/* 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". */
};
/* 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
* {
* __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;
* 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_desc);
- vr->used = p + (num+1)*(sizeof(struct vring_desc) + sizeof(__u16));
+ 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__
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);
+/* Filter out transport-specific feature bits. */
+void vring_transport_features(struct virtio_device *vdev);
irqreturn_t vring_interrupt(int irq, void *_vq);
#endif /* __KERNEL__ */