Subject: Re: [PATCH 1/2] Revert "vhost: access vq metadata through kernel virtual address"

From: "Michael S. Tsirkin" <[email-masked]>
Date: Fri, 6 Sep 2019 09:46:44 -0400

On Thu, Sep 05, 2019 at 08:27:35PM +0800, Jason Wang wrote:
> It was reported that metadata acceleration introduces several issues,
> so this patch reverts commit ff466032dc9e5a61217f22ea34b2df932786bbfc,
> 73f628ec9e6bcc45b77c53fe6d0c0ec55eaf82af and
> 0b4a7092ffe568a55bf8f3cefdf79ff666586d91.
> 
> We will rework it on the next version.
> 
> Cc: Jason Gunthorpe <[email-masked]>
> Signed-off-by: Jason Wang <[email-masked]>

I am confused by the above.
What I see upstream is 7f466032dc.

commit 7f466032dc9e5a61217f22ea34b2df932786bbfc
Author: Jason Wang <[email-masked]>
Date:   Fri May 24 04:12:18 2019 -0400

    vhost: access vq metadata through kernel virtual address

so this is what I reverted.

Pls take a look, and let me know if you see issues.

Thanks!

> ---
>  drivers/vhost/vhost.c | 515 +-----------------------------------------
>  drivers/vhost/vhost.h |  41 ----
>  2 files changed, 3 insertions(+), 553 deletions(-)
> 
> diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
> index 0536f8526359..791562e03fe0 100644
> --- a/drivers/vhost/vhost.c
> +++ b/drivers/vhost/vhost.c
> @@ -298,160 +298,6 @@ static void vhost_vq_meta_reset(struct vhost_dev *d)
>  		__vhost_vq_meta_reset(d->vqs[i]);
>  }
>  
> -#if VHOST_ARCH_CAN_ACCEL_UACCESS
> -static void vhost_map_unprefetch(struct vhost_map *map)
> -{
> -	kfree(map->pages);
> -	map->pages = NULL;
> -	map->npages = 0;
> -	map->addr = NULL;
> -}
> -
> -static void vhost_uninit_vq_maps(struct vhost_virtqueue *vq)
> -{
> -	struct vhost_map *map[VHOST_NUM_ADDRS];
> -	int i;
> -
> -	spin_lock(&vq->mmu_lock);
> -	for (i = 0; i < VHOST_NUM_ADDRS; i++) {
> -		map[i] = rcu_dereference_protected(vq->maps[i],
> -				  lockdep_is_held(&vq->mmu_lock));
> -		if (map[i])
> -			rcu_assign_pointer(vq->maps[i], NULL);
> -	}
> -	spin_unlock(&vq->mmu_lock);
> -
> -	synchronize_rcu();
> -
> -	for (i = 0; i < VHOST_NUM_ADDRS; i++)
> -		if (map[i])
> -			vhost_map_unprefetch(map[i]);
> -
> -}
> -
> -static void vhost_reset_vq_maps(struct vhost_virtqueue *vq)
> -{
> -	int i;
> -
> -	vhost_uninit_vq_maps(vq);
> -	for (i = 0; i < VHOST_NUM_ADDRS; i++)
> -		vq->uaddrs[i].size = 0;
> -}
> -
> -static bool vhost_map_range_overlap(struct vhost_uaddr *uaddr,
> -				     unsigned long start,
> -				     unsigned long end)
> -{
> -	if (unlikely(!uaddr->size))
> -		return false;
> -
> -	return !(end < uaddr->uaddr || start > uaddr->uaddr - 1 + uaddr->size);
> -}
> -
> -static void vhost_invalidate_vq_start(struct vhost_virtqueue *vq,
> -				      int index,
> -				      unsigned long start,
> -				      unsigned long end)
> -{
> -	struct vhost_uaddr *uaddr = &vq->uaddrs[index];
> -	struct vhost_map *map;
> -	int i;
> -
> -	if (!vhost_map_range_overlap(uaddr, start, end))
