1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
|
#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
/* We publish our last-seen used index at the end of the avail ring. */
#define VIRTIO_RING_F_PUBLISH_INDICES 28
/* 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];
* __u16 last_used_idx;
*
* // Padding to the next page 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];
* __u16 last_avail_idx;
* };
*/
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 = (void *)(((unsigned long)&vr->avail->ring[num] + pagesize-1)
& ~(pagesize - 1));
}
static inline unsigned vring_size(unsigned int num, unsigned long pagesize)
{
return ((sizeof(struct vring_desc) * num + sizeof(__u16) * (2 + num)
+ pagesize - 1) & ~(pagesize - 1))
+ sizeof(__u16) * 2 + sizeof(struct vring_used_elem) * num + 2;
}
/* We publish the last-seen used index at the end of the available ring, and
* vice-versa. These are at the end for backwards compatibility. */
#define vring_last_used(vr) ((vr)->avail->ring[(vr)->num])
#define vring_last_avail(vr) (*(__u16 *)&(vr)->used->ring[(vr)->num])
#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),
void (*callback)(struct virtqueue *vq));
void vring_del_virtqueue(struct virtqueue *vq);
/* Filter out unsupported transport-specific feature bits. */
u32 vring_transport_features(u32 features);
irqreturn_t vring_interrupt(int irq, void *_vq);
#endif /* __KERNEL__ */
#endif /* _LINUX_VIRTIO_RING_H */
|
