[linux.git] / include / linux / virtio_ring.h

#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

/* 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
/* 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". */
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.  We assume num is a power of 2.
 *
 * 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 to the next align boundary.
 *	char pad[];
 *
 *	// 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,
			      unsigned long align)
{
	vr->num = num;
	vr->desc = p;
	vr->avail = p + num*sizeof(struct vring_desc);
	vr->used = (void *)(((unsigned long)&vr->avail->ring[num] + align-1)
			    & ~(align - 1));
}

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;
}

#ifdef __KERNEL__
#include <linux/irqreturn.h>
struct virtio_device;
struct virtqueue;

struct virtqueue *vring_new_virtqueue(unsigned int num,
				      unsigned int vring_align,
				      struct virtio_device *vdev,
				      void *pages,
				      void (*notify)(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__ */
#endif /* _LINUX_VIRTIO_RING_H */
Commit	Line	Data
0a8a69dd RR	1	#ifndef _LINUX_VIRTIO_RING_H
	2	#define _LINUX_VIRTIO_RING_H
	3	/* An interface for efficient virtio implementation, currently for use by KVM
	4	* and lguest, but hopefully others soon. Do NOT change this since it will
	5	* break existing servers and clients.
	6	*
	7	* This header is BSD licensed so anyone can use the definitions to implement
	8	* compatible drivers/servers.
	9	*
	10	* Copyright Rusty Russell IBM Corporation 2007. */
	11	#include <linux/types.h>
	12
	13	/* This marks a buffer as continuing via the next field. */
	14	#define VRING_DESC_F_NEXT 1
	15	/* This marks a buffer as write-only (otherwise read-only). */
	16	#define VRING_DESC_F_WRITE 2
	17
426e3e0a RR	18	/* The Host uses this in used->flags to advise the Guest: don't kick me when
	19	* you add a buffer. It's unreliable, so it's simply an optimization. Guest
	20	* will still kick if it's out of buffers. */
0a8a69dd	21	#define VRING_USED_F_NO_NOTIFY 1
426e3e0a RR	22	/* The Guest uses this in avail->flags to advise the Host: don't interrupt me
	23	* when you consume a buffer. It's unreliable, so it's simply an
	24	* optimization. */
0a8a69dd RR	25	#define VRING_AVAIL_F_NO_INTERRUPT 1
	26
	27	/* Virtio ring descriptors: 16 bytes. These can chain together via "next". */
	28	struct vring_desc
	29	{
	30	/* Address (guest-physical). */
	31	__u64 addr;
	32	/* Length. */
	33	__u32 len;
	34	/* The flags as indicated above. */
	35	__u16 flags;
	36	/* We chain unused descriptors via this, too */
	37	__u16 next;
	38	};
	39
	40	struct vring_avail
	41	{
	42	__u16 flags;
	43	__u16 idx;
	44	__u16 ring[];
	45	};
	46
	47	/* u32 is used here for ids for padding reasons. */
	48	struct vring_used_elem
	49	{
	50	/* Index of start of used descriptor chain. */
	51	__u32 id;
	52	/* Total length of the descriptor chain which was used (written to) */
	53	__u32 len;
	54	};
	55
	56	struct vring_used
	57	{
	58	__u16 flags;
	59	__u16 idx;
	60	struct vring_used_elem ring[];
	61	};
	62
	63	struct vring {
	64	unsigned int num;
	65
	66	struct vring_desc *desc;
	67
	68	struct vring_avail *avail;
	69
	70	struct vring_used *used;
	71	};
	72
	73	/* The standard layout for the ring is a continuous chunk of memory which looks
42b36cc0	74	* like this. We assume num is a power of 2.
0a8a69dd RR	75	*
	76	* struct vring
	77	* {
	78	* // The actual descriptors (16 bytes each)
	79	* struct vring_desc desc[num];
	80	*
	81	* // A ring of available descriptor heads with free-running index.
	82	* __u16 avail_flags;
	83	* __u16 avail_idx;
	84	* __u16 available[num];
	85	*
5f0d1d7f	86	* // Padding to the next align boundary.
42b36cc0	87	* char pad[];
0a8a69dd RR	88	*
	89	* // A ring of used descriptor heads with free-running index.
	90	* __u16 used_flags;
	91	* __u16 used_idx;
	92	* struct vring_used_elem used[num];
	93	* };
	94	*/
42b36cc0	95	static inline void vring_init(struct vring vr, unsigned int num, void p,
5f0d1d7f	96	unsigned long align)
0a8a69dd RR	97	{
	98	vr->num = num;
	99	vr->desc = p;
44332f71	100	vr->avail = p + num*sizeof(struct vring_desc);
5f0d1d7f RR	101	vr->used = (void *)(((unsigned long)&vr->avail->ring[num] + align-1)
5f0d1d7f RR	102	& ~(align - 1));
0a8a69dd RR	103	}
0a8a69dd RR	104
5f0d1d7f	105	static inline unsigned vring_size(unsigned int num, unsigned long align)
0a8a69dd	106	{
42b36cc0	107	return ((sizeof(struct vring_desc) * num + sizeof(__u16) * (2 + num)
5f0d1d7f	108	+ align - 1) & ~(align - 1))
42b36cc0	109	+ sizeof(__u16) * 2 + sizeof(struct vring_used_elem) * num;
0a8a69dd RR	110	}
	111
	112	#ifdef __KERNEL__
	113	#include <linux/irqreturn.h>
	114	struct virtio_device;
	115	struct virtqueue;
	116
	117	struct virtqueue *vring_new_virtqueue(unsigned int num,
87c7d57c	118	unsigned int vring_align,
0a8a69dd RR	119	struct virtio_device *vdev,
	120	void *pages,
	121	void (notify)(struct virtqueue vq),
18445c4d	122	void (callback)(struct virtqueue vq));
0a8a69dd	123	void vring_del_virtqueue(struct virtqueue *vq);
e34f8725 RR	124	/* Filter out transport-specific feature bits. */
e34f8725 RR	125	void vring_transport_features(struct virtio_device *vdev);
0a8a69dd RR	126
	127	irqreturn_t vring_interrupt(int irq, void *_vq);
	128	#endif /* __KERNEL__ */
	129	#endif /* _LINUX_VIRTIO_RING_H */