> -		return;
> -
> -	spin_lock(&vq->mmu_lock);
> -	++vq->invalidate_count;
> -
> -	map = rcu_dereference_protected(vq->maps[index],
> -					lockdep_is_held(&vq->mmu_lock));
> -	if (map) {
> -		if (uaddr->write) {
> -			for (i = 0; i < map->npages; i++)
> -				set_page_dirty(map->pages[i]);
> -		}
> -		rcu_assign_pointer(vq->maps[index], NULL);
> -	}
> -	spin_unlock(&vq->mmu_lock);
> -
> -	if (map) {
> -		synchronize_rcu();
> -		vhost_map_unprefetch(map);
> -	}
> -}
> -
> -static void vhost_invalidate_vq_end(struct vhost_virtqueue *vq,
> -				    int index,
> -				    unsigned long start,
> -				    unsigned long end)
> -{
> -	if (!vhost_map_range_overlap(&vq->uaddrs[index], start, end))
> -		return;
> -
> -	spin_lock(&vq->mmu_lock);
> -	--vq->invalidate_count;
> -	spin_unlock(&vq->mmu_lock);
> -}
> -
> -static int vhost_invalidate_range_start(struct mmu_notifier *mn,
> -					const struct mmu_notifier_range *range)
> -{
> -	struct vhost_dev *dev = container_of(mn, struct vhost_dev,
> -					     mmu_notifier);
> -	int i, j;
> -
> -	if (!mmu_notifier_range_blockable(range))
> -		return -EAGAIN;
> -
> -	for (i = 0; i < dev->nvqs; i++) {
> -		struct vhost_virtqueue *vq = dev->vqs[i];
> -
> -		for (j = 0; j < VHOST_NUM_ADDRS; j++)
> -			vhost_invalidate_vq_start(vq, j,
> -						  range->start,
> -						  range->end);
> -	}
> -
> -	return 0;
> -}
> -
> -static void vhost_invalidate_range_end(struct mmu_notifier *mn,
> -				       const struct mmu_notifier_range *range)
> -{
> -	struct vhost_dev *dev = container_of(mn, struct vhost_dev,
> -					     mmu_notifier);
> -	int i, j;
> -
> -	for (i = 0; i < dev->nvqs; i++) {
> -		struct vhost_virtqueue *vq = dev->vqs[i];
> -
> -		for (j = 0; j < VHOST_NUM_ADDRS; j++)
> -			vhost_invalidate_vq_end(vq, j,
> -						range->start,
> -						range->end);
> -	}
> -}
> -
> -static const struct mmu_notifier_ops vhost_mmu_notifier_ops = {
> -	.invalidate_range_start = vhost_invalidate_range_start,
> -	.invalidate_range_end = vhost_invalidate_range_end,
> -};
> -
> -static void vhost_init_maps(struct vhost_dev *dev)
> -{
> -	struct vhost_virtqueue *vq;
> -	int i, j;
> -
> -	dev->mmu_notifier.ops = &vhost_mmu_notifier_ops;
> -
> -	for (i = 0; i < dev->nvqs; ++i) {
> -		vq = dev->vqs[i];
> -		for (j = 0; j < VHOST_NUM_ADDRS; j++)
> -			RCU_INIT_POINTER(vq->maps[j], NULL);
> -	}
> -}
> -#endif
> -
>  static void vhost_vq_reset(struct vhost_dev *dev,
>  			   struct vhost_virtqueue *vq)
>  {
> @@ -480,11 +326,7 @@ static void vhost_vq_reset(struct vhost_dev *dev,
>  	vq->busyloop_timeout = 0;
>  	vq->umem = NULL;
>  	vq->iotlb = NULL;
> -	vq->invalidate_count = 0;
>  	__vhost_vq_meta_reset(vq);
> -#if VHOST_ARCH_CAN_ACCEL_UACCESS
> -	vhost_reset_vq_maps(vq);
> -#endif
>  }
>  
>  static int vhost_worker(void *data)
> @@ -634,9 +476,7 @@ void vhost_dev_init(struct vhost_dev *dev,
>  	INIT_LIST_HEAD(&dev->read_list);
