X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=include%2Flinux%2Fvirtio_ring.h;h=abe481ed990e328bd6f5ec1f5212deeed07b9fea;hb=03054de1e0b90b33e9974107d84dabd2509f5898;hp=ac69e7bb5a14f5465df654a5d7668cb45a7669f5;hpb=43cd73658d8077ee6899b0b5029aad0cba1e9f92;p=linux-2.6

diff --git a/include/linux/virtio_ring.h b/include/linux/virtio_ring.h
index ac69e7bb5a..abe481ed99 100644
--- a/include/linux/virtio_ring.h
+++ b/include/linux/virtio_ring.h
@@ -15,9 +15,13 @@
 /* This marks a buffer as write-only (otherwise read-only). */
 #define VRING_DESC_F_WRITE	2
 
-/* This means don't notify other side when buffer added. */
+/* The Host uses this in used->flags to advise the Guest: don't kick me when
+ * you add a buffer.  It's unreliable, so it's simply an optimization.  Guest
+ * will still kick if it's out of buffers. */
 #define VRING_USED_F_NO_NOTIFY	1
-/* This means don't interrupt guest when buffer consumed. */
+/* The Guest uses this in avail->flags to advise the Host: don't interrupt me
+ * when you consume a buffer.  It's unreliable, so it's simply an
+ * optimization.  */
 #define VRING_AVAIL_F_NO_INTERRUPT	1
 
 /* Virtio ring descriptors: 16 bytes.  These can chain together via "next". */
@@ -67,7 +71,7 @@ struct vring {
 };
 
 /* The standard layout for the ring is a continuous chunk of memory which looks
- * like this.  The used fields will be aligned to a "num+1" boundary.
+ * like this.  We assume num is a power of 2.
  *
  * struct vring
  * {
@@ -79,8 +83,8 @@ struct vring {
  *	__u16 avail_idx;
  *	__u16 available[num];
  *
- *	// Padding so a correctly-chosen num value will cache-align used_idx.
- *	char pad[sizeof(struct vring_desc) - sizeof(avail_flags)];
+ *	// Padding to the next page boundary.
+ *	char pad[];
  *
  *	// A ring of used descriptor heads with free-running index.
  *	__u16 used_flags;
@@ -88,18 +92,21 @@ struct vring {
  *	struct vring_used_elem used[num];
  * };
  */
-static inline void vring_init(struct vring *vr, unsigned int num, void *p)
+static inline void vring_init(struct vring *vr, unsigned int num, void *p,
+			      unsigned long pagesize)
 {
 	vr->num = num;
 	vr->desc = p;
-	vr->avail = p + num*sizeof(struct vring);
-	vr->used = p + (num+1)*(sizeof(struct vring) + sizeof(__u16));
+	vr->avail = p + num*sizeof(struct vring_desc);
+	vr->used = (void *)(((unsigned long)&vr->avail->ring[num] + pagesize-1)
+			    & ~(pagesize - 1));
 }
 
-static inline unsigned vring_size(unsigned int num)
+static inline unsigned vring_size(unsigned int num, unsigned long pagesize)
 {
-	return (num + 1) * (sizeof(struct vring_desc) + sizeof(__u16))
-		+ sizeof(__u32) + num * sizeof(struct vring_used_elem);
+	return ((sizeof(struct vring_desc) * num + sizeof(__u16) * (2 + num)
+		 + pagesize - 1) & ~(pagesize - 1))
+		+ sizeof(__u16) * 2 + sizeof(struct vring_used_elem) * num;
 }
 
 #ifdef __KERNEL__
@@ -111,7 +118,7 @@ struct virtqueue *vring_new_virtqueue(unsigned int num,
 				      struct virtio_device *vdev,
 				      void *pages,
 				      void (*notify)(struct virtqueue *vq),
-				      bool (*callback)(struct virtqueue *vq));
+				      void (*callback)(struct virtqueue *vq));
 void vring_del_virtqueue(struct virtqueue *vq);
 
 irqreturn_t vring_interrupt(int irq, void *_vq);