Subject: Re: [PATCH v3 17/18] vhost: don't bother copying iovecs in handle_rx(), kill memcpy_toiovecend()

From: "Michael S. Tsirkin" <[email-masked]>
Date: Wed, 4 Feb 2015 10:02:27 +0100

>  		if (likely(mergeable) &&
> -		    memcpy_toiovecend(nvq->hdr, (unsigned char *)&headcount,
> -				      offsetof(typeof(hdr), num_buffers),
> -				      sizeof hdr.num_buffers)) {
> +		    copy_to_iter(&headcount, 2, &fixup) != 2) {
>  			vq_err(vq, "Failed num_buffers write");
>  			vhost_discard_vq_desc(vq, headcount);
>  			break;

BTW this will have to be re-based on top of
http://mid.gmane.org/[email-masked]
taking byte-swap into account.