>  	INIT_LIST_HEAD(&dev->pending_list);
>  	spin_lock_init(&dev->iotlb_lock);
> -#if VHOST_ARCH_CAN_ACCEL_UACCESS
> -	vhost_init_maps(dev);
> -#endif
> +
>  
>  	for (i = 0; i < dev->nvqs; ++i) {
>  		vq = dev->vqs[i];
> @@ -645,7 +485,6 @@ void vhost_dev_init(struct vhost_dev *dev,
>  		vq->heads = NULL;
>  		vq->dev = dev;
>  		mutex_init(&vq->mutex);
> -		spin_lock_init(&vq->mmu_lock);
>  		vhost_vq_reset(dev, vq);
>  		if (vq->handle_kick)
>  			vhost_poll_init(&vq->poll, vq->handle_kick,
> @@ -725,18 +564,7 @@ long vhost_dev_set_owner(struct vhost_dev *dev)
>  	if (err)
>  		goto err_cgroup;
>  
> -#if VHOST_ARCH_CAN_ACCEL_UACCESS
> -	err = mmu_notifier_register(&dev->mmu_notifier, dev->mm);
> -	if (err)
> -		goto err_mmu_notifier;
> -#endif
> -
>  	return 0;
> -
> -#if VHOST_ARCH_CAN_ACCEL_UACCESS
> -err_mmu_notifier:
> -	vhost_dev_free_iovecs(dev);
> -#endif
>  err_cgroup:
>  	kthread_stop(worker);
>  	dev->worker = NULL;
> @@ -827,107 +655,6 @@ static void vhost_clear_msg(struct vhost_dev *dev)
>  	spin_unlock(&dev->iotlb_lock);
>  }
>  
> -#if VHOST_ARCH_CAN_ACCEL_UACCESS
> -static void vhost_setup_uaddr(struct vhost_virtqueue *vq,
> -			      int index, unsigned long uaddr,
> -			      size_t size, bool write)
> -{
> -	struct vhost_uaddr *addr = &vq->uaddrs[index];
> -
> -	addr->uaddr = uaddr;
> -	addr->size = size;
> -	addr->write = write;
> -}
> -
> -static void vhost_setup_vq_uaddr(struct vhost_virtqueue *vq)
> -{
> -	vhost_setup_uaddr(vq, VHOST_ADDR_DESC,
> -			  (unsigned long)vq->desc,
> -			  vhost_get_desc_size(vq, vq->num),
> -			  false);
> -	vhost_setup_uaddr(vq, VHOST_ADDR_AVAIL,
> -			  (unsigned long)vq->avail,
> -			  vhost_get_avail_size(vq, vq->num),
> -			  false);
> -	vhost_setup_uaddr(vq, VHOST_ADDR_USED,
> -			  (unsigned long)vq->used,
> -			  vhost_get_used_size(vq, vq->num),
> -			  true);
> -}
> -
> -static int vhost_map_prefetch(struct vhost_virtqueue *vq,
> -			       int index)
> -{
> -	struct vhost_map *map;
> -	struct vhost_uaddr *uaddr = &vq->uaddrs[index];
> -	struct page **pages;
> -	int npages = DIV_ROUND_UP(uaddr->size, PAGE_SIZE);
> -	int npinned;
> -	void *vaddr, *v;
> -	int err;
> -	int i;
> -
> -	spin_lock(&vq->mmu_lock);
> -
> -	err = -EFAULT;
> -	if (vq->invalidate_count)
> -		goto err;
> -
> -	err = -ENOMEM;
> -	map = kmalloc(sizeof(*map), GFP_ATOMIC);
> -	if (!map)
> -		goto err;
> -
> -	pages = kmalloc_array(npages, sizeof(struct page *), GFP_ATOMIC);
> -	if (!pages)
> -		goto err_pages;
> -
> -	err = EFAULT;
> -	npinned = __get_user_pages_fast(uaddr->uaddr, npages,
> -					uaddr->write, pages);
> -	if (npinned > 0)
> -		release_pages(pages, npinned);
> -	if (npinned != npages)
> -		goto err_gup;
> -
> -	for (i = 0; i < npinned; i++)
> -		if (PageHighMem(pages[i]))
> -			goto err_gup;
> -
> -	vaddr = v = page_address(pages[0]);
> -
> -	/* For simplicity, fallback to userspace address if VA is not
> -	 * contigious.
