvg, &kv->group_list, node) {
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if (kvg->vfio_group != vfio_group)
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continue;
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list_del(&kvg->node);
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kvm_vfio_group_put_external_user(kvg->vfio_group);
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kfree(kvg);
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ret = 0;
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break;
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}
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kvm_arch_end_assignment(dev->kvm);
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mutex_unlock(&kv->lock);
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kvm_vfio_group_put_external_user(vfio_group);
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kvm_vfio_update_coherency(dev);
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return ret;
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}
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return -ENXIO;
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}
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static int kvm_vfio_set_attr(struct kvm_device *dev,
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struct kvm_device_attr *attr)
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{
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switch (attr->group) {
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case KVM_DEV_VFIO_GROUP:
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return kvm_vfio_set_group(dev, attr->attr, attr->addr);
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}
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return -ENXIO;
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}
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static int kvm_vfio_has_attr(struct kvm_device *dev,
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struct kvm_device_attr *attr)
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{
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switch (attr->group) {
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case KVM_DEV_VFIO_GROUP:
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switch (attr->attr) {
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case KVM_DEV_VFIO_GROUP_ADD:
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case KVM_DEV_VFIO_GROUP_DEL:
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return 0;
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}
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break;
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}
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return -ENXIO;
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}
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static void kvm_vfio_destroy(struct kvm_device *dev)
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{
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struct kvm_vfio *kv = dev->private;
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struct kvm_vfio_group *kvg, *tmp;
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list_for_each_entry_safe(kvg, tmp, &kv->group_list, node) {
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kvm_vfio_group_put_external_user(kvg->vfio_group);
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list_del(&kvg->node);
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kfree(kvg);
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kvm_arch_end_assignment(dev->kvm);
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}
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kvm_vfio_update_coherency(dev);
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kfree(kv);
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kfree(dev); /* alloc by kvm_ioctl_create_device, free by .destroy */
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}
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static int kvm_vfio_create(struct kvm_device *dev, u32 type);
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static struct kvm_device_ops kvm_vfio_ops = {
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.name = "kvm-vfio",
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.create = kvm_vfio_create,
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.destroy = kvm_vfio_destroy,
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.set_attr = kvm_vfio_set_attr,
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.has_attr = kvm_vfio_has_attr,
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};
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static int kvm_vfio_create(struct kvm_device *dev, u32 type)
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{
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struct kvm_device *tmp;
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struct kvm_vfio *kv;
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/* Only one VFIO "device" per VM */
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list_for_each_entry(tmp, &dev->kvm->devices, vm_node)
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if (tmp->ops == &kvm_vfio_ops)
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return -EBUSY;
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kv = kzalloc(sizeof(*kv), GFP_KERNEL);
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if (!kv)
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return -ENOMEM;
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INIT_LIST_HEAD(&kv->group_list);
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mutex_init(&kv->lock);
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dev->private = kv;
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return 0;
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}
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int kvm_vfio_ops_init(void)
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{
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return kvm_register_device_ops(&kvm_vfio_ops, KVM_DEV_TYPE_VFIO);
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}
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void kvm_vfio_ops_exit(void)
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{
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kvm_unregister_device_ops(KVM_DEV_TYPE_VFIO);
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}
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