Re: [PATCH net-next] vhost: switch to use new message format

[Jason Wang]

On 2018å08æ03æ 15:59, Michael S. Tsirkin wrote:
> > diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
> > index a502f1a..6f6c42d 100644
> > --- a/drivers/vhost/vhost.c
> > +++ b/drivers/vhost/vhost.c
> > @@ -315,6 +315,7 @@ static void vhost_vq_reset(struct vhost_dev *dev,
> >   	vq->log_addr = -1ull;
> >   	vq->private_data = NULL;
> >   	vq->acked_features = 0;
> > +	vq->acked_backend_features = 0;
> >   	vq->log_base = NULL;
> >   	vq->error_ctx = NULL;
> >   	vq->kick = NULL;
> > @@ -1027,28 +1028,40 @@ static int vhost_process_iotlb_msg(struct vhost_dev *dev,
> >   ssize_t vhost_chr_write_iter(struct vhost_dev *dev,
> >   			     struct iov_iter *from)
> >   {
> > -	struct vhost_msg_node node;
> > -	unsigned size = sizeof(struct vhost_msg);
> > -	size_t ret;
> > -	int err;
> > +	struct vhost_iotlb_msg msg;
> > +	size_t offset;
> > +	int type, ret;
> >   
> > -	if (iov_iter_count(from) < size)
> > -		return 0;
> > -	ret = copy_from_iter(&node.msg, size, from);
> > -	if (ret != size)
> > +	ret = copy_from_iter(&type, sizeof(type), from);
> > +	if (ret != sizeof(type))
> >   		goto done;
> >   
> > -	switch (node.msg.type) {
> > +	switch (type) {
> >   	case VHOST_IOTLB_MSG:
> > -		err = vhost_process_iotlb_msg(dev, &node.msg.iotlb);
> > -		if (err)
> > -			ret = err;
> > +		/* There maybe a hole after type for V1 message type,
> > +		 * so skip it here.
> > +		 */
> > +		offset = offsetof(struct vhost_msg, iotlb) - sizeof(int);
> > +		break;
> > +	case VHOST_IOTLB_MSG_V2:
> > +		offset = sizeof(__u32);
> >   		break;
> >   	default:
> >   		ret = -EINVAL;
> > -		break;
> > +		goto done;
> > +	}
> > +
> > +	iov_iter_advance(from, offset);
> > +	ret = copy_from_iter(&msg, sizeof(msg), from);
> > +	if (ret != sizeof(msg))
> > +		goto done;
> > +	if (vhost_process_iotlb_msg(dev, &msg)) {
> > +		ret = -EFAULT;
> > +		goto done;
> >   	}
> >   
> > +	ret = (type == VHOST_IOTLB_MSG) ? sizeof(struct vhost_msg) :
> > +	      sizeof(struct vhost_msg_v2);
> >   done:
> >   	return ret;
> >   }
> We can actually fix 32 bit apps too, checking the mode for v1.
> But that can wait for another patch.

Yes, let me do it on top.

Thanks