> -	 */
> -	for (i = 1; i < npinned; i++) {
> -		v += PAGE_SIZE;
> -		if (v != page_address(pages[i]))
> -			goto err_gup;
> -	}
> -
> -	map->addr = vaddr + (uaddr->uaddr & (PAGE_SIZE - 1));
> -	map->npages = npages;
> -	map->pages = pages;
> -
> -	rcu_assign_pointer(vq->maps[index], map);
> -	/* No need for a synchronize_rcu(). This function should be
> -	 * called by dev->worker so we are serialized with all
> -	 * readers.
> -	 */
> -	spin_unlock(&vq->mmu_lock);
> -
> -	return 0;
> -
> -err_gup:
> -	kfree(pages);
> -err_pages:
> -	kfree(map);
> -err:
> -	spin_unlock(&vq->mmu_lock);
> -	return err;
> -}
> -#endif
> -
>  void vhost_dev_cleanup(struct vhost_dev *dev)
>  {
>  	int i;
> @@ -957,16 +684,8 @@ void vhost_dev_cleanup(struct vhost_dev *dev)
>  		kthread_stop(dev->worker);
>  		dev->worker = NULL;
>  	}
> -	if (dev->mm) {
> -#if VHOST_ARCH_CAN_ACCEL_UACCESS
> -		mmu_notifier_unregister(&dev->mmu_notifier, dev->mm);
> -#endif
> +	if (dev->mm)
>  		mmput(dev->mm);
> -	}
> -#if VHOST_ARCH_CAN_ACCEL_UACCESS
> -	for (i = 0; i < dev->nvqs; i++)
> -		vhost_uninit_vq_maps(dev->vqs[i]);
> -#endif
>  	dev->mm = NULL;
>  }
>  EXPORT_SYMBOL_GPL(vhost_dev_cleanup);
> @@ -1195,26 +914,6 @@ static inline void __user *__vhost_get_user(struct vhost_virtqueue *vq,
>  
>  static inline int vhost_put_avail_event(struct vhost_virtqueue *vq)
>  {
> -#if VHOST_ARCH_CAN_ACCEL_UACCESS
> -	struct vhost_map *map;
> -	struct vring_used *used;
> -
> -	if (!vq->iotlb) {
> -		rcu_read_lock();
> -
> -		map = rcu_dereference(vq->maps[VHOST_ADDR_USED]);
> -		if (likely(map)) {
> -			used = map->addr;
> -			*((__virtio16 *)&used->ring[vq->num]) =
> -				cpu_to_vhost16(vq, vq->avail_idx);
> -			rcu_read_unlock();
> -			return 0;
> -		}
> -
> -		rcu_read_unlock();
> -	}
> -#endif
> -
>  	return vhost_put_user(vq, cpu_to_vhost16(vq, vq->avail_idx),
>  			      vhost_avail_event(vq));
>  }
> @@ -1223,27 +922,6 @@ static inline int vhost_put_used(struct vhost_virtqueue *vq,
>  				 struct vring_used_elem *head, int idx,
>  				 int count)
>  {
> -#if VHOST_ARCH_CAN_ACCEL_UACCESS
> -	struct vhost_map *map;
> -	struct vring_used *used;
> -	size_t size;
> -
> -	if (!vq->iotlb) {
> -		rcu_read_lock();
> -
> -		map = rcu_dereference(vq->maps[VHOST_ADDR_USED]);
> -		if (likely(map)) {
> -			used = map->addr;
> -			size = count * sizeof(*head);
> -			memcpy(used->ring + idx, head, size);
> -			rcu_read_unlock();
> -			return 0;
> -		}
> -
> -		rcu_read_unlock();
> -	}
> -#endif
> -
>  	return vhost_copy_to_user(vq, vq->used->ring + idx, head,
>  				  count * sizeof(*head));
>  }
> @@ -1251,25 +929,6 @@ static inline int vhost_put_used(struct vhost_virtqueue *vq,
>  static inline int vhost_put_used_flags(struct vhost_virtqueue *vq)
>  
>  {
> -#if VHOST_ARCH_CAN_ACCEL_UACCESS
> -	struct vhost_map *map;
> -	struct vring_used *used;
> -
