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-rw-r--r--include/linux/virtio_ring.h166
1 files changed, 4 insertions, 162 deletions
diff --git a/include/linux/virtio_ring.h b/include/linux/virtio_ring.h
index e338730c2660..63c6ea199519 100644
--- a/include/linux/virtio_ring.h
+++ b/include/linux/virtio_ring.h
@@ -1,171 +1,14 @@
1#ifndef _LINUX_VIRTIO_RING_H 1#ifndef _LINUX_VIRTIO_RING_H
2#define _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 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 * 3. Neither the name of IBM nor the names of its contributors
19 * may be used to endorse or promote products derived from this software
20 * without specific prior written permission.
21 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED. IN NO EVENT SHALL IBM OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 *
33 * Copyright Rusty Russell IBM Corporation 2007. */
34#include <linux/types.h>
35 3
36/* This marks a buffer as continuing via the next field. */
37#define VRING_DESC_F_NEXT 1
38/* This marks a buffer as write-only (otherwise read-only). */
39#define VRING_DESC_F_WRITE 2
40/* This means the buffer contains a list of buffer descriptors. */
41#define VRING_DESC_F_INDIRECT 4
42
43/* The Host uses this in used->flags to advise the Guest: don't kick me when
44 * you add a buffer. It's unreliable, so it's simply an optimization. Guest
45 * will still kick if it's out of buffers. */
46#define VRING_USED_F_NO_NOTIFY 1
47/* The Guest uses this in avail->flags to advise the Host: don't interrupt me
48 * when you consume a buffer. It's unreliable, so it's simply an
49 * optimization. */
50#define VRING_AVAIL_F_NO_INTERRUPT 1
51
52/* We support indirect buffer descriptors */
53#define VIRTIO_RING_F_INDIRECT_DESC 28
54
55/* The Guest publishes the used index for which it expects an interrupt
56 * at the end of the avail ring. Host should ignore the avail->flags field. */
57/* The Host publishes the avail index for which it expects a kick
58 * at the end of the used ring. Guest should ignore the used->flags field. */
59#define VIRTIO_RING_F_EVENT_IDX 29
60
61/* Virtio ring descriptors: 16 bytes. These can chain together via "next". */
62struct vring_desc {
63 /* Address (guest-physical). */
64 __u64 addr;
65 /* Length. */
66 __u32 len;
67 /* The flags as indicated above. */
68 __u16 flags;
69 /* We chain unused descriptors via this, too */
70 __u16 next;
71};
72
73struct vring_avail {
74 __u16 flags;
75 __u16 idx;
76 __u16 ring[];
77};
78
79/* u32 is used here for ids for padding reasons. */
80struct vring_used_elem {
81 /* Index of start of used descriptor chain. */
82 __u32 id;
83 /* Total length of the descriptor chain which was used (written to) */
84 __u32 len;
85};
86
87struct vring_used {
88 __u16 flags;
89 __u16 idx;
90 struct vring_used_elem ring[];
91};
92
93struct vring {
94 unsigned int num;
95
96 struct vring_desc *desc;
97
98 struct vring_avail *avail;
99
100 struct vring_used *used;
101};
102
103/* The standard layout for the ring is a continuous chunk of memory which looks
104 * like this. We assume num is a power of 2.
105 *
106 * struct vring
107 * {
108 * // The actual descriptors (16 bytes each)
109 * struct vring_desc desc[num];
110 *
111 * // A ring of available descriptor heads with free-running index.
112 * __u16 avail_flags;
113 * __u16 avail_idx;
114 * __u16 available[num];
115 * __u16 used_event_idx;
116 *
117 * // Padding to the next align boundary.
118 * char pad[];
119 *
120 * // A ring of used descriptor heads with free-running index.
121 * __u16 used_flags;
122 * __u16 used_idx;
123 * struct vring_used_elem used[num];
124 * __u16 avail_event_idx;
125 * };
126 */
127/* We publish the used event index at the end of the available ring, and vice
128 * versa. They are at the end for backwards compatibility. */
129#define vring_used_event(vr) ((vr)->avail->ring[(vr)->num])
130#define vring_avail_event(vr) (*(__u16 *)&(vr)->used->ring[(vr)->num])
131
132static inline void vring_init(struct vring *vr, unsigned int num, void *p,
133 unsigned long align)
134{
135 vr->num = num;
136 vr->desc = p;
137 vr->avail = p + num*sizeof(struct vring_desc);
138 vr->used = (void *)(((unsigned long)&vr->avail->ring[num] + sizeof(__u16)
139 + align-1) & ~(align - 1));
140}
141
142static inline unsigned vring_size(unsigned int num, unsigned long align)
143{
144 return ((sizeof(struct vring_desc) * num + sizeof(__u16) * (3 + num)
145 + align - 1) & ~(align - 1))
146 + sizeof(__u16) * 3 + sizeof(struct vring_used_elem) * num;
147}
148
149/* The following is used with USED_EVENT_IDX and AVAIL_EVENT_IDX */
150/* Assuming a given event_idx value from the other size, if
151 * we have just incremented index from old to new_idx,
152 * should we trigger an event? */
153static inline int vring_need_event(__u16 event_idx, __u16 new_idx, __u16 old)
154{
155 /* Note: Xen has similar logic for notification hold-off
156 * in include/xen/interface/io/ring.h with req_event and req_prod
157 * corresponding to event_idx + 1 and new_idx respectively.
158 * Note also that req_event and req_prod in Xen start at 1,
159 * event indexes in virtio start at 0. */
160 return (__u16)(new_idx - event_idx - 1) < (__u16)(new_idx - old);
161}
162
163#ifdef __KERNEL__
164#include <linux/irqreturn.h> 4#include <linux/irqreturn.h>
5#include <uapi/linux/virtio_ring.h>
6
165struct virtio_device; 7struct virtio_device;
166struct virtqueue; 8struct virtqueue;
167 9
168struct virtqueue *vring_new_virtqueue(unsigned int num, 10struct virtqueue *vring_new_virtqueue(unsigned int index,
11 unsigned int num,
169 unsigned int vring_align, 12 unsigned int vring_align,
170 struct virtio_device *vdev, 13 struct virtio_device *vdev,
171 bool weak_barriers, 14 bool weak_barriers,
@@ -178,5 +21,4 @@ void vring_del_virtqueue(struct virtqueue *vq);
178void vring_transport_features(struct virtio_device *vdev); 21void vring_transport_features(struct virtio_device *vdev);
179 22
180irqreturn_t vring_interrupt(int irq, void *_vq); 23irqreturn_t vring_interrupt(int irq, void *_vq);
181#endif /* __KERNEL__ */
182#endif /* _LINUX_VIRTIO_RING_H */ 24#endif /* _LINUX_VIRTIO_RING_H */
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