Re: [PATCH 11/21] vhost-vdpa: introduce asid based IOTLB

[Eli Cohen <elic@nvidia.com>]

On Wed, Dec 16, 2020 at 02:48:08PM +0800, Jason Wang wrote:
> This patch converts the vhost-vDPA device to support multiple IOTLBs
> tagged via ASID via hlist. This will be used for supporting multiple
> address spaces in the following patches.
> 
> Signed-off-by: Jason Wang <jasowang@redhat.com>
> ---
>  drivers/vhost/vdpa.c | 106 ++++++++++++++++++++++++++++++++-----------
>  1 file changed, 80 insertions(+), 26 deletions(-)
> 
> diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
> index feb6a58df22d..060d5b5b7e64 100644
> --- a/drivers/vhost/vdpa.c
> +++ b/drivers/vhost/vdpa.c
> @@ -33,13 +33,21 @@ enum {
>  
>  #define VHOST_VDPA_DEV_MAX (1U << MINORBITS)
>  
> +#define VHOST_VDPA_IOTLB_BUCKETS 16
> +
> +struct vhost_vdpa_as {
> +	struct hlist_node hash_link;
> +	struct vhost_iotlb iotlb;
> +	u32 id;
> +};
> +
>  struct vhost_vdpa {
>  	struct vhost_dev vdev;
>  	struct iommu_domain *domain;
>  	struct vhost_virtqueue *vqs;
>  	struct completion completion;
>  	struct vdpa_device *vdpa;
> -	struct vhost_iotlb *iotlb;
> +	struct hlist_head as[VHOST_VDPA_IOTLB_BUCKETS];
>  	struct device dev;
>  	struct cdev cdev;
>  	atomic_t opened;
> @@ -49,12 +57,64 @@ struct vhost_vdpa {
>  	struct eventfd_ctx *config_ctx;
>  	int in_batch;
>  	struct vdpa_iova_range range;
> +	int used_as;
>  };
>  
>  static DEFINE_IDA(vhost_vdpa_ida);
>  
>  static dev_t vhost_vdpa_major;
>  
> +static struct vhost_vdpa_as *asid_to_as(struct vhost_vdpa *v, u32 asid)
> +{
> +	struct hlist_head *head = &v->as[asid % VHOST_VDPA_IOTLB_BUCKETS];
> +	struct vhost_vdpa_as *as;
> +
> +	hlist_for_each_entry(as, head, hash_link)
> +		if (as->id == asid)
> +			return as;
> +
> +	return NULL;
> +}
> +
> +static struct vhost_vdpa_as *vhost_vdpa_alloc_as(struct vhost_vdpa *v, u32 asid)
> +{
> +	struct hlist_head *head = &v->as[asid % VHOST_VDPA_IOTLB_BUCKETS];
> +	struct vhost_vdpa_as *as;
> +
> +	if (asid_to_as(v, asid))
> +		return NULL;
> +
> +	as = kmalloc(sizeof(*as), GFP_KERNEL);

kzalloc()? See comment below.

> +	if (!as)
> +		return NULL;
> +
> +	vhost_iotlb_init(&as->iotlb, 0, 0);
> +	as->id = asid;
> +	hlist_add_head(&as->hash_link, head);
> +	++v->used_as;

Although you eventually ended up removing used_as, this is a bug since
you're incrementing a random value. Maybe it's better to be on the safe
side and use kzalloc() for as above.