> -	if (!vq->iotlb) {
> -		rcu_read_lock();
> -
> -		map = rcu_dereference(vq->maps[VHOST_ADDR_USED]);
> -		if (likely(map)) {
> -			used = map->addr;
> -			used->flags = cpu_to_vhost16(vq, vq->used_flags);
> -			rcu_read_unlock();
> -			return 0;
> -		}
> -
> -		rcu_read_unlock();
> -	}
> -#endif
> -
>  	return vhost_put_user(vq, cpu_to_vhost16(vq, vq->used_flags),
>  			      &vq->used->flags);
>  }
> @@ -1277,25 +936,6 @@ static inline int vhost_put_used_flags(struct vhost_virtqueue *vq)
>  static inline int vhost_put_used_idx(struct vhost_virtqueue *vq)
>  
>  {
> -#if VHOST_ARCH_CAN_ACCEL_UACCESS
> -	struct vhost_map *map;
> -	struct vring_used *used;
> -
> -	if (!vq->iotlb) {
> -		rcu_read_lock();
> -
> -		map = rcu_dereference(vq->maps[VHOST_ADDR_USED]);
> -		if (likely(map)) {
> -			used = map->addr;
> -			used->idx = cpu_to_vhost16(vq, vq->last_used_idx);
> -			rcu_read_unlock();
> -			return 0;
> -		}
> -
> -		rcu_read_unlock();
> -	}
> -#endif
> -
>  	return vhost_put_user(vq, cpu_to_vhost16(vq, vq->last_used_idx),
>  			      &vq->used->idx);
>  }
> @@ -1341,50 +981,12 @@ static void vhost_dev_unlock_vqs(struct vhost_dev *d)
>  static inline int vhost_get_avail_idx(struct vhost_virtqueue *vq,
>  				      __virtio16 *idx)
>  {
> -#if VHOST_ARCH_CAN_ACCEL_UACCESS
> -	struct vhost_map *map;
> -	struct vring_avail *avail;
> -
> -	if (!vq->iotlb) {
> -		rcu_read_lock();
> -
> -		map = rcu_dereference(vq->maps[VHOST_ADDR_AVAIL]);
> -		if (likely(map)) {
> -			avail = map->addr;
> -			*idx = avail->idx;
> -			rcu_read_unlock();
> -			return 0;
> -		}
> -
> -		rcu_read_unlock();
> -	}
> -#endif
> -
>  	return vhost_get_avail(vq, *idx, &vq->avail->idx);
>  }
>  
>  static inline int vhost_get_avail_head(struct vhost_virtqueue *vq,
>  				       __virtio16 *head, int idx)
>  {
> -#if VHOST_ARCH_CAN_ACCEL_UACCESS
> -	struct vhost_map *map;
> -	struct vring_avail *avail;
> -
> -	if (!vq->iotlb) {
> -		rcu_read_lock();
> -
> -		map = rcu_dereference(vq->maps[VHOST_ADDR_AVAIL]);
> -		if (likely(map)) {
> -			avail = map->addr;
> -			*head = avail->ring[idx & (vq->num - 1)];
> -			rcu_read_unlock();
> -			return 0;
> -		}
> -
> -		rcu_read_unlock();
> -	}
> -#endif
> -
>  	return vhost_get_avail(vq, *head,
>  			       &vq->avail->ring[idx & (vq->num - 1)]);
>  }
> @@ -1392,98 +994,24 @@ static inline int vhost_get_avail_head(struct vhost_virtqueue *vq,
>  static inline int vhost_get_avail_flags(struct vhost_virtqueue *vq,
>  					__virtio16 *flags)
>  {
> -#if VHOST_ARCH_CAN_ACCEL_UACCESS
> -	struct vhost_map *map;
> -	struct vring_avail *avail;
> -
> -	if (!vq->iotlb) {
> -		rcu_read_lock();
> -
> -		map = rcu_dereference(vq->maps[VHOST_ADDR_AVAIL]);
> -		if (likely(map)) {
> -			avail = map->addr;
> -			*flags = avail->flags;
> -			rcu_read_unlock();
> -			return 0;
> -		}
> -
> -		rcu_read_unlock();
> -	}
