[PATCH 2/3] kvm tools: add some helper functions for virt_queue

[Asias He <asias.hejun@gmail.com>]

Signed-off-by: Asias He <asias.hejun@gmail.com>
---
 tools/kvm/include/kvm/virtqueue.h |   42 +++++++++++++++++++++++++++++++++++++
 1 files changed, 42 insertions(+), 0 deletions(-)

diff --git a/tools/kvm/include/kvm/virtqueue.h b/tools/kvm/include/kvm/virtqueue.h
index 83f5293..de360ae 100644
--- a/tools/kvm/include/kvm/virtqueue.h
+++ b/tools/kvm/include/kvm/virtqueue.h
@@ -4,6 +4,9 @@
 #include <linux/virtio_ring.h>
 
 #include <stdint.h>
+#include <sys/uio.h>
+
+#include "kvm/kvm.h"
 
 struct virt_queue {
 	struct vring			vring;
@@ -28,4 +31,43 @@ static inline struct vring_used_elem *virt_queue__get_used_elem(struct virt_queu
 	return &queue->vring.used->ring[queue->vring.used->idx++ % queue->vring.num];
 }
 
+static inline struct vring_used_elem *virt_queue__set_used_elem(struct virt_queue *queue, uint32_t head, uint32_t len)
+{
+	struct vring_used_elem *used_elem;
+	used_elem	= &queue->vring.used->ring[queue->vring.used->idx++ % queue->vring.num];
+	used_elem->id	= head;
+	used_elem->len	= len;
+	return used_elem;
+}
+
+static inline bool virt_queue__available(struct virt_queue *vq)
+{
+	return vq->vring.avail->idx !=  vq->last_avail_idx;
+}
+
+static inline uint16_t virt_queue__get_iov(struct virt_queue *queue, struct iovec iov[], uint16_t *out, uint16_t *in, struct kvm *kvm)
+{
+	struct vring_desc *desc;
+	uint16_t head, idx;
+
+	idx = head = virt_queue__pop(queue);
+	*out = *in = 0;
+
+	do {
+		desc 				= virt_queue__get_desc(queue, idx);
+		iov[*out + *in].iov_base	= guest_flat_to_host(kvm, desc->addr);
+		iov[*out + *in].iov_len		= desc->len;
+		if (desc->flags & VRING_DESC_F_WRITE)
+			(*in)++;
+		else
+			(*out)++;
+		if (desc->flags & VRING_DESC_F_NEXT)
+			idx = desc->next;
+		else
+			break;
+	} while (1);
+
+	return head;
+}
+
 #endif /* KVM__VIRTQUEUE_H */
-- 
1.7.4.1