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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 | ||
18 | /* This means don't notify other side when buffer added. */ | |
19 | #define VRING_USED_F_NO_NOTIFY 1 | |
20 | /* This means don't interrupt guest when buffer consumed. */ | |
21 | #define VRING_AVAIL_F_NO_INTERRUPT 1 | |
22 | ||
23 | /* Virtio ring descriptors: 16 bytes. These can chain together via "next". */ | |
24 | struct vring_desc | |
25 | { | |
26 | /* Address (guest-physical). */ | |
27 | __u64 addr; | |
28 | /* Length. */ | |
29 | __u32 len; | |
30 | /* The flags as indicated above. */ | |
31 | __u16 flags; | |
32 | /* We chain unused descriptors via this, too */ | |
33 | __u16 next; | |
34 | }; | |
35 | ||
36 | struct vring_avail | |
37 | { | |
38 | __u16 flags; | |
39 | __u16 idx; | |
40 | __u16 ring[]; | |
41 | }; | |
42 | ||
43 | /* u32 is used here for ids for padding reasons. */ | |
44 | struct vring_used_elem | |
45 | { | |
46 | /* Index of start of used descriptor chain. */ | |
47 | __u32 id; | |
48 | /* Total length of the descriptor chain which was used (written to) */ | |
49 | __u32 len; | |
50 | }; | |
51 | ||
52 | struct vring_used | |
53 | { | |
54 | __u16 flags; | |
55 | __u16 idx; | |
56 | struct vring_used_elem ring[]; | |
57 | }; | |
58 | ||
59 | struct vring { | |
60 | unsigned int num; | |
61 | ||
62 | struct vring_desc *desc; | |
63 | ||
64 | struct vring_avail *avail; | |
65 | ||
66 | struct vring_used *used; | |
67 | }; | |
68 | ||
69 | /* The standard layout for the ring is a continuous chunk of memory which looks | |
70 | * like this. The used fields will be aligned to a "num+1" boundary. | |
71 | * | |
72 | * struct vring | |
73 | * { | |
74 | * // The actual descriptors (16 bytes each) | |
75 | * struct vring_desc desc[num]; | |
76 | * | |
77 | * // A ring of available descriptor heads with free-running index. | |
78 | * __u16 avail_flags; | |
79 | * __u16 avail_idx; | |
80 | * __u16 available[num]; | |
81 | * | |
82 | * // Padding so a correctly-chosen num value will cache-align used_idx. | |
83 | * char pad[sizeof(struct vring_desc) - sizeof(avail_flags)]; | |
84 | * | |
85 | * // A ring of used descriptor heads with free-running index. | |
86 | * __u16 used_flags; | |
87 | * __u16 used_idx; | |
88 | * struct vring_used_elem used[num]; | |
89 | * }; | |
90 | */ | |
91 | static inline void vring_init(struct vring *vr, unsigned int num, void *p) | |
92 | { | |
93 | vr->num = num; | |
94 | vr->desc = p; | |
44332f71 AL |
95 | vr->avail = p + num*sizeof(struct vring_desc); |
96 | vr->used = p + (num+1)*(sizeof(struct vring_desc) + sizeof(__u16)); | |
0a8a69dd RR |
97 | } |
98 | ||
99 | static inline unsigned vring_size(unsigned int num) | |
100 | { | |
101 | return (num + 1) * (sizeof(struct vring_desc) + sizeof(__u16)) | |
102 | + sizeof(__u32) + num * sizeof(struct vring_used_elem); | |
103 | } | |
104 | ||
105 | #ifdef __KERNEL__ | |
106 | #include <linux/irqreturn.h> | |
107 | struct virtio_device; | |
108 | struct virtqueue; | |
109 | ||
110 | struct virtqueue *vring_new_virtqueue(unsigned int num, | |
111 | struct virtio_device *vdev, | |
112 | void *pages, | |
113 | void (*notify)(struct virtqueue *vq), | |
114 | bool (*callback)(struct virtqueue *vq)); | |
115 | void vring_del_virtqueue(struct virtqueue *vq); | |
116 | ||
117 | irqreturn_t vring_interrupt(int irq, void *_vq); | |
118 | #endif /* __KERNEL__ */ | |
119 | #endif /* _LINUX_VIRTIO_RING_H */ |