> -#endif
> -
>  	return vhost_get_avail(vq, *flags, &vq->avail->flags);
>  }
>  
>  static inline int vhost_get_used_event(struct vhost_virtqueue *vq,
>  				       __virtio16 *event)
>  {
> -#if VHOST_ARCH_CAN_ACCEL_UACCESS
> -	struct vhost_map *map;
> -	struct vring_avail *avail;
> -
> -	if (!vq->iotlb) {
> -		rcu_read_lock();
> -		map = rcu_dereference(vq->maps[VHOST_ADDR_AVAIL]);
> -		if (likely(map)) {
> -			avail = map->addr;
> -			*event = (__virtio16)avail->ring[vq->num];
> -			rcu_read_unlock();
> -			return 0;
> -		}
> -		rcu_read_unlock();
> -	}
> -#endif
> -
>  	return vhost_get_avail(vq, *event, vhost_used_event(vq));
>  }
>  
>  static inline int vhost_get_used_idx(struct vhost_virtqueue *vq,
>  				     __virtio16 *idx)
>  {
> -#if VHOST_ARCH_CAN_ACCEL_UACCESS
> -	struct vhost_map *map;
> -	struct vring_used *used;
> -
> -	if (!vq->iotlb) {
> -		rcu_read_lock();
> -
> -		map = rcu_dereference(vq->maps[VHOST_ADDR_USED]);
> -		if (likely(map)) {
> -			used = map->addr;
> -			*idx = used->idx;
> -			rcu_read_unlock();
> -			return 0;
> -		}
> -
> -		rcu_read_unlock();
> -	}
> -#endif
> -
>  	return vhost_get_used(vq, *idx, &vq->used->idx);
>  }
>  
>  static inline int vhost_get_desc(struct vhost_virtqueue *vq,
>  				 struct vring_desc *desc, int idx)
>  {
> -#if VHOST_ARCH_CAN_ACCEL_UACCESS
> -	struct vhost_map *map;
> -	struct vring_desc *d;
> -
> -	if (!vq->iotlb) {
> -		rcu_read_lock();
> -
> -		map = rcu_dereference(vq->maps[VHOST_ADDR_DESC]);
> -		if (likely(map)) {
> -			d = map->addr;
> -			*desc = *(d + idx);
> -			rcu_read_unlock();
> -			return 0;
> -		}
> -
> -		rcu_read_unlock();
> -	}
> -#endif
> -
>  	return vhost_copy_from_user(vq, desc, vq->desc + idx, sizeof(*desc));
>  }
>  
> @@ -1824,32 +1352,12 @@ static bool iotlb_access_ok(struct vhost_virtqueue *vq,
>  	return true;
>  }
>  
> -#if VHOST_ARCH_CAN_ACCEL_UACCESS
> -static void vhost_vq_map_prefetch(struct vhost_virtqueue *vq)
> -{
> -	struct vhost_map __rcu *map;
> -	int i;
> -
> -	for (i = 0; i < VHOST_NUM_ADDRS; i++) {
> -		rcu_read_lock();
> -		map = rcu_dereference(vq->maps[i]);
> -		rcu_read_unlock();
> -		if (unlikely(!map))
> -			vhost_map_prefetch(vq, i);
> -	}
> -}
> -#endif
> -
>  int vq_meta_prefetch(struct vhost_virtqueue *vq)
>  {
>  	unsigned int num = vq->num;
>  
> -	if (!vq->iotlb) {
> -#if VHOST_ARCH_CAN_ACCEL_UACCESS
> -		vhost_vq_map_prefetch(vq);
> -#endif
> +	if (!vq->iotlb)
>  		return 1;
> -	}
>  
>  	return iotlb_access_ok(vq, VHOST_ACCESS_RO, (u64)(uintptr_t)vq->desc,
>  			       vhost_get_desc_size(vq, num), VHOST_ADDR_DESC) &&
> @@ -2060,16 +1568,6 @@ static long vhost_vring_set_num_addr(struct vhost_dev *d,
>  
>  	mutex_lock(&vq->mutex);
>  
> -#if VHOST_ARCH_CAN_ACCEL_UACCESS
> -	/* Unregister MMU notifer to allow invalidation callback
> -	 * can access vq->uaddrs[] without holding a lock.
