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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 | |
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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 | 32 | /* Virtio ring descriptors: 16 bytes. These can chain together via "next". */ |
1842f23c | 33 | struct vring_desc { |
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34 | /* Address (guest-physical). */ |
35 | __u64 addr; | |
36 | /* Length. */ | |
37 | __u32 len; | |
38 | /* The flags as indicated above. */ | |
39 | __u16 flags; | |
40 | /* We chain unused descriptors via this, too */ | |
41 | __u16 next; | |
42 | }; | |
43 | ||
1842f23c | 44 | struct vring_avail { |
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45 | __u16 flags; |
46 | __u16 idx; | |
47 | __u16 ring[]; | |
48 | }; | |
49 | ||
50 | /* u32 is used here for ids for padding reasons. */ | |
1842f23c | 51 | struct vring_used_elem { |
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52 | /* Index of start of used descriptor chain. */ |
53 | __u32 id; | |
54 | /* Total length of the descriptor chain which was used (written to) */ | |
55 | __u32 len; | |
56 | }; | |
57 | ||
1842f23c | 58 | struct vring_used { |
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59 | __u16 flags; |
60 | __u16 idx; | |
61 | struct vring_used_elem ring[]; | |
62 | }; | |
63 | ||
64 | struct vring { | |
65 | unsigned int num; | |
66 | ||
67 | struct vring_desc *desc; | |
68 | ||
69 | struct vring_avail *avail; | |
70 | ||
71 | struct vring_used *used; | |
72 | }; | |
73 | ||
74 | /* The standard layout for the ring is a continuous chunk of memory which looks | |
42b36cc0 | 75 | * like this. We assume num is a power of 2. |
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76 | * |
77 | * struct vring | |
78 | * { | |
79 | * // The actual descriptors (16 bytes each) | |
80 | * struct vring_desc desc[num]; | |
81 | * | |
82 | * // A ring of available descriptor heads with free-running index. | |
83 | * __u16 avail_flags; | |
84 | * __u16 avail_idx; | |
85 | * __u16 available[num]; | |
86 | * | |
5f0d1d7f | 87 | * // Padding to the next align boundary. |
42b36cc0 | 88 | * char pad[]; |
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89 | * |
90 | * // A ring of used descriptor heads with free-running index. | |
91 | * __u16 used_flags; | |
92 | * __u16 used_idx; | |
93 | * struct vring_used_elem used[num]; | |
94 | * }; | |
95 | */ | |
42b36cc0 | 96 | static inline void vring_init(struct vring *vr, unsigned int num, void *p, |
5f0d1d7f | 97 | unsigned long align) |
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98 | { |
99 | vr->num = num; | |
100 | vr->desc = p; | |
44332f71 | 101 | vr->avail = p + num*sizeof(struct vring_desc); |
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102 | vr->used = (void *)(((unsigned long)&vr->avail->ring[num] + align-1) |
103 | & ~(align - 1)); | |
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104 | } |
105 | ||
5f0d1d7f | 106 | static inline unsigned vring_size(unsigned int num, unsigned long align) |
0a8a69dd | 107 | { |
42b36cc0 | 108 | return ((sizeof(struct vring_desc) * num + sizeof(__u16) * (2 + num) |
5f0d1d7f | 109 | + align - 1) & ~(align - 1)) |
42b36cc0 | 110 | + sizeof(__u16) * 2 + sizeof(struct vring_used_elem) * num; |
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111 | } |
112 | ||
113 | #ifdef __KERNEL__ | |
114 | #include <linux/irqreturn.h> | |
115 | struct virtio_device; | |
116 | struct virtqueue; | |
117 | ||
118 | struct virtqueue *vring_new_virtqueue(unsigned int num, | |
87c7d57c | 119 | unsigned int vring_align, |
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120 | struct virtio_device *vdev, |
121 | void *pages, | |
122 | void (*notify)(struct virtqueue *vq), | |
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123 | void (*callback)(struct virtqueue *vq), |
124 | const char *name); | |
0a8a69dd | 125 | void vring_del_virtqueue(struct virtqueue *vq); |
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126 | /* Filter out transport-specific feature bits. */ |
127 | void vring_transport_features(struct virtio_device *vdev); | |
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128 | |
129 | irqreturn_t vring_interrupt(int irq, void *_vq); | |
130 | #endif /* __KERNEL__ */ | |
131 | #endif /* _LINUX_VIRTIO_RING_H */ |