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#ifndef _LINUX_VIRTIO_RING_H
#define _LINUX_VIRTIO_RING_H
/* An interface for efficient virtio implementation, currently for use by KVM
* and lguest, but hopefully others soon. Do NOT change this since it will
* break existing servers and clients.
*
* This header is BSD licensed so anyone can use the definitions to implement
* compatible drivers/servers.
*
* Copyright Rusty Russell IBM Corporation 2007. */
#include <linux/types.h>
/* This marks a buffer as continuing via the next field. */
#define VRING_DESC_F_NEXT 1
/* 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. */
#define VRING_USED_F_NO_NOTIFY 1
/* This means don't interrupt guest when buffer consumed. */
#define VRING_AVAIL_F_NO_INTERRUPT 1
/* Virtio ring descriptors: 16 bytes. These can chain together via "next". */
struct vring_desc
{
/* Address (guest-physical). */
__u64 addr;
/* Length. */
__u32 len;
/* The flags as indicated above. */
__u16 flags;
/* We chain unused descriptors via this, too */
__u16 next;
};
struct vring_avail
{
__u16 flags;
__u16 idx;
__u16 ring[];
};
/* u32 is used here for ids for padding reasons. */
struct vring_used_elem
{
/* Index of start of used descriptor chain. */
__u32 id;
/* Total length of the descriptor chain which was used (written to) */
__u32 len;
};
struct vring_used
{
__u16 flags;
__u16 idx;
struct vring_used_elem ring[];
};
struct vring {
unsigned int num;
struct vring_desc *desc;
struct vring_avail *avail;
struct vring_used *used;
};
/* 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.
*
* struct vring
* {
* // The actual descriptors (16 bytes each)
* struct vring_desc desc[num];
*
* // A ring of available descriptor heads with free-running index.
* __u16 avail_flags;
* __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)];
*
* // A ring of used descriptor heads with free-running index.
* __u16 used_flags;
* __u16 used_idx;
* struct vring_used_elem used[num];
* };
*/
static inline void vring_init(struct vring *vr, unsigned int num, void *p)
{
vr->num = num;
vr->desc = p;
vr->avail = p + num*sizeof(struct vring);
vr->used = p + (num+1)*(sizeof(struct vring) + sizeof(__u16));
}
static inline unsigned vring_size(unsigned int num)
{
return (num + 1) * (sizeof(struct vring_desc) + sizeof(__u16))
+ sizeof(__u32) + num * sizeof(struct vring_used_elem);
}
#ifdef __KERNEL__
#include <linux/irqreturn.h>
struct virtio_device;
struct virtqueue;
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 vring_del_virtqueue(struct virtqueue *vq);
irqreturn_t vring_interrupt(int irq, void *_vq);
#endif /* __KERNEL__ */
#endif /* _LINUX_VIRTIO_RING_H */
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