> +
> +	return as;
> +}
> +
> +static int vhost_vdpa_remove_as(struct vhost_vdpa *v, u32 asid)
> +{
> +	struct vhost_vdpa_as *as = asid_to_as(v, asid);
> +
> +	/* Remove default address space is not allowed */
> +	if (asid == 0)
> +		return -EINVAL;
> +
> +	if (!as)
> +		return -EINVAL;
> +
> +	hlist_del(&as->hash_link);
> +	vhost_iotlb_reset(&as->iotlb);
> +	kfree(as);
> +	--v->used_as;
> +
> +	return 0;
> +}
> +
>  static void handle_vq_kick(struct vhost_work *work)
>  {
>  	struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
> @@ -525,15 +585,6 @@ static void vhost_vdpa_iotlb_unmap(struct vhost_vdpa *v,
>  	}
>  }
>  
> -static void vhost_vdpa_iotlb_free(struct vhost_vdpa *v)
> -{
> -	struct vhost_iotlb *iotlb = v->iotlb;
> -
> -	vhost_vdpa_iotlb_unmap(v, iotlb, 0ULL, 0ULL - 1);
> -	kfree(v->iotlb);
> -	v->iotlb = NULL;
> -}
> -
>  static int perm_to_iommu_flags(u32 perm)
>  {
>  	int flags = 0;
> @@ -745,7 +796,8 @@ static int vhost_vdpa_process_iotlb_msg(struct vhost_dev *dev, u32 asid,
>  	struct vhost_vdpa *v = container_of(dev, struct vhost_vdpa, vdev);
>  	struct vdpa_device *vdpa = v->vdpa;
>  	const struct vdpa_config_ops *ops = vdpa->config;
> -	struct vhost_iotlb *iotlb = v->iotlb;
> +	struct vhost_vdpa_as *as = asid_to_as(v, 0);
> +	struct vhost_iotlb *iotlb = &as->iotlb;
>  	int r = 0;
>  
>  	if (asid != 0)
> @@ -856,6 +908,13 @@ static void vhost_vdpa_set_iova_range(struct vhost_vdpa *v)
>  	}
>  }
>  
> +static void vhost_vdpa_cleanup(struct vhost_vdpa *v)
> +{
> +	vhost_dev_cleanup(&v->vdev);
> +	kfree(v->vdev.vqs);
> +	vhost_vdpa_remove_as(v, 0);
> +}
> +
>  static int vhost_vdpa_open(struct inode *inode, struct file *filep)
>  {
>  	struct vhost_vdpa *v;
> @@ -886,15 +945,12 @@ static int vhost_vdpa_open(struct inode *inode, struct file *filep)
>  	vhost_dev_init(dev, vqs, nvqs, 0, 0, 0, false,
>  		       vhost_vdpa_process_iotlb_msg);
>  
> -	v->iotlb = vhost_iotlb_alloc(0, 0);
> -	if (!v->iotlb) {
> -		r = -ENOMEM;
> -		goto err_init_iotlb;
> -	}
> +	if (!vhost_vdpa_alloc_as(v, 0))
> +		goto err_alloc_as;
>  
>  	r = vhost_vdpa_alloc_domain(v);
>  	if (r)
> -		goto err_alloc_domain;
> +		goto err_alloc_as;
>  
>  	vhost_vdpa_set_iova_range(v);
>  
> @@ -902,11 +958,8 @@ static int vhost_vdpa_open(struct inode *inode, struct file *filep)
>  
>  	return 0;
>  
> -err_alloc_domain:
> -	vhost_vdpa_iotlb_free(v);
> -err_init_iotlb:
> -	vhost_dev_cleanup(&v->vdev);
> -	kfree(vqs);
> +err_alloc_as:
> +	vhost_vdpa_cleanup(v);
>  err:
>  	atomic_dec(&v->opened);
>  	return r;
> @@ -933,12 +986,10 @@ static int vhost_vdpa_release(struct inode *inode, struct file *filep)
>  	filep->private_data = NULL;
>  	vhost_vdpa_reset(v);
>  	vhost_dev_stop(&v->vdev);
> -	vhost_vdpa_iotlb_free(v);
>  	vhost_vdpa_free_domain(v);
>  	vhost_vdpa_config_put(v);
>  	vhost_vdpa_clean_irq(v);
> -	vhost_dev_cleanup(&v->vdev);
> -	kfree(v->vdev.vqs);
> +	vhost_vdpa_cleanup(v);
>  	mutex_unlock(&d->mutex);
>  
>  	atomic_dec(&v->opened);
> @@ -1033,7 +1084,7 @@ static int vhost_vdpa_probe(struct vdpa_device *vdpa)
>  	const struct vdpa_config_ops *ops = vdpa->config;
>  	struct vhost_vdpa *v;
>  	int minor;
> -	int r;
> +	int i, r;
>  
>  	/* Only support 1 address space and 1 groups */
>  	if (vdpa->ngroups != 1 || vdpa->nas != 1)
> @@ -1085,6 +1136,9 @@ static int vhost_vdpa_probe(struct vdpa_device *vdpa)
>  	init_completion(&v->completion);
>  	vdpa_set_drvdata(vdpa, v);
>  
> +	for (i = 0; i < VHOST_VDPA_IOTLB_BUCKETS; i++)
> +		INIT_HLIST_HEAD(&v->as[i]);
> +
>  	return 0;
>  
>  err:
> -- 
> 2.25.1
>