> -	 */
> -	if (d->mm)
> -		mmu_notifier_unregister(&d->mmu_notifier, d->mm);
> -
> -	vhost_uninit_vq_maps(vq);
> -#endif
> -
>  	switch (ioctl) {
>  	case VHOST_SET_VRING_NUM:
>  		r = vhost_vring_set_num(d, vq, argp);
> @@ -2081,13 +1579,6 @@ static long vhost_vring_set_num_addr(struct vhost_dev *d,
>  		BUG();
>  	}
>  
> -#if VHOST_ARCH_CAN_ACCEL_UACCESS
> -	vhost_setup_vq_uaddr(vq);
> -
> -	if (d->mm)
> -		mmu_notifier_register(&d->mmu_notifier, d->mm);
> -#endif
> -
>  	mutex_unlock(&vq->mutex);
>  
>  	return r;
> diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h
> index 42a8c2a13ab1..e9ed2722b633 100644
> --- a/drivers/vhost/vhost.h
> +++ b/drivers/vhost/vhost.h
> @@ -12,9 +12,6 @@
>  #include <linux/virtio_config.h>
>  #include <linux/virtio_ring.h>
>  #include <linux/atomic.h>
> -#include <linux/pagemap.h>
> -#include <linux/mmu_notifier.h>
> -#include <asm/cacheflush.h>
>  
>  struct vhost_work;
>  typedef void (*vhost_work_fn_t)(struct vhost_work *work);
> @@ -83,24 +80,6 @@ enum vhost_uaddr_type {
>  	VHOST_NUM_ADDRS = 3,
>  };
>  
> -struct vhost_map {
> -	int npages;
> -	void *addr;
> -	struct page **pages;
> -};
> -
> -struct vhost_uaddr {
> -	unsigned long uaddr;
> -	size_t size;
> -	bool write;
> -};
> -
> -#if defined(CONFIG_MMU_NOTIFIER) && ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE == 0
> -#define VHOST_ARCH_CAN_ACCEL_UACCESS 0
> -#else
> -#define VHOST_ARCH_CAN_ACCEL_UACCESS 0
> -#endif
> -
>  /* The virtqueue structure describes a queue attached to a device. */
>  struct vhost_virtqueue {
>  	struct vhost_dev *dev;
> @@ -111,22 +90,7 @@ struct vhost_virtqueue {
>  	struct vring_desc __user *desc;
>  	struct vring_avail __user *avail;
>  	struct vring_used __user *used;
> -
> -#if VHOST_ARCH_CAN_ACCEL_UACCESS
> -	/* Read by memory accessors, modified by meta data
> -	 * prefetching, MMU notifier and vring ioctl().
> -	 * Synchonrized through mmu_lock (writers) and RCU (writers
> -	 * and readers).
> -	 */
> -	struct vhost_map __rcu *maps[VHOST_NUM_ADDRS];
> -	/* Read by MMU notifier, modified by vring ioctl(),
> -	 * synchronized through MMU notifier
> -	 * registering/unregistering.
> -	 */
> -	struct vhost_uaddr uaddrs[VHOST_NUM_ADDRS];
> -#endif
>  	const struct vhost_umem_node *meta_iotlb[VHOST_NUM_ADDRS];
> -
>  	struct file *kick;
>  	struct eventfd_ctx *call_ctx;
>  	struct eventfd_ctx *error_ctx;
> @@ -181,8 +145,6 @@ struct vhost_virtqueue {
>  	bool user_be;
>  #endif
>  	u32 busyloop_timeout;
> -	spinlock_t mmu_lock;
> -	int invalidate_count;
>  };
>  
>  struct vhost_msg_node {
> @@ -196,9 +158,6 @@ struct vhost_msg_node {
>  
>  struct vhost_dev {
>  	struct mm_struct *mm;
> -#ifdef CONFIG_MMU_NOTIFIER
> -	struct mmu_notifier mmu_notifier;
> -#endif
>  	struct mutex mutex;
>  	struct vhost_virtqueue **vqs;
>  	int nvqs;
> -- 
> 2.19.1