Re: [PATCH RFC 2/2] vhost: packed ring support

On 2018年02月27日 17:03, Tiwei Bie wrote:

On Wed, Feb 14, 2018 at 10:37:09AM +0800, Jason Wang wrote:
[...]

quoted

+static void set_desc_used(struct vhost_virtqueue *vq,
+			  struct vring_desc_packed *desc, bool wrap_counter)
+{
+	__virtio16 flags = desc->flags;
+
+	if (wrap_counter) {
+		desc->flags |= cpu_to_vhost16(vq, DESC_AVAIL);
+		desc->flags |= cpu_to_vhost16(vq, DESC_USED);
+	} else {
+		desc->flags &= ~cpu_to_vhost16(vq, DESC_AVAIL);
+		desc->flags &= ~cpu_to_vhost16(vq, DESC_USED);
+	}
+
+	desc->flags = flags;

The `desc->flags` is restored after the change.

Right, will fix.

quoted

+}
+
+static int vhost_get_vq_desc_packed(struct vhost_virtqueue *vq,
+				    struct iovec iov[], unsigned int iov_size,
+				    unsigned int *out_num, unsigned int *in_num,
+				    struct vhost_log *log,
+				    unsigned int *log_num)
+{
+	struct vring_desc_packed desc;
+	int ret, access, i;
+	u16 avail_idx = vq->last_avail_idx;
+
+	/* When we start there are none of either input nor output. */
+	*out_num = *in_num = 0;
+	if (unlikely(log))
+		*log_num = 0;
+
+	do {
+		unsigned int iov_count = *in_num + *out_num;
+
+		i = vq->last_avail_idx & (vq->num - 1);

The queue size may not be a power of 2 in packed ring.

Will fix this too.

Thanks

Best regards,
Tiwei Bie