Re: [PATCH 10/21] vhost: support ASID in IOTLB API

[Jason Wang]

On 2020/12/29 下午6:20, Eli Cohen wrote:
> > -static int vhost_process_iotlb_msg(struct vhost_dev *dev,
> > +static int vhost_process_iotlb_msg(struct vhost_dev *dev, u16 asid,
> >   				   struct vhost_iotlb_msg *msg)
> >   {
> >   	int ret = 0;
> >   
> > +	if (asid != 0)
> > +		return -EINVAL;
> > +
> >   	mutex_lock(&dev->mutex);
> >   	vhost_dev_lock_vqs(dev);
> >   	switch (msg->type) {
> > @@ -1135,6 +1138,7 @@ ssize_t vhost_chr_write_iter(struct vhost_dev *dev,
> >   	struct vhost_iotlb_msg msg;
> >   	size_t offset;
> >   	int type, ret;
> > +	u16 asid = 0;
> You assume asid occupies just 16 bits. So maybe you should reserve the
> other 16 bits for future extension:
>
> struct vhost_msg_v2 {
>          __u32 type;
> -       __u32 reserved;
> +       __u16 asid;
> +       __u16 reserved;
>          union {
>
> Moreover, maybe this should be reflected in previous patches that use
> the asid:
>
> -static int mlx5_vdpa_set_map(struct vdpa_device *vdev, struct vhost_iotlb *iotlb)
> +static int mlx5_vdpa_set_map(struct vdpa_device *vdev, u16 asid,
> +                            struct vhost_iotlb *iotlb)
>
> -static int vhost_vdpa_process_iotlb_msg(struct vhost_dev *dev,
> +static int vhost_vdpa_process_iotlb_msg(struct vhost_dev *dev, u16 asid,
>                                          struct vhost_iotlb_msg *msg)
>
> etc.


Good catch.

This is a bug of the code actually. Since I want to stick to 32bit to be 
large enough for e.g PASID.

Will fix.

Thanks


>