1 | /* SPDX-License-Identifier: GPL-2.0 */ |
2 | #ifndef _LINUX_VIRTIO_RING_H |
3 | #define _LINUX_VIRTIO_RING_H |
4 | |
5 | #include <asm/barrier.h> |
6 | #include <linux/irqreturn.h> |
7 | #include <uapi/linux/virtio_ring.h> |
8 | |
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 |
16 | * accesses through relaxed memory I/O windows, so virt_mb() et al are |
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 | |
25 | static inline void virtio_mb(bool weak_barriers) |
26 | { |
27 | if (weak_barriers) |
28 | virt_mb(); |
29 | else |
30 | mb(); |
31 | } |
32 | |
33 | static inline void virtio_rmb(bool weak_barriers) |
34 | { |
35 | if (weak_barriers) |
36 | virt_rmb(); |
37 | else |
38 | dma_rmb(); |
39 | } |
40 | |
41 | static inline void virtio_wmb(bool weak_barriers) |
42 | { |
43 | if (weak_barriers) |
44 | virt_wmb(); |
45 | else |
46 | dma_wmb(); |
47 | } |
48 | |
49 | #define virtio_store_mb(weak_barriers, p, v) \ |
50 | do { \ |
51 | if (weak_barriers) { \ |
52 | virt_store_mb(*p, v); \ |
53 | } else { \ |
54 | WRITE_ONCE(*p, v); \ |
55 | mb(); \ |
56 | } \ |
57 | } while (0) \ |
58 | |
59 | struct virtio_device; |
60 | struct virtqueue; |
61 | struct device; |
62 | |
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_vring_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, |
75 | bool ctx, |
76 | bool (*notify)(struct virtqueue *vq), |
77 | void (*callback)(struct virtqueue *vq), |
78 | const char *name); |
79 | |
80 | /* |
81 | * Creates a virtqueue and allocates the descriptor ring with per |
82 | * virtqueue DMA device. |
83 | */ |
84 | struct virtqueue *vring_create_virtqueue_dma(unsigned int index, |
85 | unsigned int num, |
86 | unsigned int vring_align, |
87 | struct virtio_device *vdev, |
88 | bool weak_barriers, |
89 | bool may_reduce_num, |
90 | bool ctx, |
91 | bool (*notify)(struct virtqueue *vq), |
92 | void (*callback)(struct virtqueue *vq), |
93 | const char *name, |
94 | struct device *dma_dev); |
95 | |
96 | /* |
97 | * Creates a virtqueue with a standard layout but a caller-allocated |
98 | * ring. |
99 | */ |
100 | struct virtqueue *vring_new_virtqueue(unsigned int index, |
101 | unsigned int num, |
102 | unsigned int vring_align, |
103 | struct virtio_device *vdev, |
104 | bool weak_barriers, |
105 | bool ctx, |
106 | void *pages, |
107 | bool (*notify)(struct virtqueue *vq), |
108 | void (*callback)(struct virtqueue *vq), |
109 | const char *name); |
110 | |
111 | /* |
112 | * Destroys a virtqueue. If created with vring_create_virtqueue, this |
113 | * also frees the ring. |
114 | */ |
115 | void vring_del_virtqueue(struct virtqueue *vq); |
116 | |
117 | /* Filter out transport-specific feature bits. */ |
118 | void vring_transport_features(struct virtio_device *vdev); |
119 | |
120 | irqreturn_t vring_interrupt(int irq, void *_vq); |
121 | |
122 | u32 vring_notification_data(struct virtqueue *_vq); |
123 | #endif /* _LINUX_VIRTIO_RING_H */ |
124 | |