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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 | |
9fa29b9d MM |
17 | /* This means the buffer contains a list of buffer descriptors. */ |
18 | #define VRING_DESC_F_INDIRECT 4 | |
0a8a69dd | 19 | |
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20 | /* The Host uses this in used->flags to advise the Guest: don't kick me when |
21 | * you add a buffer. It's unreliable, so it's simply an optimization. Guest | |
22 | * will still kick if it's out of buffers. */ | |
0a8a69dd | 23 | #define VRING_USED_F_NO_NOTIFY 1 |
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24 | /* The Guest uses this in avail->flags to advise the Host: don't interrupt me |
25 | * when you consume a buffer. It's unreliable, so it's simply an | |
26 | * optimization. */ | |
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27 | #define VRING_AVAIL_F_NO_INTERRUPT 1 |
28 | ||
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29 | /* We support indirect buffer descriptors */ |
30 | #define VIRTIO_RING_F_INDIRECT_DESC 28 | |
31 | ||
0a8a69dd RR |
32 | /* Virtio ring descriptors: 16 bytes. These can chain together via "next". */ |
33 | struct vring_desc | |
34 | { | |
35 | /* Address (guest-physical). */ | |
36 | __u64 addr; | |
37 | /* Length. */ | |
38 | __u32 len; | |
39 | /* The flags as indicated above. */ | |
40 | __u16 flags; | |
41 | /* We chain unused descriptors via this, too */ | |
42 | __u16 next; | |
43 | }; | |
44 | ||
45 | struct vring_avail | |
46 | { | |
47 | __u16 flags; | |
48 | __u16 idx; | |
49 | __u16 ring[]; | |
50 | }; | |
51 | ||
52 | /* u32 is used here for ids for padding reasons. */ | |
53 | struct vring_used_elem | |
54 | { | |
55 | /* Index of start of used descriptor chain. */ | |
56 | __u32 id; | |
57 | /* Total length of the descriptor chain which was used (written to) */ | |
58 | __u32 len; | |
59 | }; | |
60 | ||
61 | struct vring_used | |
62 | { | |
63 | __u16 flags; | |
64 | __u16 idx; | |
65 | struct vring_used_elem ring[]; | |
66 | }; | |
67 | ||
68 | struct vring { | |
69 | unsigned int num; | |
70 | ||
71 | struct vring_desc *desc; | |
72 | ||
73 | struct vring_avail *avail; | |
74 | ||
75 | struct vring_used *used; | |
76 | }; | |
77 | ||
78 | /* The standard layout for the ring is a continuous chunk of memory which looks | |
42b36cc0 | 79 | * like this. We assume num is a power of 2. |
0a8a69dd RR |
80 | * |
81 | * struct vring | |
82 | * { | |
83 | * // The actual descriptors (16 bytes each) | |
84 | * struct vring_desc desc[num]; | |
85 | * | |
86 | * // A ring of available descriptor heads with free-running index. | |
87 | * __u16 avail_flags; | |
88 | * __u16 avail_idx; | |
89 | * __u16 available[num]; | |
90 | * | |
5f0d1d7f | 91 | * // Padding to the next align boundary. |
42b36cc0 | 92 | * char pad[]; |
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93 | * |
94 | * // A ring of used descriptor heads with free-running index. | |
95 | * __u16 used_flags; | |
96 | * __u16 used_idx; | |
97 | * struct vring_used_elem used[num]; | |
98 | * }; | |
99 | */ | |
42b36cc0 | 100 | static inline void vring_init(struct vring *vr, unsigned int num, void *p, |
5f0d1d7f | 101 | unsigned long align) |
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102 | { |
103 | vr->num = num; | |
104 | vr->desc = p; | |
44332f71 | 105 | vr->avail = p + num*sizeof(struct vring_desc); |
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106 | vr->used = (void *)(((unsigned long)&vr->avail->ring[num] + align-1) |
107 | & ~(align - 1)); | |
0a8a69dd RR |
108 | } |
109 | ||
5f0d1d7f | 110 | static inline unsigned vring_size(unsigned int num, unsigned long align) |
0a8a69dd | 111 | { |
42b36cc0 | 112 | return ((sizeof(struct vring_desc) * num + sizeof(__u16) * (2 + num) |
5f0d1d7f | 113 | + align - 1) & ~(align - 1)) |
42b36cc0 | 114 | + sizeof(__u16) * 2 + sizeof(struct vring_used_elem) * num; |
0a8a69dd RR |
115 | } |
116 | ||
117 | #ifdef __KERNEL__ | |
118 | #include <linux/irqreturn.h> | |
119 | struct virtio_device; | |
120 | struct virtqueue; | |
121 | ||
122 | struct virtqueue *vring_new_virtqueue(unsigned int num, | |
87c7d57c | 123 | unsigned int vring_align, |
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124 | struct virtio_device *vdev, |
125 | void *pages, | |
126 | void (*notify)(struct virtqueue *vq), | |
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127 | void (*callback)(struct virtqueue *vq), |
128 | const char *name); | |
0a8a69dd | 129 | void vring_del_virtqueue(struct virtqueue *vq); |
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130 | /* Filter out transport-specific feature bits. */ |
131 | void vring_transport_features(struct virtio_device *vdev); | |
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132 | |
133 | irqreturn_t vring_interrupt(int irq, void *_vq); | |
134 | #endif /* __KERNEL__ */ | |
135 | #endif /* _LINUX_VIRTIO_RING_H */ |