From 583f5dd3ab8936d495d3d967d418de9599f10de1 Mon Sep 17 00:00:00 2001
From: "Michael S. Tsirkin" <mst@redhat.com>
Date: Fri, 20 May 2011 02:10:17 +0300
Subject: [PATCH] --- yaml --- r: 252946 b: refs/heads/master c:
 770b31a85e000b0194974922f238a30ade4246b6 h: refs/heads/master v: v3

---
 [refs]                            |  2 +-
 trunk/include/linux/virtio_ring.h | 15 ++++++++++++++-
 2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/[refs] b/[refs]
index 9dc3e7616d06..d1998630057d 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: a1b383870a28cfbd1657d4922c0fafc634a62ebd
+refs/heads/master: 770b31a85e000b0194974922f238a30ade4246b6
diff --git a/trunk/include/linux/virtio_ring.h b/trunk/include/linux/virtio_ring.h
index a813e5d460eb..c4eef73deb3f 100644
--- a/trunk/include/linux/virtio_ring.h
+++ b/trunk/include/linux/virtio_ring.h
@@ -52,6 +52,12 @@
 /* We support indirect buffer descriptors */
 #define VIRTIO_RING_F_INDIRECT_DESC	28
 
+/* The Guest publishes the used index for which it expects an interrupt
+ * at the end of the avail ring. Host should ignore the avail->flags field. */
+/* The Host publishes the avail index for which it expects a kick
+ * at the end of the used ring. Guest should ignore the used->flags field. */
+#define VIRTIO_RING_F_EVENT_IDX		29
+
 /* Virtio ring descriptors: 16 bytes.  These can chain together via "next". */
 struct vring_desc {
 	/* Address (guest-physical). */
@@ -106,6 +112,7 @@ struct vring {
  *	__u16 avail_flags;
  *	__u16 avail_idx;
  *	__u16 available[num];
+ *	__u16 used_event_idx;
  *
  *	// Padding to the next align boundary.
  *	char pad[];
@@ -114,8 +121,14 @@ struct vring {
  *	__u16 used_flags;
  *	__u16 used_idx;
  *	struct vring_used_elem used[num];
+ *	__u16 avail_event_idx;
  * };
  */
+/* We publish the used event index at the end of the available ring, and vice
+ * versa. They are at the end for backwards compatibility. */
+#define vring_used_event(vr) ((vr)->avail->ring[(vr)->num])
+#define vring_avail_event(vr) (*(__u16 *)&(vr)->used->ring[(vr)->num])
+
 static inline void vring_init(struct vring *vr, unsigned int num, void *p,
 			      unsigned long align)
 {
@@ -130,7 +143,7 @@ static inline unsigned vring_size(unsigned int num, unsigned long align)
 {
 	return ((sizeof(struct vring_desc) * num + sizeof(__u16) * (2 + num)
 		 + align - 1) & ~(align - 1))
-		+ sizeof(__u16) * 2 + sizeof(struct vring_used_elem) * num;
+		+ sizeof(__u16) * 3 + sizeof(struct vring_used_elem) * num;
 }
 
 #ifdef __KERNEL__