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b2441318 | 1 | /* SPDX-License-Identifier: GPL-2.0 */ |
0a8a69dd RR |
2 | #ifndef _LINUX_VIRTIO_RING_H |
3 | #define _LINUX_VIRTIO_RING_H | |
0a8a69dd | 4 | |
c5610a5d | 5 | #include <asm/barrier.h> |
0a8a69dd | 6 | #include <linux/irqreturn.h> |
607ca46e DH |
7 | #include <uapi/linux/virtio_ring.h> |
8 | ||
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9 | /* |
10 | * Barriers in virtio are tricky. Non-SMP virtio guests can't assume | |
11 | * they're not on an SMP host system, so they need to assume real | |
12 | * barriers. Non-SMP virtio hosts could skip the barriers, but does | |
13 | * anyone care? | |
14 | * | |
15 | * For virtio_pci on SMP, we don't need to order with respect to MMIO | |
a6596127 | 16 | * accesses through relaxed memory I/O windows, so virt_mb() et al are |
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17 | * sufficient. |
18 | * | |
19 | * For using virtio to talk to real devices (eg. other heterogeneous | |
20 | * CPUs) we do need real barriers. In theory, we could be using both | |
21 | * kinds of virtio, so it's a runtime decision, and the branch is | |
22 | * actually quite cheap. | |
23 | */ | |
24 | ||
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25 | static inline void virtio_mb(bool weak_barriers) |
26 | { | |
27 | if (weak_barriers) | |
a6596127 | 28 | virt_mb(); |
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29 | else |
30 | mb(); | |
31 | } | |
32 | ||
33 | static inline void virtio_rmb(bool weak_barriers) | |
34 | { | |
35 | if (weak_barriers) | |
a6596127 | 36 | virt_rmb(); |
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37 | else |
38 | rmb(); | |
39 | } | |
40 | ||
41 | static inline void virtio_wmb(bool weak_barriers) | |
42 | { | |
43 | if (weak_barriers) | |
a6596127 | 44 | virt_wmb(); |
a9a0fef7 RR |
45 | else |
46 | wmb(); | |
47 | } | |
a9a0fef7 | 48 | |
788e5b3a MT |
49 | static inline void virtio_store_mb(bool weak_barriers, |
50 | __virtio16 *p, __virtio16 v) | |
51 | { | |
52 | if (weak_barriers) { | |
53 | virt_store_mb(*p, v); | |
54 | } else { | |
55 | WRITE_ONCE(*p, v); | |
56 | mb(); | |
57 | } | |
58 | } | |
59 | ||
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60 | struct virtio_device; |
61 | struct virtqueue; | |
62 | ||
2a2d1382 AL |
63 | /* |
64 | * Creates a virtqueue and allocates the descriptor ring. If | |
65 | * may_reduce_num is set, then this may allocate a smaller ring than | |
66 | * expected. The caller should query virtqueue_get_ring_size to learn | |
67 | * the actual size of the ring. | |
68 | */ | |
69 | struct virtqueue *vring_create_virtqueue(unsigned int index, | |
70 | unsigned int num, | |
71 | unsigned int vring_align, | |
72 | struct virtio_device *vdev, | |
73 | bool weak_barriers, | |
74 | bool may_reduce_num, | |
f94682dd | 75 | bool ctx, |
2a2d1382 AL |
76 | bool (*notify)(struct virtqueue *vq), |
77 | void (*callback)(struct virtqueue *vq), | |
78 | const char *name); | |
79 | ||
80 | /* Creates a virtqueue with a custom layout. */ | |
81 | struct virtqueue *__vring_new_virtqueue(unsigned int index, | |
82 | struct vring vring, | |
83 | struct virtio_device *vdev, | |
84 | bool weak_barriers, | |
f94682dd | 85 | bool ctx, |
2a2d1382 AL |
86 | bool (*notify)(struct virtqueue *), |
87 | void (*callback)(struct virtqueue *), | |
88 | const char *name); | |
89 | ||
90 | /* | |
91 | * Creates a virtqueue with a standard layout but a caller-allocated | |
92 | * ring. | |
93 | */ | |
17bb6d40 JW |
94 | struct virtqueue *vring_new_virtqueue(unsigned int index, |
95 | unsigned int num, | |
87c7d57c | 96 | unsigned int vring_align, |
0a8a69dd | 97 | struct virtio_device *vdev, |
7b21e34f | 98 | bool weak_barriers, |
f94682dd | 99 | bool ctx, |
0a8a69dd | 100 | void *pages, |
46f9c2b9 | 101 | bool (*notify)(struct virtqueue *vq), |
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102 | void (*callback)(struct virtqueue *vq), |
103 | const char *name); | |
2a2d1382 AL |
104 | |
105 | /* | |
106 | * Destroys a virtqueue. If created with vring_create_virtqueue, this | |
107 | * also frees the ring. | |
108 | */ | |
0a8a69dd | 109 | void vring_del_virtqueue(struct virtqueue *vq); |
2a2d1382 | 110 | |
e34f8725 RR |
111 | /* Filter out transport-specific feature bits. */ |
112 | void vring_transport_features(struct virtio_device *vdev); | |
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113 | |
114 | irqreturn_t vring_interrupt(int irq, void *_vq); | |
0a8a69dd | 115 | #endif /* _LINUX_VIRTIO_RING_H */ |